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Many Emacs commands operate on an arbitrary contiguous part of the current buffer. You can select text in two ways:
To specify the text for a command to operate on, set the mark at one end of it, and move point to the other end. The text between point and the mark is called the region. You can move point or the mark to adjust the boundaries of the region. It doesn't matter which one is set first chronologically, or which one comes earlier in the text. Once the mark has been set, it remains until it is set again at another place. The mark remains fixed with respect to the preceding character if text is inserted or deleted in a buffer. Each Emacs buffer has its own mark; when you return to a buffer that had been selected previously, it has the same mark it had before.
Many commands that insert text, such as C-y (yank) and
M-x insert-buffer, position the mark at one end of the inserted
text--the opposite end from where point is positioned, so that the region
contains the text just inserted.
Aside from delimiting the region, the mark is useful for marking
a spot that you may want to go back to. To make this feature more useful,
Emacs remembers 16 previous locations of the mark in the mark ring.
Here are some commands for setting the mark:
set-mark-command).
exchange-point-and-mark).
For example, to convert part of the buffer to all
upper-case, you can use the C-x C-u (upcase-region)
command, which operates on the text in the region. First go to the
beginning of the text you want to capitalize and type C-SPC to
put the mark there, then move to the end, and then type C-x C-u to
capitalize the selected region. You can also set the mark at the end of the
text, move to the beginning, and then type C-x C-u. Most commands
that operate on the text in the region have the word region in
their names.
The most common way to set the mark is with the C-SPC
command (set-mark-command). This command sets the mark where
point is. You can then move point away, leaving the mark behind. It is
actually incorrect to speak of the character C-SPC; there is
no such character. When you type SPC while holding down
CTRL, you get the character C-@ on most terminals. This
character is actually bound to set-mark-command. But unless you are
unlucky enough to have a terminal where typing C-SPC does
not produce C-@, you should think of this character as
C-SPC.
Since terminals have only one cursor, Emacs cannot show you where the
mark is located. Most people use the mark soon after they set it, before
they forget where it is. But you can see where the mark is with the
command C-x C-x (exchange-point-and-mark) which puts the
mark where point was and point where the mark was. The extent of the
region is unchanged, but the cursor and point are now at the previous
location of the mark.
Another way to set the mark is to push the mark to the beginning of a
buffer while leaving point at its original location. If you supply an
argument to C-< (mark-beginning-of-buffer), the mark is pushed
n/10 of the way from the true beginning of the buffer. You can
also set the mark at the end of a buffer with C->
(mark-end-of-buffer). It pushes the mark to the end of the buffer,
leaving point alone. Supplying an argument to the command pushes the mark
n/10 of the way from the true end of the buffer.
If you are using XEmacs under the X window system, you can set
the variable zmacs-regions to t. This makes the current
region (defined by point and mark) highlight and makes it available as
the X clipboard selection, which means you can use the menu bar items on
it. See section Active Regions for more information.
C-x C-x is also useful when you are satisfied with the location of
point but want to move the mark; do C-x C-x to put point there and
then you can move it. A second use of C-x C-x, if necessary, puts
the mark at the new location with point back at its original location.
Once you have created an active region, you can do many things to the text in it:
There are commands for placing point and the mark around a textual object such as a word, list, paragraph or page.
mark-word). This command and
the following one do not move point.
mark-sexp).
mark-paragraph).
mark-defun).
mark-whole-buffer).
mark-page).
M-@ (mark-word) puts the mark at the end of the next word,
while C-M-@ (mark-sexp) puts it at the end of the next Lisp
expression. These characters sometimes save you some typing.
A number of commands are available that set both point and mark and
thus delimit an object in the buffer. M-h (mark-paragraph)
moves point to the beginning of the paragraph that surrounds or follows
point, and puts the mark at the end of that paragraph
(see section Paragraphs). You can then indent, case-convert, or kill the
whole paragraph. In the same fashion, C-M-h (mark-defun)
puts point before and the mark after the current or following defun
(see section Defuns). C-x C-p (mark-page) puts point before
the current page (or the next or previous, depending on the argument),
and mark at the end (see section Pages). The mark goes after the
terminating page delimiter (to include it), while point goes after the
preceding page delimiter (to exclude it). Finally, C-x h
(mark-whole-buffer) sets up the entire buffer as the region by
putting point at the beginning and the mark at the end.
Aside from delimiting the region, the mark is also useful for marking
a spot that you may want to go back to. To make this feature more
useful, Emacs remembers 16 previous locations of the mark in the
mark ring. Most commands that set the mark push the old mark onto
this ring. To return to a marked location, use C-u C-SPC
(or C-u C-@); this is the command set-mark-command given a
numeric argument. The command moves point to where the mark was, and
restores the mark from the ring of former marks. Repeated use of this
command moves point to all the old marks on the ring, one by one.
The marks you have seen go to the end of the ring, so no marks are lost.
Each buffer has its own mark ring. All editing commands use the current buffer's mark ring. In particular, C-u C-SPC always stays in the same buffer.
Many commands that can move long distances, such as M-<
(beginning-of-buffer), start by setting the mark and saving the
old mark on the mark ring. This makes it easier for you to move back
later. Searches set the mark, unless they do not actually move point.
When a command sets the mark, `Mark Set' is printed in the
echo area.
The variable mark-ring-max is the maximum number of entries to
keep in the mark ring. If that many entries exist and another entry is
added, the last entry in the list is discarded. Repeating C-u
C-SPC circulates through the entries that are currently in the
ring.
The variable mark-ring holds the mark ring itself, as a list of
marker objects in the order most recent first. This variable is local
in every buffer.
If you are using XEmacs under X, you can use the mouse pointer
to select text. (The normal mouse pointer is an I-beam, the same
pointer that xterm uses.)
The glyph variable text-pointer-glyph controls the shape of
the mouse pointer when over text. You can also control the shape
of the mouse pointer when over nontext using nontext-pointer-glyph,
and the shape of the mouse pointer when over the modeline using
modeline-pointer-glyph. (Remember, you should use
set-glyph-image, not setq, to set one of these
variables.)
If you want to get fancy, you can set the foreground and background
colors of the mouse pointer by setting the pointer face.
There are two ways to select a region of text with the mouse:
To select a word in text, double-click with the left mouse button while the mouse cursor is over the word. The word is highlighted when selected. On monochrome monitors, a stippled background indicates that a region of text has been highlighted. On color monitors, a color background indicates highlighted text. You can triple-click to select whole lines.
To select an arbitrary region of text:
The selected region of text is highlighted.
Once a region of text is selected, it becomes the primary X selection (see section Using X Selections) as well as the Emacs selected region. You can paste it into other X applications and use the options from the Edit pull-down menu on it. Since it is also the Emacs region, you can use Emacs region commands on it.
XEmacs also provides the following mouse functions. Most of these are not bound to mouse gestures by default, but they are provided for your customization pleasure. For example, if you wanted shift-left (that is, holding down the Shift key and clicking the left mouse button) to delete the character at which you are pointing, then you could do this:
(global-set-key '(shift button1) 'mouse-del-char)
mouse-track, but also copy it to the cut buffer.
The M-x mouse-track command should be bound to a mouse button. If you click-and-drag, the selection is set to the region between the point of the initial click and the point at which you release the button. These positions do not need to be ordered.
If you click-and-release without moving the mouse, the point is moved, and the selection is disowned (there will be no selection owner.) The mark will be set to the previous position of point.
If you double-click, the selection will extend by symbols instead of by characters. If you triple-click, the selection will extend by lines.
If you drag the mouse off the top or bottom of the window, you can select pieces of text that are larger than the visible part of the buffer; the buffer will scroll as necessary.
The selected text becomes the current X selection, and is also copied to
the top of the kill ring. Point will be left at the position at
which you released the button and the mark will be left at the initial
click position. Bind a mouse click to
mouse-track-and-copy-to-cutbuffer to copy selections to the cut buffer.
(See also the mouse-track-adjust command, on Shift-button1.)
The M-x mouse-track-adjust command should be bound to a mouse
button. The selection will be enlarged or shrunk so that the point of
the mouse click is one of its endpoints. This is only meaningful
after the mouse-track command (button1) has been executed.
The M-x mouse-track-delete-and-insert command is exactly the same
as the mouse-track command on button1, except that point is
not moved; the selected text is immediately inserted after being
selected; and the text of the selection is deleted.
The M-x mouse-track-insert command is exactly the same as the
mouse-track command on button1, except that point is not moved;
the selected text is immediately inserted after being selected; and the
selection is immediately disowned afterwards.
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