Add a GrPathRange class

src/gpu/GrPath.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPath.h"
 
+template<int NumBits> static uint64_t get_top_n_float_bits(float f) {
+    char* floatData = reinterpret_cast<char*>(&f);
+    uint32_t floatBits = *reinterpret_cast<uint32_t*>(floatData);
+    return floatBits >> (32 - NumBits);
+}
+
 GrResourceKey GrPath::ComputeKey(const SkPath& path, const SkStrokeRec& stroke) {
     static const GrResourceKey::ResourceType gPathResourceType = GrResourceKey::GenerateResourceType();
     static const GrCacheID::Domain gPathDomain = GrCacheID::GenerateDomain();
 
     GrCacheID::Key key;
-    uint32_t* keyData = key.fData32;
+    uint64_t* keyData = key.fData64;
     keyData[0] = path.getGenerationID();
-
-    SK_COMPILE_ASSERT(SkPaint::kJoinCount <= 3, cap_shift_will_be_wrong);
-    keyData[1] = stroke.needToApply();
-    if (0 != keyData[1]) {
-        keyData[1] |= stroke.getJoin() << 1;
-        keyData[1] |= stroke.getCap() << 3;
-        keyData[2] = static_cast<uint32_t>(stroke.getMiter());
-        keyData[3] = static_cast<uint32_t>(stroke.getWidth());
-    } else {
-        keyData[2] = 0;
-        keyData[3] = 0;
-    }
+    keyData[1] = ComputeStrokeKey(stroke);
 
     return GrResourceKey(GrCacheID(gPathDomain, key), gPathResourceType, 0);
 }
+
+uint64_t GrPath::ComputeStrokeKey(const SkStrokeRec& stroke) {
+    enum {
+        kStyleBits = 2,
+        kJoinBits = 2,
+        kCapBits = 2,
+        kWidthBits = 29,
+        kMiterBits = 29,
+
+        kJoinShift = kStyleBits,
+        kCapShift = kJoinShift + kJoinBits,
+        kWidthShift = kCapShift + kCapBits,
+        kMiterShift = kWidthShift + kWidthBits,
+
+        kBitCount = kMiterShift + kMiterBits
+    };
+
+    SK_COMPILE_ASSERT(SkStrokeRec::kStyleCount <= (1 << kStyleBits), style_shift_will_be_wrong);
+    SK_COMPILE_ASSERT(SkPaint::kJoinCount <= (1 << kJoinBits), cap_shift_will_be_wrong);
+    SK_COMPILE_ASSERT(SkPaint::kCapCount <= (1 << kCapBits), miter_shift_will_be_wrong);
+    SK_COMPILE_ASSERT(kBitCount == 64, wrong_stroke_key_size);
+
+    if (!stroke.needToApply()) {
+        return SkStrokeRec::kFill_Style;
+    }
+
+    uint64_t key = stroke.getStyle();
+    key |= stroke.getJoin() << kJoinShift;
+    key |= stroke.getCap() << kCapShift;
+    key |= get_top_n_float_bits<kWidthBits>(stroke.getWidth()) << kWidthShift;
+    key |= get_top_n_float_bits<kMiterBits>(stroke.getMiter()) << kMiterShift;
+
+    return key;
+}