ebiten/image_test.go
2019-04-26 02:56:40 +09:00

1683 lines
38 KiB
Go

// Copyright 2016 Hajime Hoshi
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package ebiten_test
import (
"bytes"
"errors"
"image"
"image/color"
"image/draw"
_ "image/png"
"math"
"os"
"runtime"
"testing"
. "github.com/hajimehoshi/ebiten"
"github.com/hajimehoshi/ebiten/ebitenutil"
"github.com/hajimehoshi/ebiten/examples/resources/images"
"github.com/hajimehoshi/ebiten/internal/graphics"
"github.com/hajimehoshi/ebiten/internal/testflock"
)
func TestMain(m *testing.M) {
testflock.Lock()
defer testflock.Unlock()
code := 0
// Run an Ebiten process so that (*Image).At is available.
regularTermination := errors.New("regular termination")
f := func(screen *Image) error {
code = m.Run()
return regularTermination
}
if err := Run(f, 320, 240, 1, "Test"); err != nil && err != regularTermination {
panic(err)
}
os.Exit(code)
}
func openEbitenImage() (*Image, image.Image, error) {
img, _, err := image.Decode(bytes.NewReader(images.Ebiten_png))
if err != nil {
return nil, nil, err
}
eimg, err := NewImageFromImage(img, FilterNearest)
if err != nil {
return nil, nil, err
}
return eimg, img, nil
}
func abs(x int) int {
if x < 0 {
return -x
}
return x
}
// sameColors compares c1 and c2 and returns a boolean value indicating
// if the two colors are (almost) same.
//
// Pixels read from GPU might include errors (#492), and
// sameColors considers such errors as delta.
func sameColors(c1, c2 color.RGBA, delta int) bool {
return abs(int(c1.R)-int(c2.R)) <= delta &&
abs(int(c1.G)-int(c2.G)) <= delta &&
abs(int(c1.B)-int(c2.B)) <= delta &&
abs(int(c1.A)-int(c2.A)) <= delta
}
func TestImagePixels(t *testing.T) {
img0, img, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
if got := img0.Bounds().Size(); got != img.Bounds().Size() {
t.Fatalf("img size: got %d; want %d", got, img.Bounds().Size())
}
w, h := img0.Bounds().Size().X, img0.Bounds().Size().Y
// Check out of range part
w2, h2 := graphics.InternalImageSize(w), graphics.InternalImageSize(h)
for j := -100; j < h2+100; j++ {
for i := -100; i < w2+100; i++ {
got := img0.At(i, j)
want := color.RGBAModel.Convert(img.At(i, j))
if got != want {
t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
func TestImageComposition(t *testing.T) {
img2Color := color.NRGBA{0x24, 0x3f, 0x6a, 0x88}
img3Color := color.NRGBA{0x85, 0xa3, 0x08, 0xd3}
// TODO: Rename this to img0
img1, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img1.Bounds().Size().X, img1.Bounds().Size().Y
img2, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
img3, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
if err := img2.Fill(img2Color); err != nil {
t.Fatal(err)
return
}
if err := img3.Fill(img3Color); err != nil {
t.Fatal(err)
return
}
img_12_3, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
if err := img2.DrawImage(img1, nil); err != nil {
t.Fatal(err)
return
}
if err := img3.DrawImage(img2, nil); err != nil {
t.Fatal(err)
return
}
if err := img_12_3.DrawImage(img3, nil); err != nil {
t.Fatal(err)
return
}
if err := img2.Fill(img2Color); err != nil {
t.Fatal(err)
return
}
if err := img3.Fill(img3Color); err != nil {
t.Fatal(err)
return
}
img_1_23, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
if err := img3.DrawImage(img2, nil); err != nil {
t.Fatal(err)
return
}
if err := img3.DrawImage(img1, nil); err != nil {
t.Fatal(err)
return
}
if err := img_1_23.DrawImage(img3, nil); err != nil {
t.Fatal(err)
return
}
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
c1 := img_12_3.At(i, j).(color.RGBA)
c2 := img_1_23.At(i, j).(color.RGBA)
if !sameColors(c1, c2, 1) {
t.Errorf("img_12_3.At(%d, %d) = %#v; img_1_23.At(%[1]d, %[2]d) = %#[4]v", i, j, c1, c2)
}
if c1.A == 0 {
t.Fatalf("img_12_3.At(%d, %d).A = 0; nothing is rendered?", i, j)
}
if c2.A == 0 {
t.Fatalf("img_1_23.At(%d, %d).A = 0; nothing is rendered?", i, j)
}
}
}
}
func TestImageSelf(t *testing.T) {
// Note that mutex usages: without defer, unlocking is not called when panicing.
defer func() {
if r := recover(); r == nil {
t.Errorf("DrawImage must panic but not")
}
}()
img, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
img.DrawImage(img, nil)
}
func TestImageScale(t *testing.T) {
for _, scale := range []int{2, 3, 4} {
img0, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img0.Size()
img1, err := NewImage(w*scale, h*scale, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
op := &DrawImageOptions{}
op.GeoM.Scale(float64(scale), float64(scale))
if err := img1.DrawImage(img0, op); err != nil {
t.Fatal(err)
return
}
for j := 0; j < h*scale; j++ {
for i := 0; i < w*scale; i++ {
c0 := img0.At(i/scale, j/scale).(color.RGBA)
c1 := img1.At(i, j).(color.RGBA)
if c0 != c1 {
t.Fatalf("img0.At(%[1]d, %[2]d) should equal to img1.At(%[3]d, %[4]d) (with scale %[5]d) but not: %[6]v vs %[7]v", i/2, j/2, i, j, scale, c0, c1)
}
}
}
}
}
func TestImage90DegreeRotate(t *testing.T) {
img0, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img0.Size()
img1, err := NewImage(h, w, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
op := &DrawImageOptions{}
op.GeoM.Rotate(math.Pi / 2)
op.GeoM.Translate(float64(h), 0)
if err := img1.DrawImage(img0, op); err != nil {
t.Fatal(err)
return
}
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
c0 := img0.At(i, j).(color.RGBA)
c1 := img1.At(h-j-1, i).(color.RGBA)
if c0 != c1 {
t.Errorf("img0.At(%[1]d, %[2]d) should equal to img1.At(%[3]d, %[4]d) but not: %[5]v vs %[6]v", i, j, h-j-1, i, c0, c1)
}
}
}
}
func TestImageDotByDotInversion(t *testing.T) {
img0, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img0.Size()
img1, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
op := &DrawImageOptions{}
op.GeoM.Rotate(math.Pi)
op.GeoM.Translate(float64(w), float64(h))
if err := img1.DrawImage(img0, op); err != nil {
t.Fatal(err)
return
}
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
c0 := img0.At(i, j).(color.RGBA)
c1 := img1.At(w-i-1, h-j-1).(color.RGBA)
if c0 != c1 {
t.Errorf("img0.At(%[1]d, %[2]d) should equal to img1.At(%[3]d, %[4]d) but not: %[5]v vs %[6]v", i, j, w-i-1, h-j-1, c0, c1)
}
}
}
}
func TestImageReplacePixels(t *testing.T) {
// Create a dummy image so that the shared texture is used and origImg's position is shfited.
dummyImg, _ := NewImageFromImage(image.NewRGBA(image.Rect(0, 0, 16, 16)), FilterDefault)
defer dummyImg.Dispose()
_, origImg, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
// Convert to *image.RGBA just in case.
img := image.NewRGBA(origImg.Bounds())
draw.Draw(img, img.Bounds(), origImg, image.ZP, draw.Src)
size := img.Bounds().Size()
img0, err := NewImage(size.X, size.Y, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
if err := img0.ReplacePixels(img.Pix); err != nil {
t.Fatal(err)
return
}
for j := 0; j < img0.Bounds().Size().Y; j++ {
for i := 0; i < img0.Bounds().Size().X; i++ {
got := img0.At(i, j)
want := img.At(i, j)
if got != want {
t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
p := make([]uint8, 4*size.X*size.Y)
for i := range p {
p[i] = 0x80
}
if err := img0.ReplacePixels(p); err != nil {
t.Fatal(err)
return
}
// Even if p is changed after calling ReplacePixel, img0 uses the original values.
for i := range p {
p[i] = 0
}
for j := 0; j < img0.Bounds().Size().Y; j++ {
for i := 0; i < img0.Bounds().Size().X; i++ {
got := img0.At(i, j)
want := color.RGBA{0x80, 0x80, 0x80, 0x80}
if got != want {
t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
func TestImageReplacePixelsNil(t *testing.T) {
defer func() {
if r := recover(); r == nil {
t.Errorf("ReplacePixels(nil) must panic")
}
}()
img, err := NewImage(16, 16, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
img.Fill(color.White)
img.ReplacePixels(nil)
}
func TestImageDispose(t *testing.T) {
img, err := NewImage(16, 16, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
img.Fill(color.White)
if err := img.Dispose(); err != nil {
t.Errorf("img.Dipose() returns error: %v", err)
}
// The color is transparent (color.RGBA{}).
// Note that the value's type must be color.RGBA.
got := img.At(0, 0)
want := color.RGBA{}
if got != want {
t.Errorf("img.At(0, 0) got: %v, want: %v", got, want)
}
}
func min(a, b int) int {
if a < b {
return a
}
return b
}
func TestImageCompositeModeLighter(t *testing.T) {
img0, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img0.Size()
img1, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
if err := img1.Fill(color.RGBA{0x01, 0x02, 0x03, 0x04}); err != nil {
t.Fatal(err)
return
}
op := &DrawImageOptions{}
op.CompositeMode = CompositeModeLighter
if err := img1.DrawImage(img0, op); err != nil {
t.Fatal(err)
return
}
for j := 0; j < img1.Bounds().Size().Y; j++ {
for i := 0; i < img1.Bounds().Size().X; i++ {
got := img1.At(i, j).(color.RGBA)
want := img0.At(i, j).(color.RGBA)
want.R = uint8(min(0xff, int(want.R)+1))
want.G = uint8(min(0xff, int(want.G)+2))
want.B = uint8(min(0xff, int(want.B)+3))
want.A = uint8(min(0xff, int(want.A)+4))
if got != want {
t.Errorf("img1 At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
func TestNewImageFromEbitenImage(t *testing.T) {
img, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
if _, err := NewImageFromImage(img, FilterNearest); err != nil {
t.Errorf("NewImageFromImage returns error: %v", err)
}
}
func TestNewImageFromSubImage(t *testing.T) {
_, img, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := img.Bounds().Dx(), img.Bounds().Dy()
subImg := img.(*image.NRGBA).SubImage(image.Rect(1, 1, w-1, h-1))
eimg, err := NewImageFromImage(subImg, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
sw, sh := subImg.Bounds().Dx(), subImg.Bounds().Dy()
w2, h2 := eimg.Size()
if w2 != sw {
t.Errorf("eimg Width: got %#v; want %#v", w2, sw)
}
if h2 != sh {
t.Errorf("eimg Width: got %#v; want %#v", h2, sh)
}
for j := 0; j < h2; j++ {
for i := 0; i < w2; i++ {
got := eimg.At(i, j)
want := color.RGBAModel.Convert(img.At(i+1, j+1))
if got != want {
t.Errorf("img0 At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
type mutableRGBA struct {
r, g, b, a uint8
}
func (c *mutableRGBA) RGBA() (r, g, b, a uint32) {
return uint32(c.r) * 0x101, uint32(c.g) * 0x101, uint32(c.b) * 0x101, uint32(c.a) * 0x101
}
func TestImageFill(t *testing.T) {
w, h := 10, 10
img, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
clr := &mutableRGBA{0x80, 0x80, 0x80, 0x80}
if err := img.Fill(clr); err != nil {
t.Fatal(err)
return
}
clr.r = 0
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img.At(i, j)
want := color.RGBA{0x80, 0x80, 0x80, 0x80}
if got != want {
t.Errorf("img At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
// Issue #740
func TestImageClear(t *testing.T) {
const w, h = 128, 256
img, err := NewImage(w, h, FilterNearest)
if err != nil {
t.Fatal(err)
return
}
img.Fill(color.White)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img.At(i, j)
want := color.RGBA{0xff, 0xff, 0xff, 0xff}
if got != want {
t.Errorf("img At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
img.Clear()
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img.At(i, j)
want := color.RGBA{}
if got != want {
t.Errorf("img At(%d, %d): got %#v; want %#v", i, j, got, want)
}
}
}
}
// Issue #317, #558, #724
func TestImageEdge(t *testing.T) {
const (
img0Width = 16
img0Height = 16
img0InnerWidth = 10
img0InnerHeight = 10
img0OffsetWidth = (img0Width - img0InnerWidth) / 2
img0OffsetHeight = (img0Height - img0InnerHeight) / 2
img1Width = 32
img1Height = 32
)
img0, _ := NewImage(img0Width, img0Height, FilterNearest)
pixels := make([]uint8, 4*img0Width*img0Height)
for j := 0; j < img0Height; j++ {
for i := 0; i < img0Width; i++ {
idx := 4 * (i + j*img0Width)
switch {
case img0OffsetWidth <= i && i < img0Width-img0OffsetWidth &&
img0OffsetHeight <= j && j < img0Height-img0OffsetHeight:
pixels[idx] = 0xff
pixels[idx+1] = 0
pixels[idx+2] = 0
pixels[idx+3] = 0xff
default:
pixels[idx] = 0
pixels[idx+1] = 0xff
pixels[idx+2] = 0
pixels[idx+3] = 0xff
}
}
}
img0.ReplacePixels(pixels)
img1, _ := NewImage(img1Width, img1Height, FilterDefault)
red := color.RGBA{0xff, 0, 0, 0xff}
transparent := color.RGBA{0, 0, 0, 0}
angles := []float64{}
for a := 0; a < 1440; a++ {
angles = append(angles, float64(a)/1440*2*math.Pi)
}
for a := 0; a < 4096; a += 3 {
// a++ should be fine, but it takes long to test.
angles = append(angles, float64(a)/4096*2*math.Pi)
}
img0Sub := img0.SubImage(image.Rect(img0OffsetWidth, img0OffsetHeight, img0Width-img0OffsetWidth, img0Height-img0OffsetHeight)).(*Image)
for _, s := range []float64{1, 0.5, 0.25} {
for _, f := range []Filter{FilterNearest, FilterLinear} {
for _, a := range angles {
for _, testDrawTriangles := range []bool{false, true} {
img1.Clear()
w, h := img0Sub.Size()
b := img0Sub.Bounds()
var geo GeoM
geo.Translate(-float64(w)/2, -float64(h)/2)
geo.Scale(s, s)
geo.Rotate(a)
geo.Translate(img1Width/2, img1Height/2)
if !testDrawTriangles {
op := &DrawImageOptions{}
op.GeoM = geo
op.Filter = f
img1.DrawImage(img0Sub, op)
} else {
op := &DrawTrianglesOptions{}
dx0, dy0 := geo.Apply(0, 0)
dx1, dy1 := geo.Apply(float64(w), 0)
dx2, dy2 := geo.Apply(0, float64(h))
dx3, dy3 := geo.Apply(float64(w), float64(h))
vs := []Vertex{
{
DstX: float32(dx0),
DstY: float32(dy0),
SrcX: float32(b.Min.X),
SrcY: float32(b.Min.Y),
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: float32(dx1),
DstY: float32(dy1),
SrcX: float32(b.Max.X),
SrcY: float32(b.Min.Y),
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: float32(dx2),
DstY: float32(dy2),
SrcX: float32(b.Min.X),
SrcY: float32(b.Max.Y),
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: float32(dx3),
DstY: float32(dy3),
SrcX: float32(b.Max.X),
SrcY: float32(b.Max.Y),
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
}
is := graphics.QuadIndices()
op.Filter = f
img1.DrawTriangles(vs, is, img0Sub, op)
}
allTransparent := true
for j := 0; j < img1Height; j++ {
for i := 0; i < img1Width; i++ {
c := img1.At(i, j)
if c == transparent {
continue
}
allTransparent = false
switch f {
case FilterNearest:
if c == red {
continue
}
case FilterLinear:
if _, g, b, _ := c.RGBA(); g == 0 && b == 0 {
continue
}
}
t.Fatalf("img1.At(%d, %d) (filter: %d, scale: %f, angle: %f, draw-triangles?: %t) want: red or transparent, got: %v", i, j, f, s, a, testDrawTriangles, c)
}
}
if allTransparent {
t.Fatalf("img1 (filter: %d, scale: %f, angle: %f, draw-triangles?: %t) is transparent but should not", f, s, a, testDrawTriangles)
}
}
}
}
}
}
// Issue #419
func TestImageTooManyFill(t *testing.T) {
const width = 1024
indexToColor := func(index int) uint8 {
return uint8((17*index + 0x40) % 256)
}
src, _ := NewImage(1, 1, FilterNearest)
dst, _ := NewImage(width, 1, FilterNearest)
for i := 0; i < width; i++ {
c := indexToColor(i)
src.Fill(color.RGBA{c, c, c, 0xff})
op := &DrawImageOptions{}
op.GeoM.Translate(float64(i), 0)
dst.DrawImage(src, op)
}
for i := 0; i < width; i++ {
c := indexToColor(i)
got := dst.At(i, 0).(color.RGBA)
want := color.RGBA{c, c, c, 0xff}
if !sameColors(got, want, 1) {
t.Errorf("dst.At(%d, %d): got %#v, want: %#v", i, 0, got, want)
}
}
}
func BenchmarkDrawImage(b *testing.B) {
img0, _ := NewImage(16, 16, FilterNearest)
img1, _ := NewImage(16, 16, FilterNearest)
op := &DrawImageOptions{}
for i := 0; i < b.N; i++ {
img0.DrawImage(img1, op)
}
}
func TestImageLinearGradiation(t *testing.T) {
img0, _ := NewImage(2, 2, FilterNearest)
img0.ReplacePixels([]byte{
0xff, 0x00, 0x00, 0xff,
0x00, 0xff, 0x00, 0xff,
0x00, 0x00, 0xff, 0xff,
0xff, 0xff, 0xff, 0xff,
})
const w, h = 32, 32
img1, _ := NewImage(w, h, FilterNearest)
op := &DrawImageOptions{}
op.GeoM.Scale(w, h)
op.GeoM.Translate(-w/4, -h/4)
op.Filter = FilterLinear
img1.DrawImage(img0, op)
for j := 1; j < h-1; j++ {
for i := 1; i < w-1; i++ {
c := img1.At(i, j).(color.RGBA)
if c.R == 0 || c.R == 0xff {
t.Errorf("img1.At(%d, %d).R must be in between 0x01 and 0xfe but %#v", i, j, c)
}
}
}
}
func TestImageLinearEdges(t *testing.T) {
src, _ := NewImage(32, 32, FilterDefault)
dst, _ := NewImage(64, 64, FilterDefault)
src.Fill(color.RGBA{0, 0xff, 0, 0xff})
ebitenutil.DrawRect(src, 8, 8, 16, 16, color.RGBA{0xff, 0, 0, 0xff})
op := &DrawImageOptions{}
op.GeoM.Translate(8, 8)
op.GeoM.Scale(2, 2)
op.Filter = FilterLinear
dst.DrawImage(src.SubImage(image.Rect(8, 8, 24, 24)).(*Image), op)
for j := 0; j < 64; j++ {
for i := 0; i < 64; i++ {
c := dst.At(i, j).(color.RGBA)
got := c.G
want := uint8(0)
if abs(int(c.G)-int(want)) > 1 {
t.Errorf("dst At(%d, %d).G: got %#v, want: %#v", i, j, got, want)
}
}
}
}
func TestImageOutside(t *testing.T) {
src, _ := NewImage(5, 10, FilterNearest) // internal texture size is 8x16.
dst, _ := NewImage(4, 4, FilterNearest)
src.Fill(color.RGBA{0xff, 0, 0, 0xff})
cases := []struct {
X, Y, Width, Height int
}{
{-4, -4, 4, 4},
{5, 0, 4, 4},
{0, 10, 4, 4},
{5, 10, 4, 4},
{8, 0, 4, 4},
{0, 16, 4, 4},
{8, 16, 4, 4},
{8, -4, 4, 4},
{-4, 16, 4, 4},
{5, 10, 0, 0},
{5, 10, -2, -2}, // non-well-formed rectangle
}
for _, c := range cases {
dst.Clear()
op := &DrawImageOptions{}
op.GeoM.Translate(0, 0)
dst.DrawImage(src.SubImage(image.Rectangle{
Min: image.Pt(c.X, c.Y),
Max: image.Pt(c.X+c.Width, c.Y+c.Height),
}).(*Image), op)
for j := 0; j < 4; j++ {
for i := 0; i < 4; i++ {
got := dst.At(i, j).(color.RGBA)
want := color.RGBA{0, 0, 0, 0}
if got != want {
t.Errorf("src(x: %d, y: %d, w: %d, h: %d), dst At(%d, %d): got %#v, want: %#v", c.X, c.Y, c.Width, c.Height, i, j, got, want)
}
}
}
}
}
func TestImageOutsideUpperLeft(t *testing.T) {
src, _ := NewImage(4, 4, FilterNearest)
dst1, _ := NewImage(16, 16, FilterNearest)
dst2, _ := NewImage(16, 16, FilterNearest)
src.Fill(color.RGBA{0xff, 0, 0, 0xff})
op := &DrawImageOptions{}
op.GeoM.Rotate(math.Pi / 4)
dst1.DrawImage(src.SubImage(image.Rect(-4, -4, 8, 8)).(*Image), op)
op = &DrawImageOptions{}
// The outside part of the source rect is just ignored.
// This behavior was changed as of 1.9.0-alpha.
// op.GeoM.Translate(4, 4)
op.GeoM.Rotate(math.Pi / 4)
dst2.DrawImage(src, op)
for j := 0; j < 16; j++ {
for i := 0; i < 16; i++ {
got := dst1.At(i, j).(color.RGBA)
want := dst2.At(i, j).(color.RGBA)
if got != want {
t.Errorf("got: dst1.At(%d, %d): %#v, want: dst2.At(%d, %d): %#v", i, j, got, i, j, want)
}
}
}
}
func TestImageSize(t *testing.T) {
const (
w = 17
h = 31
)
img, _ := NewImage(w, h, FilterDefault)
gotW, gotH := img.Size()
if gotW != w {
t.Errorf("got: %d, want: %d", gotW, w)
}
if gotH != h {
t.Errorf("got: %d, want: %d", gotH, h)
}
}
func TestImageSize1(t *testing.T) {
src, _ := NewImage(1, 1, FilterNearest)
dst, _ := NewImage(1, 1, FilterNearest)
src.Fill(color.White)
dst.DrawImage(src, nil)
got := src.At(0, 0).(color.RGBA)
want := color.RGBA{0xff, 0xff, 0xff, 0xff}
if !sameColors(got, want, 1) {
t.Errorf("got: %#v, want: %#v", got, want)
}
}
func TestImageSize4096(t *testing.T) {
src, _ := NewImage(4096, 4096, FilterNearest)
dst, _ := NewImage(4096, 4096, FilterNearest)
pix := make([]byte, 4096*4096*4)
for i := 0; i < 4096; i++ {
j := 4095
idx := 4 * (i + j*4096)
pix[idx] = uint8(i + j)
pix[idx+1] = uint8((i + j) >> 8)
pix[idx+2] = uint8((i + j) >> 16)
pix[idx+3] = 0xff
}
for j := 0; j < 4096; j++ {
i := 4095
idx := 4 * (i + j*4096)
pix[idx] = uint8(i + j)
pix[idx+1] = uint8((i + j) >> 8)
pix[idx+2] = uint8((i + j) >> 16)
pix[idx+3] = 0xff
}
src.ReplacePixels(pix)
dst.DrawImage(src, nil)
for i := 4095; i < 4096; i++ {
j := 4095
got := dst.At(i, j).(color.RGBA)
want := color.RGBA{uint8(i + j), uint8((i + j) >> 8), uint8((i + j) >> 16), 0xff}
if got != want {
t.Errorf("At(%d, %d): got: %#v, want: %#v", i, j, got, want)
}
}
for j := 4095; j < 4096; j++ {
i := 4095
got := dst.At(i, j).(color.RGBA)
want := color.RGBA{uint8(i + j), uint8((i + j) >> 8), uint8((i + j) >> 16), 0xff}
if got != want {
t.Errorf("At(%d, %d): got: %#v, want: %#v", i, j, got, want)
}
}
}
func TestImageCopy(t *testing.T) {
defer func() {
if r := recover(); r == nil {
t.Errorf("copying image and using it must panic")
}
}()
img0, _ := NewImage(256, 256, FilterDefault)
img1 := *img0
img1.Fill(color.Transparent)
}
func TestImageStretch(t *testing.T) {
img0, _ := NewImage(16, 17, FilterDefault)
pix := make([]byte, 4*16*17)
for i := 0; i < 16*16; i++ {
pix[4*i] = 0xff
pix[4*i+3] = 0xff
}
for i := 0; i < 16; i++ {
pix[4*(16*16+i)+1] = 0xff
pix[4*(16*16+i)+3] = 0xff
}
img0.ReplacePixels(pix)
// TODO: 4096 doesn't pass on MacBook Pro (#611).
const h = 4000
img1, _ := NewImage(16, h, FilterDefault)
for i := 1; i < h; i++ {
img1.Clear()
op := &DrawImageOptions{}
op.GeoM.Scale(1, float64(i)/16)
img1.DrawImage(img0.SubImage(image.Rect(0, 0, 16, 16)).(*Image), op)
for j := -1; j <= 1; j++ {
got := img1.At(0, i+j).(color.RGBA)
want := color.RGBA{}
if j < 0 {
want = color.RGBA{0xff, 0, 0, 0xff}
}
if got != want {
t.Fatalf("At(%d, %d) (i=%d): got: %#v, want: %#v", 0, i+j, i, got, want)
}
}
}
}
func TestImageSprites(t *testing.T) {
const (
width = 512
height = 512
)
src, _ := NewImage(4, 4, FilterNearest)
src.Fill(color.RGBA{0xff, 0xff, 0xff, 0xff})
dst, _ := NewImage(width, height, FilterNearest)
for j := 0; j < height/4; j++ {
for i := 0; i < width/4; i++ {
op := &DrawImageOptions{}
op.GeoM.Translate(float64(i*4), float64(j*4))
dst.DrawImage(src, op)
}
}
for j := 0; j < height/4; j++ {
for i := 0; i < width/4; i++ {
got := dst.At(i*4, j*4).(color.RGBA)
want := color.RGBA{0xff, 0xff, 0xff, 0xff}
if !sameColors(got, want, 1) {
t.Errorf("dst.At(%d, %d): got %#v, want: %#v", i*4, j*4, got, want)
}
}
}
}
func TestImageMipmap(t *testing.T) {
src, _, err := openEbitenImage()
if err != nil {
t.Fatal(err)
return
}
w, h := src.Size()
l1, _ := NewImage(w/2, h/2, FilterDefault)
op := &DrawImageOptions{}
op.GeoM.Scale(1/2.0, 1/2.0)
op.Filter = FilterLinear
l1.DrawImage(src, op)
l1w, l1h := l1.Size()
l2, _ := NewImage(l1w/2, l1h/2, FilterDefault)
op = &DrawImageOptions{}
op.GeoM.Scale(1/2.0, 1/2.0)
op.Filter = FilterLinear
l2.DrawImage(l1, op)
gotDst, _ := NewImage(w, h, FilterDefault)
op = &DrawImageOptions{}
op.GeoM.Scale(1/5.0, 1/5.0)
op.Filter = FilterLinear
gotDst.DrawImage(src, op)
wantDst, _ := NewImage(w, h, FilterDefault)
op = &DrawImageOptions{}
op.GeoM.Scale(4.0/5.0, 4.0/5.0)
op.Filter = FilterLinear
wantDst.DrawImage(l2, op)
for j := 0; j < h; j++ {
for i := 0; i < h; i++ {
got := gotDst.At(i, j).(color.RGBA)
want := wantDst.At(i, j).(color.RGBA)
if !sameColors(got, want, 1) {
t.Errorf("At(%d, %d): got: %#v, want: %#v", i, j, got, want)
}
}
}
}
// Issue #710
func TestImageMipmapColor(t *testing.T) {
img0, _ := NewImage(256, 256, FilterDefault)
img1, _ := NewImage(128, 128, FilterDefault)
img1.Fill(color.White)
for i := 0; i < 8; i++ {
img0.Clear()
s := 1 - float64(i)/8
op := &DrawImageOptions{}
op.Filter = FilterLinear
op.GeoM.Scale(s, s)
op.ColorM.Scale(1, 1, 0, 1)
img0.DrawImage(img1, op)
op.GeoM.Translate(128, 0)
op.ColorM.Reset()
op.ColorM.Scale(0, 1, 1, 1)
img0.DrawImage(img1, op)
want := color.RGBA{0, 0xff, 0xff, 0xff}
got := img0.At(128, 0)
if got != want {
t.Errorf("want: %#v, got: %#v", want, got)
}
}
}
// Issue #725
func TestImageMiamapAndDrawTriangle(t *testing.T) {
img0, _ := NewImage(32, 32, FilterDefault)
img1, _ := NewImage(128, 128, FilterDefault)
img2, _ := NewImage(128, 128, FilterDefault)
// Fill img1 red and create img1's mipmap
img1.Fill(color.RGBA{0xff, 0, 0, 0xff})
op := &DrawImageOptions{}
op.GeoM.Scale(0.25, 0.25)
op.Filter = FilterLinear
img0.DrawImage(img1, op)
// Call DrawTriangle on img1 and fill it with green
img2.Fill(color.RGBA{0, 0xff, 0, 0xff})
vs := []Vertex{
{
DstX: 0,
DstY: 0,
SrcX: 0,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: 128,
DstY: 0,
SrcX: 128,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: 0,
DstY: 128,
SrcX: 0,
SrcY: 128,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: 128,
DstY: 128,
SrcX: 128,
SrcY: 128,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
}
img1.DrawTriangles(vs, []uint16{0, 1, 2, 1, 2, 3}, img2, nil)
// Draw img1 (green) again. Confirm mipmap is correctly updated.
img0.Clear()
op = &DrawImageOptions{}
op.GeoM.Scale(0.25, 0.25)
op.Filter = FilterLinear
img0.DrawImage(img1, op)
w, h := img0.Size()
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
c := img0.At(i, j).(color.RGBA)
if c.R != 0 {
t.Errorf("img0.At(%d, %d): red want %d got %d", i, j, 0, c.R)
}
}
}
}
func TestImageSubImageAt(t *testing.T) {
img, _ := NewImage(16, 16, FilterDefault)
img.Fill(color.RGBA{0xff, 0, 0, 0xff})
got := img.SubImage(image.Rect(1, 1, 16, 16)).At(0, 0).(color.RGBA)
want := color.RGBA{}
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
got = img.SubImage(image.Rect(1, 1, 16, 16)).At(1, 1).(color.RGBA)
want = color.RGBA{0xff, 0, 0, 0xff}
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
}
func TestImageSubImageSize(t *testing.T) {
img, _ := NewImage(16, 16, FilterDefault)
img.Fill(color.RGBA{0xff, 0, 0, 0xff})
got, _ := img.SubImage(image.Rect(1, 1, 16, 16)).(*Image).Size()
want := 15
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
}
func TestImageDrawImmediately(t *testing.T) {
const w, h = 16, 16
img0, _ := NewImage(w, h, FilterDefault)
img1, _ := NewImage(w, h, FilterDefault)
// Do not manipulate img0 here.
img0.Fill(color.RGBA{0xff, 0, 0, 0xff})
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img0.At(i, j).(color.RGBA)
want := color.RGBA{0xff, 0, 0, 0xff}
if got != want {
t.Errorf("img0.At(%d, %d): got %v, want: %v", i, j, got, want)
}
}
}
img0.DrawImage(img1, nil)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img0.At(i, j).(color.RGBA)
want := color.RGBA{0xff, 0, 0, 0xff}
if got != want {
t.Errorf("img0.At(%d, %d): got %v, want: %v", i, j, got, want)
}
}
}
}
// Issue #669, #759
func TestImageLinearFilterGlitch(t *testing.T) {
const w, h = 200, 12
const scale = 1.2
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(int(math.Floor(w*scale)), h, FilterDefault)
pix := make([]byte, 4*w*h)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
idx := i + w*j
if j < 3 {
pix[4*idx] = 0xff
pix[4*idx+1] = 0xff
pix[4*idx+2] = 0xff
pix[4*idx+3] = 0xff
} else {
pix[4*idx] = 0
pix[4*idx+1] = 0
pix[4*idx+2] = 0
pix[4*idx+3] = 0xff
}
}
}
src.ReplacePixels(pix)
op := &DrawImageOptions{}
op.GeoM.Scale(scale, 1)
op.Filter = FilterLinear
dst.DrawImage(src, op)
for j := 1; j < h-1; j++ {
offset := int(math.Ceil(scale))
for i := offset; i < int(math.Floor(w*scale))-offset; i++ {
got := dst.At(i, j).(color.RGBA)
var want color.RGBA
if j < 3 {
want = color.RGBA{0xff, 0xff, 0xff, 0xff}
} else {
want = color.RGBA{0, 0, 0, 0xff}
}
if got != want {
t.Errorf("src.At(%d, %d): got: %v, want: %v", i, j, got, want)
}
}
}
}
func TestImageAddressRepeat(t *testing.T) {
const w, h = 16, 16
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(w, h, FilterDefault)
pix := make([]byte, 4*w*h)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
idx := 4 * (i + j*w)
if 4 <= i && i < 8 && 4 <= j && j < 8 {
pix[idx] = byte(i-4) * 0x10
pix[idx+1] = byte(j-4) * 0x10
pix[idx+2] = 0
pix[idx+3] = 0xff
} else {
pix[idx] = 0
pix[idx+1] = 0
pix[idx+2] = 0xff
pix[idx+3] = 0xff
}
}
}
src.ReplacePixels(pix)
vs := []Vertex{
{
DstX: 0,
DstY: 0,
SrcX: 0,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: w,
DstY: 0,
SrcX: w,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: 0,
DstY: h,
SrcX: 0,
SrcY: h,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: w,
DstY: h,
SrcX: w,
SrcY: h,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
}
is := []uint16{0, 1, 2, 1, 2, 3}
op := &DrawTrianglesOptions{}
op.Address = AddressRepeat
dst.DrawTriangles(vs, is, src.SubImage(image.Rect(4, 4, 8, 8)).(*Image), op)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := dst.At(i, j).(color.RGBA)
want := color.RGBA{byte(i%4) * 0x10, byte(j%4) * 0x10, 0, 0xff}
if !sameColors(got, want, 1) {
t.Errorf("dst.At(%d, %d): got %v, want: %v", i, j, got, want)
}
}
}
}
func TestImageReplacePixelsAfterClear(t *testing.T) {
const w, h = 256, 256
img, _ := NewImage(w, h, FilterDefault)
img.ReplacePixels(make([]byte, 4*w*h))
// Clear used to call DrawImage to clear the image, which was the cause of crash. It is because after
// DrawImage is called, ReplacePixels for a region is forbidden.
//
// Now ReplacePixels was always called at Clear instead.
img.Clear()
img.ReplacePixels(make([]byte, 4*w*h))
// The test passes if this doesn't crash.
}
func TestImageSet(t *testing.T) {
type Pt struct {
X, Y int
}
const w, h = 16, 16
img, _ := NewImage(w, h, FilterDefault)
colors := map[Pt]color.RGBA{
{1, 2}: {3, 4, 5, 6},
{7, 8}: {9, 10, 11, 12},
{13, 14}: {15, 16, 17, 18},
}
for p, c := range colors {
img.Set(p.X, p.Y, c)
}
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := img.At(i, j).(color.RGBA)
var want color.RGBA
if c, ok := colors[Pt{i, j}]; ok {
want = c
}
if got != want {
t.Errorf("img.At(%d, %d): got: %v, want: %v", i, j, got, want)
}
}
}
}
func TestImageSetAndDraw(t *testing.T) {
type Pt struct {
X, Y int
}
const w, h = 16, 16
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(w, h, FilterDefault)
colors := map[Pt]color.RGBA{
{1, 2}: {3, 4, 5, 6},
{7, 8}: {9, 10, 11, 12},
{13, 14}: {15, 16, 17, 18},
}
for p, c := range colors {
src.Set(p.X, p.Y, c)
dst.Set(p.X+1, p.Y+1, c)
}
dst.DrawImage(src, nil)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := dst.At(i, j).(color.RGBA)
var want color.RGBA
if c, ok := colors[Pt{i, j}]; ok {
want = c
}
if c, ok := colors[Pt{i - 1, j - 1}]; ok {
want = c
}
if got != want {
t.Errorf("img.At(%d, %d): got: %v, want: %v", i, j, got, want)
}
}
}
src.Clear()
dst.Clear()
for p, c := range colors {
src.Set(p.X, p.Y, c)
dst.Set(p.X+1, p.Y+1, c)
}
op := &DrawImageOptions{}
op.GeoM.Translate(2, 2)
dst.DrawImage(src.SubImage(image.Rect(2, 2, w-2, h-2)).(*Image), op)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := dst.At(i, j).(color.RGBA)
var want color.RGBA
if 2 <= i && 2 <= j && i < w-2 && j < h-2 {
if c, ok := colors[Pt{i, j}]; ok {
want = c
}
}
if c, ok := colors[Pt{i - 1, j - 1}]; ok {
want = c
}
if got != want {
t.Errorf("img.At(%d, %d): got: %v, want: %v", i, j, got, want)
}
}
}
}
func TestImageAlphaOnBlack(t *testing.T) {
const w, h = 16, 16
src0, _ := NewImage(w, h, FilterDefault)
src1, _ := NewImage(w, h, FilterDefault)
dst0, _ := NewImage(w, h, FilterDefault)
dst1, _ := NewImage(w, h, FilterDefault)
pix0 := make([]byte, 4*w*h)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
if (i/3)%2 == (j/3)%2 {
pix0[4*(i+j*w)] = 0xff
pix0[4*(i+j*w)+1] = 0xff
pix0[4*(i+j*w)+2] = 0xff
pix0[4*(i+j*w)+3] = 0xff
}
}
}
src0.ReplacePixels(pix0)
pix1 := make([]byte, 4*w*h)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
if (i/3)%2 == (j/3)%2 {
pix1[4*(i+j*w)] = 0xff
pix1[4*(i+j*w)+1] = 0xff
pix1[4*(i+j*w)+2] = 0xff
pix1[4*(i+j*w)+3] = 0xff
} else {
pix1[4*(i+j*w)] = 0
pix1[4*(i+j*w)+1] = 0
pix1[4*(i+j*w)+2] = 0
pix1[4*(i+j*w)+3] = 0xff
}
}
}
src1.ReplacePixels(pix1)
dst0.Fill(color.Black)
dst1.Fill(color.Black)
op := &DrawImageOptions{}
op.GeoM.Scale(0.5, 0.5)
op.Filter = FilterLinear
dst0.DrawImage(src0, op)
dst1.DrawImage(src1, op)
gray := false
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := dst0.At(i, j)
want := dst1.At(i, j)
if got != want {
t.Errorf("At(%d, %d): got: %v, want: %v", i, j, got, want)
}
if r := got.(color.RGBA).R; 0 < r && r < 255 {
gray = true
}
}
}
if !gray {
t.Errorf("gray must be included in the results but not")
}
}
func TestImageDrawTrianglesWithSubImage(t *testing.T) {
const w, h = 16, 16
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(w, h, FilterDefault)
pix := make([]byte, 4*w*h)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
if 4 <= i && i < 8 && 4 <= j && j < 8 {
pix[4*(i+j*w)] = 0xff
pix[4*(i+j*w)+1] = 0
pix[4*(i+j*w)+2] = 0
pix[4*(i+j*w)+3] = 0xff
} else {
pix[4*(i+j*w)] = 0
pix[4*(i+j*w)+1] = 0xff
pix[4*(i+j*w)+2] = 0
pix[4*(i+j*w)+3] = 0xff
}
}
}
src.ReplacePixels(pix)
vs := []Vertex{
{
DstX: 0,
DstY: 0,
SrcX: 0,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: w,
DstY: 0,
SrcX: w,
SrcY: 0,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: 0,
DstY: h,
SrcX: 0,
SrcY: h,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
{
DstX: w,
DstY: h,
SrcX: w,
SrcY: h,
ColorR: 1,
ColorG: 1,
ColorB: 1,
ColorA: 1,
},
}
is := []uint16{0, 1, 2, 1, 2, 3}
op := &DrawTrianglesOptions{}
dst.DrawTriangles(vs, is, src.SubImage(image.Rect(4, 4, 8, 8)).(*Image), op)
for j := 0; j < h; j++ {
for i := 0; i < w; i++ {
got := dst.At(i, j).(color.RGBA)
var want color.RGBA
if 4 <= i && i < 8 && 4 <= j && j < 8 {
want = src.At(i, j).(color.RGBA)
}
if !sameColors(got, want, 1) {
t.Errorf("dst.At(%d, %d): got %v, want: %v", i, j, got, want)
}
}
}
}
// Issue #823
func TestImageAtAfterDisposingSubImage(t *testing.T) {
img, _ := NewImage(16, 16, FilterDefault)
img.Set(0, 0, color.White)
img.SubImage(image.Rect(0, 0, 16, 16))
runtime.GC()
got := img.At(0, 0)
want := color.RGBA{0xff, 0xff, 0xff, 0xff}
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
img.Set(0, 1, color.White)
sub := img.SubImage(image.Rect(0, 0, 16, 16)).(*Image)
sub.Dispose()
got = img.At(0, 1)
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
}
func TestImageSubImageSubImage(t *testing.T) {
img, _ := NewImage(16, 16, FilterDefault)
img.Fill(color.White)
sub0 := img.SubImage(image.Rect(0, 0, 12, 12)).(*Image)
sub1 := sub0.SubImage(image.Rect(4, 4, 16, 16)).(*Image)
cases := []struct {
X int
Y int
Color color.RGBA
}{
{
X: 0,
Y: 0,
Color: color.RGBA{},
},
{
X: 4,
Y: 4,
Color: color.RGBA{0xff, 0xff, 0xff, 0xff},
},
{
X: 15,
Y: 15,
Color: color.RGBA{},
},
}
for _, c := range cases {
got := sub1.At(c.X, c.Y)
want := c.Color
if got != want {
t.Errorf("At(%d, %d): got: %v, want: %v", c.X, c.Y, got, want)
}
}
}
// Issue 839
func TestImageTooSmallMipmap(t *testing.T) {
const w, h = 16, 16
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(w, h, FilterDefault)
src.Fill(color.White)
op := &DrawImageOptions{}
op.GeoM.Scale(1, 0.24)
op.Filter = FilterLinear
dst.DrawImage(src.SubImage(image.Rect(5, 0, 6, 16)).(*Image), op)
got := dst.At(0, 0).(color.RGBA)
want := color.RGBA{0xff, 0xff, 0xff, 0xff}
if got != want {
t.Errorf("got: %v, want: %v", got, want)
}
}
func TestImageZeroSizedMipmap(t *testing.T) {
const w, h = 16, 16
src, _ := NewImage(w, h, FilterDefault)
dst, _ := NewImage(w, h, FilterDefault)
op := &DrawImageOptions{}
op.Filter = FilterLinear
dst.DrawImage(src.SubImage(image.ZR).(*Image), op)
}