From: Nick Helm <nick@tenpoint.co.nz>
To: Emacs developers <emacs-devel@gnu.org>
Subject: mode-line size and position indicator
Date: Wed, 23 Aug 2017 15:20:27 +1200 [thread overview]
Message-ID: <m2bmn7ezr8.fsf@tenpoint.co.nz> (raw)
[-- Attachment #1: Type: text/plain, Size: 942 bytes --]
Hi all,
I've been trying to improve my C skills lately, so I thought I'd take a
crack at adding a small feature to xdisp.c.
I've written a simple mode-line indicator to visually show the relative
size and position of the window view on the current buffer. It works by
adding a new %-spec construct to decode_mode_spec.
The result is akin to a vertical scroll-bar, but it appears as a
horizontal mark on the mode-line. It may be useful to terminal users or
those who prefer to run with traditional scroll-bars turned off. I've
attached a screen-grab of what it looks like on my system.
The indicator is activated by adding %N~ to mode-line-format, where N is
a positive integer that sets the desired width of the indicator in char.
I'm under no illusions that this should be included in Emacs, and
admittedly, it is a very simple feature, but I'd appreciate any
comments or suggestions to improve the code. Patch attached.
Thanks,
Nick
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: xdisp.c.patch --]
[-- Type: text/x-patch, Size: 1584 bytes --]
--- a/src/xdisp.c 2016-10-07 15:47:28.000000000 +1300
+++ b/src/xdisp.c 2016-10-07 15:54:31.000000000 +1300
@@ -23810,6 +23813,45 @@ Add %-spec for a mode-line size and position indicator.
}
}
+ /* Indicate the relative size and position of the current window. */
+ case '~':
+ {
+ ptrdiff_t toppos = marker_position (w->start);
+ ptrdiff_t botpos = BUF_Z (b) - w->window_end_pos;
+ ptrdiff_t total = BUF_ZV (b) - BUF_BEGV (b) + 1;
+ ptrdiff_t open;
+ ptrdiff_t close;
+ int i;
+ char *p = decode_mode_spec_buf;
+
+ /* It makes little sense to pad with spaces, so use WIDTH to
+ enable the user to specify the size of the indicator. */
+
+ if (width < 3) width = 3; /* Set a minimum indicator size. */
+ width -= 2; /* Reserve space for open and close marks. */
+
+ if (total >= 1000000)
+ /* Do it differently for a large value, to avoid overflow. */
+ {
+ open = ((toppos - BUF_BEGV (b)) + (total / width) - 1) / (total / width);
+ close = ((botpos - BUF_BEGV (b) + 1) + (total / width) - 1) / (total / width);
+ }
+ else
+ {
+ open = ((toppos - BUF_BEGV (b)) * width + total - 1) / total;
+ close = ((botpos - BUF_BEGV (b) + 1) * width + total - 1) / total;
+ }
+
+ /* Build the indicator string. */
+ for (i = 0; i < open; i++) *p++ = '-';
+ *p++ = '+';
+ for (i = 0; i < (close - open); i++) *p++ = '~';
+ *p++ = '+';
+ for (i = 0; i < (width - close); i++) *p++ = '-';
+ *p = 0;
+ return decode_mode_spec_buf;
+ }
+
case 's':
/* status of process */
obj = Fget_buffer_process (Fcurrent_buffer ());
[-- Attachment #3: indicator.png --]
[-- Type: image/png, Size: 23067 bytes --]
next reply other threads:[~2017-08-23 3:20 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-23 3:20 Nick Helm [this message]
2017-08-24 16:55 ` mode-line size and position indicator Eli Zaretskii
2017-08-24 19:26 ` John Yates
2017-08-25 2:47 ` Richard Stallman
2017-08-25 9:57 ` Nick Helm
2017-08-25 12:36 ` Eli Zaretskii
2017-08-26 7:50 ` Nick Helm
-- strict thread matches above, loose matches on Subject: below --
2017-08-24 21:02 mark M
2017-08-25 6:27 ` Eli Zaretskii
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