1 files changed, 107 insertions, 0 deletions
diff --git a/src/image/ycbcr_test.go b/src/image/ycbcr_test.go
new file mode 100644
index 000000000..a5f448265
--- /dev/null
+++ b/src/image/ycbcr_test.go
@@ -0,0 +1,107 @@
+// Copyright 2012 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 (
+	"image/color"
+	"testing"
+)
+
+func TestYCbCr(t *testing.T) {
+	rects := []Rectangle{
+		Rect(0, 0, 16, 16),
+		Rect(1, 0, 16, 16),
+		Rect(0, 1, 16, 16),
+		Rect(1, 1, 16, 16),
+		Rect(1, 1, 15, 16),
+		Rect(1, 1, 16, 15),
+		Rect(1, 1, 15, 15),
+		Rect(2, 3, 14, 15),
+		Rect(7, 0, 7, 16),
+		Rect(0, 8, 16, 8),
+		Rect(0, 0, 10, 11),
+		Rect(5, 6, 16, 16),
+		Rect(7, 7, 8, 8),
+		Rect(7, 8, 8, 9),
+		Rect(8, 7, 9, 8),
+		Rect(8, 8, 9, 9),
+		Rect(7, 7, 17, 17),
+		Rect(8, 8, 17, 17),
+		Rect(9, 9, 17, 17),
+		Rect(10, 10, 17, 17),
+	}
+	subsampleRatios := []YCbCrSubsampleRatio{
+		YCbCrSubsampleRatio444,
+		YCbCrSubsampleRatio422,
+		YCbCrSubsampleRatio420,
+		YCbCrSubsampleRatio440,
+	}
+	deltas := []Point{
+		Pt(0, 0),
+		Pt(1000, 1001),
+		Pt(5001, -400),
+		Pt(-701, -801),
+	}
+	for _, r := range rects {
+		for _, subsampleRatio := range subsampleRatios {
+			for _, delta := range deltas {
+				testYCbCr(t, r, subsampleRatio, delta)
+			}
+		}
+		if testing.Short() {
+			break
+		}
+	}
+}
+
+func testYCbCr(t *testing.T, r Rectangle, subsampleRatio YCbCrSubsampleRatio, delta Point) {
+	// Create a YCbCr image m, whose bounds are r translated by (delta.X, delta.Y).
+	r1 := r.Add(delta)
+	m := NewYCbCr(r1, subsampleRatio)
+
+	// Test that the image buffer is reasonably small even if (delta.X, delta.Y) is far from the origin.
+	if len(m.Y) > 100*100 {
+		t.Errorf("r=%v, subsampleRatio=%v, delta=%v: image buffer is too large",
+			r, subsampleRatio, delta)
+		return
+	}
+
+	// Initialize m's pixels. For 422 and 420 subsampling, some of the Cb and Cr elements
+	// will be set multiple times. That's OK. We just want to avoid a uniform image.
+	for y := r1.Min.Y; y < r1.Max.Y; y++ {
+		for x := r1.Min.X; x < r1.Max.X; x++ {
+			yi := m.YOffset(x, y)
+			ci := m.COffset(x, y)
+			m.Y[yi] = uint8(16*y + x)
+			m.Cb[ci] = uint8(y + 16*x)
+			m.Cr[ci] = uint8(y + 16*x)
+		}
+	}
+
+	// Make various sub-images of m.
+	for y0 := delta.Y + 3; y0 < delta.Y+7; y0++ {
+		for y1 := delta.Y + 8; y1 < delta.Y+13; y1++ {
+			for x0 := delta.X + 3; x0 < delta.X+7; x0++ {
+				for x1 := delta.X + 8; x1 < delta.X+13; x1++ {
+					subRect := Rect(x0, y0, x1, y1)
+					sub := m.SubImage(subRect).(*YCbCr)
+
+					// For each point in the sub-image's bounds, check that m.At(x, y) equals sub.At(x, y).
+					for y := sub.Rect.Min.Y; y < sub.Rect.Max.Y; y++ {
+						for x := sub.Rect.Min.X; x < sub.Rect.Max.X; x++ {
+							color0 := m.At(x, y).(color.YCbCr)
+							color1 := sub.At(x, y).(color.YCbCr)
+							if color0 != color1 {
+								t.Errorf("r=%v, subsampleRatio=%v, delta=%v, x=%d, y=%d, color0=%v, color1=%v",
+									r, subsampleRatio, delta, x, y, color0, color1)
+								return
+							}
+						}
+					}
+				}
+			}
+		}
+	}
+}