imaging/tools_test.go

package imaging

import (
	"image"
	"testing"
)

func TestCrop(t *testing.T) {
	td := []struct {
		desc string
		src  image.Image
		r    image.Rectangle
		want *image.NRGBA
	}{
		{
			"Crop 2x3 2x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			image.Rect(-1, 0, 1, 1),
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 1),
				Stride: 2 * 4,
				Pix: []uint8{
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
				},
			},
		},
	}
	for _, d := range td {
		got := Crop(d.src, d.r)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestCropCenter(t *testing.T) {
	td := []struct {
		desc string
		src  image.Image
		w, h int
		want *image.NRGBA
	}{
		{
			"CropCenter 2x3 2x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			2, 1,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 1),
				Stride: 2 * 4,
				Pix: []uint8{
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
				},
			},
		},
		{
			"CropCenter 2x3 0x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			0, 1,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 0, 0),
				Stride: 0,
				Pix:    []uint8{},
			},
		},
		{
			"CropCenter 2x3 5x5",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			5, 5,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 3),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
		},
	}
	for _, d := range td {
		got := CropCenter(d.src, d.w, d.h)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestCropAnchor(t *testing.T) {
	td := []struct {
		desc   string
		src    image.Image
		w, h   int
		anchor Anchor
		want   *image.NRGBA
	}{
		{
			"CropAnchor 4x4 2x2 TopLeft",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			TopLeft,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 Top",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			Top,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
					0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 TopRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			TopRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 Left",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			Left,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 Center",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			Center,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b,
					0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 Right",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			Right,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 BottomLeft",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			BottomLeft,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 Bottom",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			Bottom,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
					0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b,
				},
			},
		},
		{
			"CropAnchor 4x4 2x2 BottomRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			2, 2,
			BottomRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
		},
		{
			"CropAnchor 4x4 0x0 BottomRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			0, 0,
			BottomRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 0, 0),
				Stride: 0,
				Pix:    []uint8{},
			},
		},
		{
			"CropAnchor 4x4 100x100 BottomRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			100, 100,
			BottomRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 4, 4),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
		},
		{
			"CropAnchor 4x4 1x100 BottomRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			1, 100,
			BottomRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 1, 4),
				Stride: 1 * 4,
				Pix: []uint8{
					0x0c, 0x0d, 0x0e, 0x0f,
					0x1c, 0x1d, 0x1e, 0x1f,
					0x2c, 0x2d, 0x2e, 0x2f,
					0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
		},
		{
			"CropAnchor 4x4 0x100 BottomRight",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 3, 3),
				Stride: 4 * 4,
				Pix: []uint8{
					0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
					0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
					0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
					0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
				},
			},
			0, 100,
			BottomRight,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 0, 0),
				Stride: 0,
				Pix:    []uint8{},
			},
		},
	}
	for _, d := range td {
		got := CropAnchor(d.src, d.w, d.h, d.anchor)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestPaste(t *testing.T) {
	td := []struct {
		desc string
		src1 image.Image
		src2 image.Image
		p    image.Point
		want *image.NRGBA
	}{
		{
			"Paste 2x3 2x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(1, 1, 3, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
				},
			},
			image.Pt(-1, 0),
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 3),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
		},
	}
	for _, d := range td {
		got := Paste(d.src1, d.src2, d.p)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestPasteCenter(t *testing.T) {
	td := []struct {
		desc string
		src1 image.Image
		src2 image.Image
		want *image.NRGBA
	}{
		{
			"PasteCenter 2x3 2x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0xff, 0x00, 0x00, 0x00, 0x00, 0xff, 0x00, 0x00,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(1, 1, 3, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 3),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
		},
	}
	for _, d := range td {
		got := PasteCenter(d.src1, d.src2)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestOverlay(t *testing.T) {
	td := []struct {
		desc string
		src1 image.Image
		src2 image.Image
		p    image.Point
		a    float64
		want *image.NRGBA
	}{
		{
			"Overlay 2x3 2x1 1.0",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0x60, 0x00, 0x90, 0xff, 0xff, 0x00, 0x99, 0x7f,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(1, 1, 3, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x20, 0x40, 0x80, 0x7f, 0xaa, 0xbb, 0xcc, 0xff,
				},
			},
			image.Pt(-1, 0),
			1.0,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 3),
				Stride: 2 * 4,
				Pix: []uint8{
					0x00, 0x11, 0x22, 0x33, 0xcc, 0xdd, 0xee, 0xff,
					0x40, 0x1f, 0x88, 0xff, 0xaa, 0xbb, 0xcc, 0xff,
					0x00, 0x00, 0xff, 0x00, 0x00, 0x00, 0x00, 0xff,
				},
			},
		},
		{
			"Overlay 2x2 2x2 0.5",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 1),
				Stride: 2 * 4,
				Pix: []uint8{
					0xff, 0x00, 0x00, 0xff, 0x00, 0xff, 0x00, 0xff,
					0x00, 0x00, 0xff, 0xff, 0x20, 0x20, 0x20, 0x00,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 1),
				Stride: 2 * 4,
				Pix: []uint8{
					0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0x00, 0x00,
					0xff, 0xff, 0x00, 0xff, 0x20, 0x20, 0x20, 0xff,
				},
			},
			image.Pt(-1, -1),
			0.5,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0xff, 0x7f, 0x7f, 0xff, 0x00, 0xff, 0x00, 0xff,
					0x7f, 0x7f, 0x7f, 0xff, 0x20, 0x20, 0x20, 0x7f,
				},
			},
		},
	}
	for _, d := range td {
		got := Overlay(d.src1, d.src2, d.p, d.a)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}

func TestOverlayCenter(t *testing.T) {
	td := []struct {
		desc string
		src1 image.Image
		src2 image.Image
		a    float64
		want *image.NRGBA
	}{
		{
			"OverlayCenter 2x3 2x1",
			&image.NRGBA{
				Rect:   image.Rect(-1, -1, 1, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x10, 0x10, 0x10, 0xff, 0x10, 0x10, 0x10, 0xff,
					0x10, 0x10, 0x10, 0xff, 0x10, 0x10, 0x10, 0xff,
					0x10, 0x10, 0x10, 0xff, 0x10, 0x10, 0x10, 0xff,
				},
			},
			&image.NRGBA{
				Rect:   image.Rect(1, 1, 3, 2),
				Stride: 2 * 4,
				Pix: []uint8{
					0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80, 0x80,
				},
			},
			0.5,
			&image.NRGBA{
				Rect:   image.Rect(0, 0, 2, 3),
				Stride: 2 * 4,
				Pix: []uint8{
					0x10, 0x10, 0x10, 0xff, 0x10, 0x10, 0x10, 0xff,
					0x2c, 0x2c, 0x2c, 0xff, 0x2c, 0x2c, 0x2c, 0xff,
					0x10, 0x10, 0x10, 0xff, 0x10, 0x10, 0x10, 0xff,
				},
			},
		},
	}
	for _, d := range td {
		got := OverlayCenter(d.src1, d.src2, 0.5)
		want := d.want
		if !compareNRGBA(got, want, 0) {
			t.Errorf("test [%s] failed: %#v", d.desc, got)
		}
	}
}