From 6640f60c8829670c94583b84e65ea664c9d5b8b4 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Tue, 14 Jun 2016 00:30:16 +0900
Subject: [PATCH] graphics: Bug fix: screen flicks on Android (#229)

---
 graphicscontext.go   | 18 +++++++++++++++++-
 internal/loop/run.go | 17 ++++++++++++-----
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/graphicscontext.go b/graphicscontext.go
index 9be199591..f9369552f 100644
--- a/graphicscontext.go
+++ b/graphicscontext.go
@@ -65,7 +65,7 @@ func (c *graphicsContext) needsRestoring(context *opengl.Context) (bool, error)
 	return c.screen.impl.isInvalidated(context), nil
 }
 
-func (c *graphicsContext) Update() error {
+func (c *graphicsContext) UpdateAndDraw() error {
 	if !c.initialized {
 		if err := graphics.Initialize(ui.GLContext()); err != nil {
 			return err
@@ -112,6 +112,22 @@ func (c *graphicsContext) Update() error {
 	return nil
 }
 
+func (c *graphicsContext) Draw() error {
+	if err := c.defaultRenderTarget.Clear(); err != nil {
+		return err
+	}
+	scale := float64(c.screenScale)
+	options := &DrawImageOptions{}
+	options.GeoM.Scale(scale, scale)
+	if err := c.defaultRenderTarget.DrawImage(c.screen, options); err != nil {
+		return err
+	}
+	if err := c.flush(); err != nil {
+		return err
+	}
+	return nil
+}
+
 func (c *graphicsContext) flush() error {
 	// TODO: imageM is necessary to call graphics functions. Move this to graphics package.
 	imageM.Lock()
diff --git a/internal/loop/run.go b/internal/loop/run.go
index 87d06ccb6..efa4c5a18 100644
--- a/internal/loop/run.go
+++ b/internal/loop/run.go
@@ -95,7 +95,8 @@ func (c *runContext) setRunningSlowly(isRunningSlowly bool) {
 
 type GraphicsContext interface {
 	SetSize(width, height, scale int) error
-	Update() error
+	UpdateAndDraw() error
+	Draw() error
 }
 
 func Run(g GraphicsContext, width, height, scale int, title string, fps int) error {
@@ -143,10 +144,16 @@ func Run(g GraphicsContext, width, height, scale int, title string, fps int) err
 				if tt == 0 && (int64(time.Second)/int64(fps)-int64(5*time.Millisecond)) < t {
 					tt = 1
 				}
-				for i := 0; i < tt; i++ {
-					slow := i < tt-1
-					currentRunContext.setRunningSlowly(slow)
-					if err := g.Update(); err != nil {
+				if 1 <= tt {
+					for i := 0; i < tt; i++ {
+						slow := i < tt-1
+						currentRunContext.setRunningSlowly(slow)
+						if err := g.UpdateAndDraw(); err != nil {
+							return err
+						}
+					}
+				} else {
+					if err := g.Draw(); err != nil {
 						return err
 					}
 				}