1/*
2 * Copyright 2012 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 "GrPath.h"
9
10template<int NumBits> static uint64_t get_top_n_float_bits(float f) {
11    char* floatData = reinterpret_cast<char*>(&f);
12    uint32_t floatBits = *reinterpret_cast<uint32_t*>(floatData);
13    return floatBits >> (32 - NumBits);
14}
15
16GrResourceKey GrPath::ComputeKey(const SkPath& path, const SkStrokeRec& stroke) {
17    static const GrResourceKey::ResourceType gPathResourceType = GrResourceKey::GenerateResourceType();
18    static const GrCacheID::Domain gPathDomain = GrCacheID::GenerateDomain();
19
20    GrCacheID::Key key;
21    uint64_t* keyData = key.fData64;
22    keyData[0] = path.getGenerationID();
23    keyData[1] = ComputeStrokeKey(stroke);
24
25    return GrResourceKey(GrCacheID(gPathDomain, key), gPathResourceType, 0);
26}
27
28uint64_t GrPath::ComputeStrokeKey(const SkStrokeRec& stroke) {
29    enum {
30        kStyleBits = 2,
31        kJoinBits = 2,
32        kCapBits = 2,
33        kWidthBits = 29,
34        kMiterBits = 29,
35
36        kJoinShift = kStyleBits,
37        kCapShift = kJoinShift + kJoinBits,
38        kWidthShift = kCapShift + kCapBits,
39        kMiterShift = kWidthShift + kWidthBits,
40
41        kBitCount = kMiterShift + kMiterBits
42    };
43
44    SK_COMPILE_ASSERT(SkStrokeRec::kStyleCount <= (1 << kStyleBits), style_shift_will_be_wrong);
45    SK_COMPILE_ASSERT(SkPaint::kJoinCount <= (1 << kJoinBits), cap_shift_will_be_wrong);
46    SK_COMPILE_ASSERT(SkPaint::kCapCount <= (1 << kCapBits), miter_shift_will_be_wrong);
47    SK_COMPILE_ASSERT(kBitCount == 64, wrong_stroke_key_size);
48
49    if (!stroke.needToApply()) {
50        return SkStrokeRec::kFill_Style;
51    }
52
53    uint64_t key = stroke.getStyle();
54    key |= stroke.getJoin() << kJoinShift;
55    key |= stroke.getCap() << kCapShift;
56    key |= get_top_n_float_bits<kWidthBits>(stroke.getWidth()) << kWidthShift;
57    key |= get_top_n_float_bits<kMiterBits>(stroke.getMiter()) << kMiterShift;
58
59    return key;
60}
61