using imaging package

service/imaging/mks2013_filter.go

@@ -4,34 +4,23 @@ import (
 	"math"
 
 	"github.com/disintegration/imaging"
-	"golang.org/x/image/draw"
 )
 
-var (
-	// Magic Kernel Sharp 2013
-	// http://johncostella.com/magic/
-	mks2013Filter = imaging.ResampleFilter{
-		Support: 2.5,
-		Kernel: func(x float64) float64 {
-			x = math.Abs(x)
-			if x >= 2.5 {
-				return 0.0
-			}
-			if x >= 1.5 {
-				return -0.125 * (x - 2.5) * (x - 2.5)
-			}
-			if x >= 0.5 {
-				return 0.25 * (4*x*x - 11*x + 7)
-			}
-			return 1.0625 - 1.75*x*x
-		},
-	}
-
-	// mks2013Filterのdraw.Kernelへの型キャスト
-	// Magic Kernel Sharp 2013
-	// http://johncostella.com/magic/
-	mks2013FilterKernel = draw.Kernel{
-		Support: mks2013Filter.Support,
-		At:      mks2013Filter.Kernel,
-	}
-)
+// Magic Kernel Sharp 2013
+// http://johncostella.com/magic/
+var mks2013Filter = imaging.ResampleFilter{
+	Support: 2.5,
+	Kernel: func(x float64) float64 {
+		x = math.Abs(x)
+		if x >= 2.5 {
+			return 0.0
+		}
+		if x >= 1.5 {
+			return -0.125 * (x - 2.5) * (x - 2.5)
+		}
+		if x >= 0.5 {
+			return 0.25 * (4*x*x - 11*x + 7)
+		}
+		return 1.0625 - 1.75*x*x
+	},
+}

service/imaging/processor_default.go

@@ -101,7 +101,7 @@ func (p *defaultProcessor) FitAnimationGIF(src io.Reader, width, height int) (*b
 		width = int(math.Round(floatSrcWidth * ratio))
 	}
 
-	dstImage := &gif.GIF{
+	destImage := &gif.GIF{
 		Delay:     srcImage.Delay,
 		LoopCount: srcImage.LoopCount,
 		Disposal:  srcImage.Disposal,
@@ -113,20 +113,21 @@ func (p *defaultProcessor) FitAnimationGIF(src io.Reader, width, height int) (*b
 		BackgroundIndex: srcImage.BackgroundIndex,
 	}
 
-	for _, frame := range srcImage.Image {
-		srcBounds := frame.Bounds()
+	for _, srcFrame := range srcImage.Image {
+		srcBounds := srcFrame.Bounds()
 		destBounds := image.Rect(
 			int(float64(srcBounds.Min.X)*ratio),
 			int(float64(srcBounds.Min.Y)*ratio),
 			int(float64(srcBounds.Max.X)*ratio),
 			int(float64(srcBounds.Max.Y)*ratio),
 		)
-		destFrame := image.NewPaletted(destBounds, frame.Palette)
-		mks2013FilterKernel.Scale(destFrame, destBounds, frame.SubImage(srcBounds), srcBounds, draw.Over, nil)
-		dstImage.Image = append(dstImage.Image, destFrame)
+		fittedImage := imaging.Resize(srcFrame.SubImage(srcBounds), destBounds.Dx(), destBounds.Dy(), mks2013Filter)
+		destFrame := image.NewPaletted(destBounds, srcFrame.Palette)
+		draw.Draw(destFrame, destBounds, fittedImage, image.Point{}, draw.Over)
+		destImage.Image = append(destImage.Image, destFrame)
 	}
 
-	return imaging2.GifToBytesReader(dstImage)
+	return imaging2.GifToBytesReader(destImage)
 }
 
 func (p *defaultProcessor) WaveformMp3(src io.ReadSeeker, width, height int) (r io.Reader, err error) {