From acefbcf8351180b4eff46b30491ce758dcc42feb Mon Sep 17 00:00:00 2001 From: Po Lu Date: Fri, 29 Jul 2022 17:14:05 +0800 Subject: [PATCH] Minor additions to last change * doc/emacs/xresources.texi (Table of Resources): Update description of `extended'. * etc/NEWS: Announce frame tearing reduction. * src/xterm.c (x_sync_update_finish, x_sync_update_begin) (x_update_begin, x_update_end, show_back_buffer, x_flip_and_flush) (XTframe_up_to_date, handle_one_xevent): Minor redesign of frame synchronization feature. Fix crash with overflow and checking. --- doc/emacs/xresources.texi | 4 +++- etc/NEWS | 11 +++++++++- src/xterm.c | 42 +++++++++++++++++++-------------------- 3 files changed, 33 insertions(+), 24 deletions(-) diff --git a/doc/emacs/xresources.texi b/doc/emacs/xresources.texi index 8915d2025ba..ab0df3563f5 100644 --- a/doc/emacs/xresources.texi +++ b/doc/emacs/xresources.texi @@ -382,7 +382,9 @@ which prevents blank areas of a frame that have not yet been painted from being displayed. If set to @samp{extended}, it will enable use of an alternative frame synchronization protocol, which might be supported by some compositing window managers that don't support the -protocol Emacs uses by default. +protocol Emacs uses by default, and causes Emacs to synchronize +display with the monitor refresh rate when a compatible compositing +window manager is in use. @item @code{verticalScrollBars} (class @code{ScrollBars}) Give frames scroll bars on the left if @samp{left}, on the right if diff --git a/etc/NEWS b/etc/NEWS index 43f057a407b..cd2897cd6dd 100644 --- a/etc/NEWS +++ b/etc/NEWS @@ -598,13 +598,22 @@ Only in the Lucid build, this controls colors used for highlighted menu item widgets. +++ -** On X11, Emacs now tries to synchronize window resize with the window manager. +** On X, Emacs now tries to synchronize window resize with the window manager. This leads to less flicker and empty areas of a frame being displayed when a frame is being resized. Unfortunately, it does not work on some ancient buggy window managers, so if Emacs appears to freeze, but is still responsive to input, you can turn it off by setting the X resource "synchronizeResize" to "off". ++++ +** On X, Emacs can optionally synchronize display with the graphics hardware. +When this is enabled by setting the X resource "synchronizeResize" to +"extended", frame content "tearing" is drastically reduced. This is +only supported on the Motif, Lucid, and no-toolkit builds, and +requires an X compositing manager supporting the extended frame +synchronization protocol (see +https://fishsoup.net/misc/wm-spec-synchronization.html). + +++ ** New frame parameter 'alpha-background' and X resource "alphaBackground". This controls the opacity of the text background when running on a diff --git a/src/xterm.c b/src/xterm.c index d3ffd432dd2..4d4febcc368 100644 --- a/src/xterm.c +++ b/src/xterm.c @@ -6653,14 +6653,8 @@ x_sync_update_begin (struct frame *f) if (XSyncValueLow32 (value) % 2) return; - /* Wait for a pending frame draw event if the last frame has not yet - been drawn if F isn't double buffered. (In double buffered - frames, this happens before buffer flipping). */ - -#ifdef HAVE_XDBE - if (!FRAME_X_DOUBLE_BUFFERED_P (f)) -#endif - x_sync_wait_for_frame_drawn_event (f); + /* Wait for the last frame to be drawn before drawing this one. */ + x_sync_wait_for_frame_drawn_event (f); /* Since Emacs needs a non-urgent redraw, ensure that value % 4 == 0. */ @@ -6672,11 +6666,10 @@ x_sync_update_begin (struct frame *f) XSyncValueAdd (&FRAME_X_COUNTER_VALUE (f), value, add, &overflow); - if (XSyncValueLow32 (FRAME_X_COUNTER_VALUE (f)) % 4 != 1) - emacs_abort (); - if (overflow) - XSyncIntToValue (&FRAME_X_COUNTER_VALUE (f), 1); + XSyncIntToValue (&FRAME_X_COUNTER_VALUE (f), 3); + + eassert (XSyncValueLow32 (FRAME_X_COUNTER_VALUE (f)) % 4 != 1); XSyncSetCounter (FRAME_X_DISPLAY (f), FRAME_X_EXTENDED_COUNTER (f), @@ -6741,7 +6734,10 @@ static void x_update_begin (struct frame *f) { #if defined HAVE_XSYNC && !defined USE_GTK - x_sync_update_begin (f); + /* If F is double-buffered, we can make the entire frame center + around XdbeSwapBuffers. */ + if (!FRAME_X_DOUBLE_BUFFERED_P (f)) + x_sync_update_begin (f); #else /* Nothing to do. */ #endif @@ -6847,6 +6843,9 @@ show_back_buffer (struct frame *f) /* Wait for drawing of the previous frame to complete before displaying this new frame. */ x_sync_wait_for_frame_drawn_event (f); + + /* Begin a new frame. */ + x_sync_update_begin (f); #endif #ifdef USE_CAIRO @@ -6858,7 +6857,13 @@ show_back_buffer (struct frame *f) swap_info.swap_window = FRAME_X_WINDOW (f); swap_info.swap_action = XdbeCopied; XdbeSwapBuffers (FRAME_X_DISPLAY (f), &swap_info, 1); + +#if defined HAVE_XSYNC && !defined USE_GTK + /* Finish the frame here. */ + x_sync_update_finish (f); +#endif } + FRAME_X_NEED_BUFFER_FLIP (f) = false; unblock_input (); @@ -6883,10 +6888,7 @@ x_flip_and_flush (struct frame *f) block_input (); #ifdef HAVE_XDBE if (FRAME_X_NEED_BUFFER_FLIP (f)) - { - show_back_buffer (f); - x_sync_update_finish (f); - } + show_back_buffer (f); #endif x_flush (f); unblock_input (); @@ -6941,11 +6943,6 @@ XTframe_up_to_date (struct frame *f) if (!buffer_flipping_blocked_p () && FRAME_X_NEED_BUFFER_FLIP (f)) show_back_buffer (f); - -#if defined HAVE_XSYNC && !defined USE_GTK - if (FRAME_X_DOUBLE_BUFFERED_P (f)) - x_sync_update_finish (f); -#endif #endif #ifdef HAVE_XSYNC @@ -17027,6 +17024,7 @@ handle_one_xevent (struct x_display_info *dpyinfo, XSyncIntsToValue (&FRAME_X_COUNTER_VALUE (f), event->xclient.data.l[2], event->xclient.data.l[3]); + FRAME_X_OUTPUT (f)->ext_sync_end_pending_p = true; } -- 2.39.2