Defer glClear to just before draw call

Remove some DO_DEFERRED_CLEAR call to avoid call glClear separately, like this:
glBindFramebuffer(1)
glClear
glBindFramebuffer(2)
glClear
glBindFramebuffer(1)
glDrawXXX
glBindFramebuffer(2)
glDrawXXX

These call sequences may need read and write memory back and forth.

If we call DO_DEFERRED_CLEAR just before draw call, we can bind, clear and draw in one go.
e.g.
glBindFramebuffer(1)
glClear
glDrawXXX
glBindFramebuffer(2)
glClear
glDrawXXX

BUG=skia:

Review URL: https://codereview.chromium.org/1113003005

1 files changed, 1 insertions, 1 deletions

diff --git a/src/gpu/SkGpuDevice.cpp b/src/gpu/SkGpuDevice.cpp
index 7b363635e2..e4c21ca10f 100644
--- a/src/gpu/SkGpuDevice.cpp
+++ b/src/gpu/SkGpuDevice.cpp
@@ -62,6 +62,7 @@ enum { kDefaultImageFilterCacheSize = 32 * 1024 * 1024 };
 // a sub region of a larger source image.
 #define COLOR_BLEED_TOLERANCE 0.001f
 
+// Do deferred clear just before any draw call
 #define DO_DEFERRED_CLEAR()             \
     do {                                \
         if (fNeedClear) {               \
@@ -302,7 +303,6 @@ void SkGpuDevice::prepareDraw(const SkDraw& draw) {
 }
 
 GrRenderTarget* SkGpuDevice::accessRenderTarget() {
-    DO_DEFERRED_CLEAR();
     return fRenderTarget;
 }