encode: quantized palette for GIFs (#293)

tidbyt · Jun 8, 2022 · 4d0c15f · 4d0c15f
1 parent 75ca672
commit 4d0c15f
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Showing 3 changed files with 7 additions and 26 deletions.
diff --git a/encode/encode.go b/encode/encode.go
@@ -6,9 +6,11 @@ import (
 	"fmt"
 	"image"
 	"image/color"
+	"image/draw"
 	"image/gif"
 	"time"
 
+	"github.com/ericpauley/go-quantize/quantize"
 	"github.com/pkg/errors"
 	"github.com/tidbyt/go-libwebp/webp"
 	"github.com/vmihailenco/msgpack/v5"
@@ -147,33 +149,9 @@ func (s *Screens) EncodeGIF(filters ...ImageFilter) ([]byte, error) {
 			return nil, fmt.Errorf("image %d is %T, require RGBA", imIdx, im)
 		}
 
-		palette := color.Palette{}
-		idxByColor := map[color.RGBA]int{}
-
-		// Create the palette
-		for x := 0; x < imRGBA.Bounds().Dx(); x++ {
-			for y := 0; y < imRGBA.Bounds().Dy(); y++ {
-				c := imRGBA.RGBAAt(x, y)
-				if _, found := idxByColor[c]; !found {
-					idxByColor[c] = len(palette)
-					palette = append(palette, c)
-				}
-			}
-		}
-		if len(palette) > 256 {
-			return nil, fmt.Errorf(
-				"require <=256 colors, found %d in image %d",
-				len(palette), imIdx,
-			)
-		}
-
-		// Construct the paletted image
+		palette := quantize.MedianCutQuantizer{}.Quantize(make([]color.Color, 0, 256), im)
 		imPaletted := image.NewPaletted(imRGBA.Bounds(), palette)
-		for x := 0; x < imRGBA.Bounds().Dx(); x++ {
-			for y := 0; y < imRGBA.Bounds().Dy(); y++ {
-				imPaletted.SetColorIndex(x, y, uint8(idxByColor[imRGBA.RGBAAt(x, y)]))
-			}
-		}
+		draw.Draw(imPaletted, imRGBA.Bounds(), imRGBA, image.Point{0, 0}, draw.Src)
 
 		g.Image = append(g.Image, imPaletted)
 		g.Delay = append(g.Delay, int(s.delay/10)) // in 100ths of a second

diff --git a/go.mod b/go.mod
@@ -5,6 +5,7 @@ go 1.16
 require (
 	github.com/antchfx/xmlquery v1.3.11
 	github.com/dustin/go-humanize v1.0.0
+	github.com/ericpauley/go-quantize v0.0.0-20200331213906-ae555eb2afa4 // indirect
 	github.com/fogleman/gg v1.3.0
 	github.com/fsnotify/fsnotify v1.5.4
 	github.com/go-playground/validator/v10 v10.11.0

diff --git a/go.sum b/go.sum
@@ -132,6 +132,8 @@ github.com/envoyproxy/go-control-plane v0.9.10-0.20210907150352-cf90f659a021/go.
 github.com/envoyproxy/go-control-plane v0.10.1/go.mod h1:AY7fTTXNdv/aJ2O5jwpxAPOWUZ7hQAEvzN5Pf27BkQQ=
 github.com/envoyproxy/protoc-gen-validate v0.1.0/go.mod h1:iSmxcyjqTsJpI2R4NaDN7+kN2VEUnK/pcBlmesArF7c=
 github.com/envoyproxy/protoc-gen-validate v0.6.2/go.mod h1:2t7qjJNvHPx8IjnBOzl9E9/baC+qXE/TeeyBRzgJDws=
+github.com/ericpauley/go-quantize v0.0.0-20200331213906-ae555eb2afa4 h1:BBade+JlV/f7JstZ4pitd4tHhpN+w+6I+LyOS7B4fyU=
+github.com/ericpauley/go-quantize v0.0.0-20200331213906-ae555eb2afa4/go.mod h1:H7chHJglrhPPzetLdzBleF8d22WYOv7UM/lEKYiwlKM=
 github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4=
 github.com/fatih/color v1.9.0/go.mod h1:eQcE1qtQxscV5RaZvpXrrb8Drkc3/DdQ+uUYCNjL+zU=
 github.com/fatih/color v1.13.0/go.mod h1:kLAiJbzzSOZDVNGyDpeOxJ47H46qBXwg5ILebYFFOfk=