Fixing numerical rounding edge case in SkTileGrid
BUG=https://code.google.com/p/chromium/issues/detail?id=234688
TEST=TileGrid skia unit test
Review URL: https://codereview.chromium.org/13860011
git-svn-id: http://skia.googlecode.com/svn/trunk@8839 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tests/TileGridTest.cpp b/tests/TileGridTest.cpp
index 78620b4..e409afd 100644
--- a/tests/TileGridTest.cpp
+++ b/tests/TileGridTest.cpp
@@ -178,6 +178,9 @@
SkBitmap moreThanATileBitmap;
moreThanATileBitmap.setConfig(SkBitmap::kARGB_8888_Config, 11, 11);
moreThanATileBitmap.allocPixels();
+ SkBitmap tinyBitmap;
+ tinyBitmap.setConfig(SkBitmap::kARGB_8888_Config, 2, 2);
+ tinyBitmap.allocPixels();
// Test parts of top-left tile
{
// The offset should cancel the top and left borders of the top left tile
@@ -226,6 +229,20 @@
REPORTER_ASSERT(reporter, rect2 == mockCanvas.fRects[0]);
REPORTER_ASSERT(reporter, rect3 == mockCanvas.fRects[1]);
}
+ {
+ // Regression test for crbug.com/234688
+ // Once the 2x2 device region is inset by margin, it yields an empty
+ // adjusted region, sitting right on top of the tile boundary.
+ SkDevice device(tinyBitmap);
+ MockCanvas mockCanvas(&device);
+ mockCanvas.translate(SkFloatToScalar(-8.0f), SkFloatToScalar(-8.0f));
+ picture.draw(&mockCanvas);
+ // This test passes by not asserting. We do not validate the rects recorded
+ // because the result is numerically unstable (floating point equality).
+ // The content of any one of the four tiles of the tilegrid would be a valid
+ // result since any bbox that covers the center point of the canvas will be
+ // recorded in all four tiles.
+ }
}
static void Test(skiatest::Reporter* reporter) {