Fold alpha to the draw in savelayer-draw-restore patterns with non-opaque draw

tests/RecordOptsTest.cpp

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "Test.h"
 #include "RecordTestUtils.h"
 
@@ skipping 107 matching lines @@
     SkRect bounds = SkRect::MakeWH(100, 200);
     SkRect   draw = SkRect::MakeWH(50, 60);
 
     SkPaint goodLayerPaint, badLayerPaint, worseLayerPaint;
     goodLayerPaint.setColor(0x03000000);  // Only alpha.
     badLayerPaint.setColor( 0x03040506);  // Not only alpha.
     worseLayerPaint.setXfermodeMode(SkXfermode::kDstIn_Mode);  // Any effect will do.
 
     SkPaint goodDrawPaint, badDrawPaint;
     goodDrawPaint.setColor(0xFF020202);  // Opaque.
     badDrawPaint.setColor( 0x0F020202);  // Not opaque.

[mtklein, 2015/01/13 18:48:20]

Let's rename goodDrawPaint -> opaqueDrawPaint, badDrawPaint ->
transparentDrawPaint?  badDrawPaint isn't bad anymore! :)

[Kimmo Kinnunen, 2015/01/14 13:07:51]

Done.

 
     // No change: optimization can't handle bounds.
     recorder.saveLayer(&bounds, NULL);
         recorder.drawRect(draw, goodDrawPaint);
     recorder.restore();
     if (!SkCanvas::Internal_Private_GetIgnoreSaveLayerBounds()) {
         assert_savelayer_restore(r, &record, 0, false);
     }
 
     // SaveLayer/Restore removed: no bounds + no paint = no point.
     recorder.saveLayer(NULL, NULL);
         recorder.drawRect(draw, goodDrawPaint);
     recorder.restore();
     assert_savelayer_restore(r, &record, 3, true);
 
     // TODO(mtklein): test case with null draw paint
 
     // No change: layer paint isn't alpha-only.
     recorder.saveLayer(NULL, &badLayerPaint);
         recorder.drawRect(draw, goodDrawPaint);
     recorder.restore();
     assert_savelayer_restore(r, &record, 6, false);
 
     // No change: layer paint has an effect.
     recorder.saveLayer(NULL, &worseLayerPaint);
         recorder.drawRect(draw, goodDrawPaint);
     recorder.restore();
     assert_savelayer_restore(r, &record, 9, false);
 
-    // No change: draw paint isn't opaque.
+    // SaveLayer/Restore removed: we can fold in the alpha!
     recorder.saveLayer(NULL, &goodLayerPaint);
         recorder.drawRect(draw, badDrawPaint);
     recorder.restore();
-    assert_savelayer_restore(r, &record, 12, false);
+    assert_savelayer_restore(r, &record, 12, true);
 
     // SaveLayer/Restore removed: we can fold in the alpha!
     recorder.saveLayer(NULL, &goodLayerPaint);
         recorder.drawRect(draw, goodDrawPaint);
     recorder.restore();
     assert_savelayer_restore(r, &record, 15, true);
 
     const SkRecords::DrawRect* drawRect = assert_type<SkRecords::DrawRect>(r, record, 16);
     REPORTER_ASSERT(r, drawRect != NULL);
     REPORTER_ASSERT(r, drawRect->paint.getColor() == 0x03020202);
 }