Images/Non-images post work, several bug fixes, UI fixes

http/admin/cleanup.go

@@ -0,0 +1,21 @@
+package admin
+
+import (
+	"github.com/tidwall/buntdb"
+	"go.rls.moe/nyx/http/errw"
+	"go.rls.moe/nyx/http/middle"
+	"net/http"
+)
+
+func handleCleanup(w http.ResponseWriter, r *http.Request) {
+	db := middle.GetDB(r)
+	err := db.Update(func(tx *buntdb.Tx) error {
+		/* Insert cleanup codes here */
+		return nil
+	})
+	err = db.Shrink()
+	if err != nil {
+		errw.ErrorWriter(err, w, r)
+		return
+	}
+}

http/admin/handler.go

@@ -106,6 +106,8 @@ func handleDelPost(w http.ResponseWriter, r *http.Request) {
 		}
 		reply.Text = "[deleted]"
 		reply.Metadata["deleted"] = "yes"
+		reply.Image = nil
+		reply.Thumbnail = nil
 		err = resources.UpdateReply(tx, r.Host, board, reply)
 		if err != nil {
 			return err

http/board/handler.go

@@ -11,6 +11,7 @@ import (
 	"go.rls.moe/nyx/resources"
 	"html/template"
 	"net/http"
+	"strconv"
 	"time"
 )
 
@@ -48,6 +49,10 @@ var (
 		},
 		"rateSpam":    resources.SpamScore,
 		"makeCaptcha": resources.MakeCaptcha,
+		"dateFromID":  resources.DateFromId,
+		"formatDate": func(date time.Time) string {
+			return date.Format("02 Jan 06 15:04:05")
+		},
 	}
 )
 
@@ -78,15 +83,74 @@ func Router(r chi.Router) {
 	r.Get("/:board/board.html", serveBoard)
 	r.Post("/:board/new_thread.sh", handleNewThread)
 	r.Get("/:board/:thread/thread.html", serveThread)
-	r.Get("/:board/:thread/:post/post.html", servePost)
+	r.Get("/:board/:thread/:reply/:unused.png", serveFullImage)
+	r.Get("/:board/:thread/:reply/thumb.png", serveThumb)
 	r.Post("/:board/:thread/reply.sh", handleNewReply)
 	r.Handle("/captcha/:captchaId.png", resources.ServeCaptcha)
 	r.Handle("/captcha/:captchaId.wav", resources.ServeCaptcha)
 	r.Handle("/captcha/download/:captchaId.wav", resources.ServeCaptcha)
 }
 
-func servePost(w http.ResponseWriter, r *http.Request) {
+func serveThumb(w http.ResponseWriter, r *http.Request) {
+	dat := bytes.NewBuffer([]byte{})
+	db := middle.GetDB(r)
+	err := db.View(func(tx *buntdb.Tx) error {
+		bName := chi.URLParam(r, "board")
+		tid, err := strconv.Atoi(chi.URLParam(r, "thread"))
+		if err != nil {
+			return err
+		}
+		rid, err := strconv.Atoi(chi.URLParam(r, "reply"))
+		if err != nil {
+			return err
+		}
+
+		reply, err := resources.GetReply(tx, r.Host, bName, tid, rid)
+		if err != nil {
+			return err
+		}
+		_, err = dat.Write(reply.Thumbnail)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		errw.ErrorWriter(err, w, r)
 		return
+	}
+	http.ServeContent(w, r, "thumb.png", time.Now(), bytes.NewReader(dat.Bytes()))
+}
+
+func serveFullImage(w http.ResponseWriter, r *http.Request) {
+	dat := bytes.NewBuffer([]byte{})
+	db := middle.GetDB(r)
+	err := db.View(func(tx *buntdb.Tx) error {
+		bName := chi.URLParam(r, "board")
+		tid, err := strconv.Atoi(chi.URLParam(r, "thread"))
+		if err != nil {
+			return err
+		}
+		rid, err := strconv.Atoi(chi.URLParam(r, "reply"))
+		if err != nil {
+			return err
+		}
+
+		reply, err := resources.GetReply(tx, r.Host, bName, tid, rid)
+		if err != nil {
+			return err
+		}
+		_, err = dat.Write(reply.Image)
+		if err != nil {
+			return err
+		}
+		return nil
+	})
+	if err != nil {
+		errw.ErrorWriter(err, w, r)
+		return
+	}
+	http.ServeContent(w, r, "image.png", time.Now(), bytes.NewReader(dat.Bytes()))
 }
 
 func serveDir(w http.ResponseWriter, r *http.Request) {

http/board/newreply.go

@@ -1,12 +1,18 @@
 package board
 
 import (
+	"bytes"
 	"fmt"
+	"github.com/nfnt/resize"
 	"github.com/pressly/chi"
 	"github.com/tidwall/buntdb"
 	"go.rls.moe/nyx/http/errw"
 	"go.rls.moe/nyx/http/middle"
 	"go.rls.moe/nyx/resources"
+	"image"
+	_ "image/gif"
+	_ "image/jpeg"
+	"image/png"
 	"net/http"
 	"strconv"
 )
@@ -17,6 +23,11 @@ func handleNewReply(w http.ResponseWriter, r *http.Request) {
 		errw.ErrorWriter(err, w, r)
 		return
 	}
+	err = r.ParseMultipartForm(10 * 1024 * 1024)
+	if err != nil {
+		errw.ErrorWriter(err, w, r)
+		return
+	}
 
 	if !resources.VerifyCaptcha(r) {
 		http.Redirect(w, r,
@@ -40,7 +51,7 @@ func handleNewReply(w http.ResponseWriter, r *http.Request) {
 		errw.ErrorWriter(errw.MakeErrorWithTitle("I'm sorry but I can't do that", "These are too many characters"), w, r)
 		return
 	}
-	if len(reply.Text) < 10 {
+	if len(reply.Text) < 5 {
 		errw.ErrorWriter(errw.MakeErrorWithTitle("I'm sorry but I can't do that", "These are not enough characters"), w, r)
 		return
 	}
@@ -53,6 +64,36 @@ func handleNewReply(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	{
+		file, _, err := r.FormFile("image")
+		if err != nil && err != http.ErrMissingFile {
+			errw.ErrorWriter(err, w, r)
+			return
+		} else if err != http.ErrMissingFile {
+			img, _, err := image.Decode(file)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			thumb := resize.Thumbnail(128, 128, img, resize.Lanczos3)
+			imgBuf := bytes.NewBuffer([]byte{})
+			err = png.Encode(imgBuf, img)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			fmt.Println("Image has size ", len(imgBuf.Bytes()))
+			reply.Image = imgBuf.Bytes()
+			imgBuf = bytes.NewBuffer([]byte{})
+			err = png.Encode(imgBuf, thumb)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			reply.Thumbnail = imgBuf.Bytes()
+		}
+	}
+
 	reply.Metadata = map[string]string{}
 	if r.FormValue("tripcode") != "" {
 		reply.Metadata["trip"] = resources.CalcTripCode(r.FormValue("tripcode"))

http/board/newthread.go

@@ -1,12 +1,16 @@
 package board
 
 import (
+	"bytes"
 	"fmt"
+	"github.com/nfnt/resize"
 	"github.com/pressly/chi"
 	"github.com/tidwall/buntdb"
 	"go.rls.moe/nyx/http/errw"
 	"go.rls.moe/nyx/http/middle"
 	"go.rls.moe/nyx/resources"
+	"image"
+	"image/png"
 	"net/http"
 )
 
@@ -16,6 +20,11 @@ func handleNewThread(w http.ResponseWriter, r *http.Request) {
 		errw.ErrorWriter(err, w, r)
 		return
 	}
+	err = r.ParseMultipartForm(10 * 1024 * 1024)
+	if err != nil {
+		errw.ErrorWriter(err, w, r)
+		return
+	}
 
 	if !resources.VerifyCaptcha(r) {
 		http.Redirect(w, r,
@@ -35,7 +44,7 @@ func handleNewThread(w http.ResponseWriter, r *http.Request) {
 		errw.ErrorWriter(errw.MakeErrorWithTitle("I'm sorry but I can't do that", "These are too many characters"), w, r)
 		return
 	}
-	if len(mainReply.Text) < 10 {
+	if len(mainReply.Text) < 5 {
 		errw.ErrorWriter(errw.MakeErrorWithTitle("I'm sorry but I can't do that", "These are not enough characters"), w, r)
 		return
 	}
@@ -48,6 +57,36 @@ func handleNewThread(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	{
+		file, _, err := r.FormFile("image")
+		if err != nil && err != http.ErrMissingFile {
+			errw.ErrorWriter(err, w, r)
+			return
+		} else if err != http.ErrMissingFile {
+			img, _, err := image.Decode(file)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			thumb := resize.Thumbnail(128, 128, img, resize.Lanczos3)
+			imgBuf := bytes.NewBuffer([]byte{})
+			err = png.Encode(imgBuf, img)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			fmt.Println("Image has size ", len(imgBuf.Bytes()))
+			mainReply.Image = imgBuf.Bytes()
+			imgBuf = bytes.NewBuffer([]byte{})
+			err = png.Encode(imgBuf, thumb)
+			if err != nil {
+				errw.ErrorWriter(err, w, r)
+				return
+			}
+			mainReply.Thumbnail = imgBuf.Bytes()
+		}
+	}
+
 	mainReply.Metadata = map[string]string{}
 	if r.FormValue("tripcode") != "" {
 		mainReply.Metadata["trip"] = resources.CalcTripCode(r.FormValue("tripcode"))

http/board/res/thread.tmpl.html

@@ -2,10 +2,14 @@
 <div class="postarea">
     {{ if .Thread }}
     <form id="postform"
-          action="/{{.Board.ShortName}}/{{.Thread.ID}}/reply.sh" method="POST">
+          action="/{{.Board.ShortName}}/{{.Thread.ID}}/reply.sh"
+          method="POST"
+          enctype="multipart/form-data">
     {{ else }}
     <form id="postform"
-          action="/{{.Board.ShortName}}/new_thread.sh" method="POST">
+          action="/{{.Board.ShortName}}/new_thread.sh"
+          method="POST"
+          enctype="multipart/form-data">
     {{ end }}
         <table>
             <tbody>
@@ -41,7 +45,7 @@
                                 placeholder="your comment"
                                 rows="4"
                                 cols="48"
-                                minlength="10"
+                                minlength="5"
                                 required
                         ></textarea>
                 </td>
@@ -97,9 +101,7 @@
             Anonymous
         {{ end }}
     </span></label>
-    <span class="reflink">
+    <span class="date">{{dateFromID .Reply.ID | formatDate}}</span>
-        <a href="/{{.Boardlink}}/{{.ThreadID}}/thread.html">No.{{.Reply.ID}}</a>
-    </span>
     {{ if .Session }}
     {{ if eq (.Session.CAttr "mode") "admin" }}
     <form class="delform" action="/mod/del_reply.sh" method="POST">
@@ -126,6 +128,18 @@
     <span>
         {{printf "[SpamScore: %f]" (rateSpam .Reply.Text) }}
     </span>
+    <span class="reflink">
+        <a href="/{{.Boardlink}}/{{.ThreadID}}/thread.html">No.{{.Reply.ID}}</a>
+    </span>
+    {{ if .Reply.Thumbnail }}
+    <br />
+    <a target="_blank" href="/{{.Boardlink}}/{{.ThreadID}}/{{.Reply.ID}}/{{.Reply.ID}}.png">
+    <img
+            src="/{{.Boardlink}}/{{.ThreadID}}/{{.Reply.ID}}/thumb.png"
+            class="thumb"
+    />
+    </a>
+    {{ end }}
     {{ if .Reply.Metadata.deleted }}
     <blockquote><blockquote class="deleted">
         {{ renderText .Reply.Text }}
@@ -152,7 +166,7 @@
         {{ end }}
     {{range .GetReplies}}
     {{ if ne .ID $threadrid }}
-    <table><tbody><tr><td class="doubledash">&gt;&gt;</td>
+    <table class="reply-table"><tbody><tr><td class="doubledash">&gt;&gt;</td>
         <td class="reply" id="reply{{.ID}}">
             {{ with dict "Reply" . "Boardlink" $boardlink "CSRF" $csrf "ThreadID" $threadid "Session" $session }}
             {{ template "thread/reply" . }}

http/res/custom.css

@@ -16,9 +16,17 @@ div {
     padding: 0;
 }
 
-blockquote blockquote { max-width: 80%; word-wrap: break-word; white-space: normal; }
+blockquote blockquote {
+    word-wrap: break-word;
+    word-break: break-all;
+    white-space: normal;
+    padding: 2px;
+    margin-bottom: 1em;
+    margin-top: 1em;
+    margin-left: 40px;
+    margin-right: 40px;
+}
 
-.reply blockquote, blockquote :last-child { max-width: 80%; word-wrap: break-word; white-space: normal; }
 
 .delform {
     display: inline;
@@ -32,3 +40,11 @@ blockquote blockquote { max-width: 80%; word-wrap: break-word; white-space: norm
 .deleted {
     color: #707070;
 }
+
+.reply-table {
+    display: block;
+}
+
+.reply {
+    display: table;
+}

http/res/style.css

@@ -143,14 +143,13 @@ a:hover {
 
 /* futaba_style.pl */
 
-blockquote blockquote { margin-left: 0em;  }
 form { margin-bottom: 0px }
 form .trap { display:none }
 .postarea { text-align: center }
 .postarea table { margin: 0px auto; text-align: left }
 .thumb { border: none; float: left; margin: 2px 20px }
 .nothumb { float: left; background: #eee; border: 2px dashed #aaa; text-align: center; margin: 2px 20px; padding: 1em 0.5em 1em 0.5em; }
-.reply blockquote, blockquote :last-child { margin-bottom: 0em; }
+
 .reflink a { color: inherit; text-decoration: none }
 .reply .filesize { margin-left: 20px }
 .userdelete { float: right; text-align: center; white-space: nowrap }

resources/ids.go

@@ -16,3 +16,7 @@ func getID() (int, error) {
 	id, err := fountain.NewID()
 	return int(id), err
 }
+
+func DateFromId(id int) time.Time {
+	return time.Unix(int64(fountain.IDToUnix(id)), 0).UTC()
+}

resources/reply.go

@@ -13,6 +13,7 @@ type Reply struct {
 	ID        int      `json:"id"`
 	Text      string   `json:"text"`
 	Image     []byte   `json:"image"`
+	Thumbnail []byte   `json:"thumb"`
 	Thread    int      `json:"thread"`
 	Board     string   `json:"board"`
 	Metadata  Metadata `json:"meta"`

resources/snowflakes/generator.go

@@ -27,6 +27,10 @@ type Generator struct {
 	now       int64
 }
 
+func (g *Generator) IDToUnix(id int) int {
+	return (id >> counterLen) + int(g.StartTime)
+}
+
 // NewID generates a new, unique snowflake value
 //
 // Up to 8192 snowflakes per second can be requested

resources/text.go

@@ -16,6 +16,13 @@ func OperateReplyText(unsafe string) template.HTML {
 	return template.HTML(unsafe)
 }
 
+const (
+	passScoreAggressive = 7.1
+	passScoreReactive   = 0.65
+	passScoreLimitMin   = 0.01
+	passScoreLimitMax   = 0.99
+)
+
 var (
 	blacklist = []string{
 		"spam",
@@ -25,6 +32,8 @@ var (
 		"subscription",
 		"penis",
 		"nazi",
+		"beemovie",
+		"bee movie",
 	}
 )
 
@@ -62,7 +71,13 @@ func (b *byteCounter) Write(p []byte) (n int, err error) {
 }
 
 func CaptchaPass(spamScore float64) bool {
-	chance := math.Max(0, math.Min(0.65*math.Atan(7.1*spamScore), 0.99))
+	chance := math.Max(
+		passScoreLimitMin,
+		math.Min(
+			passScoreReactive*math.Atan(
+				passScoreAggressive*spamScore,
+			),
+			passScoreLimitMax))
 	take := rand.Float64()
 	fmt.Printf("Chance: %f, Take %f", chance, take)
 	return take > chance

vendor/github.com/nfnt/resize/LICENSE

@@ -0,0 +1,13 @@
+Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.

vendor/github.com/nfnt/resize/README.md

@@ -0,0 +1,149 @@
+Resize
+======
+
+Image resizing for the [Go programming language](http://golang.org) with common interpolation methods.
+
+[![Build Status](https://travis-ci.org/nfnt/resize.svg)](https://travis-ci.org/nfnt/resize)
+
+Installation
+------------
+
+```bash
+$ go get github.com/nfnt/resize
+```
+
+It's that easy!
+
+Usage
+-----
+
+This package needs at least Go 1.1. Import package with
+
+```go
+import "github.com/nfnt/resize"
+```
+
+The resize package provides 2 functions:
+
+* `resize.Resize` creates a scaled image with new dimensions (`width`, `height`) using the interpolation function `interp`.
+  If either `width` or `height` is set to 0, it will be set to an aspect ratio preserving value.
+* `resize.Thumbnail` downscales an image preserving its aspect ratio to the maximum dimensions (`maxWidth`, `maxHeight`).
+  It will return the original image if original sizes are smaller than the provided dimensions.
+
+```go
+resize.Resize(width, height uint, img image.Image, interp resize.InterpolationFunction) image.Image
+resize.Thumbnail(maxWidth, maxHeight uint, img image.Image, interp resize.InterpolationFunction) image.Image
+```
+
+The provided interpolation functions are (from fast to slow execution time)
+
+- `NearestNeighbor`: [Nearest-neighbor interpolation](http://en.wikipedia.org/wiki/Nearest-neighbor_interpolation)
+- `Bilinear`: [Bilinear interpolation](http://en.wikipedia.org/wiki/Bilinear_interpolation)
+- `Bicubic`: [Bicubic interpolation](http://en.wikipedia.org/wiki/Bicubic_interpolation)
+- `MitchellNetravali`: [Mitchell-Netravali interpolation](http://dl.acm.org/citation.cfm?id=378514)
+- `Lanczos2`: [Lanczos resampling](http://en.wikipedia.org/wiki/Lanczos_resampling) with a=2
+- `Lanczos3`: [Lanczos resampling](http://en.wikipedia.org/wiki/Lanczos_resampling) with a=3
+
+Which of these methods gives the best results depends on your use case.
+
+Sample usage:
+
+```go
+package main
+
+import (
+	"github.com/nfnt/resize"
+	"image/jpeg"
+	"log"
+	"os"
+)
+
+func main() {
+	// open "test.jpg"
+	file, err := os.Open("test.jpg")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	// decode jpeg into image.Image
+	img, err := jpeg.Decode(file)
+	if err != nil {
+		log.Fatal(err)
+	}
+	file.Close()
+
+	// resize to width 1000 using Lanczos resampling
+	// and preserve aspect ratio
+	m := resize.Resize(1000, 0, img, resize.Lanczos3)
+
+	out, err := os.Create("test_resized.jpg")
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer out.Close()
+
+	// write new image to file
+	jpeg.Encode(out, m, nil)
+}
+```
+
+Caveats
+-------
+
+* Optimized access routines are used for `image.RGBA`, `image.NRGBA`, `image.RGBA64`, `image.NRGBA64`, `image.YCbCr`, `image.Gray`, and `image.Gray16` types. All other image types are accessed in a generic way that will result in slow processing speed.
+* JPEG images are stored in `image.YCbCr`. This image format stores data in a way that will decrease processing speed. A resize may be up to 2 times slower than with `image.RGBA`. 
+
+
+Downsizing Samples
+-------
+
+Downsizing is not as simple as it might look like. Images have to be filtered before they are scaled down, otherwise aliasing might occur.
+Filtering is highly subjective: Applying too much will blur the whole image, too little will make aliasing become apparent.
+Resize tries to provide sane defaults that should suffice in most cases.
+
+### Artificial sample
+
+Original image
+![Rings](http://nfnt.github.com/img/rings_lg_orig.png)
+
+<table>
+<tr>
+<th><img src="http://nfnt.github.com/img/rings_300_NearestNeighbor.png" /><br>Nearest-Neighbor</th>
+<th><img src="http://nfnt.github.com/img/rings_300_Bilinear.png" /><br>Bilinear</th>
+</tr>
+<tr>
+<th><img src="http://nfnt.github.com/img/rings_300_Bicubic.png" /><br>Bicubic</th>
+<th><img src="http://nfnt.github.com/img/rings_300_MitchellNetravali.png" /><br>Mitchell-Netravali</th>
+</tr>
+<tr>
+<th><img src="http://nfnt.github.com/img/rings_300_Lanczos2.png" /><br>Lanczos2</th>
+<th><img src="http://nfnt.github.com/img/rings_300_Lanczos3.png" /><br>Lanczos3</th>
+</tr>
+</table>
+
+### Real-Life sample
+
+Original image  
+![Original](http://nfnt.github.com/img/IMG_3694_720.jpg)
+
+<table>
+<tr>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_NearestNeighbor.png" /><br>Nearest-Neighbor</th>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_Bilinear.png" /><br>Bilinear</th>
+</tr>
+<tr>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_Bicubic.png" /><br>Bicubic</th>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_MitchellNetravali.png" /><br>Mitchell-Netravali</th>
+</tr>
+<tr>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_Lanczos2.png" /><br>Lanczos2</th>
+<th><img src="http://nfnt.github.com/img/IMG_3694_300_Lanczos3.png" /><br>Lanczos3</th>
+</tr>
+</table>
+
+
+License
+-------
+
+Copyright (c) 2012 Jan Schlicht <janschlicht@gmail.com>
+Resize is released under a MIT style license.

vendor/github.com/nfnt/resize/converter.go

@@ -0,0 +1,438 @@
+/*
+Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+package resize
+
+import "image"
+
+// Keep value in [0,255] range.
+func clampUint8(in int32) uint8 {
+	// casting a negative int to an uint will result in an overflown
+	// large uint. this behavior will be exploited here and in other functions
+	// to achieve a higher performance.
+	if uint32(in) < 256 {
+		return uint8(in)
+	}
+	if in > 255 {
+		return 255
+	}
+	return 0
+}
+
+// Keep value in [0,65535] range.
+func clampUint16(in int64) uint16 {
+	if uint64(in) < 65536 {
+		return uint16(in)
+	}
+	if in > 65535 {
+		return 65535
+	}
+	return 0
+}
+
+func resizeGeneric(in image.Image, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]int64
+			var sum int64
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case xi < 0:
+						xi = 0
+					case xi >= maxX:
+						xi = maxX
+					}
+
+					r, g, b, a := in.At(xi+in.Bounds().Min.X, x+in.Bounds().Min.Y).RGBA()
+
+					rgba[0] += int64(coeff) * int64(r)
+					rgba[1] += int64(coeff) * int64(g)
+					rgba[2] += int64(coeff) * int64(b)
+					rgba[3] += int64(coeff) * int64(a)
+					sum += int64(coeff)
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+
+			value := clampUint16(rgba[0] / sum)
+			out.Pix[offset+0] = uint8(value >> 8)
+			out.Pix[offset+1] = uint8(value)
+			value = clampUint16(rgba[1] / sum)
+			out.Pix[offset+2] = uint8(value >> 8)
+			out.Pix[offset+3] = uint8(value)
+			value = clampUint16(rgba[2] / sum)
+			out.Pix[offset+4] = uint8(value >> 8)
+			out.Pix[offset+5] = uint8(value)
+			value = clampUint16(rgba[3] / sum)
+			out.Pix[offset+6] = uint8(value >> 8)
+			out.Pix[offset+7] = uint8(value)
+		}
+	}
+}
+
+func resizeRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []int16, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]int32
+			var sum int32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 4
+					case xi >= maxX:
+						xi = 4 * maxX
+					default:
+						xi = 0
+					}
+
+					rgba[0] += int32(coeff) * int32(row[xi+0])
+					rgba[1] += int32(coeff) * int32(row[xi+1])
+					rgba[2] += int32(coeff) * int32(row[xi+2])
+					rgba[3] += int32(coeff) * int32(row[xi+3])
+					sum += int32(coeff)
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*4
+
+			out.Pix[xo+0] = clampUint8(rgba[0] / sum)
+			out.Pix[xo+1] = clampUint8(rgba[1] / sum)
+			out.Pix[xo+2] = clampUint8(rgba[2] / sum)
+			out.Pix[xo+3] = clampUint8(rgba[3] / sum)
+		}
+	}
+}
+
+func resizeNRGBA(in *image.NRGBA, out *image.RGBA, scale float64, coeffs []int16, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]int32
+			var sum int32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 4
+					case xi >= maxX:
+						xi = 4 * maxX
+					default:
+						xi = 0
+					}
+
+					// Forward alpha-premultiplication
+					a := int32(row[xi+3])
+					r := int32(row[xi+0]) * a
+					r /= 0xff
+					g := int32(row[xi+1]) * a
+					g /= 0xff
+					b := int32(row[xi+2]) * a
+					b /= 0xff
+
+					rgba[0] += int32(coeff) * r
+					rgba[1] += int32(coeff) * g
+					rgba[2] += int32(coeff) * b
+					rgba[3] += int32(coeff) * a
+					sum += int32(coeff)
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*4
+
+			out.Pix[xo+0] = clampUint8(rgba[0] / sum)
+			out.Pix[xo+1] = clampUint8(rgba[1] / sum)
+			out.Pix[xo+2] = clampUint8(rgba[2] / sum)
+			out.Pix[xo+3] = clampUint8(rgba[3] / sum)
+		}
+	}
+}
+
+func resizeRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]int64
+			var sum int64
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 8
+					case xi >= maxX:
+						xi = 8 * maxX
+					default:
+						xi = 0
+					}
+
+					rgba[0] += int64(coeff) * (int64(row[xi+0])<<8 | int64(row[xi+1]))
+					rgba[1] += int64(coeff) * (int64(row[xi+2])<<8 | int64(row[xi+3]))
+					rgba[2] += int64(coeff) * (int64(row[xi+4])<<8 | int64(row[xi+5]))
+					rgba[3] += int64(coeff) * (int64(row[xi+6])<<8 | int64(row[xi+7]))
+					sum += int64(coeff)
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+
+			value := clampUint16(rgba[0] / sum)
+			out.Pix[xo+0] = uint8(value >> 8)
+			out.Pix[xo+1] = uint8(value)
+			value = clampUint16(rgba[1] / sum)
+			out.Pix[xo+2] = uint8(value >> 8)
+			out.Pix[xo+3] = uint8(value)
+			value = clampUint16(rgba[2] / sum)
+			out.Pix[xo+4] = uint8(value >> 8)
+			out.Pix[xo+5] = uint8(value)
+			value = clampUint16(rgba[3] / sum)
+			out.Pix[xo+6] = uint8(value >> 8)
+			out.Pix[xo+7] = uint8(value)
+		}
+	}
+}
+
+func resizeNRGBA64(in *image.NRGBA64, out *image.RGBA64, scale float64, coeffs []int32, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]int64
+			var sum int64
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 8
+					case xi >= maxX:
+						xi = 8 * maxX
+					default:
+						xi = 0
+					}
+
+					// Forward alpha-premultiplication
+					a := int64(uint16(row[xi+6])<<8 | uint16(row[xi+7]))
+					r := int64(uint16(row[xi+0])<<8|uint16(row[xi+1])) * a
+					r /= 0xffff
+					g := int64(uint16(row[xi+2])<<8|uint16(row[xi+3])) * a
+					g /= 0xffff
+					b := int64(uint16(row[xi+4])<<8|uint16(row[xi+5])) * a
+					b /= 0xffff
+
+					rgba[0] += int64(coeff) * r
+					rgba[1] += int64(coeff) * g
+					rgba[2] += int64(coeff) * b
+					rgba[3] += int64(coeff) * a
+					sum += int64(coeff)
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+
+			value := clampUint16(rgba[0] / sum)
+			out.Pix[xo+0] = uint8(value >> 8)
+			out.Pix[xo+1] = uint8(value)
+			value = clampUint16(rgba[1] / sum)
+			out.Pix[xo+2] = uint8(value >> 8)
+			out.Pix[xo+3] = uint8(value)
+			value = clampUint16(rgba[2] / sum)
+			out.Pix[xo+4] = uint8(value >> 8)
+			out.Pix[xo+5] = uint8(value)
+			value = clampUint16(rgba[3] / sum)
+			out.Pix[xo+6] = uint8(value >> 8)
+			out.Pix[xo+7] = uint8(value)
+		}
+	}
+}
+
+func resizeGray(in *image.Gray, out *image.Gray, scale float64, coeffs []int16, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[(x-newBounds.Min.X)*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var gray int32
+			var sum int32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case xi < 0:
+						xi = 0
+					case xi >= maxX:
+						xi = maxX
+					}
+					gray += int32(coeff) * int32(row[xi])
+					sum += int32(coeff)
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x - newBounds.Min.X)
+			out.Pix[offset] = clampUint8(gray / sum)
+		}
+	}
+}
+
+func resizeGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []int32, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var gray int64
+			var sum int64
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 2
+					case xi >= maxX:
+						xi = 2 * maxX
+					default:
+						xi = 0
+					}
+					gray += int64(coeff) * int64(uint16(row[xi+0])<<8|uint16(row[xi+1]))
+					sum += int64(coeff)
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*2
+			value := clampUint16(gray / sum)
+			out.Pix[offset+0] = uint8(value >> 8)
+			out.Pix[offset+1] = uint8(value)
+		}
+	}
+}
+
+func resizeYCbCr(in *ycc, out *ycc, scale float64, coeffs []int16, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var p [3]int32
+			var sum int32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				coeff := coeffs[ci+i]
+				if coeff != 0 {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 3
+					case xi >= maxX:
+						xi = 3 * maxX
+					default:
+						xi = 0
+					}
+					p[0] += int32(coeff) * int32(row[xi+0])
+					p[1] += int32(coeff) * int32(row[xi+1])
+					p[2] += int32(coeff) * int32(row[xi+2])
+					sum += int32(coeff)
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*3
+			out.Pix[xo+0] = clampUint8(p[0] / sum)
+			out.Pix[xo+1] = clampUint8(p[1] / sum)
+			out.Pix[xo+2] = clampUint8(p[2] / sum)
+		}
+	}
+}
+
+func nearestYCbCr(in *ycc, out *ycc, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var p [3]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 3
+					case xi >= maxX:
+						xi = 3 * maxX
+					default:
+						xi = 0
+					}
+					p[0] += float32(row[xi+0])
+					p[1] += float32(row[xi+1])
+					p[2] += float32(row[xi+2])
+					sum++
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*3
+			out.Pix[xo+0] = floatToUint8(p[0] / sum)
+			out.Pix[xo+1] = floatToUint8(p[1] / sum)
+			out.Pix[xo+2] = floatToUint8(p[2] / sum)
+		}
+	}
+}

vendor/github.com/nfnt/resize/filters.go

@@ -0,0 +1,143 @@
+/*
+Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+package resize
+
+import (
+	"math"
+)
+
+func nearest(in float64) float64 {
+	if in >= -0.5 && in < 0.5 {
+		return 1
+	}
+	return 0
+}
+
+func linear(in float64) float64 {
+	in = math.Abs(in)
+	if in <= 1 {
+		return 1 - in
+	}
+	return 0
+}
+
+func cubic(in float64) float64 {
+	in = math.Abs(in)
+	if in <= 1 {
+		return in*in*(1.5*in-2.5) + 1.0
+	}
+	if in <= 2 {
+		return in*(in*(2.5-0.5*in)-4.0) + 2.0
+	}
+	return 0
+}
+
+func mitchellnetravali(in float64) float64 {
+	in = math.Abs(in)
+	if in <= 1 {
+		return (7.0*in*in*in - 12.0*in*in + 5.33333333333) * 0.16666666666
+	}
+	if in <= 2 {
+		return (-2.33333333333*in*in*in + 12.0*in*in - 20.0*in + 10.6666666667) * 0.16666666666
+	}
+	return 0
+}
+
+func sinc(x float64) float64 {
+	x = math.Abs(x) * math.Pi
+	if x >= 1.220703e-4 {
+		return math.Sin(x) / x
+	}
+	return 1
+}
+
+func lanczos2(in float64) float64 {
+	if in > -2 && in < 2 {
+		return sinc(in) * sinc(in*0.5)
+	}
+	return 0
+}
+
+func lanczos3(in float64) float64 {
+	if in > -3 && in < 3 {
+		return sinc(in) * sinc(in*0.3333333333333333)
+	}
+	return 0
+}
+
+// range [-256,256]
+func createWeights8(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int16, []int, int) {
+	filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1))
+	filterFactor := math.Min(1./(blur*scale), 1)
+
+	coeffs := make([]int16, dy*filterLength)
+	start := make([]int, dy)
+	for y := 0; y < dy; y++ {
+		interpX := scale*(float64(y)+0.5) - 0.5
+		start[y] = int(interpX) - filterLength/2 + 1
+		interpX -= float64(start[y])
+		for i := 0; i < filterLength; i++ {
+			in := (interpX - float64(i)) * filterFactor
+			coeffs[y*filterLength+i] = int16(kernel(in) * 256)
+		}
+	}
+
+	return coeffs, start, filterLength
+}
+
+// range [-65536,65536]
+func createWeights16(dy, filterLength int, blur, scale float64, kernel func(float64) float64) ([]int32, []int, int) {
+	filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1))
+	filterFactor := math.Min(1./(blur*scale), 1)
+
+	coeffs := make([]int32, dy*filterLength)
+	start := make([]int, dy)
+	for y := 0; y < dy; y++ {
+		interpX := scale*(float64(y)+0.5) - 0.5
+		start[y] = int(interpX) - filterLength/2 + 1
+		interpX -= float64(start[y])
+		for i := 0; i < filterLength; i++ {
+			in := (interpX - float64(i)) * filterFactor
+			coeffs[y*filterLength+i] = int32(kernel(in) * 65536)
+		}
+	}
+
+	return coeffs, start, filterLength
+}
+
+func createWeightsNearest(dy, filterLength int, blur, scale float64) ([]bool, []int, int) {
+	filterLength = filterLength * int(math.Max(math.Ceil(blur*scale), 1))
+	filterFactor := math.Min(1./(blur*scale), 1)
+
+	coeffs := make([]bool, dy*filterLength)
+	start := make([]int, dy)
+	for y := 0; y < dy; y++ {
+		interpX := scale*(float64(y)+0.5) - 0.5
+		start[y] = int(interpX) - filterLength/2 + 1
+		interpX -= float64(start[y])
+		for i := 0; i < filterLength; i++ {
+			in := (interpX - float64(i)) * filterFactor
+			if in >= -0.5 && in < 0.5 {
+				coeffs[y*filterLength+i] = true
+			} else {
+				coeffs[y*filterLength+i] = false
+			}
+		}
+	}
+
+	return coeffs, start, filterLength
+}

vendor/github.com/nfnt/resize/nearest.go

@@ -0,0 +1,318 @@
+/*
+Copyright (c) 2014, Charlie Vieth <charlie.vieth@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+package resize
+
+import "image"
+
+func floatToUint8(x float32) uint8 {
+	// Nearest-neighbor values are always
+	// positive no need to check lower-bound.
+	if x > 0xfe {
+		return 0xff
+	}
+	return uint8(x)
+}
+
+func floatToUint16(x float32) uint16 {
+	if x > 0xfffe {
+		return 0xffff
+	}
+	return uint16(x)
+}
+
+func nearestGeneric(in image.Image, out *image.RGBA64, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case xi < 0:
+						xi = 0
+					case xi >= maxX:
+						xi = maxX
+					}
+					r, g, b, a := in.At(xi+in.Bounds().Min.X, x+in.Bounds().Min.Y).RGBA()
+					rgba[0] += float32(r)
+					rgba[1] += float32(g)
+					rgba[2] += float32(b)
+					rgba[3] += float32(a)
+					sum++
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+			value := floatToUint16(rgba[0] / sum)
+			out.Pix[offset+0] = uint8(value >> 8)
+			out.Pix[offset+1] = uint8(value)
+			value = floatToUint16(rgba[1] / sum)
+			out.Pix[offset+2] = uint8(value >> 8)
+			out.Pix[offset+3] = uint8(value)
+			value = floatToUint16(rgba[2] / sum)
+			out.Pix[offset+4] = uint8(value >> 8)
+			out.Pix[offset+5] = uint8(value)
+			value = floatToUint16(rgba[3] / sum)
+			out.Pix[offset+6] = uint8(value >> 8)
+			out.Pix[offset+7] = uint8(value)
+		}
+	}
+}
+
+func nearestRGBA(in *image.RGBA, out *image.RGBA, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 4
+					case xi >= maxX:
+						xi = 4 * maxX
+					default:
+						xi = 0
+					}
+					rgba[0] += float32(row[xi+0])
+					rgba[1] += float32(row[xi+1])
+					rgba[2] += float32(row[xi+2])
+					rgba[3] += float32(row[xi+3])
+					sum++
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*4
+			out.Pix[xo+0] = floatToUint8(rgba[0] / sum)
+			out.Pix[xo+1] = floatToUint8(rgba[1] / sum)
+			out.Pix[xo+2] = floatToUint8(rgba[2] / sum)
+			out.Pix[xo+3] = floatToUint8(rgba[3] / sum)
+		}
+	}
+}
+
+func nearestNRGBA(in *image.NRGBA, out *image.NRGBA, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 4
+					case xi >= maxX:
+						xi = 4 * maxX
+					default:
+						xi = 0
+					}
+					rgba[0] += float32(row[xi+0])
+					rgba[1] += float32(row[xi+1])
+					rgba[2] += float32(row[xi+2])
+					rgba[3] += float32(row[xi+3])
+					sum++
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*4
+			out.Pix[xo+0] = floatToUint8(rgba[0] / sum)
+			out.Pix[xo+1] = floatToUint8(rgba[1] / sum)
+			out.Pix[xo+2] = floatToUint8(rgba[2] / sum)
+			out.Pix[xo+3] = floatToUint8(rgba[3] / sum)
+		}
+	}
+}
+
+func nearestRGBA64(in *image.RGBA64, out *image.RGBA64, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 8
+					case xi >= maxX:
+						xi = 8 * maxX
+					default:
+						xi = 0
+					}
+					rgba[0] += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
+					rgba[1] += float32(uint16(row[xi+2])<<8 | uint16(row[xi+3]))
+					rgba[2] += float32(uint16(row[xi+4])<<8 | uint16(row[xi+5]))
+					rgba[3] += float32(uint16(row[xi+6])<<8 | uint16(row[xi+7]))
+					sum++
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+			value := floatToUint16(rgba[0] / sum)
+			out.Pix[xo+0] = uint8(value >> 8)
+			out.Pix[xo+1] = uint8(value)
+			value = floatToUint16(rgba[1] / sum)
+			out.Pix[xo+2] = uint8(value >> 8)
+			out.Pix[xo+3] = uint8(value)
+			value = floatToUint16(rgba[2] / sum)
+			out.Pix[xo+4] = uint8(value >> 8)
+			out.Pix[xo+5] = uint8(value)
+			value = floatToUint16(rgba[3] / sum)
+			out.Pix[xo+6] = uint8(value >> 8)
+			out.Pix[xo+7] = uint8(value)
+		}
+	}
+}
+
+func nearestNRGBA64(in *image.NRGBA64, out *image.NRGBA64, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var rgba [4]float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 8
+					case xi >= maxX:
+						xi = 8 * maxX
+					default:
+						xi = 0
+					}
+					rgba[0] += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
+					rgba[1] += float32(uint16(row[xi+2])<<8 | uint16(row[xi+3]))
+					rgba[2] += float32(uint16(row[xi+4])<<8 | uint16(row[xi+5]))
+					rgba[3] += float32(uint16(row[xi+6])<<8 | uint16(row[xi+7]))
+					sum++
+				}
+			}
+
+			xo := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*8
+			value := floatToUint16(rgba[0] / sum)
+			out.Pix[xo+0] = uint8(value >> 8)
+			out.Pix[xo+1] = uint8(value)
+			value = floatToUint16(rgba[1] / sum)
+			out.Pix[xo+2] = uint8(value >> 8)
+			out.Pix[xo+3] = uint8(value)
+			value = floatToUint16(rgba[2] / sum)
+			out.Pix[xo+4] = uint8(value >> 8)
+			out.Pix[xo+5] = uint8(value)
+			value = floatToUint16(rgba[3] / sum)
+			out.Pix[xo+6] = uint8(value >> 8)
+			out.Pix[xo+7] = uint8(value)
+		}
+	}
+}
+
+func nearestGray(in *image.Gray, out *image.Gray, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var gray float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case xi < 0:
+						xi = 0
+					case xi >= maxX:
+						xi = maxX
+					}
+					gray += float32(row[xi])
+					sum++
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x - newBounds.Min.X)
+			out.Pix[offset] = floatToUint8(gray / sum)
+		}
+	}
+}
+
+func nearestGray16(in *image.Gray16, out *image.Gray16, scale float64, coeffs []bool, offset []int, filterLength int) {
+	newBounds := out.Bounds()
+	maxX := in.Bounds().Dx() - 1
+
+	for x := newBounds.Min.X; x < newBounds.Max.X; x++ {
+		row := in.Pix[x*in.Stride:]
+		for y := newBounds.Min.Y; y < newBounds.Max.Y; y++ {
+			var gray float32
+			var sum float32
+			start := offset[y]
+			ci := y * filterLength
+			for i := 0; i < filterLength; i++ {
+				if coeffs[ci+i] {
+					xi := start + i
+					switch {
+					case uint(xi) < uint(maxX):
+						xi *= 2
+					case xi >= maxX:
+						xi = 2 * maxX
+					default:
+						xi = 0
+					}
+					gray += float32(uint16(row[xi+0])<<8 | uint16(row[xi+1]))
+					sum++
+				}
+			}
+
+			offset := (y-newBounds.Min.Y)*out.Stride + (x-newBounds.Min.X)*2
+			value := floatToUint16(gray / sum)
+			out.Pix[offset+0] = uint8(value >> 8)
+			out.Pix[offset+1] = uint8(value)
+		}
+	}
+}

vendor/github.com/nfnt/resize/resize.go

@@ -0,0 +1,614 @@
+/*
+Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+// Package resize implements various image resizing methods.
+//
+// The package works with the Image interface described in the image package.
+// Various interpolation methods are provided and multiple processors may be
+// utilized in the computations.
+//
+// Example:
+//     imgResized := resize.Resize(1000, 0, imgOld, resize.MitchellNetravali)
+package resize
+
+import (
+	"image"
+	"runtime"
+	"sync"
+)
+
+// An InterpolationFunction provides the parameters that describe an
+// interpolation kernel. It returns the number of samples to take
+// and the kernel function to use for sampling.
+type InterpolationFunction int
+
+// InterpolationFunction constants
+const (
+	// Nearest-neighbor interpolation
+	NearestNeighbor InterpolationFunction = iota
+	// Bilinear interpolation
+	Bilinear
+	// Bicubic interpolation (with cubic hermite spline)
+	Bicubic
+	// Mitchell-Netravali interpolation
+	MitchellNetravali
+	// Lanczos interpolation (a=2)
+	Lanczos2
+	// Lanczos interpolation (a=3)
+	Lanczos3
+)
+
+// kernal, returns an InterpolationFunctions taps and kernel.
+func (i InterpolationFunction) kernel() (int, func(float64) float64) {
+	switch i {
+	case Bilinear:
+		return 2, linear
+	case Bicubic:
+		return 4, cubic
+	case MitchellNetravali:
+		return 4, mitchellnetravali
+	case Lanczos2:
+		return 4, lanczos2
+	case Lanczos3:
+		return 6, lanczos3
+	default:
+		// Default to NearestNeighbor.
+		return 2, nearest
+	}
+}
+
+// values <1 will sharpen the image
+var blur = 1.0
+
+// Resize scales an image to new width and height using the interpolation function interp.
+// A new image with the given dimensions will be returned.
+// If one of the parameters width or height is set to 0, its size will be calculated so that
+// the aspect ratio is that of the originating image.
+// The resizing algorithm uses channels for parallel computation.
+func Resize(width, height uint, img image.Image, interp InterpolationFunction) image.Image {
+	scaleX, scaleY := calcFactors(width, height, float64(img.Bounds().Dx()), float64(img.Bounds().Dy()))
+	if width == 0 {
+		width = uint(0.7 + float64(img.Bounds().Dx())/scaleX)
+	}
+	if height == 0 {
+		height = uint(0.7 + float64(img.Bounds().Dy())/scaleY)
+	}
+
+	// Trivial case: return input image
+	if int(width) == img.Bounds().Dx() && int(height) == img.Bounds().Dy() {
+		return img
+	}
+
+	if interp == NearestNeighbor {
+		return resizeNearest(width, height, scaleX, scaleY, img, interp)
+	}
+
+	taps, kernel := interp.kernel()
+	cpus := runtime.GOMAXPROCS(0)
+	wg := sync.WaitGroup{}
+
+	// Generic access to image.Image is slow in tight loops.
+	// The optimal access has to be determined from the concrete image type.
+	switch input := img.(type) {
+	case *image.RGBA:
+		// 8-bit precision
+		temp := image.NewRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights8(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				resizeRGBA(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights8(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				resizeRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.NRGBA:
+		// 8-bit precision
+		temp := image.NewRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights8(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				resizeNRGBA(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights8(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				resizeRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+
+	case *image.YCbCr:
+		// 8-bit precision
+		// accessing the YCbCr arrays in a tight loop is slow.
+		// converting the image to ycc increases performance by 2x.
+		temp := newYCC(image.Rect(0, 0, input.Bounds().Dy(), int(width)), input.SubsampleRatio)
+		result := newYCC(image.Rect(0, 0, int(width), int(height)), image.YCbCrSubsampleRatio444)
+
+		coeffs, offset, filterLength := createWeights8(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		in := imageYCbCrToYCC(input)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*ycc)
+			go func() {
+				defer wg.Done()
+				resizeYCbCr(in, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		coeffs, offset, filterLength = createWeights8(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*ycc)
+			go func() {
+				defer wg.Done()
+				resizeYCbCr(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result.YCbCr()
+	case *image.RGBA64:
+		// 16-bit precision
+		temp := image.NewRGBA64(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights16(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeRGBA64(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights16(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.NRGBA64:
+		// 16-bit precision
+		temp := image.NewRGBA64(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights16(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeNRGBA64(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights16(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.Gray:
+		// 8-bit precision
+		temp := image.NewGray(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewGray(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights8(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.Gray)
+			go func() {
+				defer wg.Done()
+				resizeGray(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights8(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.Gray)
+			go func() {
+				defer wg.Done()
+				resizeGray(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.Gray16:
+		// 16-bit precision
+		temp := image.NewGray16(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewGray16(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights16(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.Gray16)
+			go func() {
+				defer wg.Done()
+				resizeGray16(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights16(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.Gray16)
+			go func() {
+				defer wg.Done()
+				resizeGray16(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	default:
+		// 16-bit precision
+		temp := image.NewRGBA64(image.Rect(0, 0, img.Bounds().Dy(), int(width)))
+		result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeights16(temp.Bounds().Dy(), taps, blur, scaleX, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeGeneric(img, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeights16(result.Bounds().Dy(), taps, blur, scaleY, kernel)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				resizeRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	}
+}
+
+func resizeNearest(width, height uint, scaleX, scaleY float64, img image.Image, interp InterpolationFunction) image.Image {
+	taps, _ := interp.kernel()
+	cpus := runtime.GOMAXPROCS(0)
+	wg := sync.WaitGroup{}
+
+	switch input := img.(type) {
+	case *image.RGBA:
+		// 8-bit precision
+		temp := image.NewRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				nearestRGBA(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA)
+			go func() {
+				defer wg.Done()
+				nearestRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.NRGBA:
+		// 8-bit precision
+		temp := image.NewNRGBA(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewNRGBA(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.NRGBA)
+			go func() {
+				defer wg.Done()
+				nearestNRGBA(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.NRGBA)
+			go func() {
+				defer wg.Done()
+				nearestNRGBA(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.YCbCr:
+		// 8-bit precision
+		// accessing the YCbCr arrays in a tight loop is slow.
+		// converting the image to ycc increases performance by 2x.
+		temp := newYCC(image.Rect(0, 0, input.Bounds().Dy(), int(width)), input.SubsampleRatio)
+		result := newYCC(image.Rect(0, 0, int(width), int(height)), image.YCbCrSubsampleRatio444)
+
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		in := imageYCbCrToYCC(input)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*ycc)
+			go func() {
+				defer wg.Done()
+				nearestYCbCr(in, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*ycc)
+			go func() {
+				defer wg.Done()
+				nearestYCbCr(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result.YCbCr()
+	case *image.RGBA64:
+		// 16-bit precision
+		temp := image.NewRGBA64(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				nearestRGBA64(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				nearestRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.NRGBA64:
+		// 16-bit precision
+		temp := image.NewNRGBA64(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewNRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.NRGBA64)
+			go func() {
+				defer wg.Done()
+				nearestNRGBA64(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.NRGBA64)
+			go func() {
+				defer wg.Done()
+				nearestNRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.Gray:
+		// 8-bit precision
+		temp := image.NewGray(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewGray(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.Gray)
+			go func() {
+				defer wg.Done()
+				nearestGray(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.Gray)
+			go func() {
+				defer wg.Done()
+				nearestGray(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	case *image.Gray16:
+		// 16-bit precision
+		temp := image.NewGray16(image.Rect(0, 0, input.Bounds().Dy(), int(width)))
+		result := image.NewGray16(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.Gray16)
+			go func() {
+				defer wg.Done()
+				nearestGray16(input, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.Gray16)
+			go func() {
+				defer wg.Done()
+				nearestGray16(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	default:
+		// 16-bit precision
+		temp := image.NewRGBA64(image.Rect(0, 0, img.Bounds().Dy(), int(width)))
+		result := image.NewRGBA64(image.Rect(0, 0, int(width), int(height)))
+
+		// horizontal filter, results in transposed temporary image
+		coeffs, offset, filterLength := createWeightsNearest(temp.Bounds().Dy(), taps, blur, scaleX)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(temp, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				nearestGeneric(img, slice, scaleX, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+
+		// horizontal filter on transposed image, result is not transposed
+		coeffs, offset, filterLength = createWeightsNearest(result.Bounds().Dy(), taps, blur, scaleY)
+		wg.Add(cpus)
+		for i := 0; i < cpus; i++ {
+			slice := makeSlice(result, i, cpus).(*image.RGBA64)
+			go func() {
+				defer wg.Done()
+				nearestRGBA64(temp, slice, scaleY, coeffs, offset, filterLength)
+			}()
+		}
+		wg.Wait()
+		return result
+	}
+
+}
+
+// Calculates scaling factors using old and new image dimensions.
+func calcFactors(width, height uint, oldWidth, oldHeight float64) (scaleX, scaleY float64) {
+	if width == 0 {
+		if height == 0 {
+			scaleX = 1.0
+			scaleY = 1.0
+		} else {
+			scaleY = oldHeight / float64(height)
+			scaleX = scaleY
+		}
+	} else {
+		scaleX = oldWidth / float64(width)
+		if height == 0 {
+			scaleY = scaleX
+		} else {
+			scaleY = oldHeight / float64(height)
+		}
+	}
+	return
+}
+
+type imageWithSubImage interface {
+	image.Image
+	SubImage(image.Rectangle) image.Image
+}
+
+func makeSlice(img imageWithSubImage, i, n int) image.Image {
+	return img.SubImage(image.Rect(img.Bounds().Min.X, img.Bounds().Min.Y+i*img.Bounds().Dy()/n, img.Bounds().Max.X, img.Bounds().Min.Y+(i+1)*img.Bounds().Dy()/n))
+}

vendor/github.com/nfnt/resize/thumbnail.go

@@ -0,0 +1,55 @@
+/*
+Copyright (c) 2012, Jan Schlicht <jan.schlicht@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+package resize
+
+import (
+	"image"
+)
+
+// Thumbnail will downscale provided image to max width and height preserving
+// original aspect ratio and using the interpolation function interp.
+// It will return original image, without processing it, if original sizes
+// are already smaller than provided constraints.
+func Thumbnail(maxWidth, maxHeight uint, img image.Image, interp InterpolationFunction) image.Image {
+	origBounds := img.Bounds()
+	origWidth := uint(origBounds.Dx())
+	origHeight := uint(origBounds.Dy())
+	newWidth, newHeight := origWidth, origHeight
+
+	// Return original image if it have same or smaller size as constraints
+	if maxWidth >= origWidth && maxHeight >= origHeight {
+		return img
+	}
+
+	// Preserve aspect ratio
+	if origWidth > maxWidth {
+		newHeight = uint(origHeight * maxWidth / origWidth)
+		if newHeight < 1 {
+			newHeight = 1
+		}
+		newWidth = maxWidth
+	}
+
+	if newHeight > maxHeight {
+		newWidth = uint(newWidth * maxHeight / newHeight)
+		if newWidth < 1 {
+			newWidth = 1
+		}
+		newHeight = maxHeight
+	}
+	return Resize(newWidth, newHeight, img, interp)
+}

vendor/github.com/nfnt/resize/ycc.go

@@ -0,0 +1,227 @@
+/*
+Copyright (c) 2014, Charlie Vieth <charlie.vieth@gmail.com>
+
+Permission to use, copy, modify, and/or distribute this software for any purpose
+with or without fee is hereby granted, provided that the above copyright notice
+and this permission notice appear in all copies.
+
+THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
+OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
+THIS SOFTWARE.
+*/
+
+package resize
+
+import (
+	"image"
+	"image/color"
+)
+
+// ycc is an in memory YCbCr image.  The Y, Cb and Cr samples are held in a
+// single slice to increase resizing performance.
+type ycc struct {
+	// Pix holds the image's pixels, in Y, Cb, Cr order. The pixel at
+	// (x, y) starts at Pix[(y-Rect.Min.Y)*Stride + (x-Rect.Min.X)*3].
+	Pix []uint8
+	// Stride is the Pix stride (in bytes) between vertically adjacent pixels.
+	Stride int
+	// Rect is the image's bounds.
+	Rect image.Rectangle
+	// SubsampleRatio is the subsample ratio of the original YCbCr image.
+	SubsampleRatio image.YCbCrSubsampleRatio
+}
+
+// PixOffset returns the index of the first element of Pix that corresponds to
+// the pixel at (x, y).
+func (p *ycc) PixOffset(x, y int) int {
+	return (y-p.Rect.Min.Y)*p.Stride + (x-p.Rect.Min.X)*3
+}
+
+func (p *ycc) Bounds() image.Rectangle {
+	return p.Rect
+}
+
+func (p *ycc) ColorModel() color.Model {
+	return color.YCbCrModel
+}
+
+func (p *ycc) At(x, y int) color.Color {
+	if !(image.Point{x, y}.In(p.Rect)) {
+		return color.YCbCr{}
+	}
+	i := p.PixOffset(x, y)
+	return color.YCbCr{
+		p.Pix[i+0],
+		p.Pix[i+1],
+		p.Pix[i+2],
+	}
+}
+
+func (p *ycc) Opaque() bool {
+	return true
+}
+
+// SubImage returns an image representing the portion of the image p visible
+// through r. The returned value shares pixels with the original image.
+func (p *ycc) SubImage(r image.Rectangle) image.Image {
+	r = r.Intersect(p.Rect)
+	if r.Empty() {
+		return &ycc{SubsampleRatio: p.SubsampleRatio}
+	}
+	i := p.PixOffset(r.Min.X, r.Min.Y)
+	return &ycc{
+		Pix:            p.Pix[i:],
+		Stride:         p.Stride,
+		Rect:           r,
+		SubsampleRatio: p.SubsampleRatio,
+	}
+}
+
+// newYCC returns a new ycc with the given bounds and subsample ratio.
+func newYCC(r image.Rectangle, s image.YCbCrSubsampleRatio) *ycc {
+	w, h := r.Dx(), r.Dy()
+	buf := make([]uint8, 3*w*h)
+	return &ycc{Pix: buf, Stride: 3 * w, Rect: r, SubsampleRatio: s}
+}
+
+// YCbCr converts ycc to a YCbCr image with the same subsample ratio
+// as the YCbCr image that ycc was generated from.
+func (p *ycc) YCbCr() *image.YCbCr {
+	ycbcr := image.NewYCbCr(p.Rect, p.SubsampleRatio)
+	var off int
+
+	switch ycbcr.SubsampleRatio {
+	case image.YCbCrSubsampleRatio422:
+		for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ {
+			yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride
+			cy := (y - ycbcr.Rect.Min.Y) * ycbcr.CStride
+			for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ {
+				xx := (x - ycbcr.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx/2
+				ycbcr.Y[yi] = p.Pix[off+0]
+				ycbcr.Cb[ci] = p.Pix[off+1]
+				ycbcr.Cr[ci] = p.Pix[off+2]
+				off += 3
+			}
+		}
+	case image.YCbCrSubsampleRatio420:
+		for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ {
+			yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride
+			cy := (y/2 - ycbcr.Rect.Min.Y/2) * ycbcr.CStride
+			for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ {
+				xx := (x - ycbcr.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx/2
+				ycbcr.Y[yi] = p.Pix[off+0]
+				ycbcr.Cb[ci] = p.Pix[off+1]
+				ycbcr.Cr[ci] = p.Pix[off+2]
+				off += 3
+			}
+		}
+	case image.YCbCrSubsampleRatio440:
+		for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ {
+			yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride
+			cy := (y/2 - ycbcr.Rect.Min.Y/2) * ycbcr.CStride
+			for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ {
+				xx := (x - ycbcr.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx
+				ycbcr.Y[yi] = p.Pix[off+0]
+				ycbcr.Cb[ci] = p.Pix[off+1]
+				ycbcr.Cr[ci] = p.Pix[off+2]
+				off += 3
+			}
+		}
+	default:
+		// Default to 4:4:4 subsampling.
+		for y := ycbcr.Rect.Min.Y; y < ycbcr.Rect.Max.Y; y++ {
+			yy := (y - ycbcr.Rect.Min.Y) * ycbcr.YStride
+			cy := (y - ycbcr.Rect.Min.Y) * ycbcr.CStride
+			for x := ycbcr.Rect.Min.X; x < ycbcr.Rect.Max.X; x++ {
+				xx := (x - ycbcr.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx
+				ycbcr.Y[yi] = p.Pix[off+0]
+				ycbcr.Cb[ci] = p.Pix[off+1]
+				ycbcr.Cr[ci] = p.Pix[off+2]
+				off += 3
+			}
+		}
+	}
+	return ycbcr
+}
+
+// imageYCbCrToYCC converts a YCbCr image to a ycc image for resizing.
+func imageYCbCrToYCC(in *image.YCbCr) *ycc {
+	w, h := in.Rect.Dx(), in.Rect.Dy()
+	r := image.Rect(0, 0, w, h)
+	buf := make([]uint8, 3*w*h)
+	p := ycc{Pix: buf, Stride: 3 * w, Rect: r, SubsampleRatio: in.SubsampleRatio}
+	var off int
+
+	switch in.SubsampleRatio {
+	case image.YCbCrSubsampleRatio422:
+		for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ {
+			yy := (y - in.Rect.Min.Y) * in.YStride
+			cy := (y - in.Rect.Min.Y) * in.CStride
+			for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ {
+				xx := (x - in.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx/2
+				p.Pix[off+0] = in.Y[yi]
+				p.Pix[off+1] = in.Cb[ci]
+				p.Pix[off+2] = in.Cr[ci]
+				off += 3
+			}
+		}
+	case image.YCbCrSubsampleRatio420:
+		for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ {
+			yy := (y - in.Rect.Min.Y) * in.YStride
+			cy := (y/2 - in.Rect.Min.Y/2) * in.CStride
+			for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ {
+				xx := (x - in.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx/2
+				p.Pix[off+0] = in.Y[yi]
+				p.Pix[off+1] = in.Cb[ci]
+				p.Pix[off+2] = in.Cr[ci]
+				off += 3
+			}
+		}
+	case image.YCbCrSubsampleRatio440:
+		for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ {
+			yy := (y - in.Rect.Min.Y) * in.YStride
+			cy := (y/2 - in.Rect.Min.Y/2) * in.CStride
+			for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ {
+				xx := (x - in.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx
+				p.Pix[off+0] = in.Y[yi]
+				p.Pix[off+1] = in.Cb[ci]
+				p.Pix[off+2] = in.Cr[ci]
+				off += 3
+			}
+		}
+	default:
+		// Default to 4:4:4 subsampling.
+		for y := in.Rect.Min.Y; y < in.Rect.Max.Y; y++ {
+			yy := (y - in.Rect.Min.Y) * in.YStride
+			cy := (y - in.Rect.Min.Y) * in.CStride
+			for x := in.Rect.Min.X; x < in.Rect.Max.X; x++ {
+				xx := (x - in.Rect.Min.X)
+				yi := yy + xx
+				ci := cy + xx
+				p.Pix[off+0] = in.Y[yi]
+				p.Pix[off+1] = in.Cb[ci]
+				p.Pix[off+2] = in.Cr[ci]
+				off += 3
+			}
+		}
+	}
+	return &p
+}

vendor/vendor.json

@@ -62,6 +62,12 @@
 			"revision": "9d302b58e975387d0b4d9be876622c86cefe64be",
 			"revisionTime": "2017-03-09T17:28:38Z"
 		},
+		{
+			"checksumSHA1": "r5eQHkttko6kxroDEENXbmXKrSs=",
+			"path": "github.com/nfnt/resize",
+			"revision": "891127d8d1b52734debe1b3c3d7e747502b6c366",
+			"revisionTime": "2016-07-24T20:39:20Z"
+		},
 		{
 			"checksumSHA1": "BvfT3pAC+s5qn5nEDf0N7lxpBNg=",
 			"path": "github.com/pressly/chi",