In SkPixmap.cpp, change SkAlphaMul to SkMulDiv255.
Add a test that we get the same color back after calling SkBitmap::eraseColor, modulo rounding.
Also update some incorrect docs.
BUG=skia:4297
Review URL: https://codereview.chromium.org/1521673002
diff --git a/tests/BitmapTest.cpp b/tests/BitmapTest.cpp
index 2bd8490..58e3c8b 100644
--- a/tests/BitmapTest.cpp
+++ b/tests/BitmapTest.cpp
@@ -145,3 +145,24 @@
REPORTER_ASSERT(r, source.getColor(0, 0) == copy.getColor(0, 0));
}
}
+
+static void test_erasecolor_premul(skiatest::Reporter* reporter, SkColorType ct, SkColor input,
+ SkColor expected) {
+ SkBitmap bm;
+ bm.allocPixels(SkImageInfo::Make(1, 1, ct, kPremul_SkAlphaType));
+ bm.eraseColor(input);
+ SkDebugf("expected: %x actual: %x\n", expected, bm.getColor(0, 0));
+ REPORTER_ASSERT(reporter, bm.getColor(0, 0) == expected);
+}
+
+/**
+ * This test checks that eraseColor premultiplies the color correctly.
+ */
+DEF_TEST(Bitmap_eraseColor_Premul, r) {
+ SkColor color = 0x80FF0080;
+ test_erasecolor_premul(r, kAlpha_8_SkColorType, color, 0x80000000);
+ test_erasecolor_premul(r, kRGB_565_SkColorType, color, 0xFF840042);
+ test_erasecolor_premul(r, kARGB_4444_SkColorType, color, 0x88FF0080);
+ test_erasecolor_premul(r, kRGBA_8888_SkColorType, color, color);
+ test_erasecolor_premul(r, kBGRA_8888_SkColorType, color, color);
+}