+/*
+ -----------------------------------------------------------------------------
+ ZoomPixmap
+
+ Important note: The scaling code currently only supports scaling of the image
+ up or down by a power of 2 -- other scaling factors currently not supported!
+ Also not supported is scaling of pixmap masks (with depth 1); to scale them,
+ better use Pixmap_to_Mask() for now.
+ -----------------------------------------------------------------------------
+*/
+
+void ZoomPixmap(Display *display, GC gc, Pixmap src_pixmap, Pixmap dst_pixmap,
+ int src_width, int src_height,
+ int dst_width, int dst_height)
+{
+ XImage *src_ximage, *dst_ximage;
+ byte *src_ptr, *dst_ptr;
+ int bits_per_pixel;
+ int bytes_per_pixel;
+ int x, y, xx, yy, i;
+ int row_skip, col_skip;
+ int zoom_factor;
+ boolean scale_down = (src_width > dst_width);
+
+ if (scale_down)
+ {
+#if 1
+ zoom_factor = MIN(src_width / dst_width, src_height / dst_height);
+#else
+ zoom_factor = src_width / dst_width;
+#endif
+
+ /* adjust source image size to integer multiple of destination size */
+ src_width = dst_width * zoom_factor;
+ src_height = dst_height * zoom_factor;
+ }
+ else
+ {
+#if 1
+ zoom_factor = MIN(dst_width / src_width, dst_height / src_height);
+#else
+ zoom_factor = dst_width / src_width;
+#endif
+
+ /* no adjustment needed when scaling up (some pixels may be left blank) */
+ }
+
+ /* copy source pixmap to temporary image */
+ if ((src_ximage = XGetImage(display, src_pixmap, 0, 0, src_width, src_height,
+ AllPlanes, ZPixmap)) == NULL)
+ Error(ERR_EXIT, "ZoomPixmap(): XGetImage() failed");
+
+ bits_per_pixel = src_ximage->bits_per_pixel;
+ bytes_per_pixel = (bits_per_pixel + 7) / 8;
+
+ if ((dst_ximage = XCreateImage(display, visual, src_ximage->depth, ZPixmap,
+ 0, NULL, dst_width, dst_height,
+ 8, dst_width * bytes_per_pixel)) == NULL)
+ Error(ERR_EXIT, "ZoomPixmap(): XCreateImage() failed");
+
+ dst_ximage->data =
+ checked_malloc(dst_width * dst_height * bytes_per_pixel);
+ dst_ximage->byte_order = src_ximage->byte_order;
+
+ src_ptr = (byte *)src_ximage->data;
+ dst_ptr = (byte *)dst_ximage->data;
+
+ if (scale_down)
+ {
+ col_skip = (zoom_factor - 1) * bytes_per_pixel;
+ row_skip = col_skip * src_width;
+
+ /* scale image down by scaling factor 'zoom_factor' */
+ for (y = 0; y < src_height; y += zoom_factor, src_ptr += row_skip)
+ for (x = 0; x < src_width; x += zoom_factor, src_ptr += col_skip)
+ for (i = 0; i < bytes_per_pixel; i++)
+ *dst_ptr++ = *src_ptr++;
+ }
+ else
+ {
+ row_skip = src_width * bytes_per_pixel;
+
+ /* scale image up by scaling factor 'zoom_factor' */
+ for (y = 0; y < src_height; y++)
+ {
+ for (yy = 0; yy < zoom_factor; yy++)
+ {
+ if (yy > 0)
+ src_ptr -= row_skip;
+
+ for (x = 0; x < src_width; x++)
+ {
+ for (xx = 0; xx < zoom_factor; xx++)
+ for (i = 0; i < bytes_per_pixel; i++)
+ *dst_ptr++ = *(src_ptr + i);
+
+ src_ptr += bytes_per_pixel;
+ }
+ }
+ }
+ }
+
+ /* copy scaled image to destination pixmap */
+ XPutImage(display, dst_pixmap, gc, dst_ximage, 0, 0, 0, 0,
+ dst_width, dst_height);
+
+ /* free temporary images */
+ X11DestroyImage(src_ximage);
+ X11DestroyImage(dst_ximage);
+}
+