1 /* 2 * Copyright 2015 Google Inc. 3 * 4 * Use of this source code is governed by a BSD-style license that can be 5 * found in the LICENSE file. 6 */ 7 8 #include "Test.h" 9 #include "SkColor.h" 10 #include "SkColorPriv.h" 11 #include "SkTaskGroup.h" 12 #include "SkXfermode.h" 13 #include <functional> 14 15 struct Results { int diffs, diffs_0x00, diffs_0xff, diffs_by_1; }; 16 17 static bool acceptable(const Results& r) { 18 #if 0 19 SkDebugf("%d diffs, %d at 0x00, %d at 0xff, %d off by 1, all out of 65536\n", 20 r.diffs, r.diffs_0x00, r.diffs_0xff, r.diffs_by_1); 21 #endif 22 return r.diffs_by_1 == r.diffs // never off by more than 1 23 && r.diffs_0x00 == 0 // transparent must stay transparent 24 && r.diffs_0xff == 0; // opaque must stay opaque 25 } 26 27 template <typename Fn> 28 static Results test(Fn&& multiply) { 29 Results r = { 0,0,0,0 }; 30 for (int x = 0; x < 256; x++) { 31 for (int y = 0; y < 256; y++) { 32 int p = multiply(x, y), 33 ideal = (x*y+127)/255; 34 if (p != ideal) { 35 r.diffs++; 36 if (x == 0x00 || y == 0x00) { r.diffs_0x00++; } 37 if (x == 0xff || y == 0xff) { r.diffs_0xff++; } 38 if (SkTAbs(ideal - p) == 1) { r.diffs_by_1++; } 39 } 40 }} 41 return r; 42 } 43 44 DEF_TEST(Blend_byte_multiply, r) { 45 // These are all temptingly close but fundamentally broken. 46 int (*broken[])(int, int) = { 47 [](int x, int y) { return (x*y)>>8; }, 48 [](int x, int y) { return (x*y+128)>>8; }, 49 [](int x, int y) { y += y>>7; return (x*y)>>8; }, 50 }; 51 for (auto multiply : broken) { REPORTER_ASSERT(r, !acceptable(test(multiply))); } 52 53 // These are fine to use, but not perfect. 54 int (*fine[])(int, int) = { 55 [](int x, int y) { return (x*y+x)>>8; }, 56 [](int x, int y) { return (x*y+y)>>8; }, 57 [](int x, int y) { return (x*y+255)>>8; }, 58 [](int x, int y) { y += y>>7; return (x*y+128)>>8; }, 59 }; 60 for (auto multiply : fine) { REPORTER_ASSERT(r, acceptable(test(multiply))); } 61 62 // These are pefect. 63 int (*perfect[])(int, int) = { 64 [](int x, int y) { return (x*y+127)/255; }, // Duh. 65 [](int x, int y) { int p = (x*y+128); return (p+(p>>8))>>8; }, 66 [](int x, int y) { return ((x*y+128)*257)>>16; }, 67 }; 68 for (auto multiply : perfect) { REPORTER_ASSERT(r, test(multiply).diffs == 0); } 69 } 70 71 DEF_TEST(Blend_premul_begets_premul, r) { 72 // This test is quite slow, even if you have enough cores to run each mode in parallel. 73 if (!r->allowExtendedTest()) { 74 return; 75 } 76 77 // No matter what xfermode we use, premul inputs should create premul outputs. 78 auto test_mode = [&](int m) { 79 SkXfermode::Mode mode = (SkXfermode::Mode)m; 80 if (mode == SkXfermode::kSrcOver_Mode) { 81 return; // TODO: can't create a SrcOver xfermode. 82 } 83 SkAutoTUnref<SkXfermode> xfermode(SkXfermode::Create(mode)); 84 SkASSERT(xfermode); 85 // We'll test all alphas and legal color values, assuming all colors work the same. 86 // This is not true for non-separable blend modes, but this test still can't hurt. 87 for (int sa = 0; sa <= 255; sa++) { 88 for (int da = 0; da <= 255; da++) { 89 for (int s = 0; s <= sa; s++) { 90 for (int d = 0; d <= da; d++) { 91 SkPMColor src = SkPackARGB32(sa, s, s, s), 92 dst = SkPackARGB32(da, d, d, d); 93 xfermode->xfer32(&dst, &src, 1, nullptr); // To keep it simple, no AA. 94 if (!SkPMColorValid(dst)) { 95 ERRORF(r, "%08x is not premul using %s", dst, SkXfermode::ModeName(mode)); 96 } 97 }}}} 98 }; 99 100 // Parallelism helps speed things up on my desktop from ~725s to ~50s. 101 SkTaskGroup().batch(SkXfermode::kLastMode, test_mode); 102 } 103
