SkPictureShader.cpp revision c09abe66c1388c5da456c7686eab7a7928e9e9d6 
1/*
2 * Copyright 2014 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 "SkPictureShader.h"
9
10#include "SkBitmap.h"
11#include "SkBitmapProcShader.h"
12#include "SkCanvas.h"
13#include "SkMatrixUtils.h"
14#include "SkPicture.h"
15#include "SkReadBuffer.h"
16
17#if SK_SUPPORT_GPU
18#include "GrContext.h"
19#endif
20
21SkPictureShader::SkPictureShader(SkPicture* picture, TileMode tmx, TileMode tmy)
22    : fPicture(SkRef(picture))
23    , fTmx(tmx)
24    , fTmy(tmy) { }
25
26SkPictureShader::SkPictureShader(SkReadBuffer& buffer)
27        : INHERITED(buffer) {
28    fTmx = static_cast<SkShader::TileMode>(buffer.read32());
29    fTmy = static_cast<SkShader::TileMode>(buffer.read32());
30    fPicture = SkPicture::CreateFromBuffer(buffer);
31}
32
33SkPictureShader::~SkPictureShader() {
34    fPicture->unref();
35}
36
37SkPictureShader* SkPictureShader::Create(SkPicture* picture, TileMode tmx, TileMode tmy) {
38    if (!picture || 0 == picture->width() || 0 == picture->height()) {
39        return NULL;
40    }
41    return SkNEW_ARGS(SkPictureShader, (picture, tmx, tmy));
42}
43
44void SkPictureShader::flatten(SkWriteBuffer& buffer) const {
45    this->INHERITED::flatten(buffer);
46
47    buffer.write32(fTmx);
48    buffer.write32(fTmy);
49    fPicture->flatten(buffer);
50}
51
52SkShader* SkPictureShader::refBitmapShader(const SkMatrix& matrix) const {
53    SkASSERT(fPicture && fPicture->width() > 0 && fPicture->height() > 0);
54
55    SkMatrix m;
56    if (this->hasLocalMatrix()) {
57        m.setConcat(matrix, this->getLocalMatrix());
58    } else {
59        m = matrix;
60    }
61
62    // Use a rotation-invariant scale
63    SkPoint scale;
64    if (!SkDecomposeUpper2x2(m, NULL, &scale, NULL)) {
65        // Decomposition failed, use an approximation.
66        scale.set(SkScalarSqrt(m.getScaleX() * m.getScaleX() + m.getSkewX() * m.getSkewX()),
67                  SkScalarSqrt(m.getScaleY() * m.getScaleY() + m.getSkewY() * m.getSkewY()));
68    }
69    SkSize scaledSize = SkSize::Make(scale.x() * fPicture->width(), scale.y() * fPicture->height());
70
71    SkISize tileSize = scaledSize.toRound();
72    if (tileSize.isEmpty()) {
73        return NULL;
74    }
75
76    // The actual scale, compensating for rounding.
77    SkSize tileScale = SkSize::Make(SkIntToScalar(tileSize.width()) / fPicture->width(),
78                                    SkIntToScalar(tileSize.height()) / fPicture->height());
79
80    SkAutoMutexAcquire ama(fCachedBitmapShaderMutex);
81
82    if (!fCachedBitmapShader || tileScale != fCachedTileScale ||
83        this->getLocalMatrix() != fCachedLocalMatrix) {
84        SkBitmap bm;
85        if (!bm.allocN32Pixels(tileSize.width(), tileSize.height())) {
86            return NULL;
87        }
88        bm.eraseColor(SK_ColorTRANSPARENT);
89
90        SkCanvas canvas(bm);
91        canvas.scale(tileScale.width(), tileScale.height());
92        canvas.drawPicture(*fPicture);
93
94        fCachedTileScale = tileScale;
95        fCachedLocalMatrix = this->getLocalMatrix();
96
97        SkMatrix shaderMatrix = this->getLocalMatrix();
98        shaderMatrix.preScale(1 / tileScale.width(), 1 / tileScale.height());
99        fCachedBitmapShader.reset(CreateBitmapShader(bm, fTmx, fTmy, &shaderMatrix));
100    }
101
102    // Increment the ref counter inside the mutex to ensure the returned pointer is still valid.
103    // Otherwise, the pointer may have been overwritten on a different thread before the object's
104    // ref count was incremented.
105    fCachedBitmapShader.get()->ref();
106    return fCachedBitmapShader;
107}
108
109SkShader* SkPictureShader::validInternal(const ContextRec& rec, SkMatrix* totalInverse) const {
110    if (!this->INHERITED::validContext(rec, totalInverse)) {
111        return NULL;
112    }
113
114    SkAutoTUnref<SkShader> bitmapShader(this->refBitmapShader(*rec.fMatrix));
115    if (!bitmapShader || !bitmapShader->validContext(rec)) {
116        return NULL;
117    }
118
119    return bitmapShader.detach();
120}
121
122bool SkPictureShader::validContext(const ContextRec& rec, SkMatrix* totalInverse) const {
123    SkAutoTUnref<SkShader> shader(this->validInternal(rec, totalInverse));
124    return shader != NULL;
125}
126
127SkShader::Context* SkPictureShader::createContext(const ContextRec& rec, void* storage) const {
128    SkAutoTUnref<SkShader> bitmapShader(this->validInternal(rec, NULL));
129    if (!bitmapShader) {
130        return NULL;
131    }
132
133    return SkNEW_PLACEMENT_ARGS(storage, PictureShaderContext, (*this, rec, bitmapShader.detach()));
134}
135
136size_t SkPictureShader::contextSize() const {
137    return sizeof(PictureShaderContext);
138}
139
140SkPictureShader::PictureShaderContext::PictureShaderContext(
141        const SkPictureShader& shader, const ContextRec& rec, SkShader* bitmapShader)
142    : INHERITED(shader, rec)
143    , fBitmapShader(bitmapShader)
144{
145    SkASSERT(fBitmapShader);
146    fBitmapShaderContextStorage = sk_malloc_throw(fBitmapShader->contextSize());
147    fBitmapShaderContext = fBitmapShader->createContext(rec, fBitmapShaderContextStorage);
148    SkASSERT(fBitmapShaderContext);
149}
150
151SkPictureShader::PictureShaderContext::~PictureShaderContext() {
152    fBitmapShaderContext->~Context();
153    sk_free(fBitmapShaderContextStorage);
154}
155
156uint32_t SkPictureShader::PictureShaderContext::getFlags() const {
157    return fBitmapShaderContext->getFlags();
158}
159
160SkShader::Context::ShadeProc SkPictureShader::PictureShaderContext::asAShadeProc(void** ctx) {
161    return fBitmapShaderContext->asAShadeProc(ctx);
162}
163
164void SkPictureShader::PictureShaderContext::shadeSpan(int x, int y, SkPMColor dstC[], int count) {
165    SkASSERT(fBitmapShaderContext);
166    fBitmapShaderContext->shadeSpan(x, y, dstC, count);
167}
168
169void SkPictureShader::PictureShaderContext::shadeSpan16(int x, int y, uint16_t dstC[], int count) {
170    SkASSERT(fBitmapShaderContext);
171    fBitmapShaderContext->shadeSpan16(x, y, dstC, count);
172}
173
174#ifndef SK_IGNORE_TO_STRING
175void SkPictureShader::toString(SkString* str) const {
176    static const char* gTileModeName[SkShader::kTileModeCount] = {
177        "clamp", "repeat", "mirror"
178    };
179
180    str->appendf("PictureShader: [%d:%d] ",
181                 fPicture ? fPicture->width() : 0,
182                 fPicture ? fPicture->height() : 0);
183
184    str->appendf("(%s, %s)", gTileModeName[fTmx], gTileModeName[fTmy]);
185
186    this->INHERITED::toString(str);
187}
188#endif
189
190#if SK_SUPPORT_GPU
191GrEffectRef* SkPictureShader::asNewEffect(GrContext* context, const SkPaint& paint) const {
192    SkAutoTUnref<SkShader> bitmapShader(this->refBitmapShader(context->getMatrix()));
193    if (!bitmapShader) {
194        return NULL;
195    }
196    return bitmapShader->asNewEffect(context, paint);
197}
198#endif
199