Tk Source Code

 *	This should work on all platforms that set mask and shift data
 *	properly from the visualInfo. RGB is really only a 24+ bpp version
 *	whereas RGB15 is the correct version and works for 15bpp+, but it
 *	slower, so it's only used for 15bpp+.
 *
 *	Note that Win32 pre-defines those operations that we really need.
 *
 *	Note that on MacOS, if the background comes from a Retina display
 *	then it will be twice as wide and twice as high as the photoimage.
 *
 *----------------------------------------------------------------------
 */

#ifndef _WIN32
#define GetRValue(rgb)	(UCHAR(((rgb) & red_mask) >> red_shift))
#define GetGValue(rgb)	(UCHAR(((rgb) & green_mask) >> green_shift))
#define GetBValue(rgb)	(UCHAR(((rgb) & blue_mask) >> blue_shift))

				 * draw. */
    int width, int height)	/* Width & height of image to draw. */
{
    int x, y, line;
    unsigned long pixel;
    unsigned char r, g, b, alpha, unalpha, *masterPtr;
    unsigned char *alphaAr = iPtr->masterPtr->pix32;
#if defined(MAC_OSX_TK)
    /* Background "pixels" are actually 2^pp x 2^pp blocks of subpixels.  Each
     * block gets blended with the color of one image pixel.  Since we iterate
     * over the background subpixels, we reset the width and height to the
     * subpixel dimensions of the background image we are using.
     */
    int pp = bgImg->pixelpower;
    width = width << pp;
    height = height << pp;
#endif
    /*
     * This blending is an integer version of the Source-Over compositing rule
     * (see Porter&Duff, "Compositing Digital Images", proceedings of SIGGRAPH
     * 1984) that has been hard-coded (for speed) to work with targetting a
     * solid surface.
     *
     * The 'unalpha' field must be 255-alpha; it is separated out to encourage

	    }
	}
	return;
    }
#endif /* !_WIN32 && !MAC_OSX_TK */

    for (y = 0; y < height; y++) {
# if !defined(MAC_OSX_TK)
	line = (y + yOffset) * iPtr->masterPtr->width;
	for (x = 0; x < width; x++) {
	    masterPtr = alphaAr + ((line + x + xOffset) * 4);
#else
	/* Repeat each image row and column 2^pp times. */
	line = ((y>>pp) + yOffset) * iPtr->masterPtr->width;
	for (x = 0; x < width; x++) {
	    masterPtr = alphaAr + ((line + (x>>pp) + xOffset) * 4);
#endif
	    alpha = masterPtr[3];

	    /*
	     * Ignore pixels that are fully transparent
	     */

	    if (alpha) {

	 * Pull the current background from the display to blend with
	 */

	bgImg = XGetImage(display, drawable, drawableX, drawableY,
		(unsigned int)width, (unsigned int)height, AllPlanes, ZPixmap);
	if (bgImg == NULL) {
	    Tk_DeleteErrorHandler(handler);
	    /* We failed to get the image, so draw without blending alpha.
	     * It's the best we can do.
	     */
	    goto fallBack;
	}

	BlendComplexAlpha(bgImg, instancePtr, imageX, imageY, width, height);

	/*
	 * Color info is unimportant as we only do this operation for depth >=

    if (!TkMacOSXSetupDrawingContext(d, gc, 1, &dc)) {
	return BadDrawable;
    }
    if (dc.context) {
	CGImageRef img = CreateCGImageWithXImage(image);

	if (img) {
	    /* If the XImage has big pixels, rescale the source dimensions.*/
	    int pp = image->pixelpower;
	    DrawCGImage(d, gc, dc.context, img, gc->foreground, gc->background,
		    CGRectMake(0, 0, image->width<<pp, image->height<<pp),
		    CGRectMake(src_x<<pp, src_y<<pp, width<<pp, height<<pp),
		    CGRectMake(dest_x, dest_y, width, height));
	    CFRelease(img);
	} else {
	    TkMacOSXDbgMsg("Invalid source drawable");
	}
    } else {
	TkMacOSXDbgMsg("Invalid destination drawable");

    ximage->height = height;
    ximage->width = width;
    ximage->depth = depth;
    ximage->xoffset = offset;
    ximage->format = format;
    ximage->data = data;
    ximage->obdata = NULL;
    /* The default pixelpower is 0.  This must be explicitly set to 1 in the
     * case of an XImage extracted from a Retina display.
     */
    ximage->pixelpower = 0;

    if (format == ZPixmap) {
	ximage->bits_per_pixel = 32;
	ximage->bitmap_unit = 32;
    } else {
	ximage->bits_per_pixel = 1;
	ximage->bitmap_unit = 8;

 * XGetImage --
 *
 *	This function copies data from a pixmap or window into an XImage.
 *
 * Results:
 *	Returns a newly allocated XImage containing the data from the given
 *	rectangle of the given drawable, or NULL if the XImage could not be
 *	constructed.  NOTE: If we are copying from a window on a Retina
 *	display, the dimensions of the XImage will be 2*width x 2*height.
 *
 * Side effects:
 *	None.
 *
 *----------------------------------------------------------------------
 */

    char *           bitmap = NULL;
    char *           image_data=NULL;
    int	        depth = 32;
    int	        offset = 0;
    int	        bitmap_pad = 0;
    int	        bytes_per_row = 4*width;
    int                size;
    MacDrawable *macDraw = (MacDrawable *) d;
    NSWindow *win = TkMacOSXDrawableWindow(d);
    /* This code assumes that backing scale factors are integers.  Currently
     * Retina displays use a scale factor of 2.0 and normal displays use 1.0.
     * We do not support any other values here.
     */
    int scalefactor = 1;
    if (win && [win respondsToSelector:@selector(backingScaleFactor)]) { 
	scalefactor = ([win backingScaleFactor] == 2.0) ? 2 : 1;
    }
    int scaled_height = height * scalefactor;
    int scaled_width = width * scalefactor;

    if (format == ZPixmap) {
	if (width == 0 || height == 0) {
	    /* This happens all the time.
	    TkMacOSXDbgMsg("XGetImage: empty image requested");
	    */
	    return NULL;
	}

	bitmap_rep =  BitmapRepFromDrawableRect(d, x, y, width, height);
	bitmap_fmt = [bitmap_rep bitmapFormat];

	if ( bitmap_rep == Nil                        ||
	     (bitmap_fmt != 0 && bitmap_fmt != 1)     ||
	     [bitmap_rep samplesPerPixel] != 4 ||
	     [bitmap_rep isPlanar] != 0               ) {
	    TkMacOSXDbgMsg("XGetImage: Failed to construct NSBitmapRep");
	    return NULL;
	}

	NSSize image_size = NSMakeSize(width, height);
	NSImage* ns_image = [[NSImage alloc]initWithSize:image_size];
	[ns_image addRepresentation:bitmap_rep];

	/* Assume premultiplied nonplanar data with 4 bytes per pixel.*/
	if ( [bitmap_rep isPlanar ] == 0 &&
	     [bitmap_rep samplesPerPixel] == 4 ) {
	    bytes_per_row = [bitmap_rep bytesPerRow];
	    assert(bytes_per_row == 4 * scaled_width);
	    assert([bitmap_rep bytesPerPlane] == bytes_per_row * scaled_height);
	    size = bytes_per_row*scaled_height;
	    image_data = (char*)[bitmap_rep bitmapData];
	    if ( image_data ) {
		int row, n, m;
		bitmap = ckalloc(size);
		/*
		  Oddly enough, the bitmap has the top row at the beginning,
		  and the pixels are in BGRA or ABGR format.
		*/
		if (bitmap_fmt == 0) {
		    /* BGRA */
		    for (row=0, n=0; row<scaled_height; row++, n+=bytes_per_row) {
			for (m=n; m<n+bytes_per_row; m+=4) {
			    *(bitmap+m)   = *(image_data+m+2);
			    *(bitmap+m+1) = *(image_data+m+1);
			    *(bitmap+m+2) = *(image_data+m);
			    *(bitmap+m+3) = *(image_data+m+3);
			}
		    }
		} else {
		    /* ABGR */
		    for (row=0, n=0; row<scaled_height; row++, n+=bytes_per_row) {
			for (m=n; m<n+bytes_per_row; m+=4) {
			    *(bitmap+m)   = *(image_data+m+3);
			    *(bitmap+m+1) = *(image_data+m+2);
			    *(bitmap+m+2) = *(image_data+m+1);
			    *(bitmap+m+3) = *(image_data+m);
			}
		    }
		}
	    }
	}
	if (bitmap) {
	    imagePtr = XCreateImage(display, NULL, depth, format, offset,
				    (char*)bitmap, scaled_width, scaled_height,
				    bitmap_pad, bytes_per_row);
	    if (scalefactor == 2) {
	    	imagePtr->pixelpower = 1;
	     }
	    [ns_image removeRepresentation:bitmap_rep]; /*releases the rep*/
	    [ns_image release];
	}
    } else {
	TkMacOSXDbgMsg("Could not extract image from drawable.");
    }
    return imagePtr;

    int depth;			/* depth of image */
    int bytes_per_line;		/* accelarator to next line */
    int bits_per_pixel;		/* bits per pixel (ZPixmap) */
    unsigned long red_mask;	/* bits in z arrangment */
    unsigned long green_mask;
    unsigned long blue_mask;
    XPointer obdata;		/* hook for the object routines to hang on */
#if defined(MAC_OSX_TK)
    int pixelpower;		/* n such that pixels are 2^n x 2^n blocks*/
#endif
    struct funcs {		/* image manipulation routines */
	struct _XImage *(*create_image)();
#if NeedFunctionPrototypes
	int (*destroy_image)        (struct _XImage *);
	unsigned long (*get_pixel)  (struct _XImage *, int, int);
	int (*put_pixel)            (struct _XImage *, int, int, unsigned long);
	struct _XImage *(*sub_image)(struct _XImage *, int, int, unsigned int, unsigned int);