SkRecordDraw: don't bother clipping an empty clip down further

BUG=skia:2378
R=fmalita@chromium.org, mtklein@google.com, fmalita@google.com

Author: mtklein@chromium.org

Review URL: https://codereview.chromium.org/231933003

git-svn-id: http://skia.googlecode.com/svn/trunk@14126 2bbb7eff-a529-9590-31e7-b0007b416f81

2 files changed, 13 insertions, 5 deletions

diff --git a/src/record/SkRecordDraw.cpp b/src/record/SkRecordDraw.cpp
index 4782344bed..ddde2fede8 100644
--- a/src/record/SkRecordDraw.cpp
+++ b/src/record/SkRecordDraw.cpp
@@ -37,13 +37,20 @@ template <> void Draw::operator()(const SkRecords::PushCull& r) {
     template <> void Draw::operator()(const SkRecords::T& r) { fCanvas->call; this->updateClip(); }
 CASE(Restore, restore());
 CASE(SaveLayer, saveLayer(r.bounds, r.paint, r.flags));
+#undef CASE
+
+// These certainly do change the clip,
+// but we can skip them if they're intersecting with a clip that's already empty.
+#define CASE(T, call)  template <> void Draw::operator()(const SkRecords::T& r) {                \
+    if (!(fClipEmpty && SkRegion::kIntersect_Op == r.op)) { fCanvas->call; this->updateClip(); } \
+}
 CASE(ClipPath, clipPath(r.path, r.op, r.doAA));
 CASE(ClipRRect, clipRRect(r.rrect, r.op, r.doAA));
 CASE(ClipRect, clipRect(r.rect, r.op, r.doAA));
 CASE(ClipRegion, clipRegion(r.region, r.op));
 #undef CASE
 
-// Commands which must run regardless of the clip.
+// Commands which must run regardless of the clip, but don't change it themselves.
 #define CASE(T, call) \
     template <> void Draw::operator()(const SkRecords::T& r) { fCanvas->call; }
 CASE(Save, save(r.flags));
diff --git a/tests/RecordDrawTest.cpp b/tests/RecordDrawTest.cpp
index 6468e72c9d..98ec506b1e 100644
--- a/tests/RecordDrawTest.cpp
+++ b/tests/RecordDrawTest.cpp
@@ -43,14 +43,15 @@ DEF_TEST(RecordDraw_Clipping, r) {
     SkRecord record;
     SkRecorder recorder(SkRecorder::kWriteOnly_Mode, &record, W, H);
 
-    // 8 draw commands.
-    // The inner clipRect makes the clip empty, so the inner drawRect does nothing.
+    // 9 draw commands.
     recorder.save();
         recorder.clipRect(SkRect::MakeLTRB(0, 0, 100, 100));
         recorder.drawRect(SkRect::MakeLTRB(20, 20, 40, 40), SkPaint());
         recorder.save();
+            // This first clipRect makes the clip empty, so the next two commands do nothing.
             recorder.clipRect(SkRect::MakeLTRB(200, 200, 300, 300));
-            recorder.drawRect(SkRect::MakeLTRB(220, 220, 240, 240), SkPaint());
+            recorder.clipRect(SkRect::MakeLTRB(210, 210, 250, 250));              // Skipped
+            recorder.drawRect(SkRect::MakeLTRB(220, 220, 240, 240), SkPaint());   // Skipped
         recorder.restore();
     recorder.restore();
 
@@ -59,6 +60,6 @@ DEF_TEST(RecordDraw_Clipping, r) {
     SkRecorder rerecorder(SkRecorder::kReadWrite_Mode, &rerecord, W, H);
     SkRecordDraw(record, &rerecorder);
 
-    // All commands except the drawRect will be preserved.
+    // All commands except the two marked // Skipped above will be preserved.
     REPORTER_ASSERT(r, 7 == rerecord.count());
 }