create GrTestUtils.h, move some common functions into it

include/gpu/GrTestUtils.h

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrTestUtils_DEFINED
+#define GrTestUtils_DEFINED
+
+#include "GrColor.h"
+#include "SkRandom.h"
+
+class SkMatrix;
+
+namespace GrTest {
+/**
+ * A helper for use in Test functions.
+ */
+const SkMatrix& TestMatrix(SkRandom*);
+
+}
+
+static inline GrColor GrRandomColor(SkRandom* random) {
+    // There are only a few cases of random colors which interest us
+    enum ColorMode {
+        kAllOnes_ColorMode,
+        kAllZeros_ColorMode,
+        kAlphaOne_ColorMode,
+        kRandom_ColorMode,
+        kLast_ColorMode = kRandom_ColorMode
+    };
+
+    ColorMode colorMode = ColorMode(random->nextULessThan(kLast_ColorMode + 1));
+    GrColor color;
+    switch (colorMode) {
+        case kAllOnes_ColorMode:
+            color = GrColorPackRGBA(0xFF, 0xFF, 0xFF, 0xFF);
+            break;
+        case kAllZeros_ColorMode:
+            color = GrColorPackRGBA(0, 0, 0, 0);
+            break;
+        case kAlphaOne_ColorMode:
+            color = GrColorPackRGBA(random->nextULessThan(256),
+                                    random->nextULessThan(256),
+                                    random->nextULessThan(256),
+                                    0xFF);
+            break;
+        case kRandom_ColorMode:
+            uint8_t alpha = random->nextULessThan(256);
+            color = GrColorPackRGBA(random->nextRangeU(0, alpha),
+                                    random->nextRangeU(0, alpha),
+                                    random->nextRangeU(0, alpha),
+                                    alpha);
+            break;
+    }
+    GrColorIsPMAssert(color);
+    return color;
+}
+
+static inline uint8_t GrRandomCoverage(SkRandom* random) {
+    enum CoverageMode {
+        kZero_CoverageMode,
+        kAllOnes_CoverageMode,
+        kRandom_CoverageMode,
+        kLast_CoverageMode = kRandom_CoverageMode
+    };
+
+    CoverageMode colorMode = CoverageMode(random->nextULessThan(kLast_CoverageMode + 1));
+    uint8_t coverage;
+    switch (colorMode) {
+        case kZero_CoverageMode:
+            coverage = 0;
+        case kAllOnes_CoverageMode:
+            coverage = 0xff;
+            break;
+        case kRandom_CoverageMode:
+            coverage = random->nextULessThan(256);
+            break;
+    }
+    return coverage;
+}
+
+#endif