11cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger 21cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger/* 31cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * Copyright 2011 Google Inc. 41cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * 51cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * Use of this source code is governed by a BSD-style license that can be 61cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger * found in the LICENSE file. 71cab2921ab279367f8206cdadc9259d12e603548Derek Sollenberger */ 8da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#include "Test.h" 9da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#include "SkColorPriv.h" 10da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#include "SkXfermode.h" 11da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 12da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed// our std SkAlpha255To256 13da3b8b285a5e3e6f344461d67e3370b27701756dMike Reedstatic int test_srcover0(unsigned dst, unsigned alpha) { 14da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed return alpha + SkAlphaMul(dst, SkAlpha255To256(255 - alpha)); 15da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed} 16da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 17da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed// faster hack +1 18da3b8b285a5e3e6f344461d67e3370b27701756dMike Reedstatic int test_srcover1(unsigned dst, unsigned alpha) { 19da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed return alpha + SkAlphaMul(dst, 256 - alpha); 20da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed} 21da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 22da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed// slower "correct" 23da3b8b285a5e3e6f344461d67e3370b27701756dMike Reedstatic int test_srcover2(unsigned dst, unsigned alpha) { 24da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed return alpha + SkMulDiv255Round(dst, 255 - alpha); 25da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed} 26da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 27da3b8b285a5e3e6f344461d67e3370b27701756dMike Reedstatic void test_srcover_hack(skiatest::Reporter* reporter) { 28da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed /* Here's the idea. Can we ensure that when we blend on top of an opaque 29da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed dst, that the result always stay's opaque (i.e. exactly 255)? 30da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed */ 31da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 32da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned i; 33da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed int opaqueCounter0 = 0; 34da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed int opaqueCounter1 = 0; 35da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed int opaqueCounter2 = 0; 36da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed for (i = 0; i <= 255; i++) { 37da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned result0 = test_srcover0(0xFF, i); 38da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned result1 = test_srcover1(0xFF, i); 39da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned result2 = test_srcover2(0xFF, i); 40da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed opaqueCounter0 += (result0 == 0xFF); 41da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed opaqueCounter1 += (result1 == 0xFF); 42da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed opaqueCounter2 += (result2 == 0xFF); 43da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed } 44da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#if 0 45da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed SkDebugf("---- opaque test: [%d %d %d]\n", 46da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed opaqueCounter0, opaqueCounter1, opaqueCounter2); 47da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#endif 48da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed // we acknowledge that technique0 does not always return opaque 49f95abb54afa5469c53d3ac899ecbce8a386471c1Mike Reed REPORTER_ASSERT(reporter, opaqueCounter0 == 256); 50da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed REPORTER_ASSERT(reporter, opaqueCounter1 == 256); 51da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed REPORTER_ASSERT(reporter, opaqueCounter2 == 256); 52da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 53da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed // Now ensure that we never over/underflow a byte 54da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed for (i = 0; i <= 255; i++) { 55da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed for (unsigned dst = 0; dst <= 255; dst++) { 56da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned r0 = test_srcover0(dst, i); 57da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned r1 = test_srcover1(dst, i); 58da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned r2 = test_srcover2(dst, i); 59da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed unsigned max = SkMax32(dst, i); 60da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed // ignore the known failure 61da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed if (dst != 255) { 62da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed REPORTER_ASSERT(reporter, r0 <= 255 && r0 >= max); 63da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed } 64da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed REPORTER_ASSERT(reporter, r1 <= 255 && r1 >= max); 65da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed REPORTER_ASSERT(reporter, r2 <= 255 && r2 >= max); 66da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 67da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#if 0 68da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed // this shows where r1 (faster) differs from r2 (more exact) 69da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed if (r1 != r2) { 70da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed SkDebugf("--- dst=%d i=%d r1=%d r2=%d exact=%g\n", 71da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed dst, i, r1, r2, i + dst - dst*i/255.0f); 72da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed } 73da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#endif 74da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed } 75da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed } 76da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed} 77da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed 78da3b8b285a5e3e6f344461d67e3370b27701756dMike Reed#include "TestClassDef.h" 79da3b8b285a5e3e6f344461d67e3370b27701756dMike ReedDEFINE_TESTCLASS("SrcOver", SrcOverTestClass, test_srcover_hack) 80