libgo/go/image/ycbcr_test.go

   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
   5 package image
   6
   7 import (
   8         "image/color"
   9         "testing"
  10 )
  11
  12 func 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
  61 func 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
 111 func 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 }