From 0c611d875b2fc1bb0ec726f897a3648f0af41d72 Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Sun, 10 Jul 2016 05:59:21 +0900
Subject: [PATCH] graphics: Bug fix: glTexSubImage2D on Android now works
 (#211)

---
 image.go                     | 2 --
 internal/graphics/command.go | 4 ++++
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/image.go b/image.go
index c8bea2cc0..665a2bef8 100644
--- a/image.go
+++ b/image.go
@@ -182,8 +182,6 @@ func (i *Image) Dispose() error {
 // This function may be slow (as for implementation, this calls glTexSubImage2D).
 //
 // This function is concurrent-safe.
-//
-// BUG(hajimehoshi) ReplacePixels might not work on Android (#211).
 func (i *Image) ReplacePixels(p []uint8) error {
 	return i.impl.ReplacePixels(p)
 }
diff --git a/internal/graphics/command.go b/internal/graphics/command.go
index dae275ed7..06ba84d49 100644
--- a/internal/graphics/command.go
+++ b/internal/graphics/command.go
@@ -157,6 +157,10 @@ func (c *replacePixelsCommand) Exec(context *opengl.Context) error {
 	if err := context.FillFramebuffer(0, 0, 0.5, 1); err != nil {
 		return err
 	}
+	// This is necessary on Android. We can't call glClear just before glTexSubImage2D without
+	// glFlush. glTexSubImage2D didn't work without this hack at least on Nexus 5x (#211).
+	// TODO: Can we have a better way like optimizing commands?
+	context.Flush()
 	context.BindTexture(c.dst.texture.native)
 	context.TexSubImage2D(c.pixels, c.dst.width, c.dst.height)
 	return nil