hwui: Caches: use mBoundTextures only for GL_TEXTURE_2D

bug:17441218

GLConsumer uses glBindTexture() directly instead of going through
Caches::bindTexture(). This can cause libhwui to draw with the wrong
texture bound in the following case which involves 2 TextureViews:

Frame 1:
GLConsumer::updateTexImage() calls glBindTexture(GL_TEXTURE_EXTERNAL_OES, 1)
HWUI renders TextureView A:
    calls Caches::bindTexture(GL_TEXTURE_EXTERNAL_OES, 1) and draws

Frame 2:
GLConsumer::updateTexImage() calls glBindTexture(GL_TEXTURE_EXTERNAL_OES, 1)
GLConsumer::updateTexImage() calls glBindTexture(GL_TEXTURE_EXTERNAL_OES, 2)
HWUI renders TextureView A:
    calls Caches::bindTexture(GL_TEXTURE_EXTERNAL_OES, 1) and draws
HWUI renders TextureView B:
    calls Caches::bindTexture(GL_TEXTURE_EXTERNAL_OES, 2) and draws

In this case, HWUI will incorrectly draw TextureView A using texture 2 on
frame 2, because mBoundTextures[0]=1, even though the texture currently
bound to GL_TEXTURE_EXTERNAL_OES is 2.

Since GLConsumer is always used with a target of GL_TEXTURE_EXTERNAL_OES,
work around this problem by having mBoundTextures[] store only the
textures bound to the target GL_TEXTURE_2D. This is the common case
where the extra performance is needed. Since it's legal to have
different textures bound to GL_TEXTURE_2D and GL_TEXTURE_EXTERNAL_OES
on one texture unit, Caches::bindTexture() does not need to clear
mBoundTextures[mTextureUnit] when target != GL_TEXTURE_2D.

Change-Id: I8bc54ab8adcfacad7f3ed17a31236dc7a86c967a
Signed-off-by: Fred Fettinger <fred.fettinger@motorola.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/libs/hwui/Caches.cpp b/libs/hwui/Caches.cpp
index 9855f718930d..f853d1faedea 100644
--- a/libs/hwui/Caches.cpp
+++ b/libs/hwui/Caches.cpp
@@ -551,9 +551,13 @@ void Caches::bindTexture(GLuint texture) {
 }
 
 void Caches::bindTexture(GLenum target, GLuint texture) {
-    if (mBoundTextures[mTextureUnit] != texture) {
+    if (target == GL_TEXTURE_2D) {
+        bindTexture(texture);
+    } else {
+        // GLConsumer directly calls glBindTexture() with
+        // target=GL_TEXTURE_EXTERNAL_OES, don't cache this target
+        // since the cached state could be stale
         glBindTexture(target, texture);
-        mBoundTextures[mTextureUnit] = texture;
     }
 }