1// Copyright 2012 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5package image
6
7import (
8	"image/color"
9	"testing"
10)
11
12func TestYCbCr(t *testing.T) {
13	rects := []Rectangle{
14		Rect(0, 0, 16, 16),
15		Rect(1, 0, 16, 16),
16		Rect(0, 1, 16, 16),
17		Rect(1, 1, 16, 16),
18		Rect(1, 1, 15, 16),
19		Rect(1, 1, 16, 15),
20		Rect(1, 1, 15, 15),
21		Rect(2, 3, 14, 15),
22		Rect(7, 0, 7, 16),
23		Rect(0, 8, 16, 8),
24		Rect(0, 0, 10, 11),
25		Rect(5, 6, 16, 16),
26		Rect(7, 7, 8, 8),
27		Rect(7, 8, 8, 9),
28		Rect(8, 7, 9, 8),
29		Rect(8, 8, 9, 9),
30		Rect(7, 7, 17, 17),
31		Rect(8, 8, 17, 17),
32		Rect(9, 9, 17, 17),
33		Rect(10, 10, 17, 17),
34	}
35	subsampleRatios := []YCbCrSubsampleRatio{
36		YCbCrSubsampleRatio444,
37		YCbCrSubsampleRatio422,
38		YCbCrSubsampleRatio420,
39		YCbCrSubsampleRatio440,
40		YCbCrSubsampleRatio411,
41		YCbCrSubsampleRatio410,
42	}
43	deltas := []Point{
44		Pt(0, 0),
45		Pt(1000, 1001),
46		Pt(5001, -400),
47		Pt(-701, -801),
48	}
49	for _, r := range rects {
50		for _, subsampleRatio := range subsampleRatios {
51			for _, delta := range deltas {
52				testYCbCr(t, r, subsampleRatio, delta)
53			}
54		}
55		if testing.Short() {
56			break
57		}
58	}
59}
60
61func testYCbCr(t *testing.T, r Rectangle, subsampleRatio YCbCrSubsampleRatio, delta Point) {
62	// Create a YCbCr image m, whose bounds are r translated by (delta.X, delta.Y).
63	r1 := r.Add(delta)
64	m := NewYCbCr(r1, subsampleRatio)
65
66	// Test that the image buffer is reasonably small even if (delta.X, delta.Y) is far from the origin.
67	if len(m.Y) > 100*100 {
68		t.Errorf("r=%v, subsampleRatio=%v, delta=%v: image buffer is too large",
69			r, subsampleRatio, delta)
70		return
71	}
72
73	// Initialize m's pixels. For 422 and 420 subsampling, some of the Cb and Cr elements
74	// will be set multiple times. That's OK. We just want to avoid a uniform image.
75	for y := r1.Min.Y; y < r1.Max.Y; y++ {
76		for x := r1.Min.X; x < r1.Max.X; x++ {
77			yi := m.YOffset(x, y)
78			ci := m.COffset(x, y)
79			m.Y[yi] = uint8(16*y + x)
80			m.Cb[ci] = uint8(y + 16*x)
81			m.Cr[ci] = uint8(y + 16*x)
82		}
83	}
84
85	// Make various sub-images of m.
86	for y0 := delta.Y + 3; y0 < delta.Y+7; y0++ {
87		for y1 := delta.Y + 8; y1 < delta.Y+13; y1++ {
88			for x0 := delta.X + 3; x0 < delta.X+7; x0++ {
89				for x1 := delta.X + 8; x1 < delta.X+13; x1++ {
90					subRect := Rect(x0, y0, x1, y1)
91					sub := m.SubImage(subRect).(*YCbCr)
92
93					// For each point in the sub-image's bounds, check that m.At(x, y) equals sub.At(x, y).
94					for y := sub.Rect.Min.Y; y < sub.Rect.Max.Y; y++ {
95						for x := sub.Rect.Min.X; x < sub.Rect.Max.X; x++ {
96							color0 := m.At(x, y).(color.YCbCr)
97							color1 := sub.At(x, y).(color.YCbCr)
98							if color0 != color1 {
99								t.Errorf("r=%v, subsampleRatio=%v, delta=%v, x=%d, y=%d, color0=%v, color1=%v",
100									r, subsampleRatio, delta, x, y, color0, color1)
101								return
102							}
103						}
104					}
105				}
106			}
107		}
108	}
109}
110
111func TestYCbCrSlicesDontOverlap(t *testing.T) {
112	m := NewYCbCr(Rect(0, 0, 8, 8), YCbCrSubsampleRatio420)
113	names := []string{"Y", "Cb", "Cr"}
114	slices := [][]byte{
115		m.Y[:cap(m.Y)],
116		m.Cb[:cap(m.Cb)],
117		m.Cr[:cap(m.Cr)],
118	}
119	for i, slice := range slices {
120		want := uint8(10 + i)
121		for j := range slice {
122			slice[j] = want
123		}
124	}
125	for i, slice := range slices {
126		want := uint8(10 + i)
127		for j, got := range slice {
128			if got != want {
129				t.Fatalf("m.%s[%d]: got %d, want %d", names[i], j, got, want)
130			}
131		}
132	}
133}
134