Fix rendering issue with layers.

A change was made earlier in the renderer to not snap the current clip rect
on every clip operation. The clip rect must not be snapped to pixel boundaries
before being used for pixel precision operations. Some operations were doing
this correctly, others were not. For instance, a layer was always created by
rounding to the correct pixels, but composing a layer was done with a non
rounded clip, thus resulting in slightly odd behaviors.

Change-Id: I31c2cf0a343450470bcd449c3f13fe37648b9c7c

2 files changed, 24 insertions, 18 deletions

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index faad297..7495a06 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -353,19 +353,22 @@ bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
 
     // Window coordinates of the layer
     Rect bounds(left, top, right, bottom);
-    if (!fboLayer) {
+    if (fboLayer) {
+        // Clear the previous layer regions before we change the viewport
+        clearLayerRegions();
+    } else {
         mSnapshot->transform->mapRect(bounds);
 
         // Layers only make sense if they are in the framebuffer's bounds
         bounds.intersect(*snapshot->clipRect);
 
+        // We cannot work with sub-pixels in this case
+        bounds.snapToPixelBoundaries();
+
         // When the layer is not an FBO, we may use glCopyTexImage so we
         // need to make sure the layer does not extend outside the bounds
         // of the framebuffer
         bounds.intersect(snapshot->previous->viewport);
-
-        // We cannot work with sub-pixels in this case
-        bounds.snapToPixelBoundaries();
     }
 
     if (bounds.isEmpty() || bounds.getWidth() > mMaxTextureSize ||
@@ -454,14 +457,14 @@ bool OpenGLRenderer::createLayer(sp<Snapshot> snapshot, float left, float top,
         // Copy the framebuffer into the layer
         glBindTexture(GL_TEXTURE_2D, layer->texture);
 
-         if (layer->empty) {
-             glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bounds.left, mHeight - bounds.bottom,
-                     layer->width, layer->height, 0);
-             layer->empty = false;
-         } else {
-             glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, bounds.left, mHeight - bounds.bottom,
-                     bounds.getWidth(), bounds.getHeight());
-          }
+        if (layer->empty) {
+            glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, bounds.left,
+                    snapshot->height - bounds.bottom, layer->width, layer->height, 0);
+            layer->empty = false;
+        } else {
+            glCopyTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, bounds.left,
+                    snapshot->height - bounds.bottom, bounds.getWidth(), bounds.getHeight());
+        }
 
         // Enqueue the buffer coordinates to clear the corresponding region later
         mLayers.push(new Rect(bounds));
@@ -487,7 +490,8 @@ void OpenGLRenderer::composeLayer(sp<Snapshot> current, sp<Snapshot> previous) {
     }
 
     // Restore the clip from the previous snapshot
-    const Rect& clip = *previous->clipRect;
+    Rect& clip(*previous->clipRect);
+    clip.snapToPixelBoundaries();
     glScissor(clip.left, previous->height - clip.bottom, clip.getWidth(), clip.getHeight());
 
     Layer* layer = current->layer;
@@ -795,7 +799,8 @@ void OpenGLRenderer::drawLines(float* points, int count, SkPaint* paint) {
 }
 
 void OpenGLRenderer::drawColor(int color, SkXfermode::Mode mode) {
-    const Rect& clip = *mSnapshot->clipRect;
+    Rect& clip(*mSnapshot->clipRect);
+    clip.snapToPixelBoundaries();
     drawColorRect(clip.left, clip.top, clip.right, clip.bottom, color, mode, true);
 }
 
@@ -863,6 +868,7 @@ void OpenGLRenderer::drawText(const char* text, int bytesCount, int count,
             paint->getTextSize());
 
     Rect clipRect(*mSnapshot->clipRect);
+    clipRect.snapToPixelBoundaries();
     glScissor(clipRect.left, mSnapshot->height - clipRect.bottom,
             clipRect.getWidth(), clipRect.getHeight());
 
diff --git a/libs/hwui/Rect.h b/libs/hwui/Rect.h
index c571ea1..8f3655c 100644
--- a/libs/hwui/Rect.h
+++ b/libs/hwui/Rect.h
@@ -149,10 +149,10 @@ struct Rect {
     }
 
     void snapToPixelBoundaries() {
-        left = floorf(left);
-        top = floorf(top);
-        right = ceilf(right);
-        bottom = ceilf(bottom);
+        left = floorf(left + 0.5f);
+        top = floorf(top + 0.5f);
+        right = floorf(right + 0.5f);
+        bottom = floorf(bottom + 0.5f);
     }
 
     void dump() const {