SkCreateCGImageRef.cpp revision 8ede49268daa98c4b2bce1c379aeb592f96243ee 
1#include "SkCGUtils.h"
2#include "SkBitmap.h"
3
4extern CGImageRef SkCreateCGImageRef(const SkBitmap&);
5
6static void SkBitmap_ReleaseInfo(void* info, const void* pixelData, size_t size) {
7    SkBitmap* bitmap = reinterpret_cast<SkBitmap*>(info);
8    delete bitmap;
9}
10
11static SkBitmap* prepareForImageRef(const SkBitmap& bm,
12                                    size_t* bitsPerComponent,
13                                    CGBitmapInfo* info) {
14    switch (bm.config()) {
15        case SkBitmap::kARGB_8888_Config:
16            *bitsPerComponent = 8;
17            // try to match our rgba ordering in SkColorPriv, but take into
18            // account that the data layout could have been overridden in
19            // SkUserConfig.
20#define HAS_ARGB_SHIFTS(a, r, g, b) \
21            (SK_A32_SHIFT == (a) && SK_R32_SHIFT == (r) \
22             && SK_G32_SHIFT == (g) && SK_B32_SHIFT == (b))
23#if defined(SK_CPU_LENDIAN) && HAS_ARGB_SHIFTS(24, 0, 8, 16) \
24 || defined(SK_CPU_BENDIAN) && HAS_ARGB_SHIFTS(0, 24, 16, 8)
25            // The default rgba ordering from SkColorPriv.h
26            *info = kCGBitmapByteOrder32Big |
27                    kCGImageAlphaPremultipliedLast;
28#elif defined(SK_CPU_LENDIAN) && HAS_ARGB_SHIFTS(24, 16, 8, 0) \
29   || defined(SK_CPU_BENDIAN) && HAS_ARGB_SHIFTS(24, 16, 8, 0)
30            // Matches the CGBitmapInfo that Apple recommends for best
31            // performance, used by google chrome.
32            *info = kCGBitmapByteOrder32Host |
33                    kCGImageAlphaPremultipliedFirst;
34#else
35// ...add more formats as required...
36#warning Cannot convert SkBitmap to CGImageRef with these shiftmasks. \
37            This will probably not work.
38            // Legacy behavior. Perhaps turn this into an error at some
39            // point.
40            *info = kCGBitmapByteOrder32Big |
41                    kCGImageAlphaPremultipliedLast;
42#endif
43#undef HAS_ARGB_SHIFTS
44            break;
45        case SkBitmap::kRGB_565_Config:
46            // doesn't see quite right. Are they thinking 1555?
47            *bitsPerComponent = 5;
48            *info = kCGBitmapByteOrder16Little;
49            break;
50        case SkBitmap::kARGB_4444_Config:
51            *bitsPerComponent = 4;
52            *info = kCGBitmapByteOrder16Little | kCGImageAlphaPremultipliedLast;
53            break;
54        default:
55            return NULL;
56    }
57
58    return new SkBitmap(bm);
59}
60
61CGImageRef SkCreateCGImageRef(const SkBitmap& bm) {
62    size_t bitsPerComponent;
63    CGBitmapInfo info;
64
65    SkBitmap* bitmap = prepareForImageRef(bm, &bitsPerComponent, &info);
66    if (NULL == bitmap) {
67        return NULL;
68    }
69
70    const int w = bitmap->width();
71    const int h = bitmap->height();
72    const size_t s = bitmap->getSize();
73
74    // our provider "owns" the bitmap*, and will take care of deleting it
75	// we initially lock it, so we can access the pixels. The bitmap will be deleted in the release
76	// proc, which will in turn unlock the pixels
77	bitmap->lockPixels();
78    CGDataProviderRef dataRef = CGDataProviderCreateWithData(bitmap, bitmap->getPixels(), s,
79															 SkBitmap_ReleaseInfo);
80
81    CGColorSpaceRef space = CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
82    CGImageRef ref = CGImageCreate(w, h, bitsPerComponent,
83                                   bitmap->bytesPerPixel() * 8,
84                                   bitmap->rowBytes(), space, info, dataRef,
85                                   NULL, false, kCGRenderingIntentDefault);
86    CGColorSpaceRelease(space);
87    CGDataProviderRelease(dataRef);
88    return ref;
89}
90
91
92