image: add Paletted.Set, and a basic test of the concrete image types.
R=r
CC=golang-dev
https://golang.org/cl/4589045
diff --git a/src/pkg/image/image.go b/src/pkg/image/image.go
index bf75a51..f4c38d2 100644
--- a/src/pkg/image/image.go
+++ b/src/pkg/image/image.go
@@ -563,14 +563,19 @@
if len(p) == 0 {
return nil
}
+ return p[p.Index(c)]
+}
+
+// Index returns the index of the palette color closest to c in Euclidean
+// R,G,B space.
+func (p PalettedColorModel) Index(c Color) int {
cr, cg, cb, _ := c.RGBA()
// Shift by 1 bit to avoid potential uint32 overflow in sum-squared-difference.
cr >>= 1
cg >>= 1
cb >>= 1
- result := Color(nil)
- bestSSD := uint32(1<<32 - 1)
- for _, v := range p {
+ ret, bestSSD := 0, uint32(1<<32-1)
+ for i, v := range p {
vr, vg, vb, _ := v.RGBA()
vr >>= 1
vg >>= 1
@@ -578,11 +583,10 @@
dr, dg, db := diff(cr, vr), diff(cg, vg), diff(cb, vb)
ssd := (dr * dr) + (dg * dg) + (db * db)
if ssd < bestSSD {
- bestSSD = ssd
- result = v
+ ret, bestSSD = i, ssd
}
}
- return result
+ return ret
}
// A Paletted is an in-memory image backed by a 2-D slice of uint8 values and a PalettedColorModel.
@@ -610,6 +614,13 @@
return p.Palette[p.Pix[y*p.Stride+x]]
}
+func (p *Paletted) Set(x, y int, c Color) {
+ if !(Point{x, y}.In(p.Rect)) {
+ return
+ }
+ p.Pix[y*p.Stride+x] = uint8(p.Palette.Index(c))
+}
+
func (p *Paletted) ColorIndexAt(x, y int) uint8 {
if !(Point{x, y}.In(p.Rect)) {
return 0
diff --git a/src/pkg/image/image_test.go b/src/pkg/image/image_test.go
new file mode 100644
index 0000000..17e3147
--- /dev/null
+++ b/src/pkg/image/image_test.go
@@ -0,0 +1,71 @@
+// Copyright 2011 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package image
+
+import (
+ "testing"
+)
+
+func cmp(t *testing.T, cm ColorModel, c0, c1 Color) bool {
+ r0, g0, b0, a0 := cm.Convert(c0).RGBA()
+ r1, g1, b1, a1 := cm.Convert(c1).RGBA()
+ return r0 == r1 && g0 == g1 && b0 == b1 && a0 == a1
+}
+
+func TestImage(t *testing.T) {
+ type buffered interface {
+ Image
+ Set(int, int, Color)
+ SubImage(Rectangle) Image
+ }
+ testImage := []Image{
+ NewRGBA(10, 10),
+ NewRGBA64(10, 10),
+ NewNRGBA(10, 10),
+ NewNRGBA64(10, 10),
+ NewAlpha(10, 10),
+ NewAlpha16(10, 10),
+ NewGray(10, 10),
+ NewGray16(10, 10),
+ NewPaletted(10, 10, PalettedColorModel{
+ Transparent,
+ Opaque,
+ }),
+ }
+ for _, m := range testImage {
+ b := m.(buffered)
+ if !Rect(0, 0, 10, 10).Eq(b.Bounds()) {
+ t.Errorf("%T: want bounds %v, got %v", b, Rect(0, 0, 10, 10), b.Bounds())
+ continue
+ }
+ if !cmp(t, b.ColorModel(), Transparent, b.At(6, 3)) {
+ t.Errorf("%T: at (6, 3), want a zero color, got %v", b, b.At(6, 3))
+ continue
+ }
+ b.Set(6, 3, Opaque)
+ if !cmp(t, b.ColorModel(), Opaque, b.At(6, 3)) {
+ t.Errorf("%T: at (6, 3), want a non-zero color, got %v", b, b.At(6, 3))
+ continue
+ }
+ b = b.SubImage(Rect(3, 2, 9, 8)).(buffered)
+ if !Rect(3, 2, 9, 8).Eq(b.Bounds()) {
+ t.Errorf("%T: sub-image want bounds %v, got %v", b, Rect(3, 2, 9, 8), b.Bounds())
+ continue
+ }
+ if !cmp(t, b.ColorModel(), Opaque, b.At(6, 3)) {
+ t.Errorf("%T: sub-image at (6, 3), want a non-zero color, got %v", b, b.At(6, 3))
+ continue
+ }
+ if !cmp(t, b.ColorModel(), Transparent, b.At(3, 3)) {
+ t.Errorf("%T: sub-image at (3, 3), want a zero color, got %v", b, b.At(3, 3))
+ continue
+ }
+ b.Set(3, 3, Opaque)
+ if !cmp(t, b.ColorModel(), Opaque, b.At(3, 3)) {
+ t.Errorf("%T: sub-image at (3, 3), want a non-zero color, got %v", b, b.At(3, 3))
+ continue
+ }
+ }
+}
