Add SaveLayer-Draw-Restore optimization.

tests/RecordOptsTest.cpp

Index: tests/RecordOptsTest.cpp
diff --git a/tests/RecordOptsTest.cpp b/tests/RecordOptsTest.cpp
index 260b97b3e8535a48c4c517e88c66ec10a9edf46c..90347eda1f5836a64b7cfa6d21bb9f2fe5e2c3df 100644
--- a/tests/RecordOptsTest.cpp
+++ b/tests/RecordOptsTest.cpp
@@ -12,6 +12,8 @@
 #include "SkRecorder.h"
 #include "SkRecords.h"
 
+#include "SkXfermode.h"
+
 static const int W = 1920, H = 1080;
 
 // If the command we're reading is a U, set ptr to it, otherwise set it to NULL.
@@ -151,3 +153,76 @@ DEF_TEST(RecordOpts_NoopSaveRestores, r) {
     assert_type<SkRecords::DrawRect>(r, record, 9);
     assert_type<SkRecords::Restore>(r, record, 10);
 }
+
+static void assert_savelayer_restore(skiatest::Reporter* r,
+                                     SkRecord* record,
+                                     unsigned i,
+                                     bool shouldBeNoOped) {
+    SkRecordNoopSaveLayerDrawRestores(record);
+    if (shouldBeNoOped) {
+        assert_type<SkRecords::NoOp>(r, *record, i);
+        assert_type<SkRecords::NoOp>(r, *record, i+2);
+    } else {
+        assert_type<SkRecords::SaveLayer>(r, *record, i);
+        assert_type<SkRecords::Restore>(r, *record, i+2);
+    }
+}
+
+DEF_TEST(RecordOpts_NoopSaveLayerDrawRestore, r) {
+    SkRecord record;
+    SkRecorder recorder(SkRecorder::kWriteOnly_Mode, &record, W, H);
+
+    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.
+
+    // No change: optimization can't handle bounds.
+    recorder.saveLayer(&bounds, NULL);
+        recorder.drawRect(draw, goodDrawPaint);
+    recorder.restore();
+    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.
+    recorder.saveLayer(NULL, &goodLayerPaint);
+        recorder.drawRect(draw, badDrawPaint);
+    recorder.restore();
+    assert_savelayer_restore(r, &record, 12, false);
+
+    // 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);
+}