Implement double buffering on MS Windows

* etc/NEWS: Announce changes.
* src/w32fns.c (w32_set_inhibit_double_buffering): New function.
(w32_wnd_proc):
(Fx_create_frame):
(w32_create_tip_frame): Set `inhibit-double-buffering' parameter.
(w32_frame_parm_handlers): Add new handler.

* src/w32term.c (w32_show_back_buffer):
(w32_release_paint_buffer): New functions.
(w32_frame_up_to_date): Show back buffer if applicable.
(w32_buffer_flipping_unblocked_hook): New hook.
(w32_scroll_run): Use BitBlt to scroll instead of window
scrolling functions.
(w32_scroll_bar_clear): Don't clear scroll bars when double
buffered.
(w32_read_socket): Flip buffers after reading input events in
some cases.
(w32_free_frame_resources): Free back buffer.
(w32_create_terminal): Add new hook.

* src/w32term.h (struct w32_output): New fields for handling
back buffers.
* src/w32xfns.c (select_palette): Fix indentation.
(get_frame_dc, release_frame_dc): Return back buffer when
appropriate and set dirty flag.

1 files changed, 31 insertions, 2 deletions

diff --git a/src/w32fns.c b/src/w32fns.c
index a880136d0ac..d4e4b2a30bf 100644
--- a/src/w32fns.c
+++ b/src/w32fns.c
@@ -1802,6 +1802,25 @@ w32_set_tool_bar_lines (struct frame *f, Lisp_Object value, Lisp_Object oldval)
   w32_change_tool_bar_height (f, nlines * FRAME_LINE_HEIGHT (f));
 }
 
+static void
+w32_set_inhibit_double_buffering (struct frame *f,
+				  Lisp_Object new_value,
+				  Lisp_Object old_value)
+{
+  block_input ();
+
+  if (NILP (new_value))
+    FRAME_OUTPUT_DATA (f)->want_paint_buffer = 1;
+  else
+    {
+      FRAME_OUTPUT_DATA (f)->want_paint_buffer = 0;
+      w32_release_paint_buffer (f);
+
+      SET_FRAME_GARBAGED (f);
+    }
+
+  unblock_input ();
+}
 
 /* Set the pixel height of the tool bar of frame F to HEIGHT.  */
 void
@@ -4093,7 +4112,9 @@ w32_wnd_proc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
     {
     case WM_ERASEBKGND:
       f = w32_window_to_frame (dpyinfo, hwnd);
-      if (f)
+
+      enter_crit ();
+      if (f && !FRAME_OUTPUT_DATA (f)->paint_buffer)
 	{
 	  HDC hdc = get_frame_dc (f);
 	  GetUpdateRect (hwnd, &wmsg.rect, FALSE);
@@ -4107,6 +4128,7 @@ w32_wnd_proc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
 		     wmsg.rect.right, wmsg.rect.bottom));
 #endif /* W32_DEBUG_DISPLAY */
 	}
+      leave_crit ();
       return 1;
     case WM_PALETTECHANGED:
       /* ignore our own changes */
@@ -6080,6 +6102,10 @@ DEFUN ("x-create-frame", Fx_create_frame, Sx_create_frame,
                          ? make_fixnum (0) : make_fixnum (1),
                          NULL, NULL, RES_TYPE_NUMBER);
 
+  gui_default_parameter (f, parameters, Qinhibit_double_buffering, Qnil,
+                         "inhibitDoubleBuffering", "InhibitDoubleBuffering",
+                         RES_TYPE_BOOLEAN);
+
   gui_default_parameter (f, parameters, Qbuffer_predicate, Qnil,
                          "bufferPredicate", "BufferPredicate", RES_TYPE_SYMBOL);
   gui_default_parameter (f, parameters, Qtitle, Qnil,
@@ -7096,6 +7122,9 @@ w32_create_tip_frame (struct w32_display_info *dpyinfo, Lisp_Object parms)
                          "alpha", "Alpha", RES_TYPE_NUMBER);
   gui_default_parameter (f, parms, Qalpha_background, Qnil,
                          "alphaBackground", "AlphaBackground", RES_TYPE_NUMBER);
+  gui_default_parameter (f, parms, Qinhibit_double_buffering, Qnil,
+                         "inhibitDoubleBuffering", "InhibitDoubleBuffering",
+                         RES_TYPE_BOOLEAN);
 
   /* Add `tooltip' frame parameter's default value. */
   if (NILP (Fframe_parameter (frame, Qtooltip)))
@@ -10432,7 +10461,7 @@ frame_parm_handler w32_frame_parm_handlers[] =
   gui_set_alpha,
   0, /* x_set_sticky */
   0, /* x_set_tool_bar_position */
-  0, /* x_set_inhibit_double_buffering */
+  w32_set_inhibit_double_buffering,
   w32_set_undecorated,
   w32_set_parent_frame,
   w32_set_skip_taskbar,