vector: bug fix: FillRect or other utility functions on a sub-image didn't work correctly

Closes #3330

Author: hajimehoshi

image.go

@@ -71,6 +71,7 @@ type Image struct {
 	atime atomic.Int64
 
 	// usageCallbacks are callbacks that are invoked when the image is used.
+	// usageCallbacks is valid only when the image is not a sub-image.
 	usageCallbacks map[int64]func()
 
 	// inUsageCallbacks reports whether the image is in usageCallbacks.
@@ -1601,6 +1602,9 @@ func addUsageCallback(img *Image, callback func()) int64 {
 }
 
 func (i *Image) addUsageCallback(callback func()) int64 {
+	if i.isSubImage() {
+		return i.original.addUsageCallback(callback)
+	}
 	if i.usageCallbacks == nil {
 		i.usageCallbacks = map[int64]func(){}
 	}
@@ -1615,10 +1619,19 @@ func removeUsageCallback(img *Image, token int64) {
 }
 
 func (i *Image) removeUsageCallback(token int64) {
+	if i.isSubImage() {
+		i.original.removeUsageCallback(token)
+		return
+	}
 	delete(i.usageCallbacks, token)
 }
 
 func (i *Image) invokeUsageCallbacks() {
+	if i.isSubImage() {
+		i.original.invokeUsageCallbacks()
+		return
+	}
+
 	if i.inUsageCallbacks {
 		return
 	}

vector/util_test.go

@@ -15,6 +15,7 @@
 package vector_test
 
 import (
+	"image"
 	"image/color"
 	"testing"
 
@@ -44,3 +45,98 @@ func TestStrokeRectAntiAlias(t *testing.T) {
 		t.Errorf("got: %v, want: %v", got, want)
 	}
 }
+
+// Issue #3330
+func TestFillRectSubImage(t *testing.T) {
+	dst := ebiten.NewImage(16, 16)
+
+	dst2 := dst.SubImage(image.Rect(0, 0, 8, 8)).(*ebiten.Image)
+	vector.FillRect(dst2, 0, 0, 8, 8, color.White, true)
+	if got, want := dst.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+
+	dst3 := dst2.SubImage(image.Rect(4, 4, 8, 8)).(*ebiten.Image)
+	vector.FillRect(dst3, 4, 4, 4, 4, color.Black, true)
+	if got, want := dst.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst3.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+}
+
+// Issue #3330
+func TestFillCircleSubImage(t *testing.T) {
+	dst := ebiten.NewImage(16, 16)
+
+	dst2 := dst.SubImage(image.Rect(0, 0, 8, 8)).(*ebiten.Image)
+	vector.FillCircle(dst2, 4, 4, 4, color.White, true)
+	if got, want := dst.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+
+	dst3 := dst2.SubImage(image.Rect(4, 4, 8, 8)).(*ebiten.Image)
+	vector.FillCircle(dst3, 6, 6, 4, color.Black, true)
+	if got, want := dst.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst3.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+}
+
+// Issue #3330
+func TestFillPathSubImage(t *testing.T) {
+	dst := ebiten.NewImage(16, 16)
+
+	dst2 := dst.SubImage(image.Rect(0, 0, 8, 8)).(*ebiten.Image)
+	var p vector.Path
+	p.MoveTo(0, 0)
+	p.LineTo(8, 0)
+	p.LineTo(8, 8)
+	p.LineTo(0, 8)
+	p.Close()
+	op := &vector.DrawPathOptions{}
+	op.ColorScale.ScaleWithColor(color.White)
+	op.AntiAlias = true
+	vector.FillPath(dst2, &p, nil, op)
+	if got, want := dst.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0xff, 0xff, 0xff, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+
+	dst3 := dst2.SubImage(image.Rect(4, 4, 8, 8)).(*ebiten.Image)
+	var p2 vector.Path
+	p2.MoveTo(4, 4)
+	p2.LineTo(8, 4)
+	p2.LineTo(8, 8)
+	p2.LineTo(4, 8)
+	p2.Close()
+	op.ColorScale.Reset()
+	op.ColorScale.ScaleWithColor(color.Black)
+	vector.FillPath(dst3, &p2, nil, op)
+	if got, want := dst.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst2.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+	if got, want := dst3.At(5, 5), (color.RGBA{0x00, 0x00, 0x00, 0xff}); got != want {
+		t.Errorf("got: %v, want: %v", got, want)
+	}
+}