SkSurface_Raster.cpp revision 672588b684d484dce6ae251e9e163e4a46924322 
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 "SkSurface_Base.h"
9#include "SkImagePriv.h"
10#include "SkCanvas.h"
11#include "SkDevice.h"
12#include "SkMallocPixelRef.h"
13
14static const size_t kIgnoreRowBytesValue = (size_t)~0;
15
16class SkSurface_Raster : public SkSurface_Base {
17public:
18    static bool Valid(const SkImageInfo&, size_t rb = kIgnoreRowBytesValue);
19
20    SkSurface_Raster(const SkImageInfo&, void*, size_t rb);
21    SkSurface_Raster(const SkImageInfo&, SkPixelRef*, size_t rb);
22
23    virtual SkCanvas* onNewCanvas() SK_OVERRIDE;
24    virtual SkSurface* onNewSurface(const SkImageInfo&) SK_OVERRIDE;
25    virtual SkImage* onNewImageSnapshot() SK_OVERRIDE;
26    virtual void onDraw(SkCanvas*, SkScalar x, SkScalar y,
27                        const SkPaint*) SK_OVERRIDE;
28    virtual void onCopyOnWrite(ContentChangeMode) SK_OVERRIDE;
29
30private:
31    SkBitmap    fBitmap;
32    bool        fWeOwnThePixels;
33
34    typedef SkSurface_Base INHERITED;
35};
36
37///////////////////////////////////////////////////////////////////////////////
38
39bool SkSurface_Raster::Valid(const SkImageInfo& info, size_t rowBytes) {
40    static const size_t kMaxTotalSize = SK_MaxS32;
41
42    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
43
44    int shift = 0;
45    switch (config) {
46        case SkBitmap::kA8_Config:
47            shift = 0;
48            break;
49        case SkBitmap::kRGB_565_Config:
50            shift = 1;
51            break;
52        case SkBitmap::kARGB_8888_Config:
53            shift = 2;
54            break;
55        default:
56            return false;
57    }
58
59    // TODO: examine colorspace
60
61    if (kIgnoreRowBytesValue == rowBytes) {
62        return true;
63    }
64
65    uint64_t minRB = (uint64_t)info.fWidth << shift;
66    if (minRB > rowBytes) {
67        return false;
68    }
69
70    size_t alignedRowBytes = rowBytes >> shift << shift;
71    if (alignedRowBytes != rowBytes) {
72        return false;
73    }
74
75    uint64_t size = (uint64_t)info.fHeight * rowBytes;
76    if (size > kMaxTotalSize) {
77        return false;
78    }
79
80    return true;
81}
82
83SkSurface_Raster::SkSurface_Raster(const SkImageInfo& info, void* pixels, size_t rb)
84        : INHERITED(info.fWidth, info.fHeight) {
85    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
86    fBitmap.setConfig(config, info.fWidth, info.fHeight, rb, info.fAlphaType);
87    fBitmap.setPixels(pixels);
88    fWeOwnThePixels = false;    // We are "Direct"
89}
90
91SkSurface_Raster::SkSurface_Raster(const SkImageInfo& info, SkPixelRef* pr, size_t rb)
92        : INHERITED(info.fWidth, info.fHeight) {
93    SkBitmap::Config config = SkImageInfoToBitmapConfig(info);
94    fBitmap.setConfig(config, info.fWidth, info.fHeight, rb, info.fAlphaType);
95    fBitmap.setPixelRef(pr);
96    fWeOwnThePixels = true;
97
98    if (!SkAlphaTypeIsOpaque(info.fAlphaType)) {
99        fBitmap.eraseColor(SK_ColorTRANSPARENT);
100    }
101}
102
103SkCanvas* SkSurface_Raster::onNewCanvas() {
104    return SkNEW_ARGS(SkCanvas, (fBitmap));
105}
106
107SkSurface* SkSurface_Raster::onNewSurface(const SkImageInfo& info) {
108    return SkSurface::NewRaster(info);
109}
110
111void SkSurface_Raster::onDraw(SkCanvas* canvas, SkScalar x, SkScalar y,
112                              const SkPaint* paint) {
113    canvas->drawBitmap(fBitmap, x, y, paint);
114}
115
116SkImage* SkSurface_Raster::onNewImageSnapshot() {
117    return SkNewImageFromBitmap(fBitmap, fWeOwnThePixels);
118}
119
120void SkSurface_Raster::onCopyOnWrite(ContentChangeMode mode) {
121    // are we sharing pixelrefs with the image?
122    SkASSERT(NULL != this->getCachedImage());
123    if (SkBitmapImageGetPixelRef(this->getCachedImage()) == fBitmap.pixelRef()) {
124        SkASSERT(fWeOwnThePixels);
125        if (kDiscard_ContentChangeMode == mode) {
126            fBitmap.setPixelRef(NULL);
127            fBitmap.allocPixels();
128        } else {
129            SkBitmap prev(fBitmap);
130            prev.deepCopyTo(&fBitmap, prev.config());
131        }
132        // Now fBitmap is a deep copy of itself (and therefore different from
133        // what is being used by the image. Next we update the canvas to use
134        // this as its backend, so we can't modify the image's pixels anymore.
135        SkASSERT(NULL != this->getCachedCanvas());
136        this->getCachedCanvas()->getDevice()->replaceBitmapBackendForRasterSurface(fBitmap);
137    }
138}
139
140///////////////////////////////////////////////////////////////////////////////
141
142SkSurface* SkSurface::NewRasterDirect(const SkImageInfo& info, void* pixels, size_t rowBytes) {
143    if (!SkSurface_Raster::Valid(info, rowBytes)) {
144        return NULL;
145    }
146    if (NULL == pixels) {
147        return NULL;
148    }
149
150    return SkNEW_ARGS(SkSurface_Raster, (info, pixels, rowBytes));
151}
152
153SkSurface* SkSurface::NewRaster(const SkImageInfo& info) {
154    if (!SkSurface_Raster::Valid(info)) {
155        return NULL;
156    }
157
158    SkAutoTUnref<SkPixelRef> pr(SkMallocPixelRef::NewAllocate(info, 0, NULL));
159    if (NULL == pr.get()) {
160        return NULL;
161    }
162    return SkNEW_ARGS(SkSurface_Raster, (info, pr, info.minRowBytes()));
163}
164