Overdraw avoidance and merging of clipped ops

bug:8951267

If an opaque op, or group of opaque ops covers the invalidate region,
skip draw operations that precede it.

Clipped operations may now be merged, but only if they share a
clipRect - this is a very case for e.g. ListView, where all background
elements may now be a part of the same MergingDrawBatch.

It is this more aggressive merging that groups together clipped
background elements in the ListView case, enabling the overdraw
avoidance skipping the window background.

Change-Id: Ib0961977e272c5ac37f59e4c67d828467422d259

1 files changed, 38 insertions, 20 deletions

diff --git a/libs/hwui/OpenGLRenderer.cpp b/libs/hwui/OpenGLRenderer.cpp
index d95a62c19d39..5ac06cf04113 100644
--- a/libs/hwui/OpenGLRenderer.cpp
+++ b/libs/hwui/OpenGLRenderer.cpp
@@ -1360,15 +1360,26 @@ bool OpenGLRenderer::storeDisplayState(DeferredDisplayState& state, int stateDef
         // state has bounds initialized in local coordinates
         if (!state.mBounds.isEmpty()) {
             currentMatrix.mapRect(state.mBounds);
-            state.mClipped = !currentClip.contains(state.mBounds);
-            if (!state.mBounds.intersect(currentClip)) {
+            Rect clippedBounds(state.mBounds);
+            if(!clippedBounds.intersect(currentClip)) {
                 // quick rejected
                 return true;
             }
+
+            state.mClipSideFlags = kClipSide_Unclipped;
+            if (!currentClip.contains(state.mBounds)) {
+                int& flags = state.mClipSideFlags;
+                // op partially clipped, so record which sides are clipped for clip-aware merging
+                if (currentClip.left > state.mBounds.left) flags |= kClipSide_Left;
+                if (currentClip.top > state.mBounds.top) flags |= kClipSide_Top;
+                if (currentClip.right < state.mBounds.right) flags |= kClipSide_Right;
+                if (currentClip.bottom < state.mBounds.bottom) flags |= kClipSide_Bottom;
+            }
+            state.mBounds.set(clippedBounds);
         } else {
             // If we don't have bounds, let's assume we're clipped
             // to prevent merging
-            state.mClipped = true;
+            state.mClipSideFlags = kClipSide_Full;
             state.mBounds.set(currentClip);
         }
     }
@@ -1392,14 +1403,27 @@ void OpenGLRenderer::restoreDisplayState(const DeferredDisplayState& state, bool
     mSnapshot->alpha = state.mAlpha;
 
     if (state.mClipValid && !skipClipRestore) {
-        mSnapshot->setClip(state.mClip.left, state.mClip.top, state.mClip.right, state.mClip.bottom);
+        mSnapshot->setClip(state.mClip.left, state.mClip.top,
+                state.mClip.right, state.mClip.bottom);
         dirtyClip();
     }
 }
 
-void OpenGLRenderer::setFullScreenClip() {
-    mSnapshot->setClip(0, 0, mWidth, mHeight);
+/**
+ * Merged multidraw (such as in drawText and drawBitmaps rely on the fact that no clipping is done
+ * in the draw path. Instead, clipping is done ahead of time - either as a single clip rect (when at
+ * least one op is clipped), or disabled entirely (because no merged op is clipped)
+ *
+ * This method should be called when restoreDisplayState() won't be restoring the clip
+ */
+void OpenGLRenderer::setupMergedMultiDraw(const Rect* clipRect) {
+    if (clipRect != NULL) {
+        mSnapshot->setClip(clipRect->left, clipRect->top, clipRect->right, clipRect->bottom);
+    } else {
+        mSnapshot->setClip(0, 0, mWidth, mHeight);
+    }
     dirtyClip();
+    mCaches.setScissorEnabled(clipRect != NULL || mScissorOptimizationDisabled);
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -1965,7 +1989,8 @@ status_t OpenGLRenderer::drawDisplayList(DisplayList* displayList, Rect& dirty,
             return status | replayStruct.mDrawGlStatus;
         }
 
-        DeferredDisplayList deferredList;
+        bool avoidOverdraw = !mCaches.debugOverdraw && !mCountOverdraw; // shh, don't tell devs!
+        DeferredDisplayList deferredList(*(mSnapshot->clipRect), avoidOverdraw);
         DeferStateStruct deferStruct(deferredList, *this, replayFlags);
         displayList->defer(deferStruct, 0);
 
@@ -2016,10 +2041,6 @@ void OpenGLRenderer::drawAlphaBitmap(Texture* texture, float left, float top, Sk
 
 status_t OpenGLRenderer::drawBitmaps(SkBitmap* bitmap, int bitmapCount, TextureVertex* vertices,
         bool transformed, const Rect& bounds, SkPaint* paint) {
-
-    // merged draw operations don't need scissor, but clip should still be valid
-    mCaches.setScissorEnabled(mScissorOptimizationDisabled);
-
     mCaches.activeTexture(0);
     Texture* texture = getTexture(bitmap);
     if (!texture) return DrawGlInfo::kStatusDone;
@@ -2860,16 +2881,13 @@ status_t OpenGLRenderer::drawText(const char* text, int bytesCount, int count, f
         const float* positions, SkPaint* paint, float totalAdvance, const Rect& bounds,
         DrawOpMode drawOpMode) {
 
-    if (drawOpMode == kDrawOpMode_Immediate &&
-            (text == NULL || count == 0 || mSnapshot->isIgnored() || canSkipText(paint))) {
-        return DrawGlInfo::kStatusDone;
-    }
-
     if (drawOpMode == kDrawOpMode_Immediate) {
-        if (quickReject(bounds)) return DrawGlInfo::kStatusDone;
-    } else {
-        // merged draw operations don't need scissor, but clip should still be valid
-        mCaches.setScissorEnabled(mScissorOptimizationDisabled);
+        // The checks for corner-case ignorable text and quick rejection is only done for immediate
+        // drawing as ops from DeferredDisplayList are already filtered for these
+        if (text == NULL || count == 0 || mSnapshot->isIgnored() || canSkipText(paint) ||
+                quickReject(bounds)) {
+            return DrawGlInfo::kStatusDone;
+        }
     }
 
     const float oldX = x;