Make RTree handle the case where the playback canvas has empty clip bounds

tests/PictureBBHTest.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 "SkCanvas.h"
+#include "SkBBoxHierarchy.h"
+#include "SkPaint.h"
+#include "SkPicture.h"
+#include "SkPictureRecorder.h"
+
+#include "Test.h"
+
+class PictureBBHTestBase {
+public:
+    PictureBBHTestBase(int playbackWidth, int playbackHeight,
+        int recordWidth, int recordHeight) {
+
+        fResultBitmap.allocN32Pixels(playbackWidth, playbackHeight);
+        fPictureWidth = recordWidth;
+        fPictureHeight = recordHeight;
+    }
+
+    virtual ~PictureBBHTestBase() { }
+
+    virtual void doTest(SkCanvas& playbackCanvas, SkCanvas& recordingCanvas) = 0;
+
+    void run(skiatest::Reporter* reporter) {
+        // No BBH
+        this->run(NULL, reporter);
+
+        // With a Tile Grid
+        SkTileGridFactory::TileGridInfo gridInfo;
+        gridInfo.fMargin.setEmpty();
+        gridInfo.fOffset.setZero();
+        gridInfo.fTileInterval.set(1, 1);
+        SkTileGridFactory gridFactory(gridInfo);
+        this->run(&gridFactory, reporter);
+
+        // With an R-Tree
+        SkRTreeFactory RTreeFactory;
+        this->run(&RTreeFactory, reporter);
+    }
+
+private:
+    void run(SkBBHFactory* factory, skiatest::Reporter* reporter) {
+        SkCanvas playbackCanvas(fResultBitmap);
+        playbackCanvas.clear(SK_ColorGREEN);
+        SkPictureRecorder recorder;
+        SkCanvas* recordCanvas = recorder.beginRecording(SkIntToScalar(fPictureWidth), SkIntToScalar(fPictureHeight), factory);
+        this->doTest(playbackCanvas, *recordCanvas);
+        SkAutoTUnref<SkPicture> picture(recorder.endRecording());
+        playbackCanvas.drawPicture(picture);
+        REPORTER_ASSERT(reporter, SK_ColorGREEN == fResultBitmap.getColor(0, 0));
+    }
+
+    SkBitmap fResultBitmap;
+    int fPictureWidth, fPictureHeight;
+};
+
+// Test to verify the playback of an empty picture
+// 
+class DrawEmptyPictureBBHTest : public PictureBBHTestBase {
+public:
+    DrawEmptyPictureBBHTest()
+        : PictureBBHTestBase(2, 2, 1, 1) { }
+    virtual ~DrawEmptyPictureBBHTest() { }
+
+    virtual void doTest(SkCanvas&, SkCanvas&) SK_OVERRIDE { }
+};
+
+// Test to verify the playback of a picture into a canvas that has
+// an empty clip.
+//
+class EmptyClipPictureBBHTest : public PictureBBHTestBase {
+public:
+    EmptyClipPictureBBHTest() 
+        : PictureBBHTestBase(2, 2, 3, 3) { }
+
+    virtual void doTest(SkCanvas& playbackCanvas, SkCanvas& recordingCanvas) SK_OVERRIDE {
+        // intersect with out of bounds rect -> empty clip.
+        playbackCanvas.clipRect(SkRect::MakeXYWH(SkIntToScalar(10), SkIntToScalar(10),
+            SkIntToScalar(1), SkIntToScalar(1)), SkRegion::kIntersect_Op);
+        SkPaint paint;
+        recordingCanvas.drawRect(SkRect::MakeXYWH(SkIntToScalar(0), SkIntToScalar(0),
+            SkIntToScalar(3), SkIntToScalar(3)), paint);
+    }
+
+    virtual ~EmptyClipPictureBBHTest() { }
+};
+
+DEF_TEST(PictureBBH, reporter) {
+
+    DrawEmptyPictureBBHTest emptyPictureTest;
+    emptyPictureTest.run(reporter);
+
+    EmptyClipPictureBBHTest emptyClipPictureTest;
+    emptyClipPictureTest.run(reporter);
+}