Tk Source Code

#include "tkMacOSXConstants.h"
#include "tkMacOSXImage.h"
#include "tkColor.h"
#include "xbytes.h"

static CGImageRef CreateCGImageFromPixmap(Drawable pixmap);
static CGImageRef CreateCGImageFromDrawableRect( Drawable drawable, int force_1x_scale,
     int x, int y, unsigned int width, unsigned int height, CGFloat *scale);
static inline CGRect ClipCopyRects(CGRect srcBounds, CGRect dstBounds,
     int src_x, int src_y, unsigned int width,  unsigned int height);

/* Pixel formats
 *
 * Tk uses the XImage structure defined in Xlib.h for storing images.  The
 * image data in an XImage is a 32-bit aligned array of bytes.  Interpretation

static CGImageRef
CreateCGImageFromDrawableRect(
    Drawable drawable,
    int force_1x_scale,
    int x,
    int y,
    unsigned int width,
    unsigned int height,
    CGFloat *scalePtr)
{
    MacDrawable *mac_drawable = (MacDrawable *)drawable;
    CGContextRef cg_context = NULL;
    CGImageRef cg_image = NULL, result = NULL;
    CGFloat scaleFactor = 1.0;
    if (mac_drawable->flags & TK_IS_PIXMAP) {
	cg_context = TkMacOSXGetCGContextForDrawable(drawable);
	CGContextRetain(cg_context);
    } else {
	NSView *view = TkMacOSXGetNSViewForDrawable(mac_drawable);
	if (view == nil) {
	    TkMacOSXDbgMsg("Invalid source drawable");
	    return NULL;
	}
	scaleFactor = view.layer.contentsScale;
	cg_context = ((TKContentView *)view).tkLayerBitmapContext;
	CGContextRetain(cg_context);
    }
    if (scalePtr != nil) {
	*scalePtr = scaleFactor;
    }
    if (cg_context) {
	cg_image = CGBitmapContextCreateImage(cg_context);
	CGContextRelease(cg_context);
    }
    if (cg_image) {

	CGRect rect = CGRectMake(x + mac_drawable->xOff, y + mac_drawable->yOff,
				 width, height);

	rect = CGRectApplyAffineTransform(rect, CGAffineTransformMakeScale(scaleFactor, scaleFactor));

	if (force_1x_scale && (scaleFactor != 1.0)) {
	    // See https://web.archive.org/web/20200219030756/http://blog.foundry376.com/2008/07/scaling-a-cgimage/#comment-200
	    // create context, keeping original image properties
	    CGColorSpaceRef colorspace = CGImageGetColorSpace(cg_image);
	    cg_context = CGBitmapContextCreate(NULL, width, height,


		    CGImageGetBitsPerComponent(cg_image),
		    //CGImageGetBytesPerRow(cg_image), // wastes space?
		    CGImageGetBitsPerPixel(cg_image) * width / 8,
		    colorspace,
		    CGImageGetAlphaInfo(cg_image));
	    CGColorSpaceRelease(colorspace);
	    if (cg_context) {
		// Extract the subimage in the specified rectangle.
		CGImageRef subimage = CGImageCreateWithImageInRect(cg_image, rect);
		// Draw the subimage in our context (resizing it to fit).
		CGContextDrawImage(cg_context, CGRectMake(0, 0, width, height),
			subimage);
		// We will return the image we just drew.
		result = CGBitmapContextCreateImage(cg_context);
		CGContextRelease(cg_context);
		CGImageRelease(subimage);
	    }
	} else {
	    // No resizing is needed.  Just return the subimage
	    result = CGImageCreateWithImageInRect(cg_image, rect);
	}
	CGImageRelease(cg_image);
    }
    return result;
}

/*

    if (format == ZPixmap) {
	CGImageRef cgImage;
	if (width == 0 || height == 0) {
	    return NULL;
	}

	// Request 1x-scale image for compatibility
	cgImage = CreateCGImageFromDrawableRect(drawable, 1, x, y, width, height, nil);
	if (cgImage) {
	    bitmapRep = [NSBitmapImageRep alloc];
	    [bitmapRep initWithCGImage:cgImage];
	    CFRelease(cgImage);
	} else {
	    TkMacOSXDbgMsg("XGetImage: Failed to construct CGImage");
	    return NULL;

    NSRect srcRect, dstRect;
    int result = 0;
    NSView *view = TkMacOSXGetNSViewForDrawable(drawable);
    CGRect viewBounds = [view bounds];

    /*
     * To compute the damage region correctly we need to clip the source and
     * destination rectangles to the NSView bounds in the same way that
     * XCopyArea does.
     */

    CGRect bounds = ClipCopyRects(viewBounds, viewBounds, x, y, width, height);
    unsigned int w = bounds.size.width;
    unsigned int h = bounds.size.height;

    if (XCopyArea(Tk_Display(tkwin), drawable, drawable, gc, x, y,

    int dst_x,			/* Dest X & Y on dest rect. */
    int dst_y)
{
    TkMacOSXDrawingContext dc;
    CGImageRef img = NULL;
    CGRect dstRect;

    // XXXX Need to deal with pixmaps!

    NSView *srcView = TkMacOSXGetNSViewForDrawable(src);
    NSView *dstView = TkMacOSXGetNSViewForDrawable(dst);
    CGRect srcBounds = [srcView bounds];
    CGRect dstBounds = [dstView bounds];

    // To avoid distorting the image when it is drawn we must ensure that
    // the source and destination rectangles have the same size.  This is
    // tricky because each of those rectangles will be clipped to the
    // bounds of its containing NSView.  If the source gets clipped and
    // the destination does not, for example, then the shapes will differ.
    // We deal with this by reducing their common size  enough so that both
    // rectangles are  contained in their respective views.

    CGRect bounds = ClipCopyRects(srcBounds, dstBounds, src_x, src_y, width, height);
    width = (int) bounds.size.width;
    height = (int) bounds.size.height;
    CGFloat scaleFactor;

    LastKnownRequestProcessed(display)++;
    if (!width || !height) {
	return BadDrawable;
    }

    if (!TkMacOSXSetupDrawingContext(dst, gc, &dc)) {
	TkMacOSXDbgMsg("Failed to setup drawing context.");
	return BadDrawable;
    }

    if (!dc.context) {
	TkMacOSXDbgMsg("Invalid destination drawable - no context.");
	return BadDrawable;
    }


    img = CreateCGImageFromDrawableRect(src, 0, src_x, src_y, width, height, &scaleFactor);

    if (img) {
	unsigned int w = (unsigned int) (CGImageGetWidth(img) / scaleFactor);
	unsigned int h = (unsigned int) (CGImageGetHeight(img) / scaleFactor);
	dstRect = CGRectMake(dst_x, dst_y, w, h);
	TkMacOSXDrawCGImage(dst, gc, dc.context, img,
		gc->foreground, gc->background, dstRect);
	CFRelease(img);
    } else {
	TkMacOSXDbgMsg("Failed to construct CGImage.");
    }