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Adjustments to double buffering on MS Windows

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* src/w32fns.c (w32_set_inhibit_double_buffering): Add comment
describing double buffering.
(w32_wnd_proc): Respect `w32-disable-double-buffering'.
(globals_of_w32fns): New variable
`w32-disable-double-buffering'.

* src/w32term.c (w32_show_back_buffer): Return immediately if
double buffering is disabled on the frame.
(w32_scroll_run): Use old scrolling code if
`w32-disable-double-buffering' is enabled.
(w32_scroll_bar_clear): Document why we don't clear scroll bars
when double buffering is enabled.
(w32_read_socket): Respect `w32-disable-double-buffering' and
clean up some code.

* src/w32xfns.c (get_frame_dc): Respect
`w32-disable-double-buffering'.
This commit is contained in:
Po Lu 2022-04-30 15:49:06 +08:00
parent 1648791e7c
commit 1321b5989c
3 changed files with 87 additions and 15 deletions
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16
src/w32fns.c
View file

@ -1802,9 +1802,16 @@ 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));
}
/* Enable or disable double buffering on F.
When double buffering is enabled, all drawing happens on a back
buffer (a bitmap), which is then displayed as a single operation
after redisplay is complete. This avoids flicker caused by the
results of an incomplete redisplay becoming visible. */
static void
w32_set_inhibit_double_buffering (struct frame *f,
Lisp_Object new_value,
/* This parameter is unused. */
Lisp_Object old_value)
{
block_input ();
@ -4114,7 +4121,8 @@ w32_wnd_proc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
f = w32_window_to_frame (dpyinfo, hwnd);
enter_crit ();
if (f && !FRAME_OUTPUT_DATA (f)->paint_buffer)
if (f && (w32_disable_double_buffering
|| !FRAME_OUTPUT_DATA (f)->paint_buffer))
{
HDC hdc = get_frame_dc (f);
GetUpdateRect (hwnd, &wmsg.rect, FALSE);
@ -11236,6 +11244,12 @@ see `w32-ansi-code-page'. */);
w32_multibyte_code_page = _getmbcp ();
#endif
DEFVAR_BOOL ("w32-disable-double-buffering", w32_disable_double_buffering,
doc: /* Completely disable double buffering.
This variable is used for debugging, and takes precedence over any
value of the `inhibit-double-buffering' frame parameter. */);
w32_disable_double_buffering = false;
if (os_subtype == OS_SUBTYPE_NT)
w32_unicode_gui = 1;
else

80
src/w32term.c
View file

@ -283,6 +283,9 @@ w32_show_back_buffer (struct frame *f)
output = FRAME_OUTPUT_DATA (f);
if (!output->want_paint_buffer || w32_disable_double_buffering)
return;
enter_crit ();
if (output->paint_buffer)
@ -2935,6 +2938,8 @@ w32_scroll_run (struct window *w, struct run *run)
struct frame *f = XFRAME (w->frame);
int x, y, width, height, from_y, to_y, bottom_y;
HDC hdc;
HWND hwnd = FRAME_W32_WINDOW (f);
HRGN expect_dirty = NULL;
/* Get frame-relative bounding box of the text display area of W,
without mode lines. Include in this box the left and right
@ -2953,6 +2958,9 @@ w32_scroll_run (struct window *w, struct run *run)
height = bottom_y - from_y;
else
height = run->height;
if (w32_disable_double_buffering)
expect_dirty = CreateRectRgn (x, y + height, x + width, bottom_y);
}
else
{
@ -2962,15 +2970,55 @@ w32_scroll_run (struct window *w, struct run *run)
height = bottom_y - to_y;
else
height = run->height;
if (w32_disable_double_buffering)
expect_dirty = CreateRectRgn (x, y, x + width, to_y);
}
block_input ();
/* Cursor off. Will be switched on again in gui_update_window_end. */
gui_clear_cursor (w);
hdc = get_frame_dc (f);
BitBlt (hdc, x, to_y, width, height, hdc, x, from_y, SRCCOPY);
release_frame_dc (f, hdc);
if (!w32_disable_double_buffering)
{
hdc = get_frame_dc (f);
BitBlt (hdc, x, to_y, width, height, hdc, x, from_y, SRCCOPY);
release_frame_dc (f, hdc);
}
else
{
RECT from;
RECT to;
HRGN dirty = CreateRectRgn (0, 0, 0, 0);
HRGN combined = CreateRectRgn (0, 0, 0, 0);
from.left = to.left = x;
from.right = to.right = x + width;
from.top = from_y;
from.bottom = from_y + height;
to.top = y;
to.bottom = bottom_y;
ScrollWindowEx (hwnd, 0, to_y - from_y, &from, &to, dirty,
NULL, SW_INVALIDATE);
/* Combine this with what we expect to be dirty. This covers the
case where not all of the region we expect is actually dirty. */
CombineRgn (combined, dirty, expect_dirty, RGN_OR);
/* If the dirty region is not what we expected, redraw the entire frame. */
if (!EqualRgn (combined, expect_dirty))
SET_FRAME_GARBAGED (f);
DeleteObject (dirty);
DeleteObject (combined);
}
unblock_input ();
if (w32_disable_double_buffering
&& expect_dirty)
DeleteObject (expect_dirty);
}
@ -4840,7 +4888,12 @@ w32_scroll_bar_clear (struct frame *f)
{
Lisp_Object bar;
if (FRAME_OUTPUT_DATA (f)->paint_buffer)
/* Return if double buffering is enabled, since clearing a frame
actually clears just the back buffer, so avoid clearing all of
the scroll bars, since that causes the scroll bars to
flicker. */
if (!w32_disable_double_buffering
&& FRAME_OUTPUT_DATA (f)->want_paint_buffer)
return;
/* We can have scroll bars even if this is 0,
@ -4958,6 +5011,11 @@ w32_read_socket (struct terminal *terminal,
struct input_event inev;
int do_help = 0;
/* WM_WINDOWPOSCHANGED makes the buffer dirty, but there's no
reason to flush the back buffer after receiving such an
event, and that also causes flicker. */
bool ignore_dirty_back_buffer = false;
/* DebPrint (("w32_read_socket: %s time:%u\n", */
/* w32_name_of_message (msg.msg.message), */
/* msg.msg.time)); */
@ -5005,8 +5063,8 @@ w32_read_socket (struct terminal *terminal,
}
else
{
enter_crit ();
if (!FRAME_OUTPUT_DATA (f)->paint_buffer)
if (w32_disable_double_buffering
|| !FRAME_OUTPUT_DATA (f)->paint_buffer)
{
/* Erase background again for safety. But don't do
that if the frame's 'garbaged' flag is set, since
@ -5031,7 +5089,6 @@ w32_read_socket (struct terminal *terminal,
}
else
w32_show_back_buffer (f);
leave_crit ();
}
}
break;
@ -5484,6 +5541,7 @@ w32_read_socket (struct terminal *terminal,
case WM_WINDOWPOSCHANGED:
f = w32_window_to_frame (dpyinfo, msg.msg.hwnd);
ignore_dirty_back_buffer = true;
if (f)
{
@ -5894,11 +5952,9 @@ w32_read_socket (struct terminal *terminal,
that is the case, flush any changes that have been made to
the front buffer. */
if (f && FRAME_OUTPUT_DATA (f)->paint_buffer_dirty
/* WM_WINDOWPOSCHANGED makes the buffer dirty, but there's
no reason to flush it here, and that also causes
flicker. */
&& !f->garbaged && msg.msg.message != WM_WINDOWPOSCHANGED)
if (f && !w32_disable_double_buffering
&& FRAME_OUTPUT_DATA (f)->paint_buffer_dirty
&& !f->garbaged && ignore_dirty_back_buffer)
w32_show_back_buffer (f);
}

6
src/w32xfns.c
View file

@ -171,7 +171,8 @@ get_frame_dc (struct frame *f)
if (output->paint_dc)
{
if (output->paint_buffer_width != FRAME_PIXEL_WIDTH (f)
|| output->paint_buffer_height != FRAME_PIXEL_HEIGHT (f))
|| output->paint_buffer_height != FRAME_PIXEL_HEIGHT (f)
|| w32_disable_double_buffering)
w32_release_paint_buffer (f);
else
{
@ -188,7 +189,8 @@ get_frame_dc (struct frame *f)
{
select_palette (f, hdc);
if (FRAME_OUTPUT_DATA (f)->want_paint_buffer)
if (!w32_disable_double_buffering
&& FRAME_OUTPUT_DATA (f)->want_paint_buffer)
{
back_buffer
= CreateCompatibleBitmap (hdc, FRAME_PIXEL_WIDTH (f),