7d57124a2a
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1733113002 Review URL: https://codereview.chromium.org/1733113002
77 lines
2.4 KiB
C++
77 lines
2.4 KiB
C++
/*
|
|
* Copyright 2011 Google Inc.
|
|
*
|
|
* Use of this source code is governed by a BSD-style license that can be
|
|
* found in the LICENSE file.
|
|
*/
|
|
|
|
#include "SkColorPriv.h"
|
|
#include "SkXfermode.h"
|
|
#include "Test.h"
|
|
|
|
// our std SkAlpha255To256
|
|
static int test_srcover0(unsigned dst, unsigned alpha) {
|
|
return alpha + SkAlphaMul(dst, SkAlpha255To256(255 - alpha));
|
|
}
|
|
|
|
// faster hack +1
|
|
static int test_srcover1(unsigned dst, unsigned alpha) {
|
|
return alpha + SkAlphaMul(dst, 256 - alpha);
|
|
}
|
|
|
|
// slower "correct"
|
|
static int test_srcover2(unsigned dst, unsigned alpha) {
|
|
return alpha + SkMulDiv255Round(dst, 255 - alpha);
|
|
}
|
|
|
|
DEF_TEST(SrcOver, reporter) {
|
|
/* Here's the idea. Can we ensure that when we blend on top of an opaque
|
|
dst, that the result always stay's opaque (i.e. exactly 255)?
|
|
*/
|
|
|
|
unsigned i;
|
|
int opaqueCounter0 = 0;
|
|
int opaqueCounter1 = 0;
|
|
int opaqueCounter2 = 0;
|
|
for (i = 0; i <= 255; i++) {
|
|
unsigned result0 = test_srcover0(0xFF, i);
|
|
unsigned result1 = test_srcover1(0xFF, i);
|
|
unsigned result2 = test_srcover2(0xFF, i);
|
|
opaqueCounter0 += (result0 == 0xFF);
|
|
opaqueCounter1 += (result1 == 0xFF);
|
|
opaqueCounter2 += (result2 == 0xFF);
|
|
}
|
|
#if 0
|
|
INFOF(reporter, "---- opaque test: [%d %d %d]\n",
|
|
opaqueCounter0, opaqueCounter1, opaqueCounter2);
|
|
#endif
|
|
// we acknowledge that technique0 does not always return opaque
|
|
REPORTER_ASSERT(reporter, opaqueCounter0 == 256);
|
|
REPORTER_ASSERT(reporter, opaqueCounter1 == 256);
|
|
REPORTER_ASSERT(reporter, opaqueCounter2 == 256);
|
|
|
|
// Now ensure that we never over/underflow a byte
|
|
for (i = 0; i <= 255; i++) {
|
|
for (unsigned dst = 0; dst <= 255; dst++) {
|
|
unsigned r0 = test_srcover0(dst, i);
|
|
unsigned r1 = test_srcover1(dst, i);
|
|
unsigned r2 = test_srcover2(dst, i);
|
|
unsigned max = SkMax32(dst, i);
|
|
// ignore the known failure
|
|
if (dst != 255) {
|
|
REPORTER_ASSERT(reporter, r0 <= 255 && r0 >= max);
|
|
}
|
|
REPORTER_ASSERT(reporter, r1 <= 255 && r1 >= max);
|
|
REPORTER_ASSERT(reporter, r2 <= 255 && r2 >= max);
|
|
|
|
#if 0
|
|
// this shows where r1 (faster) differs from r2 (more exact)
|
|
if (r1 != r2) {
|
|
INFOF(reporter, "--- dst=%d i=%d r1=%d r2=%d exact=%g\n",
|
|
dst, i, r1, r2, i + dst - dst*i/255.0f);
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
}
|