Add SkPaint::getHash().

tests/PaintTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkBlurMask.h"
 #include "SkBlurMaskFilter.h"
 #include "SkLayerDrawLooper.h"
@@ skipping 325 matching lines @@
     ASSERT(other.getTextScaleX() == paint.getTextScaleX());
     ASSERT(other.getTextSize()   == paint.getTextSize());
     ASSERT(other.getLooper()     == paint.getLooper());
 
     // We have to be a little looser and compare just the modes.  Pointers might not be the same.
     SkXfermode::Mode otherMode, paintMode;
     ASSERT(other.getXfermode()->asMode(&otherMode));
     ASSERT(paint.getXfermode()->asMode(&paintMode));
     ASSERT(otherMode == paintMode);
 }
+
+DEF_TEST(Paint_getHash, r) {
+    // Try not to inspect the actual hash values in here.
+    // We might want to change the hash function.
+
+    SkPaint paint;
+    const uint32_t defaultHash = paint.getHash();
+
+    // Check that some arbitrary field affects the hash.
+    paint.setColor(0xFF00FF00);
+    REPORTER_ASSERT(r, paint.getHash() != defaultHash);
+    paint.setColor(SK_ColorBLACK);  // Reset to default value.
+    REPORTER_ASSERT(r, paint.getHash() == defaultHash);
+
+    // SkTypeface is the first field we hash, so test it specially.
+    paint.setTypeface(SkTypeface::RefDefault())->unref();
+    REPORTER_ASSERT(r, paint.getHash() != defaultHash);
+    paint.setTypeface(NULL);
+    REPORTER_ASSERT(r, paint.getHash() == defaultHash);
+
+    // This is part of fBitfields, the last field we hash.
+    paint.setHinting(SkPaint::kSlight_Hinting);
+    REPORTER_ASSERT(r, paint.getHash() != defaultHash);
+    paint.setHinting(SkPaint::kNormal_Hinting);
+    REPORTER_ASSERT(r, paint.getHash() == defaultHash);
+}