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         }
  41         deltas := []Point{
  42                 Pt(0, 0),
  43                 Pt(1000, 1001),
  44                 Pt(5001, -400),
  45                 Pt(-701, -801),
  46         }
  47         for _, r := range rects {
  48                 for _, subsampleRatio := range subsampleRatios {
  49                         for _, delta := range deltas {
  50                                 testYCbCr(t, r, subsampleRatio, delta)
  51                         }
  52                 }
  53                 if testing.Short() {
  54                         break
  55                 }
  56         }
  57 }
  58
  59 func testYCbCr(t *testing.T, r Rectangle, subsampleRatio YCbCrSubsampleRatio, delta Point) {
  60         // Create a YCbCr image m, whose bounds are r translated by (delta.X, delta.Y).
  61         r1 := r.Add(delta)
  62         m := NewYCbCr(r1, subsampleRatio)
  63
  64         // Test that the image buffer is reasonably small even if (delta.X, delta.Y) is far from the origin.
  65         if len(m.Y) > 100*100 {
  66                 t.Errorf("r=%v, subsampleRatio=%v, delta=%v: image buffer is too large",
  67                         r, subsampleRatio, delta)
  68                 return
  69         }
  70
  71         // Initialize m's pixels. For 422 and 420 subsampling, some of the Cb and Cr elements
  72         // will be set multiple times. That's OK. We just want to avoid a uniform image.
  73         for y := r1.Min.Y; y < r1.Max.Y; y++ {
  74                 for x := r1.Min.X; x < r1.Max.X; x++ {
  75                         yi := m.YOffset(x, y)
  76                         ci := m.COffset(x, y)
  77                         m.Y[yi] = uint8(16*y + x)
  78                         m.Cb[ci] = uint8(y + 16*x)
  79                         m.Cr[ci] = uint8(y + 16*x)
  80                 }
  81         }
  82
  83         // Make various sub-images of m.
  84         for y0 := delta.Y + 3; y0 < delta.Y+7; y0++ {
  85                 for y1 := delta.Y + 8; y1 < delta.Y+13; y1++ {
  86                         for x0 := delta.X + 3; x0 < delta.X+7; x0++ {
  87                                 for x1 := delta.X + 8; x1 < delta.X+13; x1++ {
  88                                         subRect := Rect(x0, y0, x1, y1)
  89                                         sub := m.SubImage(subRect).(*YCbCr)
  90
  91                                         // For each point in the sub-image's bounds, check that m.At(x, y) equals sub.At(x, y).
  92                                         for y := sub.Rect.Min.Y; y < sub.Rect.Max.Y; y++ {
  93                                                 for x := sub.Rect.Min.X; x < sub.Rect.Max.X; x++ {
  94                                                         color0 := m.At(x, y).(color.YCbCr)
  95                                                         color1 := sub.At(x, y).(color.YCbCr)
  96                                                         if color0 != color1 {
  97                                                                 t.Errorf("r=%v, subsampleRatio=%v, delta=%v, x=%d, y=%d, color0=%v, color1=%v",
  98                                                                         r, subsampleRatio, delta, x, y, color0, color1)
  99                                                                 return
 100                                                         }
 101                                                 }
 102                                         }
 103                                 }
 104                         }
 105                 }
 106         }
 107 }