add compiletime build tag 'disableimagecrush' to remove cgo dependency

image.go

@@ -4,8 +4,6 @@ import (
 	"bytes"
 	"image"
 	"image/jpeg"
-
-	"code.ivysaur.me/imagequant"
 )
 
 func (this *Thumbnailer) RenderScaledImage(src image.Image) ([]byte, error) {
@@ -60,7 +58,7 @@ func (this *Thumbnailer) RenderScaledImage(src image.Image) ([]byte, error) {
 
 	switch this.ofmt {
 	case OUTPUT_PNG_CRUSH:
-		return crush(dest, imagequant.SPEED_FASTEST)
+		return crushFast(dest)
 
 	case OUTPUT_JPG:
 		buff := bytes.Buffer{}

imagecrush.go

@@ -1,3 +1,5 @@
+//+build !disableimagecrush
+
 package thumbnail
 
 import (
@@ -51,6 +53,10 @@ func rgb8PaletteToGoImage(w, h int, rgb8data []byte, pal color.Palette) image.Im
 	return ret
 }
 
+func crushFast(img image.Image) ([]byte, error) {
+	return crush(img, imagequant.SPEED_FASTEST)
+}
+
 func crush(img image.Image, speed int) ([]byte, error) {
 
 	width := img.Bounds().Max.X

imagecrush_disabled.go

@@ -0,0 +1,12 @@
+// +build disableimagecrush
+
+package thumbnail
+
+import (
+	"errors"
+	"image"
+)
+
+func crushFast(img image.Image) ([]byte, error) {
+	return nil, errors.New("Pngquant not compiled in")
+}