From c54dc8ee1c7232e5f0f4567efd042fdd3e863346 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sat, 20 Aug 2016 23:25:45 +0900
Subject: [PATCH] graphics: Less calls of ReadPixelsFromVRAM

---
 imageimpl.go              | 11 ++---------
 internal/pixels/pixels.go |  6 +++---
 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/imageimpl.go b/imageimpl.go
index a11b31468..2cd3fbf30 100644
--- a/imageimpl.go
+++ b/imageimpl.go
@@ -212,19 +212,12 @@ func (i *imageImpl) resetPixelsIfDependingOn(target *imageImpl, context *opengl.
 	if target.isDisposed() {
 		return errors.New("ebiten: target is already disposed")
 	}
-	// target is an image begin tried to mutate.
+	// target is an image that is about to be tried mutating.
 	// If pixels object is related to that image, the pixels must be reset.
 	if !i.pixels.DependsOn(target.image) {
 		return nil
 	}
-	if context == nil || i.volatile {
-		// context is nil when this is not initialized yet.
-		i.pixels.MakeStale()
-		return nil
-	}
-	if err := i.pixels.ReadPixelsFromVRAM(i.image, context); err != nil {
-		return err
-	}
+	i.pixels.MakeStale()
 	return nil
 }
 
diff --git a/internal/pixels/pixels.go b/internal/pixels/pixels.go
index c1189786d..7481f2b24 100644
--- a/internal/pixels/pixels.go
+++ b/internal/pixels/pixels.go
@@ -91,7 +91,7 @@ func (p *Pixels) AppendDrawImageHistory(image *graphics.Image, vertices []int16,
 // This means Pixels members must match with acutal state in VRAM.
 func (p *Pixels) At(idx int, image *graphics.Image, context *opengl.Context) (color.Color, error) {
 	if p.basePixels == nil || p.drawImageHistory != nil || p.stale {
-		if err := p.ReadPixelsFromVRAM(image, context); err != nil {
+		if err := p.readPixelsFromVRAM(image, context); err != nil {
 			return nil, err
 		}
 	}
@@ -111,7 +111,7 @@ func (p *Pixels) DependsOn(target *graphics.Image) bool {
 	return false
 }
 
-func (p *Pixels) ReadPixelsFromVRAM(image *graphics.Image, context *opengl.Context) error {
+func (p *Pixels) readPixelsFromVRAM(image *graphics.Image, context *opengl.Context) error {
 	var err error
 	p.basePixels, err = image.Pixels(context)
 	if err != nil {
@@ -127,7 +127,7 @@ func (p *Pixels) ReadPixelsFromVRAMIfStale(image *graphics.Image, context *openg
 	if !p.stale {
 		return nil
 	}
-	return p.ReadPixelsFromVRAM(image, context)
+	return p.readPixelsFromVRAM(image, context)
 }
 
 func (p *Pixels) HasDependency() bool {