Rework x_scroll_run on cairo

* src/xterm.c (x_scroll_run) [USE_CAIRO]: Use FRAME_CR_CONTEXT or surface type
for conditions to call XCopyArea rather than FRAME_X_DOUBLE_BUFFERED_P.
Set compositing operator to CAIRO_OPERATOR_SOURCE when copying image.

1 files changed, 43 insertions, 41 deletions

diff --git a/src/xterm.c b/src/xterm.c
index 3cd95b7a65d..1608621fc49 100644
--- a/src/xterm.c
+++ b/src/xterm.c
@@ -4393,51 +4393,53 @@ x_scroll_run (struct window *w, struct run *run)
   gui_clear_cursor (w);
 
 #ifdef USE_CAIRO
-  if (FRAME_X_DOUBLE_BUFFERED_P (f))
-    {
-      cairo_t *cr = FRAME_CR_CONTEXT (f);
-      if (cr)
-        cairo_surface_flush (cairo_get_target (cr));
-      XCopyArea (FRAME_X_DISPLAY (f),
-                 FRAME_X_DRAWABLE (f), FRAME_X_DRAWABLE (f),
-                 f->output_data.x->normal_gc,
-                 x, from_y,
-                 width, height,
-                 x, to_y);
-      if (cr)
-        cairo_surface_mark_dirty_rectangle (cairo_get_target (cr),
-                                            x, to_y, width, height);
-    }
-  else if (FRAME_CR_CONTEXT (f))
+  if (FRAME_CR_CONTEXT (f))
     {
-      cairo_surface_t *s = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
-                                                       width, height);
-      cairo_t *cr = cairo_create (s);
-      cairo_set_source_surface (cr, cairo_get_target (FRAME_CR_CONTEXT (f)),
-                                -x, -from_y);
-      cairo_paint (cr);
-      cairo_destroy (cr);
+      cairo_surface_t *surface = cairo_get_target (FRAME_CR_CONTEXT (f));
+      if (cairo_surface_get_type (surface) == CAIRO_SURFACE_TYPE_XLIB)
+        {
+          eassert (cairo_xlib_surface_get_display (surface)
+                   == FRAME_X_DISPLAY (f));
+          eassert (cairo_xlib_surface_get_drawable (surface)
+                   == FRAME_X_RAW_DRAWABLE (f));
+          cairo_surface_flush (surface);
+          XCopyArea (FRAME_X_DISPLAY (f),
+                     FRAME_X_DRAWABLE (f), FRAME_X_DRAWABLE (f),
+                     f->output_data.x->normal_gc,
+                     x, from_y,
+                     width, height,
+                     x, to_y);
+          cairo_surface_mark_dirty_rectangle (surface, x, to_y, width, height);
+        }
+      else
+        {
+          cairo_surface_t *s
+            = cairo_surface_create_similar (surface,
+                                            cairo_surface_get_content (surface),
+                                            width, height);
+          cairo_t *cr = cairo_create (s);
+          cairo_set_source_surface (cr, surface, -x, -from_y);
+          cairo_paint (cr);
+          cairo_destroy (cr);
 
-      cr = FRAME_CR_CONTEXT (f);
-      cairo_save (cr);
-      cairo_set_source_surface (cr, s, x, to_y);
-      cairo_rectangle (cr, x, to_y, width, height);
-      cairo_fill (cr);
-      cairo_restore (cr);
-      cairo_surface_destroy (s);
+          cr = FRAME_CR_CONTEXT (f);
+          cairo_save (cr);
+          cairo_set_source_surface (cr, s, x, to_y);
+          cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
+          cairo_rectangle (cr, x, to_y, width, height);
+          cairo_fill (cr);
+          cairo_restore (cr);
+          cairo_surface_destroy (s);
+        }
     }
   else
-    {
-      SET_FRAME_GARBAGED (f);
-    }
-#else
-  XCopyArea (FRAME_X_DISPLAY (f),
-             FRAME_X_DRAWABLE (f), FRAME_X_DRAWABLE (f),
-             f->output_data.x->normal_gc,
-             x, from_y,
-             width, height,
-             x, to_y);
-#endif
+#endif  /* USE_CAIRO */
+    XCopyArea (FRAME_X_DISPLAY (f),
+               FRAME_X_DRAWABLE (f), FRAME_X_DRAWABLE (f),
+               f->output_data.x->normal_gc,
+               x, from_y,
+               width, height,
+               x, to_y);
 
   unblock_input ();
 }