FAQ: add some details about the w3m img hack

... and an example patch to switch from double-buffering to a single buffer.

diff --git a/FAQ b/FAQ
index 85534a4..fb40264 100644 (file)
--- a/FAQ
+++ b/FAQ
@@ -2,12 +2,14 @@
 
 Use the excellent tool of [utmp](https://git.suckless.org/utmp/) for this task.
 
 
 Use the excellent tool of [utmp](https://git.suckless.org/utmp/) for this task.
 

+

 ## Some _random program_ complains that st is unknown/not recognised/unsupported/whatever!
 
 It means that st doesn’t have any terminfo entry on your system. Chances are
 you did not `make install`. If you just want to test it without installing it,
 you can manually run `tic -sx st.info`.
 
 ## Some _random program_ complains that st is unknown/not recognised/unsupported/whatever!
 
 It means that st doesn’t have any terminfo entry on your system. Chances are
 you did not `make install`. If you just want to test it without installing it,
 you can manually run `tic -sx st.info`.
 

+

 ## Nothing works, and nothing is said about an unknown terminal!
 
 * Some programs just assume they’re running in xterm i.e. they don’t rely on
 ## Nothing works, and nothing is said about an unknown terminal!
 
 * Some programs just assume they’re running in xterm i.e. they don’t rely on


@@ -15,6 +17,7 @@ you can manually run `tic -sx st.info`.
 * Some programs don’t complain about the lacking st description and default to
   another terminal. In that case see the question about terminfo.
 
 * Some programs don’t complain about the lacking st description and default to
   another terminal. In that case see the question about terminfo.
 

+

 ## How do I scroll back up?
 
 * Using a terminal multiplexer.
 ## How do I scroll back up?
 
 * Using a terminal multiplexer.


@@ -23,11 +26,13 @@ you can manually run `tic -sx st.info`.
 * Using the excellent tool of [scroll](https://git.suckless.org/scroll/).
 * Using the scrollback [patch](https://st.suckless.org/patches/scrollback/).
 
 * Using the excellent tool of [scroll](https://git.suckless.org/scroll/).
 * Using the scrollback [patch](https://st.suckless.org/patches/scrollback/).
 

+

 ## I would like to have utmp and/or scroll functionality by default
 
 You can add the absolute patch of both programs in your config.h
 file. You only have to modify the value of utmp and scroll variables.
 
 ## I would like to have utmp and/or scroll functionality by default
 
 You can add the absolute patch of both programs in your config.h
 file. You only have to modify the value of utmp and scroll variables.
 

+

 ## Why doesn't the Del key work in some programs?
 
 Taken from the terminfo manpage:
 ## Why doesn't the Del key work in some programs?
 
 Taken from the terminfo manpage:


@@ -83,12 +88,14 @@ If you are using zsh, then read the zsh FAQ
 
 Putting these lines into your .zshrc will fix the problems.
 
 
 Putting these lines into your .zshrc will fix the problems.
 

+

 ## How can I use meta in 8bit mode?
 
 St supports meta in 8bit mode, but the default terminfo entry doesn't
 use this capability. If you want it, you have to use the 'st-meta' value
 in TERM.
 
 ## How can I use meta in 8bit mode?
 
 St supports meta in 8bit mode, but the default terminfo entry doesn't
 use this capability. If you want it, you have to use the 'st-meta' value
 in TERM.
 

+

 ## I cannot compile st in OpenBSD
 
 OpenBSD lacks librt, despite it being mandatory in POSIX
 ## I cannot compile st in OpenBSD
 
 OpenBSD lacks librt, despite it being mandatory in POSIX


@@ -97,6 +104,7 @@ If you want to compile st for OpenBSD you have to remove -lrt from config.mk, an
 st will compile without any loss of functionality, because all the functions are
 included in libc on this platform.
 
 st will compile without any loss of functionality, because all the functions are
 included in libc on this platform.
 

+

 ## The Backspace Case
 
 St is emulating the Linux way of handling backspace being delete and delete being
 ## The Backspace Case
 
 St is emulating the Linux way of handling backspace being delete and delete being


@@ -158,19 +166,60 @@ terminal users wants its backspace to be how he feels it:
        [1] http://www.ibb.net/~anne/keyboard.html
        [2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html
 
        [1] http://www.ibb.net/~anne/keyboard.html
        [2] http://www.tldp.org/HOWTO/Keyboard-and-Console-HOWTO-5.html
 

+

 ## But I really want the old grumpy behaviour of my terminal
 
 Apply [1].
 
 [1] https://st.suckless.org/patches/delkey
 
 ## But I really want the old grumpy behaviour of my terminal
 
 Apply [1].
 
 [1] https://st.suckless.org/patches/delkey
 

-## Why do images not work in st (in programs such as w3m)?

 
 

-This is a terrible hack that overdraws an image on top of the terminal emulator
-window. It also relies on a very specific way the terminal draws it's contents.
+## Why do images not work in st using the w3m image hack?
+
+w3mimg uses a hack that draws an image on top of the terminal emulator Drawable
+window. The hack relies on the terminal to use a single buffer to draw its
+contents directly.
+
+st uses double-buffered drawing so the image is quickly replaced and may show a
+short flicker effect.
+
+Below is a patch example to change st double-buffering to a single Drawable
+buffer.
+
+diff --git a/x.c b/x.c
+--- a/x.c
++++ b/x.c
+@@ -561,10 +561,6 @@ xresize(int col, int row)
+       win.tw = MAX(1, col * win.cw);
+       win.th = MAX(1, row * win.ch);
+ 
+-      XFreePixmap(xw.dpy, xw.buf);
+-      xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
+-                      DefaultDepth(xw.dpy, xw.scr));
+-      XftDrawChange(xw.draw, xw.buf);
+       xclear(0, 0, win.w, win.h);
+ }
+ 
+@@ -921,8 +917,7 @@ xinit(void)
+       gcvalues.graphics_exposures = False;
+       dc.gc = XCreateGC(xw.dpy, parent, GCGraphicsExposures,
+                       &gcvalues);
+-      xw.buf = XCreatePixmap(xw.dpy, xw.win, win.w, win.h,
+-                      DefaultDepth(xw.dpy, xw.scr));
++      xw.buf = xw.win;
+       XSetForeground(xw.dpy, dc.gc, dc.col[defaultbg].pixel);
+       XFillRectangle(xw.dpy, xw.buf, dc.gc, 0, 0, win.w, win.h);
+ 
+@@ -1386,8 +1381,6 @@ void
+ draw(void)
+ {
+       drawregion(0, 0, term.col, term.row);
+-      XCopyArea(xw.dpy, xw.buf, xw.win, dc.gc, 0, 0, win.w,
+-                      win.h, 0, 0);
+       XSetForeground(xw.dpy, dc.gc,
+                       dc.col[IS_SET(MODE_REVERSE)?
+                               defaultfg : defaultbg].pixel);

 
 

-A more proper (but limited way) would be using sixels. Which st doesn't
-support.

 
 ## BadLength X error in Xft when trying to render emoji
 
 
 ## BadLength X error in Xft when trying to render emoji