SkRecordDraw: skip draw ops when the clip is empty

tests/RecordDrawTest.cpp

+#include "Test.h"
+
+#include "SkDebugCanvas.h"
+#include "SkRecord.h"
+#include "SkRecordCulling.h"
+#include "SkRecordDraw.h"
+#include "SkRecorder.h"
+#include "SkRecords.h"
+
+static const int W = 1920, H = 1080;
+
+DEF_TEST(RecordDraw_Culling, r) {
+    // Record these 7 drawing commands verbatim.
+    SkRecord record;
+    SkRecorder recorder(SkRecorder::kWriteOnly_Mode, &record, W, H);
+
+    recorder.pushCull(SkRect::MakeWH(100, 100));
+        recorder.drawRect(SkRect::MakeWH(10, 10), SkPaint());
+        recorder.drawRect(SkRect::MakeWH(30, 30), SkPaint());
+        recorder.pushCull(SkRect::MakeWH(5, 5));
+            recorder.drawRect(SkRect::MakeWH(1, 1), SkPaint());
+        recorder.popCull();
+    recorder.popCull();
+
+    // Take a pass over to match up pushCulls and popCulls.
+    SkRecordAnnotateCullingPairs(&record);
+
+    // Rerecord into another SkRecord using full SkCanvas semantics,
+    // tracking clips and allowing SkRecordDraw's quickReject() calls to work.
+    SkRecord rerecord;
+    SkRecorder rerecorder(SkRecorder::kReadWrite_Mode, &rerecord, W, H);
+    // This clip intersects the outer cull, but allows us to quick reject the inner one.
+    rerecorder.clipRect(SkRect::MakeLTRB(20, 20, 200, 200));
+
+    SkRecordDraw(record, &rerecorder);
+
+    // We'll keep the clipRect call from above, and the outer two drawRects, and the push/pop pair.
+    // If culling weren't working, we'd see 8 commands recorded here.
+    REPORTER_ASSERT(r, 5 == rerecord.count());
+}
+
+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.
+    recorder.save();
+        recorder.clipRect(SkRect::MakeLTRB(0, 0, 100, 100));
+        recorder.drawRect(SkRect::MakeLTRB(20, 20, 40, 40), SkPaint());
+        recorder.save();
+            recorder.clipRect(SkRect::MakeLTRB(200, 200, 300, 300));
+            recorder.drawRect(SkRect::MakeLTRB(220, 220, 240, 240), SkPaint());
+        recorder.restore();
+    recorder.restore();
+
+    // Same deal as above: we need full SkCanvas semantics for clip skipping to work.
+    SkRecord rerecord;
+    SkRecorder rerecorder(SkRecorder::kReadWrite_Mode, &rerecord, W, H);
+    SkRecordDraw(record, &rerecorder);
+
+    // All commands except the drawRect will be preserved.
+    REPORTER_ASSERT(r, 7 == rerecord.count());
+}