80e39a77b1
git-svn-id: http://skia.googlecode.com/svn/trunk@143 2bbb7eff-a529-9590-31e7-b0007b416f81
73 lines
2.4 KiB
C++
73 lines
2.4 KiB
C++
#include "Test.h"
|
|
#include "SkColorPriv.h"
|
|
#include "SkXfermode.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);
|
|
}
|
|
|
|
static void test_srcover_hack(skiatest::Reporter* 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
|
|
SkDebugf("---- opaque test: [%d %d %d]\n",
|
|
opaqueCounter0, opaqueCounter1, opaqueCounter2);
|
|
#endif
|
|
// we acknowledge that technique0 does not always return opaque
|
|
REPORTER_ASSERT(reporter, opaqueCounter0 == 129);
|
|
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) {
|
|
SkDebugf("--- dst=%d i=%d r1=%d r2=%d exact=%g\n",
|
|
dst, i, r1, r2, i + dst - dst*i/255.0f);
|
|
}
|
|
#endif
|
|
}
|
|
}
|
|
}
|
|
|
|
#include "TestClassDef.h"
|
|
DEFINE_TESTCLASS("SrcOver", SrcOverTestClass, test_srcover_hack)
|