From e8e502cc26e689a3d7b477a9dbb83389f42a6d7f Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Wed, 3 May 2017 03:03:13 +0900
Subject: [PATCH] graphics: Bug fix: disposing check must be done before any
 operations

---
 image.go | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/image.go b/image.go
index 4c918b665..446e2ac40 100644
--- a/image.go
+++ b/image.go
@@ -191,6 +191,9 @@ func (i *Image) Fill(clr color.Color) error {
 //
 // DrawImage always returns nil as of 1.5.0-alpha.
 func (i *Image) DrawImage(image *Image, options *DrawImageOptions) error {
+	if i.restorable == nil {
+		return nil
+	}
 	theImagesForRestoring.resetPixelsIfDependingOn(i)
 	// Calculate vertices before locking because the user can do anything in
 	// options.ImageParts interface without deadlock (e.g. Call Image functions).
@@ -216,9 +219,6 @@ func (i *Image) DrawImage(image *Image, options *DrawImageOptions) error {
 	if i == image {
 		panic("ebiten: Image.DrawImage: image must be different from the receiver")
 	}
-	if i.restorable == nil {
-		return nil
-	}
 	mode := opengl.CompositeMode(options.CompositeMode)
 	i.restorable.DrawImage(image.restorable, vs, options.ColorM.impl, mode)
 	return nil
@@ -283,14 +283,14 @@ func (i *Image) Dispose() error {
 //
 // ReplacePixels always returns nil as of 1.5.0-alpha.
 func (i *Image) ReplacePixels(p []uint8) error {
+	if i.restorable == nil {
+		return nil
+	}
 	theImagesForRestoring.resetPixelsIfDependingOn(i)
 	w, h := i.restorable.Size()
 	if l := 4 * w * h; len(p) != l {
 		panic(fmt.Sprintf("ebiten: len(p) was %d but must be %d", len(p), l))
 	}
-	if i.restorable == nil {
-		return nil
-	}
 	w2, h2 := graphics.NextPowerOf2Int(w), graphics.NextPowerOf2Int(h)
 	pix := make([]uint8, 4*w2*h2)
 	for j := 0; j < h; j++ {