Fix for saveLayer() with filters vs. the BBox Hierarchy.

When building acceleration structures for SkPicture, we must transform
the primitive's bounds not only by its own SkPaint, but by the paints of
any saveLayer()s currently active above it.

We do this by pushing the SkPaint onto a stack on
saveLayer(), and popping them on restore(). We also push
a NULL paint in save(), so that the pushes and pops are
balanced.

BUG=skia:2734
R=mtklein@google.com, reed@google.com

Author: senorblanco@chromium.org

Review URL: https://codereview.chromium.org/380373003

1 files changed, 64 insertions, 0 deletions

diff --git a/tests/ImageFilterTest.cpp b/tests/ImageFilterTest.cpp
index 32822087ba..7da4a911ef 100644
--- a/tests/ImageFilterTest.cpp
+++ b/tests/ImageFilterTest.cpp
@@ -409,6 +409,70 @@ DEF_TEST(ImageFilterDrawTiled, reporter) {
     }
 }
 
+static void drawBlurredRect(SkCanvas* canvas) {
+    SkAutoTUnref<SkImageFilter> filter(SkBlurImageFilter::Create(SkIntToScalar(8), 0));
+    SkPaint filterPaint;
+    filterPaint.setColor(SK_ColorWHITE);
+    filterPaint.setImageFilter(filter);
+    canvas->saveLayer(NULL, &filterPaint);
+    SkPaint whitePaint;
+    whitePaint.setColor(SK_ColorWHITE);
+    canvas->drawRect(SkRect::Make(SkIRect::MakeWH(4, 4)), whitePaint);
+    canvas->restore();
+}
+
+static void drawPictureClipped(SkCanvas* canvas, const SkRect& clipRect, const SkPicture* picture) {
+    canvas->save();
+    canvas->clipRect(clipRect);
+    canvas->drawPicture(picture);
+    canvas->restore();
+}
+
+DEF_TEST(ImageFilterDrawTiledBlurRTree, reporter) {
+    // Check that the blur filter when recorded with RTree acceleration,
+    // and drawn tiled (with subsequent clip rects) exactly
+    // matches the same filter drawn with without RTree acceleration.
+    // This tests that the "bleed" from the blur into the otherwise-blank
+    // tiles is correctly rendered.
+    // Tests pass by not asserting.
+
+    int width = 16, height = 8;
+    SkBitmap result1, result2;
+    result1.allocN32Pixels(width, height);
+    result2.allocN32Pixels(width, height);
+    SkCanvas canvas1(result1);
+    SkCanvas canvas2(result2);
+    int tileSize = 8;
+
+    canvas1.clear(0);
+    canvas2.clear(0);
+
+    SkRTreeFactory factory;
+
+    SkPictureRecorder recorder1, recorder2;
+    // The only difference between these two pictures is that one has RTree aceleration.
+    SkCanvas* recordingCanvas1 = recorder1.beginRecording(width, height, NULL, 0);
+    SkCanvas* recordingCanvas2 = recorder2.beginRecording(width, height, &factory, 0);
+    drawBlurredRect(recordingCanvas1);
+    drawBlurredRect(recordingCanvas2);
+    SkAutoTUnref<SkPicture> picture1(recorder1.endRecording());
+    SkAutoTUnref<SkPicture> picture2(recorder2.endRecording());
+    for (int y = 0; y < height; y += tileSize) {
+        for (int x = 0; x < width; x += tileSize) {
+            SkRect tileRect = SkRect::Make(SkIRect::MakeXYWH(x, y, tileSize, tileSize));
+            drawPictureClipped(&canvas1, tileRect, picture1);
+            drawPictureClipped(&canvas2, tileRect, picture2);
+        }
+    }
+    for (int y = 0; y < height; y++) {
+        int diffs = memcmp(result1.getAddr32(0, y), result2.getAddr32(0, y), result1.rowBytes());
+        REPORTER_ASSERT(reporter, !diffs);
+        if (diffs) {
+            break;
+        }
+    }
+}
+
 DEF_TEST(ImageFilterMatrixConvolution, reporter) {
     // Check that a 1x3 filter does not cause a spurious assert.
     SkScalar kernel[3] = {