1/*
2 * Copyright 2018 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
9#include "src/gpu/gradients/GrGradientBitmapCache.h"
10
11#include "include/private/SkFloatBits.h"
12#include "include/private/SkHalf.h"
13#include "include/private/SkMalloc.h"
14#include "include/private/SkTemplates.h"
15
16#include <functional>
17
18struct GrGradientBitmapCache::Entry {
19 Entry* fPrev;
20 Entry* fNext;
21
22 void* fBuffer;
23 size_t fSize;
24 SkBitmap fBitmap;
25
26 Entry(const void* buffer, size_t size, const SkBitmap& bm)
27 : fPrev(nullptr),
28 fNext(nullptr),
29 fBitmap(bm) {
30 fBuffer = sk_malloc_throw(size);
31 fSize = size;
32 memcpy(fBuffer, buffer, size);
33 }
34
35 ~Entry() { sk_free(fBuffer); }
36
37 bool equals(const void* buffer, size_t size) const {
38 return (fSize == size) && !memcmp(fBuffer, buffer, size);
39 }
40};
41
42GrGradientBitmapCache::GrGradientBitmapCache(int max, int res)
43 : fMaxEntries(max)
44 , fResolution(res) {
45 fEntryCount = 0;
46 fHead = fTail = nullptr;
47
48 this->validate();
49}
50
51GrGradientBitmapCache::~GrGradientBitmapCache() {
52 this->validate();
53
54 Entry* entry = fHead;
55 while (entry) {
56 Entry* next = entry->fNext;
57 delete entry;
58 entry = next;
59 }
60}
61
62GrGradientBitmapCache::Entry* GrGradientBitmapCache::release(Entry* entry) const {
63 if (entry->fPrev) {
64 SkASSERT(fHead != entry);
65 entry->fPrev->fNext = entry->fNext;
66 } else {
67 SkASSERT(fHead == entry);
68 fHead = entry->fNext;
69 }
70 if (entry->fNext) {
71 SkASSERT(fTail != entry);
72 entry->fNext->fPrev = entry->fPrev;
73 } else {
74 SkASSERT(fTail == entry);
75 fTail = entry->fPrev;
76 }
77 return entry;
78}
79
80void GrGradientBitmapCache::attachToHead(Entry* entry) const {
81 entry->fPrev = nullptr;
82 entry->fNext = fHead;
83 if (fHead) {
84 fHead->fPrev = entry;
85 } else {
86 fTail = entry;
87 }
88 fHead = entry;
89}
90
91bool GrGradientBitmapCache::find(const void* buffer, size_t size, SkBitmap* bm) const {
92 AutoValidate av(this);
93
94 Entry* entry = fHead;
95 while (entry) {
96 if (entry->equals(buffer, size)) {
97 if (bm) {
98 *bm = entry->fBitmap;
99 }
100 // move to the head of our list, so we purge it last
101 this->release(entry);
102 this->attachToHead(entry);
103 return true;
104 }
105 entry = entry->fNext;
106 }
107 return false;
108}
109
110void GrGradientBitmapCache::add(const void* buffer, size_t len, const SkBitmap& bm) {
111 AutoValidate av(this);
112
113 if (fEntryCount == fMaxEntries) {
114 SkASSERT(fTail);
115 delete this->release(fTail);
116 fEntryCount -= 1;
117 }
118
119 Entry* entry = new Entry(buffer, len, bm);
120 this->attachToHead(entry);
121 fEntryCount += 1;
122}
123
124///////////////////////////////////////////////////////////////////////////////
125
126
127void GrGradientBitmapCache::fillGradient(const SkPMColor4f* colors, const SkScalar* positions,
128 int count, SkColorType colorType, SkBitmap* bitmap) {
129 SkHalf* pixelsF16 = reinterpret_cast<SkHalf*>(bitmap->getPixels());
130 uint32_t* pixels32 = reinterpret_cast<uint32_t*>(bitmap->getPixels());
131
132 typedef std::function<void(const Sk4f&, int)> pixelWriteFn_t;
133
134 pixelWriteFn_t writeF16Pixel = [&](const Sk4f& x, int index) {
135 Sk4h c = SkFloatToHalf_finite_ftz(x);
136 pixelsF16[4*index+0] = c[0];
137 pixelsF16[4*index+1] = c[1];
138 pixelsF16[4*index+2] = c[2];
139 pixelsF16[4*index+3] = c[3];
140 };
141 pixelWriteFn_t write8888Pixel = [&](const Sk4f& c, int index) {
142 pixels32[index] = Sk4f_toL32(c);
143 };
144
145 pixelWriteFn_t writePixel =
146 (colorType == kRGBA_F16_SkColorType) ? writeF16Pixel : write8888Pixel;
147
148 int prevIndex = 0;
149 for (int i = 1; i < count; i++) {
150 // Historically, stops have been mapped to [0, 256], with 256 then nudged to the next
151 // smaller value, then truncate for the texture index. This seems to produce the best
152 // results for some common distributions, so we preserve the behavior.
153 int nextIndex = std::min(positions[i] * fResolution,
154 SkIntToScalar(fResolution - 1));
155
156 if (nextIndex > prevIndex) {
157 Sk4f c0 = Sk4f::Load(colors[i - 1].vec()),
158 c1 = Sk4f::Load(colors[i ].vec());
159
160 Sk4f step = Sk4f(1.0f / static_cast<float>(nextIndex - prevIndex));
161 Sk4f delta = (c1 - c0) * step;
162
163 for (int curIndex = prevIndex; curIndex <= nextIndex; ++curIndex) {
164 writePixel(c0, curIndex);
165 c0 += delta;
166 }
167 }
168 prevIndex = nextIndex;
169 }
170 SkASSERT(prevIndex == fResolution - 1);
171}
172
173void GrGradientBitmapCache::getGradient(const SkPMColor4f* colors, const SkScalar* positions,
174 int count, SkColorType colorType, SkAlphaType alphaType, SkBitmap* bitmap) {
175 // build our key: [numColors + colors[] + positions[] + alphaType + colorType ]
176 static_assert(sizeof(SkPMColor4f) % sizeof(int32_t) == 0, "");
177 const int colorsAsIntCount = count * sizeof(SkPMColor4f) / sizeof(int32_t);
178 int keyCount = 1 + colorsAsIntCount + 1 + 1;
179 if (count > 2) {
180 keyCount += count - 1;
181 }
182
183 SkAutoSTMalloc<64, int32_t> storage(keyCount);
184 int32_t* buffer = storage.get();
185
186 *buffer++ = count;
187 memcpy(buffer, colors, count * sizeof(SkPMColor4f));
188 buffer += colorsAsIntCount;
189 if (count > 2) {
190 for (int i = 1; i < count; i++) {
191 *buffer++ = SkFloat2Bits(positions[i]);
192 }
193 }
194 *buffer++ = static_cast<int32_t>(alphaType);
195 *buffer++ = static_cast<int32_t>(colorType);
196 SkASSERT(buffer - storage.get() == keyCount);
197
198 ///////////////////////////////////
199
200 // acquire lock for checking/adding to cache
201 SkAutoMutexExclusive ama(fMutex);
202 size_t size = keyCount * sizeof(int32_t);
203 if (!this->find(storage.get(), size, bitmap)) {
204 SkImageInfo info = SkImageInfo::Make(fResolution, 1, colorType, alphaType);
205 bitmap->allocPixels(info);
206 GrGradientBitmapCache::fillGradient(colors, positions, count, colorType, bitmap);
207 bitmap->setImmutable();
208 this->add(storage.get(), size, *bitmap);
209 }
210}
211
212///////////////////////////////////////////////////////////////////////////////
213
214#ifdef SK_DEBUG
215
216void GrGradientBitmapCache::validate() const {
217 SkASSERT(fEntryCount >= 0 && fEntryCount <= fMaxEntries);
218
219 if (fEntryCount > 0) {
220 SkASSERT(nullptr == fHead->fPrev);
221 SkASSERT(nullptr == fTail->fNext);
222
223 if (fEntryCount == 1) {
224 SkASSERT(fHead == fTail);
225 } else {
226 SkASSERT(fHead != fTail);
227 }
228
229 Entry* entry = fHead;
230 int count = 0;
231 while (entry) {
232 count += 1;
233 entry = entry->fNext;
234 }
235 SkASSERT(count == fEntryCount);
236
237 entry = fTail;
238 while (entry) {
239 count -= 1;
240 entry = entry->fPrev;
241 }
242 SkASSERT(0 == count);
243 } else {
244 SkASSERT(nullptr == fHead);
245 SkASSERT(nullptr == fTail);
246 }
247}
248
249#endif
250