SrcOverTest.cpp revision e4fafb146e85cdfcf9d5418597b6818aa0754ada
1ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com/* 2ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com * Copyright 2011 Google Inc. 3ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com * 4ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com * Use of this source code is governed by a BSD-style license that can be 5ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com * found in the LICENSE file. 6ec3ed6a5ebf6f2c406d7bcf94b6bc34fcaeb976eepoger@google.com */ 7e4fafb146e85cdfcf9d5418597b6818aa0754adatfarina@chromium.org 8d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#include "Test.h" 9e4fafb146e85cdfcf9d5418597b6818aa0754adatfarina@chromium.org#include "TestClassDef.h" 10d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#include "SkColorPriv.h" 11d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#include "SkXfermode.h" 12d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com 13d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com// our std SkAlpha255To256 14d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.comstatic int test_srcover0(unsigned dst, unsigned alpha) { 15d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com return alpha + SkAlphaMul(dst, SkAlpha255To256(255 - alpha)); 16d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com} 17d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com 18d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com// faster hack +1 19d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.comstatic int test_srcover1(unsigned dst, unsigned alpha) { 20d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com return alpha + SkAlphaMul(dst, 256 - alpha); 21d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com} 22d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com 23d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com// slower "correct" 24d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.comstatic int test_srcover2(unsigned dst, unsigned alpha) { 25d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com return alpha + SkMulDiv255Round(dst, 255 - alpha); 26d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com} 27d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com 28e4fafb146e85cdfcf9d5418597b6818aa0754adatfarina@chromium.orgDEF_TEST(SrcOver, reporter) { 29d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com /* Here's the idea. Can we ensure that when we blend on top of an opaque 30d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com dst, that the result always stay's opaque (i.e. exactly 255)? 31d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com */ 3280e39a77b16f4396eed230efea1d0b2fc8cbfb00reed@android.com 33d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned i; 34d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com int opaqueCounter0 = 0; 35d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com int opaqueCounter1 = 0; 36d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com int opaqueCounter2 = 0; 37d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com for (i = 0; i <= 255; i++) { 38d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned result0 = test_srcover0(0xFF, i); 39d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned result1 = test_srcover1(0xFF, i); 40d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned result2 = test_srcover2(0xFF, i); 41d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com opaqueCounter0 += (result0 == 0xFF); 42d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com opaqueCounter1 += (result1 == 0xFF); 43d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com opaqueCounter2 += (result2 == 0xFF); 44d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com } 45d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#if 0 46d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com SkDebugf("---- opaque test: [%d %d %d]\n", 47d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com opaqueCounter0, opaqueCounter1, opaqueCounter2); 48d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#endif 49d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com // we acknowledge that technique0 does not always return opaque 509781ca586618cc8ea055f54021e706824313d4f5reed@android.com REPORTER_ASSERT(reporter, opaqueCounter0 == 256); 51d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com REPORTER_ASSERT(reporter, opaqueCounter1 == 256); 52d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com REPORTER_ASSERT(reporter, opaqueCounter2 == 256); 5380e39a77b16f4396eed230efea1d0b2fc8cbfb00reed@android.com 54d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com // Now ensure that we never over/underflow a byte 55d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com for (i = 0; i <= 255; i++) { 56d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com for (unsigned dst = 0; dst <= 255; dst++) { 57d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned r0 = test_srcover0(dst, i); 58d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned r1 = test_srcover1(dst, i); 59d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned r2 = test_srcover2(dst, i); 60d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com unsigned max = SkMax32(dst, i); 61d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com // ignore the known failure 62d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com if (dst != 255) { 63d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com REPORTER_ASSERT(reporter, r0 <= 255 && r0 >= max); 64d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com } 65d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com REPORTER_ASSERT(reporter, r1 <= 255 && r1 >= max); 66d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com REPORTER_ASSERT(reporter, r2 <= 255 && r2 >= max); 6780e39a77b16f4396eed230efea1d0b2fc8cbfb00reed@android.com 68d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#if 0 69d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com // this shows where r1 (faster) differs from r2 (more exact) 70d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com if (r1 != r2) { 7180e39a77b16f4396eed230efea1d0b2fc8cbfb00reed@android.com SkDebugf("--- dst=%d i=%d r1=%d r2=%d exact=%g\n", 7280e39a77b16f4396eed230efea1d0b2fc8cbfb00reed@android.com dst, i, r1, r2, i + dst - dst*i/255.0f); 73d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com } 74d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com#endif 75d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com } 76d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com } 77d66efc273e4996fb18f343bd30dcd506a1698b5breed@android.com} 78