Don't draw onto a hw surface using the software renderer

Bug #6485955

If an invalidate gets scheduled right before the EGL surface is destroyed,
the next draw pass is done in software. This causes the software renderer
to connect to the surface forever which prevents the hardware renderer
from coming back when the screen is turned back on.

The fix here is to ignore the draw request when hw acceleration is requested
but not yet available. Proper software fallback will still happen when an
error is encountered with hardware rendering (in which case hw acceleration
will not be marked as requested anymore.)

Change-Id: I1edc4a51c8dd38240aa2345092a18a081a756fc1

Author: Romain Guy

core/java/android/view/ViewRootImpl.java

@@ -2183,6 +2183,18 @@ private void draw(boolean fullRedrawNeeded) {
     private boolean drawSoftware(Surface surface, AttachInfo attachInfo, int yoff,
             boolean scalingRequired, Rect dirty) {
 
+        // If we get here with a disabled & requested hardware renderer, something went
+        // wrong (an invalidate posted right before we destroyed the hardware surface
+        // for instance) so we should just bail out. Locking the surface with software
+        // rendering at this point would lock it forever and prevent hardware renderer
+        // from doing its job when it comes back.
+        if (attachInfo.mHardwareRenderer != null && !attachInfo.mHardwareRenderer.isEnabled() &&
+                attachInfo.mHardwareRenderer.isRequested()) {
+            mFullRedrawNeeded = true;
+            scheduleTraversals();
+            return false;
+        }
+
         // Draw with software renderer.
         Canvas canvas;
         try {