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Source file src/image/draw/draw_test.go

Documentation: image/draw

  // 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"
  	"image/color"
  	"image/png"
  	"os"
  	"testing"
  )
  
  func eq(c0, c1 color.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.NewUniform(color.RGBA{0, 0, uint8(alpha), uint8(alpha)})
  }
  
  func fillAlpha(alpha int) image.Image {
  	return image.NewUniform(color.Alpha{uint8(alpha)})
  }
  
  func vgradGreen(alpha int) image.Image {
  	m := image.NewRGBA(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.RGBA{0, uint8(y * alpha / 15), 0, uint8(alpha)})
  		}
  	}
  	return m
  }
  
  func vgradAlpha(alpha int) image.Image {
  	m := image.NewAlpha(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.Alpha{uint8(y * alpha / 15)})
  		}
  	}
  	return m
  }
  
  func vgradGreenNRGBA(alpha int) image.Image {
  	m := image.NewNRGBA(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.RGBA{0, uint8(y * 0x11), 0, uint8(alpha)})
  		}
  	}
  	return m
  }
  
  func vgradCr() image.Image {
  	m := &image.YCbCr{
  		Y:              make([]byte, 16*16),
  		Cb:             make([]byte, 16*16),
  		Cr:             make([]byte, 16*16),
  		YStride:        16,
  		CStride:        16,
  		SubsampleRatio: image.YCbCrSubsampleRatio444,
  		Rect:           image.Rect(0, 0, 16, 16),
  	}
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Cr[y*m.CStride+x] = uint8(y * 0x11)
  		}
  	}
  	return m
  }
  
  func vgradGray() image.Image {
  	m := image.NewGray(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.Gray{uint8(y * 0x11)})
  		}
  	}
  	return m
  }
  
  func vgradMagenta() image.Image {
  	m := image.NewCMYK(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.CMYK{0, uint8(y * 0x11), 0, 0x3f})
  		}
  	}
  	return m
  }
  
  func hgradRed(alpha int) Image {
  	m := image.NewRGBA(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.RGBA{uint8(x * alpha / 15), 0, 0, uint8(alpha)})
  		}
  	}
  	return m
  }
  
  func gradYellow(alpha int) Image {
  	m := image.NewRGBA(image.Rect(0, 0, 16, 16))
  	for y := 0; y < 16; y++ {
  		for x := 0; x < 16; x++ {
  			m.Set(x, y, color.RGBA{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 color.Color
  }
  
  var drawTests = []drawTest{
  	// Uniform mask (0% opaque).
  	{"nop", vgradGreen(255), fillAlpha(0), Over, color.RGBA{136, 0, 0, 255}},
  	{"clear", vgradGreen(255), fillAlpha(0), Src, color.RGBA{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, color.RGBA{88, 0, 90, 255}},
  	{"fillSrc", fillBlue(90), fillAlpha(255), Src, color.RGBA{0, 0, 90, 90}},
  	{"fillAlpha", fillBlue(90), fillAlpha(192), Over, color.RGBA{100, 0, 68, 255}},
  	{"fillAlphaSrc", fillBlue(90), fillAlpha(192), Src, color.RGBA{0, 0, 68, 68}},
  	{"fillNil", fillBlue(90), nil, Over, color.RGBA{88, 0, 90, 255}},
  	{"fillNilSrc", fillBlue(90), nil, Src, color.RGBA{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, color.RGBA{88, 48, 0, 255}},
  	{"copySrc", vgradGreen(90), fillAlpha(255), Src, color.RGBA{0, 48, 0, 90}},
  	{"copyAlpha", vgradGreen(90), fillAlpha(192), Over, color.RGBA{100, 36, 0, 255}},
  	{"copyAlphaSrc", vgradGreen(90), fillAlpha(192), Src, color.RGBA{0, 36, 0, 68}},
  	{"copyNil", vgradGreen(90), nil, Over, color.RGBA{88, 48, 0, 255}},
  	{"copyNilSrc", vgradGreen(90), nil, Src, color.RGBA{0, 48, 0, 90}},
  	// Uniform mask (100%, 75%, nil) and variable NRGBA source.
  	// At (x, y) == (8, 8):
  	// The destination pixel is {136, 0, 0, 255}.
  	// The source pixel is {0, 136, 0, 90} in NRGBA-space, which is {0, 48, 0, 90} in RGBA-space.
  	// The result pixel is different than in the "copy*" test cases because of rounding errors.
  	{"nrgba", vgradGreenNRGBA(90), fillAlpha(255), Over, color.RGBA{88, 46, 0, 255}},
  	{"nrgbaSrc", vgradGreenNRGBA(90), fillAlpha(255), Src, color.RGBA{0, 46, 0, 90}},
  	{"nrgbaAlpha", vgradGreenNRGBA(90), fillAlpha(192), Over, color.RGBA{100, 34, 0, 255}},
  	{"nrgbaAlphaSrc", vgradGreenNRGBA(90), fillAlpha(192), Src, color.RGBA{0, 34, 0, 68}},
  	{"nrgbaNil", vgradGreenNRGBA(90), nil, Over, color.RGBA{88, 46, 0, 255}},
  	{"nrgbaNilSrc", vgradGreenNRGBA(90), nil, Src, color.RGBA{0, 46, 0, 90}},
  	// Uniform mask (100%, 75%, nil) and variable YCbCr source.
  	// At (x, y) == (8, 8):
  	// The destination pixel is {136, 0, 0, 255}.
  	// The source pixel is {0, 0, 136} in YCbCr-space, which is {11, 38, 0, 255} in RGB-space.
  	{"ycbcr", vgradCr(), fillAlpha(255), Over, color.RGBA{11, 38, 0, 255}},
  	{"ycbcrSrc", vgradCr(), fillAlpha(255), Src, color.RGBA{11, 38, 0, 255}},
  	{"ycbcrAlpha", vgradCr(), fillAlpha(192), Over, color.RGBA{42, 28, 0, 255}},
  	{"ycbcrAlphaSrc", vgradCr(), fillAlpha(192), Src, color.RGBA{8, 28, 0, 192}},
  	{"ycbcrNil", vgradCr(), nil, Over, color.RGBA{11, 38, 0, 255}},
  	{"ycbcrNilSrc", vgradCr(), nil, Src, color.RGBA{11, 38, 0, 255}},
  	// Uniform mask (100%, 75%, nil) and variable Gray source.
  	// At (x, y) == (8, 8):
  	// The destination pixel is {136, 0, 0, 255}.
  	// The source pixel is {136} in Gray-space, which is {136, 136, 136, 255} in RGBA-space.
  	{"gray", vgradGray(), fillAlpha(255), Over, color.RGBA{136, 136, 136, 255}},
  	{"graySrc", vgradGray(), fillAlpha(255), Src, color.RGBA{136, 136, 136, 255}},
  	{"grayAlpha", vgradGray(), fillAlpha(192), Over, color.RGBA{136, 102, 102, 255}},
  	{"grayAlphaSrc", vgradGray(), fillAlpha(192), Src, color.RGBA{102, 102, 102, 192}},
  	{"grayNil", vgradGray(), nil, Over, color.RGBA{136, 136, 136, 255}},
  	{"grayNilSrc", vgradGray(), nil, Src, color.RGBA{136, 136, 136, 255}},
  	// Uniform mask (100%, 75%, nil) and variable CMYK source.
  	// At (x, y) == (8, 8):
  	// The destination pixel is {136, 0, 0, 255}.
  	// The source pixel is {0, 136, 0, 63} in CMYK-space, which is {192, 89, 192} in RGB-space.
  	{"cmyk", vgradMagenta(), fillAlpha(255), Over, color.RGBA{192, 89, 192, 255}},
  	{"cmykSrc", vgradMagenta(), fillAlpha(255), Src, color.RGBA{192, 89, 192, 255}},
  	{"cmykAlpha", vgradMagenta(), fillAlpha(192), Over, color.RGBA{178, 67, 145, 255}},
  	{"cmykAlphaSrc", vgradMagenta(), fillAlpha(192), Src, color.RGBA{145, 67, 145, 192}},
  	{"cmykNil", vgradMagenta(), nil, Over, color.RGBA{192, 89, 192, 255}},
  	{"cmykNilSrc", vgradMagenta(), nil, Src, color.RGBA{192, 89, 192, 255}},
  	// 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, color.RGBA{81, 0, 102, 255}},
  	{"genericSrc", fillBlue(255), vgradAlpha(192), Src, color.RGBA{0, 0, 102, 102}},
  }
  
  func makeGolden(dst image.Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, 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()
  	sb := src.Bounds()
  	mb := image.Rect(-1e9, -1e9, 1e9, 1e9)
  	if mask != nil {
  		mb = mask.Bounds()
  	}
  	golden := image.NewRGBA(image.Rect(0, 0, b.Max.X, b.Max.Y))
  	for y := r.Min.Y; y < r.Max.Y; y++ {
  		sy := y + sp.Y - r.Min.Y
  		my := y + mp.Y - r.Min.Y
  		for x := r.Min.X; x < r.Max.X; x++ {
  			if !(image.Pt(x, y).In(b)) {
  				continue
  			}
  			sx := x + sp.X - r.Min.X
  			if !(image.Pt(sx, sy).In(sb)) {
  				continue
  			}
  			mx := x + mp.X - r.Min.X
  			if !(image.Pt(mx, my).In(mb)) {
  				continue
  			}
  
  			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, color.RGBA64{
  				uint16((dr*a + sr*ma) / M),
  				uint16((dg*a + sg*ma) / M),
  				uint16((db*a + sb*ma) / M),
  				uint16((da*a + sa*ma) / M),
  			})
  		}
  	}
  	return golden.SubImage(b)
  }
  
  func TestDraw(t *testing.T) {
  	rr := []image.Rectangle{
  		image.Rect(0, 0, 0, 0),
  		image.Rect(0, 0, 16, 16),
  		image.Rect(3, 5, 12, 10),
  		image.Rect(0, 0, 9, 9),
  		image.Rect(8, 8, 16, 16),
  		image.Rect(8, 0, 9, 16),
  		image.Rect(0, 8, 16, 9),
  		image.Rect(8, 8, 9, 9),
  		image.Rect(8, 8, 8, 8),
  	}
  	for _, r := range rr {
  	loop:
  		for _, test := range drawTests {
  			dst := hgradRed(255).(*image.RGBA).SubImage(r).(Image)
  			// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
  			golden := makeGolden(dst, image.Rect(0, 0, 16, 16), test.src, image.ZP, test.mask, image.ZP, test.op)
  			b := dst.Bounds()
  			if !b.Eq(golden.Bounds()) {
  				t.Errorf("draw %v %s: bounds %v versus %v", r, test.desc, dst.Bounds(), golden.Bounds())
  				continue
  			}
  			// Draw the same combination onto the actual dst using the optimized DrawMask implementation.
  			DrawMask(dst, image.Rect(0, 0, 16, 16), test.src, image.ZP, test.mask, image.ZP, test.op)
  			if image.Pt(8, 8).In(r) {
  				// 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 %v %s: at (8, 8) %v versus %v", r, 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 %v %s: at (%d, %d), %v versus golden %v", r, 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 := m.SubImage(image.Rect(5, 5, 10, 10)).(*image.RGBA)
  				src := m.SubImage(image.Rect(5+xoff, 5+yoff, 10+xoff, 10+yoff)).(*image.RGBA)
  				b := dst.Bounds()
  				// Draw the (src, mask, op) onto a copy of dst using a slow but obviously correct implementation.
  				golden := makeGolden(dst, b, src, src.Bounds().Min, nil, image.ZP, op)
  				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
  						}
  					}
  				}
  			}
  		}
  	}
  }
  
  // TestNonZeroSrcPt checks drawing with a non-zero src point parameter.
  func TestNonZeroSrcPt(t *testing.T) {
  	a := image.NewRGBA(image.Rect(0, 0, 1, 1))
  	b := image.NewRGBA(image.Rect(0, 0, 2, 2))
  	b.Set(0, 0, color.RGBA{0, 0, 0, 5})
  	b.Set(1, 0, color.RGBA{0, 0, 5, 5})
  	b.Set(0, 1, color.RGBA{0, 5, 0, 5})
  	b.Set(1, 1, color.RGBA{5, 0, 0, 5})
  	Draw(a, image.Rect(0, 0, 1, 1), b, image.Pt(1, 1), Over)
  	if !eq(color.RGBA{5, 0, 0, 5}, a.At(0, 0)) {
  		t.Errorf("non-zero src pt: want %v got %v", color.RGBA{5, 0, 0, 5}, a.At(0, 0))
  	}
  }
  
  func TestFill(t *testing.T) {
  	rr := []image.Rectangle{
  		image.Rect(0, 0, 0, 0),
  		image.Rect(0, 0, 40, 30),
  		image.Rect(10, 0, 40, 30),
  		image.Rect(0, 20, 40, 30),
  		image.Rect(10, 20, 40, 30),
  		image.Rect(10, 20, 15, 25),
  		image.Rect(10, 0, 35, 30),
  		image.Rect(0, 15, 40, 16),
  		image.Rect(24, 24, 25, 25),
  		image.Rect(23, 23, 26, 26),
  		image.Rect(22, 22, 27, 27),
  		image.Rect(21, 21, 28, 28),
  		image.Rect(20, 20, 29, 29),
  	}
  	for _, r := range rr {
  		m := image.NewRGBA(image.Rect(0, 0, 40, 30)).SubImage(r).(*image.RGBA)
  		b := m.Bounds()
  		c := color.RGBA{11, 0, 0, 255}
  		src := &image.Uniform{C: c}
  		check := func(desc string) {
  			for y := b.Min.Y; y < b.Max.Y; y++ {
  				for x := b.Min.X; x < b.Max.X; x++ {
  					if !eq(c, m.At(x, y)) {
  						t.Errorf("%s fill: at (%d, %d), sub-image bounds=%v: want %v got %v", desc, x, y, r, c, m.At(x, y))
  						return
  					}
  				}
  			}
  		}
  		// Draw 1 pixel at a time.
  		for y := b.Min.Y; y < b.Max.Y; y++ {
  			for x := b.Min.X; x < b.Max.X; x++ {
  				DrawMask(m, image.Rect(x, y, x+1, y+1), src, image.ZP, nil, image.ZP, Src)
  			}
  		}
  		check("pixel")
  		// Draw 1 row at a time.
  		c = color.RGBA{0, 22, 0, 255}
  		src = &image.Uniform{C: c}
  		for y := b.Min.Y; y < b.Max.Y; y++ {
  			DrawMask(m, image.Rect(b.Min.X, y, b.Max.X, y+1), src, image.ZP, nil, image.ZP, Src)
  		}
  		check("row")
  		// Draw 1 column at a time.
  		c = color.RGBA{0, 0, 33, 255}
  		src = &image.Uniform{C: c}
  		for x := b.Min.X; x < b.Max.X; x++ {
  			DrawMask(m, image.Rect(x, b.Min.Y, x+1, b.Max.Y), src, image.ZP, nil, image.ZP, Src)
  		}
  		check("column")
  		// Draw the whole image at once.
  		c = color.RGBA{44, 55, 66, 77}
  		src = &image.Uniform{C: c}
  		DrawMask(m, b, src, image.ZP, nil, image.ZP, Src)
  		check("whole")
  	}
  }
  
  // TestFloydSteinbergCheckerboard tests that the result of Floyd-Steinberg
  // error diffusion of a uniform 50% gray source image with a black-and-white
  // palette is a checkerboard pattern.
  func TestFloydSteinbergCheckerboard(t *testing.T) {
  	b := image.Rect(0, 0, 640, 480)
  	// We can't represent 50% exactly, but 0x7fff / 0xffff is close enough.
  	src := &image.Uniform{color.Gray16{0x7fff}}
  	dst := image.NewPaletted(b, color.Palette{color.Black, color.White})
  	FloydSteinberg.Draw(dst, b, src, image.Point{})
  	nErr := 0
  	for y := b.Min.Y; y < b.Max.Y; y++ {
  		for x := b.Min.X; x < b.Max.X; x++ {
  			got := dst.Pix[dst.PixOffset(x, y)]
  			want := uint8(x+y) % 2
  			if got != want {
  				t.Errorf("at (%d, %d): got %d, want %d", x, y, got, want)
  				if nErr++; nErr == 10 {
  					t.Fatal("there may be more errors")
  				}
  			}
  		}
  	}
  }
  
  // embeddedPaletted is an Image that behaves like an *image.Paletted but whose
  // type is not *image.Paletted.
  type embeddedPaletted struct {
  	*image.Paletted
  }
  
  // TestPaletted tests that the drawPaletted function behaves the same
  // regardless of whether dst is an *image.Paletted.
  func TestPaletted(t *testing.T) {
  	f, err := os.Open("../testdata/video-001.png")
  	if err != nil {
  		t.Fatalf("open: %v", err)
  	}
  	defer f.Close()
  	src, err := png.Decode(f)
  	if err != nil {
  		t.Fatalf("decode: %v", err)
  	}
  	b := src.Bounds()
  
  	cgaPalette := color.Palette{
  		color.RGBA{0x00, 0x00, 0x00, 0xff},
  		color.RGBA{0x55, 0xff, 0xff, 0xff},
  		color.RGBA{0xff, 0x55, 0xff, 0xff},
  		color.RGBA{0xff, 0xff, 0xff, 0xff},
  	}
  	drawers := map[string]Drawer{
  		"src":             Src,
  		"floyd-steinberg": FloydSteinberg,
  	}
  
  loop:
  	for dName, d := range drawers {
  		dst0 := image.NewPaletted(b, cgaPalette)
  		dst1 := image.NewPaletted(b, cgaPalette)
  		d.Draw(dst0, b, src, image.Point{})
  		d.Draw(embeddedPaletted{dst1}, b, src, image.Point{})
  		for y := b.Min.Y; y < b.Max.Y; y++ {
  			for x := b.Min.X; x < b.Max.X; x++ {
  				if !eq(dst0.At(x, y), dst1.At(x, y)) {
  					t.Errorf("%s: at (%d, %d), %v versus %v",
  						dName, x, y, dst0.At(x, y), dst1.At(x, y))
  					continue loop
  				}
  			}
  		}
  	}
  }
  

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