From c10a493cafd2c0f7cb4ad9d5bf183ff7cc126cfa Mon Sep 17 00:00:00 2001
From: James Zern <jzern@google.com>
Date: Sat, 25 Nov 2017 18:21:44 -0800
Subject: [PATCH] vwebp: disable double buffering on windows & mac

this results in flickering with animated webp + alpha. disabling the
option is a workaround to restore the behavior to the previous release.

BUG=webp:365

Change-Id: Iac7fcc0d483837e76cc54ad3f26c4e0e5511e31d
---
 examples/vwebp.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/examples/vwebp.c b/examples/vwebp.c
index 6376e563..b19465cd 100644
--- a/examples/vwebp.c
+++ b/examples/vwebp.c
@@ -378,13 +378,23 @@ static void HandleDisplay(void) {
     }
   }
   glPopMatrix();
+#if defined(__APPLE__) || defined(_WIN32)
+  glFlush();
+#else
   glutSwapBuffers();
+#endif
 }
 
 static void StartDisplay(void) {
   const int width = kParams.canvas_width;
   const int height = kParams.canvas_height;
+  // TODO(webp:365) GLUT_DOUBLE results in flickering / old frames to be
+  // partially displayed with animated webp + alpha.
+#if defined(__APPLE__) || defined(_WIN32)
+  glutInitDisplayMode(GLUT_RGBA);
+#else
   glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
+#endif
   glutInitWindowSize(width, height);
   glutCreateWindow("WebP viewer");
   glutDisplayFunc(HandleDisplay);