src/utils/mac/SkCreateCGImageRef.cpp

#include "SkCGUtils.h"
#include "SkBitmap.h"
#include "SkColorPriv.h"

extern CGImageRef SkCreateCGImageRef(const SkBitmap&);

static void SkBitmap_ReleaseInfo(void* info, const void* pixelData, size_t size) {
    SkBitmap* bitmap = reinterpret_cast<SkBitmap*>(info);
    delete bitmap;
}

#define HAS_ARGB_SHIFTS(a, r, g, b) \
    (SK_A32_SHIFT == (a) && SK_R32_SHIFT == (r) \
    && SK_G32_SHIFT == (g) && SK_B32_SHIFT == (b))

static SkBitmap* prepareForImageRef(const SkBitmap& bm,
                                    size_t* bitsPerComponent,
                                    CGBitmapInfo* info) {
    bool upscaleTo32 = false;

    switch (bm.config()) {
        case SkBitmap::kRGB_565_Config:
            upscaleTo32 = true;
            // fall through
        case SkBitmap::kARGB_8888_Config:
            *bitsPerComponent = 8;
#if defined(SK_CPU_LENDIAN) && HAS_ARGB_SHIFTS(24, 0, 8, 16) \
 || defined(SK_CPU_BENDIAN) && HAS_ARGB_SHIFTS(0, 24, 16, 8)
            *info = kCGBitmapByteOrder32Big;
#elif defined(SK_CPU_LENDIAN) && HAS_ARGB_SHIFTS(24, 16, 8, 0) \
   || defined(SK_CPU_BENDIAN) && HAS_ARGB_SHIFTS(24, 16, 8, 0)
            // Matches the CGBitmapInfo that Apple recommends for best
            // performance, used by google chrome.
            *info = kCGBitmapByteOrder32Little;
#else
// ...add more formats as required...
#warning Cannot convert SkBitmap to CGImageRef with these shiftmasks. \
            This will probably not work.
            // Legacy behavior. Perhaps turn this into an error at some
            // point.
            *info = kCGBitmapByteOrder32Big;
#endif
            break;
#if 0
        case SkBitmap::kRGB_565_Config:
            // doesn't see quite right. Are they thinking 1555?
            *bitsPerComponent = 5;
            *info = kCGBitmapByteOrder16Little;
            break;
#endif
        case SkBitmap::kARGB_4444_Config:
            *bitsPerComponent = 4;
            *info = kCGBitmapByteOrder16Little | kCGImageAlphaPremultipliedLast;
            break;
        default:
            return NULL;
    }

    if (!bm.isOpaque()) {
        *info |= kCGImageAlphaPremultipliedLast;
    }

    SkBitmap* copy;
    if (upscaleTo32) {
        copy = new SkBitmap;
        // here we make a ceep copy of the pixels, since CG won't take our
        // 565 directly
        bm.copyTo(copy, SkBitmap::kARGB_8888_Config);
    } else {
        copy = new SkBitmap(bm);
    }
    return copy;
}

#undef HAS_ARGB_SHIFTS

CGImageRef SkCreateCGImageRef(const SkBitmap& bm) {
    size_t bitsPerComponent;
    CGBitmapInfo info;

    SkBitmap* bitmap = prepareForImageRef(bm, &bitsPerComponent, &info);
    if (NULL == bitmap) {
        return NULL;
    }

    const int w = bitmap->width();
    const int h = bitmap->height();
    const size_t s = bitmap->getSize();

    // our provider "owns" the bitmap*, and will take care of deleting it
	// we initially lock it, so we can access the pixels. The bitmap will be deleted in the release
	// proc, which will in turn unlock the pixels
	bitmap->lockPixels();
    CGDataProviderRef dataRef = CGDataProviderCreateWithData(bitmap, bitmap->getPixels(), s,
															 SkBitmap_ReleaseInfo);

    CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
    CGImageRef ref = CGImageCreate(w, h, bitsPerComponent,
                                   bitmap->bytesPerPixel() * 8,
                                   bitmap->rowBytes(), space, info, dataRef,
                                   NULL, false, kCGRenderingIntentDefault);
    CGColorSpaceRelease(space);
    CGDataProviderRelease(dataRef);
    return ref;
}

void SkCGDrawBitmap(CGContextRef cg, const SkBitmap& bm, float x, float y) {
    CGImageRef img = SkCreateCGImageRef(bm);

    if (img) {
        CGRect r = CGRectMake(0, 0, bm.width(), bm.height());
        
        CGContextSaveGState(cg);
        CGContextTranslateCTM(cg, x, r.size.height + y);
        CGContextScaleCTM(cg, 1, -1);
        
        CGContextDrawImage(cg, r, img);
        
        CGContextRestoreGState(cg);
        
        CGImageRelease(img);
    }
}