1 files changed, 228 insertions, 0 deletions
diff --git a/libgo/go/exp/draw/draw_test.go b/libgo/go/exp/draw/draw_test.go
new file mode 100644
index 000000000..90c9e823d
--- /dev/null
+++ b/libgo/go/exp/draw/draw_test.go
@@ -0,0 +1,228 @@
+// Copyright 2010 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 draw
+
+import (
+	"image"
+	"testing"
+)
+
+func eq(c0, c1 image.Color) bool {
+	r0, g0, b0, a0 := c0.RGBA()
+	r1, g1, b1, a1 := c1.RGBA()
+	return r0 == r1 && g0 == g1 && b0 == b1 && a0 == a1
+}
+
+func fillBlue(alpha int) image.Image {
+	return image.NewColorImage(image.RGBAColor{0, 0, uint8(alpha), uint8(alpha)})
+}
+
+func fillAlpha(alpha int) image.Image {
+	return image.NewColorImage(image.AlphaColor{uint8(alpha)})
+}
+
+func vgradGreen(alpha int) image.Image {
+	m := image.NewRGBA(16, 16)
+	for y := 0; y < 16; y++ {
+		for x := 0; x < 16; x++ {
+			m.Set(x, y, image.RGBAColor{0, uint8(y * alpha / 15), 0, uint8(alpha)})
+		}
+	}
+	return m
+}
+
+func vgradAlpha(alpha int) image.Image {
+	m := image.NewAlpha(16, 16)
+	for y := 0; y < 16; y++ {
+		for x := 0; x < 16; x++ {
+			m.Set(x, y, image.AlphaColor{uint8(y * alpha / 15)})
+		}
+	}
+	return m
+}
+
+func hgradRed(alpha int) Image {
+	m := image.NewRGBA(16, 16)
+	for y := 0; y < 16; y++ {
+		for x := 0; x < 16; x++ {
+			m.Set(x, y, image.RGBAColor{uint8(x * alpha / 15), 0, 0, uint8(alpha)})
+		}
+	}
+	return m
+}
+
+func gradYellow(alpha int) Image {
+	m := image.NewRGBA(16, 16)
+	for y := 0; y < 16; y++ {
+		for x := 0; x < 16; x++ {
+			m.Set(x, y, image.RGBAColor{uint8(x * alpha / 15), uint8(y * alpha / 15), 0, uint8(alpha)})
+		}
+	}
+	return m
+}
+
+type drawTest struct {
+	desc     string
+	src      image.Image
+	mask     image.Image
+	op       Op
+	expected image.Color
+}
+
+var drawTests = []drawTest{
+	// Uniform mask (0% opaque).
+	{"nop", vgradGreen(255), fillAlpha(0), Over, image.RGBAColor{136, 0, 0, 255}},
+	{"clear", vgradGreen(255), fillAlpha(0), Src, image.RGBAColor{0, 0, 0, 0}},
+	// Uniform mask (100%, 75%, nil) and uniform source.
+	// At (x, y) == (8, 8):
+	// The destination pixel is {136, 0, 0, 255}.
+	// The source pixel is {0, 0, 90, 90}.
+	{"fill", fillBlue(90), fillAlpha(255), Over, image.RGBAColor{88, 0, 90, 255}},
+	{"fillSrc", fillBlue(90), fillAlpha(255), Src, image.RGBAColor{0, 0, 90, 90}},
+	{"fillAlpha", fillBlue(90), fillAlpha(192), Over, image.RGBAColor{100, 0, 68, 255}},
+	{"fillAlphaSrc", fillBlue(90), fillAlpha(192), Src, image.RGBAColor{0, 0, 68, 68}},
+	{"fillNil", fillBlue(90), nil, Over, image.RGBAColor{88, 0, 90, 255}},
+	{"fillNilSrc", fillBlue(90), nil, Src, image.RGBAColor{0, 0, 90, 90}},
+	// Uniform mask (100%, 75%, nil) and variable source.
+	// At (x, y) == (8, 8):
+	// The destination pixel is {136, 0, 0, 255}.
+	// The source pixel is {0, 48, 0, 90}.
+	{"copy", vgradGreen(90), fillAlpha(255), Over, image.RGBAColor{88, 48, 0, 255}},
+	{"copySrc", vgradGreen(90), fillAlpha(255), Src, image.RGBAColor{0, 48, 0, 90}},
+	{"copyAlpha", vgradGreen(90), fillAlpha(192), Over, image.RGBAColor{100, 36, 0, 255}},
+	{"copyAlphaSrc", vgradGreen(90), fillAlpha(192), Src, image.RGBAColor{0, 36, 0, 68}},
+	{"copyNil", vgradGreen(90), nil, Over, image.RGBAColor{88, 48, 0, 255}},
+	{"copyNilSrc", vgradGreen(90), nil, Src, image.RGBAColor{0, 48, 0, 90}},
+	// Variable mask and variable source.
+	// At (x, y) == (8, 8):
+	// The destination pixel is {136, 0, 0, 255}.
+	// The source pixel is {0, 0, 255, 255}.
+	// The mask pixel's alpha is 102, or 40%.
+	{"generic", fillBlue(255), vgradAlpha(192), Over, image.RGBAColor{81, 0, 102, 255}},
+	{"genericSrc", fillBlue(255), vgradAlpha(192), Src, image.RGBAColor{0, 0, 102, 102}},
+}
+
+func makeGolden(dst, src, mask image.Image, op Op) image.Image {
+	// Since golden is a newly allocated image, we don't have to check if the
+	// input source and mask images and the output golden image overlap.
+	b := dst.Bounds()
+	sx0 := src.Bounds().Min.X - b.Min.X
+	sy0 := src.Bounds().Min.Y - b.Min.Y
+	var mx0, my0 int
+	if mask != nil {
+		mx0 = mask.Bounds().Min.X - b.Min.X
+		my0 = mask.Bounds().Min.Y - b.Min.Y
+	}
+	golden := image.NewRGBA(b.Max.X, b.Max.Y)
+	for y := b.Min.Y; y < b.Max.Y; y++ {
+		my, sy := my0+y, sy0+y
+		for x := b.Min.X; x < b.Max.X; x++ {
+			mx, sx := mx0+x, sx0+x
+			const M = 1<<16 - 1
+			var dr, dg, db, da uint32
+			if op == Over {
+				dr, dg, db, da = dst.At(x, y).RGBA()
+			}
+			sr, sg, sb, sa := src.At(sx, sy).RGBA()
+			ma := uint32(M)
+			if mask != nil {
+				_, _, _, ma = mask.At(mx, my).RGBA()
+			}
+			a := M - (sa * ma / M)
+			golden.Set(x, y, image.RGBA64Color{
+				uint16((dr*a + sr*ma) / M),
+				uint16((dg*a + sg*ma) / M),
+				uint16((db*a + sb*ma) / M),
+				uint16((da*a + sa*ma) / M),
+			})
+		}
+	}
+	golden.Rect = b
+	return golden
+}
+
+func TestDraw(t *testing.T) {
+loop:
+	for _, test := range drawTests {
+		dst := hgradRed(255)
+		// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
+		golden := makeGolden(dst, test.src, test.mask, test.op)
+		b := dst.Bounds()
+		if !b.Eq(golden.Bounds()) {
+			t.Errorf("draw %s: bounds %v versus %v", test.desc, dst.Bounds(), golden.Bounds())
+			continue
+		}
+		// Draw the same combination onto the actual dst using the optimized DrawMask implementation.
+		DrawMask(dst, b, test.src, image.ZP, test.mask, image.ZP, test.op)
+		// Check that the resultant pixel at (8, 8) matches what we expect
+		// (the expected value can be verified by hand).
+		if !eq(dst.At(8, 8), test.expected) {
+			t.Errorf("draw %s: at (8, 8) %v versus %v", test.desc, dst.At(8, 8), test.expected)
+			continue
+		}
+		// Check that the resultant dst image matches the golden output.
+		for y := b.Min.Y; y < b.Max.Y; y++ {
+			for x := b.Min.X; x < b.Max.X; x++ {
+				if !eq(dst.At(x, y), golden.At(x, y)) {
+					t.Errorf("draw %s: at (%d, %d), %v versus golden %v", test.desc, x, y, dst.At(x, y), golden.At(x, y))
+					continue loop
+				}
+			}
+		}
+	}
+}
+
+func TestDrawOverlap(t *testing.T) {
+	for _, op := range []Op{Over, Src} {
+		for yoff := -2; yoff <= 2; yoff++ {
+		loop:
+			for xoff := -2; xoff <= 2; xoff++ {
+				m := gradYellow(127).(*image.RGBA)
+				dst := &image.RGBA{
+					Pix:    m.Pix,
+					Stride: m.Stride,
+					Rect:   image.Rect(5, 5, 10, 10),
+				}
+				src := &image.RGBA{
+					Pix:    m.Pix,
+					Stride: m.Stride,
+					Rect:   image.Rect(5+xoff, 5+yoff, 10+xoff, 10+yoff),
+				}
+				// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
+				golden := makeGolden(dst, src, nil, op)
+				b := dst.Bounds()
+				if !b.Eq(golden.Bounds()) {
+					t.Errorf("drawOverlap xoff=%d,yoff=%d: bounds %v versus %v", xoff, yoff, dst.Bounds(), golden.Bounds())
+					continue
+				}
+				// Draw the same combination onto the actual dst using the optimized DrawMask implementation.
+				DrawMask(dst, b, src, src.Bounds().Min, nil, image.ZP, op)
+				// Check that the resultant dst image matches the golden output.
+				for y := b.Min.Y; y < b.Max.Y; y++ {
+					for x := b.Min.X; x < b.Max.X; x++ {
+						if !eq(dst.At(x, y), golden.At(x, y)) {
+							t.Errorf("drawOverlap xoff=%d,yoff=%d: at (%d, %d), %v versus golden %v", xoff, yoff, x, y, dst.At(x, y), golden.At(x, y))
+							continue loop
+						}
+					}
+				}
+			}
+		}
+	}
+}
+
+// TestIssue836 verifies http://code.google.com/p/go/issues/detail?id=836.
+func TestIssue836(t *testing.T) {
+	a := image.NewRGBA(1, 1)
+	b := image.NewRGBA(2, 2)
+	b.Set(0, 0, image.RGBAColor{0, 0, 0, 5})
+	b.Set(1, 0, image.RGBAColor{0, 0, 5, 5})
+	b.Set(0, 1, image.RGBAColor{0, 5, 0, 5})
+	b.Set(1, 1, image.RGBAColor{5, 0, 0, 5})
+	Draw(a, image.Rect(0, 0, 1, 1), b, image.Pt(1, 1))
+	if !eq(image.RGBAColor{5, 0, 0, 5}, a.At(0, 0)) {
+		t.Errorf("Issue 836: want %v got %v", image.RGBAColor{5, 0, 0, 5}, a.At(0, 0))
+	}
+}