view man/xemacs/display.texi @ 939:025200a2163c

[xemacs-hg @ 2002-07-31 07:23:39 by michaels] 2002-07-17 Marcus Crestani <crestani@informatik.uni-tuebingen.de> Markus Kaltenbach <makalten@informatik.uni-tuebingen.de> Mike Sperber <mike@xemacs.org> configure flag to turn these changes on: --use-kkcc First we added a dumpable flag to lrecord_implementation. It shows, if the object is dumpable and should be processed by the dumper. * lrecord.h (struct lrecord_implementation): added dumpable flag (MAKE_LRECORD_IMPLEMENTATION): fitted the different makro definitions to the new lrecord_implementation and their calls. Then we changed mark_object, that it no longer needs a mark method for those types that have pdump descritions. * alloc.c: (mark_object): If the object has a description, the new mark algorithm is called, and the object is marked according to its description. Otherwise it uses the mark method like before. These procedures mark objects according to their descriptions. They are modeled on the corresponding pdumper procedures. (mark_with_description): (get_indirect_count): (structure_size): (mark_struct_contents): These procedures still call mark_object, this is needed while there are Lisp_Objects without descriptions left. We added pdump descriptions for many Lisp_Objects: * extents.c: extent_auxiliary_description * database.c: database_description * gui.c: gui_item_description * scrollbar.c: scrollbar_instance_description * toolbar.c: toolbar_button_description * event-stream.c: command_builder_description * mule-charset.c: charset_description * device-msw.c: devmode_description * dialog-msw.c: mswindows_dialog_id_description * eldap.c: ldap_description * postgresql.c: pgconn_description pgresult_description * tooltalk.c: tooltalk_message_description tooltalk_pattern_description * ui-gtk.c: emacs_ffi_description emacs_gtk_object_description * events.c: * events.h: * event-stream.c: * event-Xt.c: * event-gtk.c: * event-tty.c: To write a pdump description for Lisp_Event, we converted every struct in the union event to a Lisp_Object. So we created nine new Lisp_Objects: Lisp_Key_Data, Lisp_Button_Data, Lisp_Motion_Data, Lisp_Process_Data, Lisp_Timeout_Data, Lisp_Eval_Data, Lisp_Misc_User_Data, Lisp_Magic_Data, Lisp_Magic_Eval_Data. We also wrote makro selectors and mutators for the fields of the new designed Lisp_Event and added everywhere these new abstractions. We implemented XD_UNION support in (mark_with_description), so we can describe exspecially console/device specific data with XD_UNION. To describe with XD_UNION, we added a field to these objects, which holds the variant type of the object. This field is initialized in the appendant constructor. The variant is an integer, it has also to be described in an description, if XD_UNION is used. XD_UNION is used in following descriptions: * console.c: console_description (get_console_variant): returns the variant (create_console): added variant initialization * console.h (console_variant): the different console types * console-impl.h (struct console): added enum console_variant contype * device.c: device_description (Fmake_device): added variant initialization * device-impl.h (struct device): added enum console_variant devtype * objects.c: image_instance_description font_instance_description (Fmake_color_instance): added variant initialization (Fmake_font_instance): added variant initialization * objects-impl.h (struct Lisp_Color_Instance): added color_instance_type * objects-impl.h (struct Lisp_Font_Instance): added font_instance_type * process.c: process_description (make_process_internal): added variant initialization * process.h (process_variant): the different process types
author michaels
date Wed, 31 Jul 2002 07:23:39 +0000 (2002-07-31)
parents 3ecd8885ac67
children c6b1500299a7
line wrap: on
line source

@node Display, Search, Registers, Top
@chapter Controlling the Display

  Since only part of a large buffer fits in the window, XEmacs tries to show
the part that is likely to be interesting.  The display control commands
allow you to specify which part of the text you want to see.

@table @kbd
@item C-l
Clear frame and redisplay, scrolling the selected window to center
point vertically within it (@code{recenter}).
@item C-v
@itemx pgdn
@itemx next
Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
On most X keyboards, you can get this functionality using the key
labelled @samp{Page Down}, which generates either @kbd{next} or @kbd{pgdn}.
@item M-v
@itemx pgup
@itemx prior
Scroll backward (@code{scroll-down}).  On most X keyboards, you can get
this functionality using the key labelled @samp{Page Up}, which
generates either @kbd{prior} or @kbd{pgup}.
@item @var{arg} C-l
Scroll so point is on line @var{arg} (@code{recenter}).
@item C-x <
@itemx C-pgdn
@itemx C-next
Scroll text in current window to the left (@code{scroll-left}).
@item C-x >
@itemx C-pgup
@itemx C-prior
Scroll to the right (@code{scroll-right}).
@item C-x $
Make deeply indented lines invisible (@code{set-selective-display}).
@end table

@menu
* Scrolling::	           Moving text up and down in a window.
* Horizontal Scrolling::   Moving text left and right in a window.
* Selective Display::      Hiding lines with lots of indentation.
* Display Vars::           Information on variables for customizing display.
@end menu

@node Scrolling, Horizontal Scrolling, Display, Display
@section Scrolling

  If a buffer contains text that is too large to fit entirely within the
window that is displaying the buffer, XEmacs shows a contiguous section of
the text.  The section shown always contains point.

@cindex scrolling
  @dfn{Scrolling} means moving text up or down in the window so that
different parts of the text are visible.  Scrolling forward means that text
moves up, and new text appears at the bottom.  Scrolling backward moves
text down and new text appears at the top.

  Scrolling happens automatically if you move point past the bottom or top
of the window.  You can also explicitly request scrolling with the commands
in this section.

@ifinfo
@table @kbd
@item C-l
Clear frame and redisplay, scrolling the selected window to center
point vertically within it (@code{recenter}).
@item C-v
@itemx pgdn
@itemx next
Scroll forward (a windowful or a specified number of lines) (@code{scroll-up}).
@item M-v
@itemx pgup
@itemx prior
Scroll backward (@code{scroll-down}).
@item @var{arg} C-l
Scroll so point is on line @var{arg} (@code{recenter}).
@end table
@end ifinfo

@kindex C-l
@findex recenter
  The most basic scrolling command is @kbd{C-l} (@code{recenter}) with no
argument.  It clears the entire frame and redisplays all windows.  In
addition, it scrolls the selected window so that point is halfway down
from the top of the window.

@kindex C-v
@kindex M-v
@kindex pgup
@kindex pgdn
@kindex next
@kindex prior
@findex scroll-up
@findex scroll-down
  The scrolling commands @kbd{C-v} and @kbd{M-v} let you move all the text
in the window up or down a few lines.  @kbd{C-v} (@code{scroll-up}) with an
argument shows you that many more lines at the bottom of the window, moving
the text and point up together as @kbd{C-l} might.  @kbd{C-v} with a
negative argument shows you more lines at the top of the window.
@kbd{Meta-v} (@code{scroll-down}) is like @kbd{C-v}, but moves in the
opposite direction.@refill

@vindex next-screen-context-lines
  To read the buffer a windowful at a time, use @kbd{C-v} with no
argument.  @kbd{C-v} takes the last two lines at the bottom of the
window and puts them at the top, followed by nearly a whole windowful of
lines not previously visible.  Point moves to the new top of the window
if it was in the text scrolled off the top.  @kbd{M-v} with no argument
moves backward with similar overlap.  The number of lines of overlap
across a @kbd{C-v} or @kbd{M-v} is controlled by the variable
@code{next-screen-context-lines}; by default, it is two.

  Another way to scroll is using @kbd{C-l} with a numeric argument.
@kbd{C-l} does not clear the frame when given an argument; it only
scrolls the selected window.  With a positive argument @var{n}, @kbd{C-l}
repositions text to put point @var{n} lines down from the top.  An
argument of zero puts point on the very top line.  Point does not move
with respect to the text; rather, the text and point move rigidly on the
frame.  @kbd{C-l} with a negative argument puts point that many lines
from the bottom of the window.  For example, @kbd{C-u - 1 C-l} puts
point on the bottom line, and @kbd{C-u - 5 C-l} puts it five lines from
the bottom.  Just @kbd{C-u} as argument, as in @kbd{C-u C-l}, scrolls
point to the center of the frame.

@vindex scroll-step
  Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable @code{scroll-step} has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point back
into visibility, that is what happens.

  Scrolling happens automatically if point has moved out of the visible
portion of the text when it is time to display.  Usually scrolling is
done  to put point vertically centered within the window.  However, if
the variable @code{scroll-step} has a non-zero value, an attempt is made to
scroll the buffer by that many lines; if that is enough to bring point back
into visibility, that is what happens.

@vindex scroll-conservatively
  If you set @code{scroll-step} to a small value because you want to use 
arrow keys to scroll the screen without recentering, the redisplay
preemption will likely make XEmacs keep recentering the screen when
scrolling fast, regardless of @code{scroll-step}.  To prevent this, set
@code{scroll-conservatively} to a small value, which will have the
result of overriding the redisplay preemption.

@node Horizontal Scrolling,, Scrolling, Display
@section Horizontal Scrolling

@ifinfo
@table @kbd
@item C-x <
Scroll text in current window to the left (@code{scroll-left}).
@item C-x >
Scroll to the right (@code{scroll-right}).
@end table
@end ifinfo

@kindex C-x <
@kindex C-x >
@findex scroll-left
@findex scroll-right
@cindex horizontal scrolling
  The text in a window can also be scrolled horizontally.  This means that
each line of text is shifted sideways in the window, and one or more
characters at the beginning of each line are not displayed at all.  When a
window has been scrolled horizontally in this way, text lines are truncated
rather than continued (@pxref{Continuation Lines}), with a @samp{$} appearing
in the first column when there is text truncated to the left, and in the
last column when there is text truncated to the right.

  The command @kbd{C-x <} (@code{scroll-left}) scrolls the selected
window to the left by @var{n} columns with argument @var{n}.  With no
argument, it scrolls by almost the full width of the window (two columns
less, to be precise).  @kbd{C-x >} (@code{scroll-right}) scrolls
similarly to the right.  The window cannot be scrolled any farther to
the right once it is displaying normally (with each line starting at the
window's left margin); attempting to do so has no effect.

@node Selective Display, Display Vars, Display, Display
@section Selective Display
@findex set-selective-display
@kindex C-x $

  XEmacs can hide lines indented more than a certain number
of columns (you specify how many columns).  This allows you  to get an
overview of a part of a program.

  To hide lines, type @kbd{C-x $} (@code{set-selective-display}) with a
numeric argument @var{n}.  (@xref{Arguments}, for information on giving
the argument.)  Lines with at least @var{n} columns of indentation
disappear from the screen.  The only indication of their presence are
three dots (@samp{@dots{}}), which appear at the end of each visible
line that is followed by one or more invisible ones.@refill

  The invisible lines are still present in the buffer, and most editing
commands see them as usual, so it is very easy to put point in the middle
of invisible text.  When this happens, the cursor appears at the end of the
previous line, after the three dots.  If point is at the end of the visible
line, before the newline that ends it, the cursor appears before the three
dots.

  The commands @kbd{C-n} and @kbd{C-p} move across the invisible lines
as if they were not there.

  To make everything visible again, type @kbd{C-x $} with no argument.

@node Display Vars,, Selective Display, Display
@section Variables Controlling Display

  This section contains information for customization only.  Beginning
users should skip it.

@vindex no-redraw-on-reenter
  When you reenter XEmacs after suspending, XEmacs normally clears the
screen and redraws the entire display.  On some terminals with more than
one page of memory, it is possible to arrange the termcap entry so that
the @samp{ti} and @samp{te} strings (output to the terminal when XEmacs
is entered and exited, respectively) switch between pages of memory so
as to use one page for XEmacs and another page for other output.  In that
case, you might want to set the variable @code{no-redraw-on-reenter} to
non-@code{nil} so that XEmacs will assume, when resumed, that the screen
page it is using still contains what XEmacs last wrote there.

@vindex echo-keystrokes
  The variable @code{echo-keystrokes} controls the echoing of multi-character
keys; its value is the number of seconds of pause required to cause echoing
to start, or zero, meaning don't echo at all.  @xref{Echo Area}.

@vindex ctl-arrow
  If the variable @code{ctl-arrow} is @code{nil}, control characters in the
buffer are displayed with octal escape sequences, all except newline and
tab.  If its value is @code{t}, then control characters will be printed 
with an up-arrow, for example @kbd{^A}.  

If its value is not @code{t} and not @code{nil}, then characters whose
code is greater than 160 (that is, the space character (32) with its
high bit set) will be assumed to be printable, and will be displayed
without alteration.  This is the default when running under X Windows,
since XEmacs assumes an ISO/8859-1 character set (also known as
``Latin1'').  The @code{ctl-arrow} variable may also be set to an
integer, in which case all characters whose codes are greater than or
equal to that value will be assumed to be printable.

Altering the value of @code{ctl-arrow} makes it local to the current
buffer; until that time, the default value is in effect.  @xref{Locals}.

@vindex tab-width
  Normally, a tab character in the buffer is displayed as whitespace which
extends to the next display tab stop position, and display tab stops come
at intervals equal to eight spaces.  The number of spaces per tab is
controlled by the variable @code{tab-width}, which is made local by
changing it, just like @code{ctl-arrow}.  Note that how the tab character
in the buffer is displayed has nothing to do with the definition of
@key{TAB} as a command.

@vindex selective-display-ellipses
  If you set the variable @code{selective-display-ellipses} to @code{nil},
the three dots at the end of a line that precedes invisible
lines do not appear.  There is no visible indication of the invisible lines.
This variable becomes local automatically when set.