emacs-27 62a6934 1/2: Fix crash when using XRender and restoring image from X (bug#44930)

[Alan Third]

branch: emacs-27
commit 62a6934af9c110c28fc1f69f4bb1b79ce9d0c43d
Author: Alan Third <alan@idiocy.org>
Commit: Alan Third <alan@idiocy.org>

    Fix crash when using XRender and restoring image from X (bug#44930)
    
    * src/dispextern.h (struct image): Add original dimension elements.
    * src/image.c (image_set_transform): Store the original dimensions.
    (image_get_x_image): If we're using transforms use the original
    dimensions with XGetImage.
---
 src/dispextern.h | 4 ++++
 src/image.c      | 9 +++++++++
 2 files changed, 13 insertions(+)

diff --git a/src/dispextern.h b/src/dispextern.h
index 6b72e68..4455627 100644
--- a/src/dispextern.h
+++ b/src/dispextern.h
@@ -3047,6 +3047,10 @@ struct image
 # if !defined USE_CAIRO && defined HAVE_XRENDER
   /* Picture versions of pixmap and mask for compositing.  */
   Picture picture, mask_picture;
+
+  /* We need to store the original image dimensions in case we have to
+     call XGetImage.  */
+  int original_width, original_height;
 # endif
 #endif /* HAVE_X_WINDOWS */
 #ifdef HAVE_NTGUI
diff --git a/src/image.c b/src/image.c
index 956fb13..7beb135 100644
--- a/src/image.c
+++ b/src/image.c
@@ -2103,6 +2103,10 @@ image_set_transform (struct frame *f, struct image *img)
 # if !defined USE_CAIRO && defined HAVE_XRENDER
   if (!img->picture)
     return;
+
+  /* Store the original dimensions as we'll overwrite them later.  */
+  img->original_width = img->width;
+  img->original_height = img->height;
 # endif
 
   /* Determine size.  */
@@ -2930,6 +2934,11 @@ image_get_x_image (struct frame *f, struct image *img, 
bool mask_p)
 
   if (ximg_in_img)
     return ximg_in_img;
+#ifdef HAVE_XRENDER
+  else if (img->picture)
+    return XGetImage (FRAME_X_DISPLAY (f), !mask_p ? img->pixmap : img->mask,
+                     0, 0, img->original_width, img->original_height, ~0, 
ZPixmap);
+#endif
   else
     return XGetImage (FRAME_X_DISPLAY (f), !mask_p ? img->pixmap : img->mask,
                      0, 0, img->width, img->height, ~0, ZPixmap);