Replace buggy_blend_modes GM with an exhaustive test.
The new test is disabled by default, as it's quite slow.
We can run it if we suspect problems by passing -x to DM.
This test would have been failing before the bug fix, and now is passing.
Assuming the Priv on the end means it's not considered public API...
TBR=reed@google.com
BUG=skia:4052
Review URL: https://codereview.chromium.org/1228333003
diff --git a/tests/BlendTest.cpp b/tests/BlendTest.cpp
index a0a84d7..d816b72 100644
--- a/tests/BlendTest.cpp
+++ b/tests/BlendTest.cpp
@@ -1,5 +1,15 @@
+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
#include "Test.h"
#include "SkColor.h"
+#include "SkColorPriv.h"
+#include "SkTaskGroup.h"
+#include "SkXfermode.h"
#define ASSERT(x) REPORTER_ASSERT(r, x)
@@ -256,3 +266,36 @@
// all others
//
// Algorithms that make sense to use in Skia: blend_256_round, blend_256_round_alt, blend_perfect
+
+DEF_TEST(Blend_premul_begets_premul, r) {
+ // This test is quite slow, even if you have enough cores to run each mode in parallel.
+ if (!r->allowExtendedTest()) {
+ return;
+ }
+
+ // No matter what xfermode we use, premul inputs should create premul outputs.
+ auto test_mode = [&](int m) {
+ SkXfermode::Mode mode = (SkXfermode::Mode)m;
+ if (mode == SkXfermode::kSrcOver_Mode) {
+ return; // TODO: can't create a SrcOver xfermode.
+ }
+ SkAutoTUnref<SkXfermode> xfermode(SkXfermode::Create(mode));
+ SkASSERT(xfermode);
+ // We'll test all alphas and legal color values, assuming all colors work the same.
+ // This is not true for non-separable blend modes, but this test still can't hurt.
+ for (int sa = 0; sa <= 255; sa++) {
+ for (int da = 0; da <= 255; da++) {
+ for (int s = 0; s <= sa; s++) {
+ for (int d = 0; d <= da; d++) {
+ SkPMColor src = SkPackARGB32(sa, s, s, s),
+ dst = SkPackARGB32(da, d, d, d);
+ xfermode->xfer32(&dst, &src, 1, nullptr); // To keep it simple, no AA.
+ if (!SkPMColorValid(dst)) {
+ ERRORF(r, "%08x is not premul using %s", dst, SkXfermode::ModeName(mode));
+ }
+ }}}}
+ };
+
+ // Parallelism helps speed things up on my desktop from ~725s to ~50s.
+ sk_parallel_for(SkXfermode::kLastMode, test_mode);
+}