C++ CGContextDrawImage函数代码示例

DragImageRef scaleDragImage(DragImageRef image, FloatSize scale)
{
    // FIXME: due to the way drag images are done on windows we need 
    // to preprocess the alpha channel <rdar://problem/5015946>

    if (!image)
        return 0;
    CGContextRef targetContext;
    CGContextRef srcContext;
    CGImageRef srcImage;
    IntSize srcSize = dragImageSize(image);
    IntSize dstSize(static_cast<int>(srcSize.width() * scale.width()), static_cast<int>(srcSize.height() * scale.height()));
    HBITMAP hbmp = 0;
    HWndDC dc(0);
    HDC dstDC = CreateCompatibleDC(dc);
    if (!dstDC)
        goto exit;

    hbmp = allocImage(dstDC, dstSize, &targetContext);
    if (!hbmp)
        goto exit;

    srcContext = createCgContextFromBitmap(image);
    srcImage = CGBitmapContextCreateImage(srcContext);
    CGRect rect;
    rect.origin.x = 0;
    rect.origin.y = 0;
    rect.size = dstSize;
    CGContextDrawImage(targetContext, rect, srcImage);
    CGImageRelease(srcImage);
    CGContextRelease(srcContext);
    CGContextRelease(targetContext);
    ::DeleteObject(image);
    image = 0;

exit:
    if (!hbmp)
        hbmp = image;
    if (dstDC)
        DeleteDC(dstDC);
    return hbmp;
}

String ImageBuffer::toDataURL(const String& mimeType, const double* quality, CoordinateSystem) const
{
    ASSERT(MIMETypeRegistry::isSupportedImageMIMETypeForEncoding(mimeType));

    if (context().isAcceleratedContext())
        flushContext();

    RetainPtr<CFStringRef> uti = utiFromMIMEType(mimeType);
    ASSERT(uti);

    RefPtr<Uint8ClampedArray> premultipliedData;
    RetainPtr<CGImageRef> image;

    if (CFEqual(uti.get(), jpegUTI())) {
        // JPEGs don't have an alpha channel, so we have to manually composite on top of black.
        premultipliedData = getPremultipliedImageData(IntRect(IntPoint(0, 0), logicalSize()));
        if (!premultipliedData)
            return "data:,";

        RetainPtr<CGDataProviderRef> dataProvider;
        dataProvider = adoptCF(CGDataProviderCreateWithData(0, premultipliedData->data(), 4 * logicalSize().width() * logicalSize().height(), 0));
        if (!dataProvider)
            return "data:,";

        image = adoptCF(CGImageCreate(logicalSize().width(), logicalSize().height(), 8, 32, 4 * logicalSize().width(),
                                    deviceRGBColorSpaceRef(), kCGBitmapByteOrderDefault | kCGImageAlphaNoneSkipLast,
                                    dataProvider.get(), 0, false, kCGRenderingIntentDefault));
    } else if (m_resolutionScale == 1) {
        image = copyNativeImage(CopyBackingStore);
        image = createCroppedImageIfNecessary(image.get(), internalSize());
    } else {
        image = copyNativeImage(DontCopyBackingStore);
        RetainPtr<CGContextRef> context = adoptCF(CGBitmapContextCreate(0, logicalSize().width(), logicalSize().height(), 8, 4 * logicalSize().width(), deviceRGBColorSpaceRef(), kCGImageAlphaPremultipliedLast));
        CGContextSetBlendMode(context.get(), kCGBlendModeCopy);
        CGContextClipToRect(context.get(), CGRectMake(0, 0, logicalSize().width(), logicalSize().height()));
        FloatSize imageSizeInUserSpace = scaleSizeToUserSpace(logicalSize(), m_data.backingStoreSize, internalSize());
        CGContextDrawImage(context.get(), CGRectMake(0, 0, imageSizeInUserSpace.width(), imageSizeInUserSpace.height()), image.get());
        image = adoptCF(CGBitmapContextCreateImage(context.get()));
    }

    return CGImageToDataURL(image.get(), mimeType, quality);
}

void BitmapImage::checkForSolidColor()
{
    m_checkedForSolidColor = true;
    m_isSolidColor = false;

    if (frameCount() > 1)
        return;

    if (!haveFrameAtIndex(0)) {
        IntSize size = m_source.frameSizeAtIndex(0, 0);
        if (size.width() != 1 || size.height() != 1)
            return;

        if (!ensureFrameIsCached(0))
            return;
    }

    CGImageRef image = nullptr;
    if (m_frames.size())
        image = m_frames[0].m_frame;

    if (!image)
        return;

    // Currently we only check for solid color in the important special case of a 1x1 image.
    if (CGImageGetWidth(image) == 1 && CGImageGetHeight(image) == 1) {
        unsigned char pixel[4]; // RGBA
        RetainPtr<CGContextRef> bitmapContext = adoptCF(CGBitmapContextCreate(pixel, 1, 1, 8, sizeof(pixel), deviceRGBColorSpaceRef(),
            kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big));
        if (!bitmapContext)
            return;
        GraphicsContext(bitmapContext.get()).setCompositeOperation(CompositeCopy);
        CGRect destinationRect = CGRectMake(0, 0, 1, 1);
        CGContextDrawImage(bitmapContext.get(), destinationRect, image);
        if (!pixel[3])
            m_solidColor = Color(0, 0, 0, 0);
        else
            m_solidColor = Color(pixel[0] * 255 / pixel[3], pixel[1] * 255 / pixel[3], pixel[2] * 255 / pixel[3], pixel[3]);

        m_isSolidColor = true;
    }
}

OSStatus GeneratePreviewForURL(void *thisInterface, QLPreviewRequestRef preview, CFURLRef url, CFStringRef contentTypeUTI, CFDictionaryRef options)
{
	CGDataProviderRef dataProvider = CGDataProviderCreateWithURL(url);
	if (!dataProvider) return -1;
	CFDataRef data = CGDataProviderCopyData(dataProvider);
	CGDataProviderRelease(dataProvider);
	if (!data) return -1;
	
	int width, height, channels;
	unsigned char* rgbadata = SOIL_load_image_from_memory(CFDataGetBytePtr(data), CFDataGetLength(data), &width, &height, &channels, SOIL_LOAD_RGBA);
	CFStringRef format=CFStringCreateWithBytes(NULL, CFDataGetBytePtr(data) + 0x54, 4, kCFStringEncodingASCII, false);
    CFRelease(data);
	if (!rgbadata) return -1;
	
	CGColorSpaceRef rgb = CGColorSpaceCreateDeviceRGB();
	CGContextRef context = CGBitmapContextCreate(rgbadata, width, height, 8, width * 4, rgb, kCGImageAlphaPremultipliedLast);
	SOIL_free_image_data(rgbadata);
	CGColorSpaceRelease(rgb);
	if (!context) return -1;

	CGImageRef image = CGBitmapContextCreateImage(context);
	CGContextRelease(context);
	if (!image) return -1;

	/* Add basic metadata to title */
	CFStringRef name = CFURLCopyLastPathComponent(url);
	CFTypeRef keys[1] = {kQLPreviewPropertyDisplayNameKey};
	CFTypeRef values[1] = {CFStringCreateWithFormat(NULL, NULL, CFSTR("%@ (%dx%d %@)"), name, width, height, format)};
 	CFDictionaryRef properties = CFDictionaryCreate(NULL, (const void**)keys, (const void**)values, 1, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
	CFRelease(name);

	context = QLPreviewRequestCreateContext(preview, CGSizeMake(width, height), true, properties);
	CGContextDrawImage(context, CGRectMake(0, 0, width, height), image);
	QLPreviewRequestFlushContext(preview, context);
	
	CGContextRelease(context);
	CFRelease(format);
	CFRelease(properties);
	
	return noErr;
}

void BitmapImage::checkForSolidColor()
{
    m_checkedForSolidColor = true;
    if (frameCount() > 1) {
        m_isSolidColor = false;
        return;
    }

#if !PLATFORM(IOS)
    CGImageRef image = frameAtIndex(0);
#else
    // Note, checkForSolidColor() may be called from frameAtIndex(). On iOS frameAtIndex() gets passed a scaleHint
    // argument which it uses to tell CG to create a scaled down image. Since we don't know the scaleHint here, if
    // we call frameAtIndex() again, we would pass it the default scale of 1 and would end up recreating the image.
    // So we do a quick check and call frameAtIndex(0) only if we haven't yet created an image.
    CGImageRef image = nullptr;
    if (m_frames.size())
        image = m_frames[0].m_frame;

    if (!image)
        image = frameAtIndex(0);
#endif

    // Currently we only check for solid color in the important special case of a 1x1 image.
    if (image && CGImageGetWidth(image) == 1 && CGImageGetHeight(image) == 1) {
        unsigned char pixel[4]; // RGBA
        RetainPtr<CGContextRef> bitmapContext = adoptCF(CGBitmapContextCreate(pixel, 1, 1, 8, sizeof(pixel), deviceRGBColorSpaceRef(),
                                                kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big));
        if (!bitmapContext)
            return;
        GraphicsContext(bitmapContext.get()).setCompositeOperation(CompositeCopy);
        CGRect destinationRect = CGRectMake(0, 0, 1, 1);
        CGContextDrawImage(bitmapContext.get(), destinationRect, image);
        if (!pixel[3])
            m_solidColor = Color(0, 0, 0, 0);
        else
            m_solidColor = Color(pixel[0] * 255 / pixel[3], pixel[1] * 255 / pixel[3], pixel[2] * 255 / pixel[3], pixel[3]);

        m_isSolidColor = true;
    }
}

static wxBitmap DoGetAsBitmap(const wxRect *subrect)
{
    CGRect cgbounds = CGDisplayBounds(CGMainDisplayID());

    wxRect rect = subrect ? *subrect : wxRect(0, 0, cgbounds.size.width, cgbounds.size.height);

    wxBitmap bmp(rect.GetSize().GetWidth(), rect.GetSize().GetHeight(), 32);

    CGDisplayCreateImageFunc createImage =
        (CGDisplayCreateImageFunc) dlsym(RTLD_NEXT, "CGDisplayCreateImage");
    if (createImage == NULL)
    {
        return bmp;
    }

    CGRect srcRect = CGRectMake(rect.x, rect.y, rect.width, rect.height);

    CGContextRef context = (CGContextRef)bmp.GetHBITMAP();

    CGContextSaveGState(context);

    CGContextTranslateCTM( context, 0,  cgbounds.size.height );
    CGContextScaleCTM( context, 1, -1 );

    if ( subrect )
        srcRect = CGRectOffset( srcRect, -subrect->x, -subrect->y ) ;

    CGImageRef image = NULL;

    image = createImage(kCGDirectMainDisplay);

    wxASSERT_MSG(image, wxT("wxScreenDC::GetAsBitmap - unable to get screenshot."));

    CGContextDrawImage(context, srcRect, image);

    CGImageRelease(image);

    CGContextRestoreGState(context);

    return bmp;
}

RefPtr<Image> ImageBuffer::copyImage(BackingStoreCopy copyBehavior, ScaleBehavior scaleBehavior) const
{
    RetainPtr<CGImageRef> image;
    if (m_resolutionScale == 1 || scaleBehavior == Unscaled) {
        image = copyNativeImage(copyBehavior);
        image = createCroppedImageIfNecessary(image.get(), internalSize());
    } else {
        image = copyNativeImage(DontCopyBackingStore);
        RetainPtr<CGContextRef> context = adoptCF(CGBitmapContextCreate(0, logicalSize().width(), logicalSize().height(), 8, 4 * logicalSize().width(), deviceRGBColorSpaceRef(), kCGImageAlphaPremultipliedLast));
        CGContextSetBlendMode(context.get(), kCGBlendModeCopy);
        CGContextClipToRect(context.get(), FloatRect(FloatPoint::zero(), logicalSize()));
        FloatSize imageSizeInUserSpace = scaleSizeToUserSpace(logicalSize(), m_data.backingStoreSize, internalSize());
        CGContextDrawImage(context.get(), FloatRect(FloatPoint::zero(), imageSizeInUserSpace), image.get());
        image = adoptCF(CGBitmapContextCreateImage(context.get()));
    }

    if (!image)
        return nullptr;

    return BitmapImage::create(image.get());
}

bool GiCanvasIos::drawImage(CGImageRef image, const Box2d& rectM)
{
    CGContextRef context = m_draw->getContext();
    bool ret = false;
    
    if (context && image) {
        Point2d ptD = rectM.center() * m_draw->xf().modelToDisplay();
        Box2d rect = rectM * m_draw->xf().modelToDisplay();
        
        CGAffineTransform af = CGAffineTransformMake(1, 0, 0, -1, 0, m_draw->height());
        af = CGAffineTransformTranslate(af, ptD.x - rect.width() * 0.5f, 
                                        m_draw->height() - (ptD.y + rect.height() * 0.5f));
        
        CGContextConcatCTM(context, af);
        CGContextDrawImage(context, CGRectMake(0, 0, rect.width(), rect.height()), image);
        CGContextConcatCTM(context, CGAffineTransformInvert(af));
        ret = true;
    }
    
    return ret;
}

CGImageRef CGimageResize(CGImageRef image, CGSize maxSize)
{
    // calcualte size
    CGFloat ratio = MAX(CGImageGetWidth(image)/maxSize.width,CGImageGetHeight(image)/maxSize.height);
    size_t width = CGImageGetWidth(image)/ratio;
    size_t height = CGImageGetHeight(image)/ratio;
    // resize
    CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(NULL, width, height,
                                                 8, width*4, colorspace, kCGImageAlphaPremultipliedLast);
    CGColorSpaceRelease(colorspace);
    
    if(context == NULL) return nil;
    
    // draw image to context (resizing it)
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), image);
    // extract resulting image from context
    CGImageRef imgRef = CGBitmapContextCreateImage(context);
    CGContextRelease(context);
    
    return imgRef;
}

cv::Mat &osx_cv::toMat(
        const CGImageRef &image,
        cv::Mat &out,
        osx::disp::RGBType destType
        ) {
    cv::Mat temp;

    size_t w = CGImageGetWidth(image), h = CGImageGetHeight(image);

    if (CGImageGetBitsPerPixel(image) != 32) {
        throw invalid_argument("`image` must be 32 bits per pixel");
    }

    temp.create(int(h), int(w), CV_8UC4);

    CGColorSpaceRef colorSpace = CGImageGetColorSpace(image);

    CGContextRef context = CGBitmapContextCreate(
            temp.data,
            w,
            h,
            CGImageGetBitsPerComponent(image),
            CGImageGetBytesPerRow(image),
            colorSpace,
            CGImageGetAlphaInfo(image)
    );

    CGContextDrawImage(
            context,
            CGRectMake(0, 0, (CGFloat)w, (CGFloat)h),
            image
            );

    _cvtRGBColor(temp, out, CGImageGetAlphaInfo(image), destType);

    CGContextRelease(context);

    return out;
}

void DrawSubCGImage (CGContextRef ctx, CGImageRef image, CGRect src, CGRect dst)
{
    float	w = (float) CGImageGetWidth(image);
    float	h = (float) CGImageGetHeight(image);

	CGRect	drawRect = CGRectMake(0.0f, 0.0f, w, h);

	if (!CGRectEqualToRect(src, dst))
	{
		float	sx = CGRectGetWidth(dst)  / CGRectGetWidth(src);
		float	sy = CGRectGetHeight(dst) / CGRectGetHeight(src);
		float	dx = CGRectGetMinX(dst) - (CGRectGetMinX(src) * sx);
		float	dy = CGRectGetMinY(dst) - (CGRectGetMinY(src) * sy);

		drawRect = CGRectMake(dx, dy, w * sx, h * sy);
	}

	CGContextSaveGState(ctx);
	CGContextClipToRect(ctx, dst);
	CGContextDrawImage(ctx, drawRect, image);
	CGContextRestoreGState(ctx);
}

bool nglImageCGCodec::Feed(nglIStream* pIStream)
{
  if (!mpCGImage)
  {
    mpCGImage = ReadInfo(pIStream); ///< shall allocate the buffer
  }
  if (!mpCGImage)
    return false;

  mpIStream = pIStream;
// Use the generic RGB color space.
  CGColorSpaceRef pCGColors = CGColorSpaceCreateDeviceRGB();
  if (pCGColors == NULL)
  {
    NGL_OUT(_T("nglImageCGCodec::Feed Error allocating color space\n"));
    return false;
  }

  nglImageInfo info;
  mpImage->GetInfo(info);
  NGL_ASSERT(info.mpBuffer);

// Create the bitmap context. 
// The image will be converted to the format specified here by CGBitmapContextCreate.
  CGContextRef pCGContext =
    CGBitmapContextCreate(info.mpBuffer, info.mWidth, info.mHeight,
                          info.mBitDepth/4, info.mBytesPerLine,
                          pCGColors, kCGImageAlphaPremultipliedLast);//kCGImageAlphaPremultipliedFirst);

  CGColorSpaceRelease(pCGColors);
  CGRect rect = { {0,0}, {info.mWidth, info.mHeight} };
  CGContextClearRect(pCGContext, rect);
  CGContextDrawImage(pCGContext, rect, mpCGImage);
  CGContextRelease(pCGContext);

  SendData(1.0f);
  return (pIStream->GetState()==eStreamWait) || (pIStream->GetState()==eStreamReady);;
}

bool SkImageDecoder_CG::onDecode(SkStream* stream, SkBitmap* bm, Mode mode) {
    CGImageSourceRef imageSrc = SkStreamToCGImageSource(stream);

    if (NULL == imageSrc) {
        return false;
    }
    SkAutoTCallVProc<const void, CFRelease> arsrc(imageSrc);
    
    CGImageRef image = CGImageSourceCreateImageAtIndex(imageSrc, 0, NULL);
    if (NULL == image) {
        return false;
    }
    SkAutoTCallVProc<CGImage, CGImageRelease> arimage(image);
    
    const int width = CGImageGetWidth(image);
    const int height = CGImageGetHeight(image);
    bm->setConfig(SkBitmap::kARGB_8888_Config, width, height);
    if (SkImageDecoder::kDecodeBounds_Mode == mode) {
        return true;
    }
    
    if (!this->allocPixelRef(bm, NULL)) {
        return false;
    }
    
    bm->lockPixels();
    bm->eraseColor(0);

    // use the same colorspace, so we don't change the pixels at all
    CGColorSpaceRef cs = CGImageGetColorSpace(image);
    CGContextRef cg = CGBitmapContextCreate(bm->getPixels(), width, height,
                                            8, bm->rowBytes(), cs, BITMAP_INFO);
    CGContextDrawImage(cg, CGRectMake(0, 0, width, height), image);
    CGContextRelease(cg);

    bm->unlockPixels();
    return true;
}

DragImageRef createDragImageFromImage(Image* img)
{
    HBITMAP hbmp = 0;
    HDC dc = GetDC(0);
    HDC workingDC = CreateCompatibleDC(dc);
    CGContextRef drawContext = 0;
    if (!workingDC)
        goto exit;

    hbmp = allocImage(workingDC, img->size(), &drawContext);

    if (!hbmp)
        goto exit;

    if (!drawContext) {
        ::DeleteObject(hbmp);
        hbmp = 0;
    }

    CGImageRef srcImage = img->getCGImageRef();
    CGRect rect;
    rect.size = img->size();
    rect.origin.x = 0;
    rect.origin.y = -rect.size.height;
    static const CGFloat white [] = {1.0, 1.0, 1.0, 1.0};
    CGContextScaleCTM(drawContext, 1, -1);
    CGContextSetFillColor(drawContext, white);
    CGContextFillRect(drawContext, rect);
    CGContextSetBlendMode(drawContext, kCGBlendModeNormal);
    CGContextDrawImage(drawContext, rect, srcImage);
    CGContextRelease(drawContext);

exit:
    if (workingDC)
        DeleteDC(workingDC);
    ReleaseDC(0, dc);
    return hbmp;
}

cv::Mat CGImageToMat(CGImageRef image) {

  CGColorSpaceRef colorSpace = CGImageGetColorSpace(image);

  CGFloat cols = CGImageGetWidth(image);
  CGFloat rows = CGImageGetHeight(image);

  cv::Mat cvMat(rows, cols, CV_8UC4); // 8 bits per component, 4 channels (color channels + alpha)

  CGContextRef contextRef = CGBitmapContextCreate(cvMat.data,                 // Pointer to  data
						  cols,                       // Width of bitmap
						  rows,                       // Height of bitmap
						  8,                          // Bits per component
						  cvMat.step[0],              // Bytes per row
						  colorSpace,                 // Colorspace
						  kCGImageAlphaNoneSkipLast |
						  kCGBitmapByteOrderDefault); // Bitmap info flags

  CGContextDrawImage(contextRef, CGRectMake(0, 0, cols, rows), image);
  CGContextRelease(contextRef);

  return cvMat;
}