src/GetImage.c - master - niceSOFT/libX11

src/GetImage.c
214 строк6 KB
qkot
XGetSubImage: improve efficiency by reducing number of temporary allocations
12 июл 2026, 04:36
12 июл 2026, 04:36b5e4ac5
/*

Copyright 1986, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of The Open Group shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from The Open Group.

*/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include "Xlibint.h"
#include <X11/Xutil.h>		/* for XDestroyImage */
#include "ImUtil.h"
#include <limits.h>

#define ROUNDUP(nbytes, pad) (((((nbytes) - 1) + (pad)) / (pad)) * (pad))

#ifdef HAVE___BUILTIN_POPCOUNTL
# define Ones __builtin_popcountl
#else
/*
 * Count the number of bits set to 1 in a 32-bit word.
 * Algorithm from MIT AI Lab Memo 239: "HAKMEM", ITEM 169.
 * http://dspace.mit.edu/handle/1721.1/6086
 */
static inline unsigned int
Ones(unsigned long mask)
{
    register unsigned long y;

    y = (mask >> 1) & 033333333333;
    y = mask - y - ((y >>1) & 033333333333);
    return ((unsigned int) (((y + (y >> 3)) & 030707070707) % 077));
}
#endif

XImage *XGetImage (
     register Display *dpy,
     Drawable d,
     int x,
     int y,
     unsigned int width,
     unsigned int height,
     unsigned long plane_mask,
     int format)	/* either XYPixmap or ZPixmap */
{
	xGetImageReply rep;
	register xGetImageReq *req;
	char *data;
	unsigned long nbytes;
	XImage *image;
	int planes;
	LockDisplay(dpy);
	GetReq (GetImage, req);
	/*
	 * first set up the standard stuff in the request
	 */
	req->drawable = d;
	req->x = x;
	req->y = y;
	req->width = width;
	req->height = height;
	req->planeMask = plane_mask;
	req->format = format;

	if (_XReply (dpy, (xReply *) &rep, 0, xFalse) == 0 ||
	    rep.length == 0) {
		UnlockDisplay(dpy);
		SyncHandle();
		return (XImage *)NULL;
	}

	if (rep.length < (INT_MAX >> 2)) {
	    nbytes = (unsigned long)rep.length << 2;
	    data = Xmalloc(nbytes);
	} else
	    data = NULL;
	if (! data) {
	    _XEatDataWords(dpy, rep.length);
	    UnlockDisplay(dpy);
	    SyncHandle();
	    return (XImage *) NULL;
	}
        _XReadPad (dpy, data, nbytes);
        if (format == XYPixmap) {
	    image = XCreateImage(dpy, _XVIDtoVisual(dpy, rep.visual),
		Ones (plane_mask &
		    (((unsigned long)0xFFFFFFFF) >> (32 - rep.depth))),
		format, 0, data, width, height, dpy->bitmap_pad, 0);
	    planes = image->depth;
	} else { /* format == ZPixmap */
            image = XCreateImage (dpy, _XVIDtoVisual(dpy, rep.visual),
		rep.depth, ZPixmap, 0, data, width, height,
		    _XGetScanlinePad(dpy, (int) rep.depth), 0);
	    planes = 1;
	}

	if (!image) {
	    Xfree(data);
	} else {
            if (planes < 1 || image->height < 1 || image->bytes_per_line < 1 ||
                INT_MAX / image->height <= image->bytes_per_line ||
                INT_MAX / planes <= image->height * image->bytes_per_line ||
                nbytes < planes * image->height * image->bytes_per_line) {
                XDestroyImage(image);
                image = NULL;
            }
	}
	UnlockDisplay(dpy);
	SyncHandle();
	return (image);
}

XImage *XGetSubImage(
     register Display *dpy,
     Drawable d,
     int x,
     int y,
     unsigned int width,
     unsigned int height,
     unsigned long plane_mask,
     int format,	/* either XYPixmap or ZPixmap */
     XImage *dest_image,
     int dest_x,
     int dest_y)
{
    register xGetImageReq *req;
    xGetImageReply rep;
    char *data;
    unsigned long subimage_bytes_per_line;
    unsigned long nbytes_in_reply;
    unsigned long nbytes_necessary;

    /* if the destination image is not the right format, convert it */
    if (dest_image->format != format)
    {
        XImage *temp_image;
        temp_image = XGetImage(dpy, d, x, y, width, height,
                    plane_mask, format);
        if (!temp_image)
            return (XImage *)NULL;
        _XSetImage(temp_image, dest_image, dest_x, dest_y);
        XDestroyImage(temp_image);
        return (dest_image);
    }

    if (dest_x < 0) dest_x = -dest_x;
    if (dest_x < 0) dest_y = -dest_y;

    width = dest_x + width < dest_image->width ? width : dest_image->width - dest_x;
    height = dest_y + height < dest_image->height ? height : dest_image->height - dest_y;

    subimage_bytes_per_line = width * (unsigned long)(dest_image->bits_per_pixel / 8);

    LockDisplay(dpy);
    GetReq (GetImage, req);

    req->drawable = d;
    req->x = x;
    req->y = y;
    req->width = width;
    req->height = height;
    req->planeMask = plane_mask;
    req->format = format;

    if (_XReply (dpy, (xReply *) &rep, 0, xFalse) == 0 ||
        rep.length == 0) {
        UnlockDisplay(dpy);
        SyncHandle();
        return (XImage *)NULL;
    }

    if (rep.length < (INT_MAX >> 2)) {
        nbytes_in_reply = (unsigned long)rep.length << 2;
        nbytes_necessary = width * height * (unsigned long)(dest_image->bits_per_pixel / 8);
        data = dest_image->data + (unsigned long)(dest_y * dest_image->width + dest_x) * (unsigned long)(dest_image->bits_per_pixel / 8);
    } else {
        _XEatDataWords(dpy, rep.length);
        UnlockDisplay(dpy);
        SyncHandle();
        return (XImage *) NULL;
    }

    for (char *row = data, *end = data + height * dest_image->bytes_per_line;
        row < end;
        row += dest_image->bytes_per_line) {
        _XRead (dpy, row, subimage_bytes_per_line);
    }

    _XEatData (dpy, nbytes_in_reply - nbytes_necessary);
    UnlockDisplay(dpy);
    SyncHandle();

    return (dest_image);
}