From b146e5d1b4a98b9eadc9cf385617b33ca88f44fa Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 24 Jul 2016 00:02:45 +0900
Subject: [PATCH] graphics: Bug fix: Errors should be returned after checking
 the history

---
 pixels.go | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pixels.go b/pixels.go
index b378ccb23..73aadfd0f 100644
--- a/pixels.go
+++ b/pixels.go
@@ -92,15 +92,15 @@ func (p *pixels) hasHistoryWith(target *Image) bool {
 }
 
 func (p *pixels) resetHistoryIfNeeded(image *graphics.Image, target *Image, context *opengl.Context) error {
-	if context == nil {
-		return errors.New("ebiten: OpenGL context is missing: before running the main loop, it is forbidden to manipulate images that is used as a drawing source once.")
-	}
 	if p.drawImageHistory == nil {
 		return nil
 	}
 	if !p.hasHistoryWith(target) {
 		return nil
 	}
+	if context == nil {
+		return errors.New("ebiten: OpenGL context is missing: before running the main loop, it is forbidden to manipulate images that is used as a drawing source once.")
+	}
 	var err error
 	p.basePixels, err = image.Pixels(context)
 	if err != nil {