pixels: Bug fix: Reset pixels correctly

imageimpl.go

@@ -226,12 +226,18 @@ func (i *imageImpl) resetPixelsIfNeeded(target *imageImpl, context *opengl.Conte
 	if target.isDisposed() {
 		return errors.New("ebiten: target is already disposed")
 	}
+	if i.pixels == nil {
+		return nil
+	}
+	if !i.pixels.NeedsReset(target.image) {
+		return nil
+	}
 	if context == nil {
 		// context is null when this is not initialized yet.
 		i.pixels = nil
 		return nil
 	}
-	if err := i.pixels.ResetIfNeeded(target.image, context); err != nil {
+	if err := i.pixels.Reset(context); err != nil {
 		return err
 	}
 	return nil

internal/pixels/pixels.go

@@ -116,21 +116,14 @@ func (p *Pixels) Reset(context *opengl.Context) error {
 	return nil
 }
 
-func (p *Pixels) ResetIfNeeded(target *graphics.Image, context *opengl.Context) error {
+func (p *Pixels) NeedsReset(target *graphics.Image) bool {
 	if p.drawImageHistory == nil {
-		return nil
+		return false
 	}
 	if !p.hasHistoryWith(target) {
-		return nil
+		return false
 	}
-	var err error
+	return true
-	p.basePixels, err = p.image.Pixels(context)
-	if err != nil {
-		return err
-	}
-	p.baseColor = nil
-	p.drawImageHistory = nil
-	return nil
 }
 
 func (p *Pixels) HasHistory() bool {