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Merge from origin/emacs-27

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45a64c97c7 (origin/emacs-27) Clarify semantics of trace-function CONT...
821760fdc4 Don't let a code literal get modified in mml parsing (Bug#...
74a92be16d * lisp/simple.el (kill-ring-save): Doc fix.  (Bug#40797)
3d0e859692 Minor doc clarification regarding fringe bitmaps
4d86c7f822 Fix documentation of fringe bitmaps
a76af88dd8 Tweak mutability doc a bit more
f7e488d206 Calc: fix autoload errors (bug#40800)
369761b36d ; * src/xdisp.c: Improve the introductory commentary.
a92ca1f177 Improve indexing of ELisp manual
5a25d17760 * lisp/image-mode.el (image-transform-resize): Remove FIXM...
37ebec3a95 Improve the default value of 'doc-view-ghostscript-program'.
ba6104d1e8 Change doc-view-mode-map prefix key 's' to 'c'.
400ff5cd19 Improve wording about constants
d2836fe71b Improve the default value of 'doc-view-ghostscript-program'.
fc55f65305 Minor improvements in documentation of the last change
a64da75961 Add image-auto-resize defcustoms to image-mode.el
692ad40539 Improve the documentation of tab-bar and tab-line

# Conflicts:
#	etc/NEWS
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Glenn Morris 2020-04-25 07:50:21 -07:00
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1
doc/emacs/display.texi
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@ -735,6 +735,7 @@ in a way that does not interact well with @code{highlight}.
@cindex @code{tab-line} face
Similar to @code{mode-line} for a window's tab line, which appears
at the top of a window with tabs representing window buffers.
@xref{Tab Line}.
@item vertical-border
@cindex @code{vertical-border} face
This face is used for the vertical divider between windows on text

1
doc/emacs/emacs.texi
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@ -517,6 +517,7 @@ Multiple Windows
* Displaying Buffers:: How Emacs picks a window for displaying a buffer.
* Temporary Displays:: Displaying non-editable buffers.
* Window Convenience:: Convenience functions for window handling.
* Tab Line:: Window tab line.
Displaying a Buffer in a Window

37
doc/emacs/files.texi
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@ -2113,8 +2113,6 @@ point. Partial Completion mode offers other features extending
@findex image-mode
@findex image-toggle-display
@findex image-next-file
@findex image-previous-file
@cindex images, viewing
Visiting image files automatically selects Image mode. In this
major mode, you can type @kbd{C-c C-c} (@code{image-toggle-display})
@ -2122,12 +2120,34 @@ to toggle between displaying the file as an image in the Emacs buffer,
and displaying its underlying text (or raw byte) representation.
Additionally you can type @kbd{C-c C-x} (@code{image-toggle-hex-display})
to toggle between displaying the file as an image in the Emacs buffer,
and displaying it in hex representation.
Displaying the file as an image works only if Emacs is compiled with
support for displaying such images. If the displayed image is wider
or taller than the frame, the usual point motion keys (@kbd{C-f},
@kbd{C-p}, and so forth) cause different parts of the image to be
displayed. You can press @kbd{n} (@code{image-next-file}) and @kbd{p}
and displaying it in hex representation. Displaying the file as an
image works only if Emacs is compiled with support for displaying
such images.
@vindex image-auto-resize
@vindex image-auto-resize-on-window-resize
If the displayed image is wider or taller than the window in which it
is displayed, the usual point motion keys (@kbd{C-f}, @kbd{C-p}, and
so forth) cause different parts of the image to be displayed.
However, by default images are resized automatically to fit the
window, so this is only necessary if you customize the default
behavior by using the options @code{image-auto-resize} and
@code{image-auto-resize-on-window-resize}.
@findex image-transform-fit-both
@findex image-transform-set-scale
@findex image-transform-reset
To resize the image manually you can use the command
@code{image-transform-fit-both} bound to @kbd{s b}
that fits the image to both the window height and width.
To scale the image specifying a scale factor, use the command
@code{image-transform-set-scale} bound to @kbd{s s}.
To reset all transformations to the initial state, use
@code{image-transform-reset} bound to @kbd{s 0}.
@findex image-next-file
@findex image-previous-file
You can press @kbd{n} (@code{image-next-file}) and @kbd{p}
(@code{image-previous-file}) to visit the next image file and the
previous image file in the same directory, respectively.
@ -2195,7 +2215,6 @@ can be used to transform the image in question to @acronym{PNG} before
displaying. GraphicsMagick, ImageMagick and @command{ffmpeg} are
currently supported for image conversions.
@findex thumbs-mode
@cindex mode, Thumbs
The Image-Dired package can also be used to view images as

70
doc/emacs/frames.texi
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@ -1262,6 +1262,12 @@ sessions (@pxref{Saving Emacs Sessions}), the tabs from the Tab Bar are
recorded in the desktop file, together with their associated window
configurations, and will be available after restoring the session.
Note that the Tab Bar is different from the Tab Line (@pxref{Tab Line}).
Whereas tabs on the Tab Line at the top of each window are used to
switch between buffers, tabs on the Tab Bar at the top of each frame
are used to switch between window configurations containing several
windows.
@findex tab-bar-mode
To toggle the use of tab bars, type @kbd{M-x tab-bar-mode}. This
command applies to all frames, including frames yet to be created. To
@ -1275,9 +1281,11 @@ is turned on automatically. If the value is @code{t}, then
tabs. The value @code{1} hides the tab bar when it has only one tab,
and shows it again when more tabs are created. The value @code{nil}
always keeps the tab bar hidden; in this case it's still possible to
use persistent named window configurations without using the tab bar
by typing the related commands: @kbd{M-x tab-new}, @kbd{M-x tab-next},
@kbd{M-x tab-close}, @kbd{M-x tab-switcher}, etc.
switch between named window configurations without the tab bar by
using @kbd{M-x tab-next}, @kbd{M-x tab-switcher}, and other commands
that provide completion on tab names. Also it's possible to create
and close tabs without the tab bar by using commands @kbd{M-x
tab-new}, @kbd{M-x tab-close}, etc.
@kindex C-x t
The prefix key @kbd{C-x t} is analogous to @kbd{C-x 5}.
@ -1286,7 +1294,8 @@ Whereas each @kbd{C-x 5} command pops up a buffer in a different frame
tab with a different window configuration in the selected frame.
The various @kbd{C-x t} commands differ in how they find or create the
buffer to select:
buffer to select. The following commands can be used to select a buffer
in a new tab:
@table @kbd
@item C-x t 2
@ -1295,19 +1304,18 @@ buffer to select:
Add a new tab (@code{tab-new}). You can control the choice of the
buffer displayed in a new tab by customizing the variable
@code{tab-bar-new-tab-choice}.
@item C-x t b @var{bufname} @key{RET}
Select buffer @var{bufname} in another tab. This runs
@code{switch-to-buffer-other-tab}.
@item C-x t f @var{filename} @key{RET}
Visit file @var{filename} and select its buffer in another tab. This
runs @code{find-file-other-tab}. @xref{Visiting}.
@item C-x t d @var{directory} @key{RET}
Select a Dired buffer for directory @var{directory} in another tab.
This runs @code{dired-other-tab}. @xref{Dired}.
@item C-x t r @var{tabname} @key{RET}
Renames the current tab to @var{tabname}. You can control the
programmatic name given to a tab by default by customizing the
variable @code{tab-bar-tab-name-function}.
@end table
@vindex tab-bar-new-tab-choice
@ -1316,7 +1324,7 @@ current before calling the command that adds a new tab.
To start a new tab with other buffers, customize the variable
@code{tab-bar-new-tab-choice}.
The following commands are used to delete and operate on tabs:
The following commands can be used to delete tabs:
@table @kbd
@item C-x t 0
@ -1325,19 +1333,45 @@ To start a new tab with other buffers, customize the variable
Close the selected tab (@code{tab-close}). It has no effect if there
is only one tab.
@item C-x t o
@kindex C-x t o
@kindex C-TAB
@findex tab-next
Switch to another tab. If you repeat this command, it cycles through
all the tabs on the selected frame. With a positive numeric argument
N, it switches to the next Nth tab; with a negative argument −N, it
switches back to the previous Nth tab.
@item C-x t 1
@kindex C-x t 1
@findex tab-close-other
Close all tabs on the selected frame, except the selected one.
@end table
The following commands can be used to switch between tabs:
@table @kbd
@item C-x t o
@itemx C-@key{TAB}
@kindex C-x t o
@kindex C-TAB
@findex tab-next
Switch to the next tab. If you repeat this command, it cycles through
all the tabs on the selected frame. With a positive numeric argument
N, it switches to the next Nth tab; with a negative argument −N, it
switches back to the previous Nth tab.
@item S-C-@key{TAB}
@kindex S-C-TAB
@findex tab-previous
Switch to the previous tab. With a positive numeric argument N, it
switches to the previous Nth tab; with a negative argument −N, it
switches back to the next Nth tab.
@end table
The following commands can be used to operate on tabs:
@table @kbd
@item C-x t r @var{tabname} @key{RET}
Rename the current tab to @var{tabname}. You can control the
programmatic name given to a tab by default by customizing the
variable @code{tab-bar-tab-name-function}.
@item C-x t m
Move the current tab N positions to the right with a positive numeric
argument N. With a negative argument −N, it moves the current tab
N positions to the left.
@end table
@node Dialog Boxes

2
doc/emacs/glossary.texi
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@ -1367,7 +1367,7 @@ configurations. @xref{Tab Bars}.
@item Tab Line
The tab line is a line of tabs at the top of an Emacs window.
Clicking on one of these tabs switches window buffers.
Clicking on one of these tabs switches window buffers. @xref{Tab Line}.
@anchor{Glossary---Tags Table}
@item Tags Table

10
doc/emacs/misc.texi
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@ -617,12 +617,12 @@ of pages to display. A slice is a rectangle within the page area;
once you specify a slice in DocView, it applies to whichever page you
look at.
To specify the slice numerically, type @kbd{s s}
To specify the slice numerically, type @kbd{c s}
(@code{doc-view-set-slice}); then enter the top left pixel position
and the slice's width and height.
@c ??? how does this work?
A more convenient graphical way to specify the slice is with @kbd{s
A more convenient graphical way to specify the slice is with @kbd{c
m} (@code{doc-view-set-slice-using-mouse}), where you use the mouse to
select the slice. Simply press and hold the left mouse button at the
upper-left corner of the region you want to have in the slice, then
@ -631,10 +631,10 @@ button.
The most convenient way is to set the optimal slice by using
BoundingBox information automatically determined from the document by
typing @kbd{s b} (@code{doc-view-set-slice-from-bounding-box}).
typing @kbd{c b} (@code{doc-view-set-slice-from-bounding-box}).
@findex doc-view-reset-slice
To cancel the selected slice, type @kbd{s r}
To cancel the selected slice, type @kbd{c r}
(@code{doc-view-reset-slice}). Then DocView shows the entire page
including its entire margins.
@ -791,7 +791,7 @@ the same number of columns as provided by the shell.
@vindex shell-command-prompt-show-cwd
To make the above commands show the current directory in their
prompts, customize the variable @code{shell-command-prompt-show-cwd}
to a non-nil value.
to a non-@code{nil} value.
@kindex M-|
@findex shell-command-on-region

2
doc/emacs/modes.texi
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@ -299,7 +299,7 @@ Bars}.
Tab Bar mode gives each frame a tab bar. @xref{Tab Bars}.
@item
Tab Line mode gives each window a tab line.
Tab Line mode gives each window a tab line. @xref{Tab Line}.
@item
Transient Mark mode highlights the region, and makes many Emacs

37
doc/emacs/windows.texi
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@ -21,6 +21,7 @@ one frame.
* Change Window:: Deleting windows and changing their sizes.
* Displaying Buffers:: How Emacs picks a window for displaying a buffer.
* Window Convenience:: Convenience functions for window handling.
* Tab Line:: Window tab line.
@end menu
@node Basic Window
@ -542,16 +543,6 @@ Reference Manual}), and cannot exceed the size of the containing frame.
@node Window Convenience
@section Convenience Features for Window Handling
@findex global-tab-line-mode
@cindex tab line
The command @code{global-tab-line-mode} toggles the display of a
@dfn{tab line} on the top screen line of each window. The tab line
shows special buttons (``tabs'') for each buffer that was displayed in
a window, and allows switching to any of these buffers by clicking the
corresponding button. You can add a tab by clicking on the @kbd{+}
icon and delete a tab by clicking on the @kbd{x} icon of a tab. The
mouse wheel on the tab line scrolls the tabs horizontally.
@findex winner-mode
@vindex winner-dont-bind-my-keys
@vindex winner-ring-size
@ -616,3 +607,29 @@ shown in different windows. @xref{Comparing Files}.
Scroll All mode (@kbd{M-x scroll-all-mode}) is a global minor mode
that causes scrolling commands and point motion commands to apply to
every single window.
@node Tab Line
@section Window Tab Line
@findex global-tab-line-mode
@cindex tab line
The command @code{global-tab-line-mode} toggles the display of
a @dfn{tab line} on the top screen line of each window. The Tab Line
shows special buttons (``tabs'') for each buffer that was displayed in
a window, and allows switching to any of these buffers by clicking the
corresponding button. Clicking on the @kbd{+} icon adds a new buffer
to the window-local tab line of buffers, and clicking on the @kbd{x}
icon of a tab deletes it. The mouse wheel on the tab line scrolls
the tabs horizontally.
Selecting the previous window-local tab is the same as typing @kbd{C-x
@key{LEFT}} (@code{previous-buffer}), selecting the next tab is the
same as @kbd{C-x @key{RIGHT}} (@code{next-buffer}). Both commands
support a numeric prefix argument as a repeat count.
Note that the Tab Line is different from the Tab Bar (@pxref{Tab Bars}).
Whereas tabs on the Tab Bar at the top of each frame are used to
switch between window configurations containing several windows,
tabs on the Tab Line at the top of each window are used to switch
between buffers.

10
doc/lispref/display.texi
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@ -4155,8 +4155,8 @@ topmost and bottommost buffer text line; and @code{top-bottom}
indicates where there is just one line of text in the buffer.
@item @code{empty-line}
Used to indicate empty lines when @code{indicate-empty-lines} is
non-@code{nil}.
Used to indicate empty lines after the buffer end when
@code{indicate-empty-lines} is non-@code{nil}.
@item @code{overlay-arrow}
Used for overlay arrows (@pxref{Overlay Arrow}).
@ -4298,6 +4298,7 @@ The former is used by overlay arrows. The latter is unused.
@itemx @code{bottom-left-angle}, @code{bottom-right-angle}
@itemx @code{top-left-angle}, @code{top-right-angle}
@itemx @code{left-bracket}, @code{right-bracket}
@itemx @code{empty-line}
Used to indicate buffer boundaries.
@item @code{filled-rectangle}, @code{hollow-rectangle}
@ -4305,7 +4306,7 @@ Used to indicate buffer boundaries.
@itemx @code{vertical-bar}, @code{horizontal-bar}
Used for different types of fringe cursors.
@item @code{empty-line}, @code{exclamation-mark}, @code{question-mark}
@item @code{exclamation-mark}, @code{question-mark}
Not used by core Emacs features.
@end table
@ -4338,7 +4339,8 @@ The argument @var{bits} specifies the image to use. It should be
either a string or a vector of integers, where each element (an
integer) corresponds to one row of the bitmap. Each bit of an integer
corresponds to one pixel of the bitmap, where the low bit corresponds
to the rightmost pixel of the bitmap.
to the rightmost pixel of the bitmap. (Note that this order of bits
is opposite of the order in XBM images; @pxref{XBM Images}.)
The height is normally the length of @var{bits}. However, you
can specify a different height with non-@code{nil} @var{height}. The width

6
doc/lispref/eval.texi
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@ -606,6 +606,12 @@ Here are some examples of expressions that use @code{quote}:
@end group
@end example
Although the expressions @code{(list '+ 1 2)} and @code{'(+ 1 2)}
both yield lists equal to @code{(+ 1 2)}, the former yields a
freshly-minted mutable list whereas the latter yields a constant list
built from conses that may be shared with other constants.
@xref{Constants and Mutability}.
Other quoting constructs include @code{function} (@pxref{Anonymous
Functions}), which causes an anonymous lambda expression written in Lisp
to be compiled, and @samp{`} (@pxref{Backquote}), which is used to quote

7
doc/lispref/lists.texi
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@ -1625,10 +1625,9 @@ keys may not be symbols:
'(("simple leaves" . oak)
("compound leaves" . horsechestnut)))
;; @r{The @code{copy-sequence} means the keys are not @code{eq}.}
(assq (copy-sequence "simple leaves") leaves)
@result{} nil
(assoc (copy-sequence "simple leaves") leaves)
(assq "simple leaves" leaves)
@result{} @r{Unspecified; might be @code{nil} or non-@code{nil}.}
(assoc "simple leaves" leaves)
@result{} ("simple leaves" . oak)
@end smallexample
@end defun

21
doc/lispref/objects.texi
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@ -46,7 +46,7 @@ you store in it, type and all. (Actually, a small number of Emacs
Lisp variables can only take on values of a certain type.
@xref{Variables with Restricted Values}.)
Some Lisp objects are @dfn{constant}: their values never change.
Some Lisp objects are @dfn{constant}: their values should never change.
Others are @dfn{mutable}: their values can be changed via destructive
operations that involve side effects.
@ -2388,22 +2388,28 @@ that for two strings to be equal, they have the same text properties.
@cindex constants
@cindex mutable objects
Some Lisp objects are constant: their values never change.
Some Lisp objects are constant: their values should never change
during a single execution of Emacs running well-behaved Lisp code.
For example, you can create a new integer by calculating one, but you
cannot modify the value of an existing integer.
Other Lisp objects are mutable: their values can be changed
Other Lisp objects are mutable: it is safe to change their values
via destructive operations involving side effects. For example, an
existing marker can be changed by moving the marker to point to
somewhere else.
Although numbers are always constants and markers are always
Although all numbers are constants and all markers are
mutable, some types contain both constant and mutable members. These
types include conses, vectors, strings, and symbols. For example, the string
literal @code{"aaa"} yields a constant string, whereas the function
call @code{(make-string 3 ?a)} yields a mutable string that can be
changed via later calls to @code{aset}.
A mutable object can become constant if it is part of an expression
that is evaluated, because a program should not modify an object
that is being evaluated. The reverse does not occur: constant objects
should stay constant.
Trying to modify a constant variable signals an error
(@pxref{Constant Variables}).
A program should not attempt to modify other types of constants because the
@ -2411,9 +2417,10 @@ resulting behavior is undefined: the Lisp interpreter might or might
not detect the error, and if it does not detect the error the
interpreter can behave unpredictably thereafter. Another way to put
this is that although mutable objects are safe to change and constant
symbols reliably reject attempts to change them, other constants are
not safely mutable: if you try to change one your program might
behave as you expect but it might crash or worse. This problem occurs
variables reliably prevent attempts to change them, other constants
are not safely mutable: if a misbehaving program tries to change such a
constant then the constant's value might actually change, or the
program might crash or worse. This problem occurs
with types that have both constant and mutable members, and that have
mutators like @code{setcar} and @code{aset} that are valid on mutable
objects but hazardous on constants.

1
doc/lispref/tips.texi
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@ -8,6 +8,7 @@
@cindex tips for writing Lisp
@cindex standards of coding style
@cindex coding standards
@cindex best practices
This chapter describes no additional features of Emacs Lisp. Instead
it gives advice on making effective use of the features described in the

64
etc/NEWS.27
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@ -866,6 +866,11 @@ its functions.
*** A new user option 'doc-view-pdftotext-program-args' has been added
to allow controlling how the conversion to text is done.
+++
*** The prefix key 's' was changed to 'c' for slicing commands
to avoid conflicts with image-mode key 's'. The new key 'c' still
has good mnemonics of "cut", "clip", "crop".
** Ido
---
@ -2720,8 +2725,8 @@ left to higher-level functions.
+++
*** Tab Bar mode
The new command 'tab-bar-mode' enables the tab bar at the top of each
frame, where you can use tabs to switch between named persistent
window configurations.
frame (including TTY frames), where you can use tabs to switch between
named persistent window configurations.
The 'C-x t' sequence is the new prefix key for tab-related commands:
'C-x t 2' creates a new tab; 'C-x t 0' deletes the current tab;
@ -2738,6 +2743,11 @@ when its value is "on", "yes" or "1".
The user option 'tab-bar-position' specifies where to show the tab bar.
Tab-related commands can be used even without the tab bar when
'tab-bar-mode' is disabled by a nil value of the user option
'tab-bar-show'. Without the tab bar you can switch between tabs
using completion on tab names, or using 'tab-switcher'.
Read the new Info node "(emacs) Tab Bars" for full description
of all related features.
@ -2752,6 +2762,9 @@ a repeat count. Clicking on the plus icon adds a new buffer to the
window-local tab line of buffers. Using the mouse wheel on the tab
line scrolls tabs.
Read the new Info node "(emacs) Tab Line" for full description
of all related features.
+++
** fileloop.el lets one setup multifile operations like search&replace.
@ -3515,9 +3528,32 @@ functions.
*** 'image-mode' now uses this library to automatically rotate images
according to the orientation in the Exif data, if any.
+++
*** The command 'image-rotate' now accepts a prefix argument.
With a prefix argument, 'image-rotate' now rotates the image at point
90 degrees counter-clockwise, instead of the default clockwise.
+++
*** In 'image-mode' the image is resized automatically to fit in window.
The image will resize upon first display and whenever the window's
dimensions change.
By default, the image will resize upon first display and whenever the
window's dimensions change. Two user options 'image-auto-resize' and
'image-auto-resize-on-window-resize' control the resizing behavior
(including the possibility to disable auto-resizing). A new key
prefix 's' contains the commands that can be used to fit the image to
the window manually.
---
*** Some 'image-mode' variables are now buffer-local.
The image parameters 'image-transform-rotation',
'image-transform-scale' and 'image-transform-resize' are now declared
buffer-local, so each buffer could have its own values for these
parameters.
+++
*** Three new 'image-mode' commands have been added: 'm', which marks
the file in the dired buffer(s) for the directory the file is in; 'u',
which unmarks the file; and 'w', which pushes the current buffer's file
name to the kill ring.
---
*** New library image-converter.
@ -3538,26 +3574,6 @@ These now default to using 'image-mode'.
some years back. It now respects 'imagemagick-types-inhibit' as a way
to disable that.
---
*** Some 'image-mode' variables are now buffer-local.
The image parameters 'image-transform-rotation',
'image-transform-scale' and 'image-transform-resize' are now declared
buffer-local, so each buffer could have its own values for these
parameters.
+++
*** Three new 'image-mode' commands have been added: 'm', which marks
the file in the dired buffer(s) for the directory the file is in; 'u',
which unmarks the file; and 'w', which pushes the current buffer's file
name to the kill ring.
+++
*** The command 'image-rotate' now accepts a prefix argument.
With a prefix argument, 'image-rotate' now rotates the image at point
90 degrees counter-clockwise, instead of the default clockwise.
*** 'image-mode' has a new key prefix 's' for transformation commands.
** Modules
---

9
lisp/calc/calc-ext.el
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@ -674,7 +674,6 @@
(define-key calc-mode-map "Z/" 'calc-kbd-break)
(define-key calc-mode-map "Z`" 'calc-kbd-push)
(define-key calc-mode-map "Z'" 'calc-kbd-pop)
(define-key calc-mode-map "Z=" 'calc-kbd-report)
(define-key calc-mode-map "Z#" 'calc-kbd-query)
(calc-init-prefixes)
@ -845,8 +844,8 @@ math-bernoulli-number math-gammap1-raw)
("calc-incom" calc-digit-dots)
("calc-keypd" calc-do-keypad
calc-keypad-x-left-click calc-keypad-x-middle-click
calc-keypad-x-right-click)
calc-keypad-left-click calc-keypad-middle-click
calc-keypad-right-click)
("calc-lang" calc-set-language
math-read-big-balance math-read-big-rec)
@ -1003,7 +1002,7 @@ calc-find-root calc-poly-interp)
calc-floor calc-idiv calc-increment calc-mant-part calc-max calc-min
calc-round calc-scale-float calc-sign calc-trunc calc-xpon-part)
("calc-bin" calc-and calc-binary-radix calc-clip calc-twos-complement-mode
("calc-bin" calc-and calc-binary-radix calc-clip
calc-decimal-radix calc-diff calc-hex-radix calc-leading-zeros
calc-lshift-arith calc-lshift-binary calc-not calc-octal-radix calc-or calc-radix
calc-rotate-binary calc-rshift-arith calc-rshift-binary calc-word-size
@ -1116,7 +1115,7 @@ calc-equal-to calc-get-user-defn calc-greater-equal calc-greater-than
calc-in-set calc-kbd-break calc-kbd-else calc-kbd-else-if
calc-kbd-end-for calc-kbd-end-if calc-kbd-end-loop calc-kbd-end-repeat
calc-kbd-for calc-kbd-if calc-kbd-loop calc-kbd-pop calc-kbd-push
calc-kbd-query calc-kbd-repeat calc-kbd-report calc-less-equal
calc-kbd-query calc-kbd-repeat calc-less-equal
calc-less-than calc-logical-and calc-logical-if calc-logical-not
calc-logical-or calc-not-equal-to calc-pass-errors calc-remove-equal
calc-timing calc-user-define calc-user-define-composition

5
lisp/calc/calc-prog.el
View file

@ -1452,11 +1452,6 @@ Redefine the corresponding command."
(error "%s" "Unbalanced Z' in keyboard macro")))
;; (defun calc-kbd-report (msg)
;; (interactive "sMessage: ")
;; (calc-wrapper
;; (math-working msg (calc-top-n 1))))
(defun calc-kbd-query ()
(interactive)
(let ((defining-kbd-macro nil)

32
lisp/doc-view.el
View file

@ -59,16 +59,16 @@
;; will be remembered and applied to all pages of the current
;; document. This enables you to cut away the margins of a document
;; to save some space. To select a slice you can use
;; `doc-view-set-slice' (bound to `s s') which will query you for the
;; `doc-view-set-slice' (bound to `c s') which will query you for the
;; coordinates of the slice's top-left corner and its width and
;; height. A much more convenient way to do the same is offered by
;; the command `doc-view-set-slice-using-mouse' (bound to `s m').
;; the command `doc-view-set-slice-using-mouse' (bound to `c m').
;; After invocation you only have to press mouse-1 at the top-left
;; corner and drag it to the bottom-right corner of the desired slice.
;; Even more accurate and convenient is to use
;; `doc-view-set-slice-from-bounding-box' (bound to `s b') which uses
;; `doc-view-set-slice-from-bounding-box' (bound to `c b') which uses
;; the BoundingBox information of the current page to set an optimal
;; slice. To reset the slice use `doc-view-reset-slice' (bound to `s
;; slice. To reset the slice use `doc-view-reset-slice' (bound to `c
;; r').
;;
;; You can also search within the document. The command `doc-view-search'
@ -155,9 +155,19 @@
(defcustom doc-view-ghostscript-program
(cond
((memq system-type '(windows-nt ms-dos))
"gswin32c")
(t
"gs"))
(cond
;; Windows Ghostscript
((executable-find "gswin64c") "gswin64c")
((executable-find "gswin32c") "gswin32c")
;; The GS wrapper coming with TeX Live
((executable-find "rungs") "rungs")
;; The MikTeX builtin GS Check if mgs is functional for external
;; non-MikTeX apps. Was available under:
;; http://blog.miktex.org/post/2005/04/07/Starting-mgsexe-at-the-DOS-Prompt.aspx
((and (executable-find "mgs")
(= 0 (shell-command "mgs -q -dNODISPLAY -c quit")))
"mgs")))
(t "gs"))
"Program to convert PS and PDF files to PNG."
:type 'file
:version "27.1")
@ -421,10 +431,10 @@ Typically \"page-%s.png\".")
;; Killing the buffer (and the process)
(define-key map (kbd "K") 'doc-view-kill-proc)
;; Slicing the image
(define-key map (kbd "s s") 'doc-view-set-slice)
(define-key map (kbd "s m") 'doc-view-set-slice-using-mouse)
(define-key map (kbd "s b") 'doc-view-set-slice-from-bounding-box)
(define-key map (kbd "s r") 'doc-view-reset-slice)
(define-key map (kbd "c s") 'doc-view-set-slice)
(define-key map (kbd "c m") 'doc-view-set-slice-using-mouse)
(define-key map (kbd "c b") 'doc-view-set-slice-from-bounding-box)
(define-key map (kbd "c r") 'doc-view-reset-slice)
;; Searching
(define-key map (kbd "C-s") 'doc-view-search)
(define-key map (kbd "<find>") 'doc-view-search)

4
lisp/emacs-lisp/trace.el
View file

@ -292,7 +292,9 @@ If `current-prefix-arg' is non-nil, also read a buffer and a \"context\"
(defun trace-function-foreground (function &optional buffer context)
"Trace calls to function FUNCTION.
With a prefix argument, also prompt for the trace buffer (default
`trace-buffer'), and a Lisp expression CONTEXT.
`trace-buffer'), and a Lisp expression CONTEXT. When called from
Lisp, CONTEXT should be a function of no arguments which returns
a value to insert into BUFFER during the trace.
Tracing a function causes every call to that function to insert
into BUFFER Lisp-style trace messages that display the function's

2
lisp/gnus/mml.el
View file

@ -281,7 +281,7 @@ part. This is for the internal use, you should never modify the value.")
(setq tag (mml-read-tag)
no-markup-p nil
warn nil)
(setq tag (list 'part '(type . "text/plain"))
(setq tag (list 'part (cons 'type "text/plain"))
no-markup-p t
warn t))
(setq raw (cdr (assq 'raw tag))

55
lisp/image-mode.el
View file

@ -53,11 +53,37 @@ See `image-mode-winprops'.")
"Special hook run when image data is requested in a new window.
It is called with one argument, the initial WINPROPS.")
;; FIXME this doesn't seem mature yet. Document in manual when it is.
(defcustom image-auto-resize t
"Non-nil to resize the image upon first display.
Its value should be one of the following:
- nil, meaning no resizing.
- t, meaning to fit the image to the window height and width.
- `fit-height', meaning to fit the image to the window height.
- `fit-width', meaning to fit the image to the window width.
- A number, which is a scale factor (the default size is 1)."
:type '(choice (const :tag "No resizing" nil)
(other :tag "Fit height and width" t)
(const :tag "Fit height" fit-height)
(const :tag "Fit width" fit-width)
(number :tag "Scale factor" 1))
:version "27.1"
:group 'image)
(defcustom image-auto-resize-on-window-resize 1
"Non-nil to resize the image whenever the window's dimensions change.
This will always keep the image fit to the window.
When non-nil, the value should be a number of seconds to wait before
resizing according to the value specified in `image-auto-resize'."
:type '(choice (const :tag "No auto-resize on window size change" nil)
(integer :tag "Wait for number of seconds before resize" 1))
:version "27.1"
:group 'image)
(defvar-local image-transform-resize nil
"The image resize operation.
Its value should be one of the following:
- nil, meaning no resizing.
- t, meaning to fit the image to the window height and width.
- `fit-height', meaning to fit the image to the window height.
- `fit-width', meaning to fit the image to the window width.
- A number, which is a scale factor (the default size is 1).")
@ -427,9 +453,10 @@ call."
(define-key map "sf" 'image-mode-fit-frame)
(define-key map "sh" 'image-transform-fit-to-height)
(define-key map "sw" 'image-transform-fit-to-width)
(define-key map "sb" 'image-transform-fit-both)
(define-key map "ss" 'image-transform-set-scale)
(define-key map "sr" 'image-transform-set-rotation)
(define-key map "s0" 'image-transform-reset)
(define-key map "ss" 'image-transform-set-scale)
;; Multi-frame keys
(define-key map (kbd "RET") 'image-toggle-animation)
@ -482,6 +509,10 @@ call."
:help "Resize image to match the window height"]
["Fit to Window Width" image-transform-fit-to-width
:help "Resize image to match the window width"]
["Fit to Window Height and Width" image-transform-fit-both
:help "Resize image to match the window height and width"]
["Set Scale..." image-transform-set-scale
:help "Resize image by specified scale factor"]
["Rotate Image..." image-transform-set-rotation
:help "Rotate the image"]
["Reset Transformations" image-transform-reset
@ -569,6 +600,7 @@ Key bindings:
(major-mode-suspend)
(setq major-mode 'image-mode)
(setq image-transform-resize image-auto-resize)
(if (not (image-get-display-property))
(progn
@ -611,7 +643,8 @@ Key bindings:
(add-hook 'change-major-mode-hook #'image-toggle-display-text nil t)
(add-hook 'after-revert-hook #'image-after-revert-hook nil t)
(add-hook 'window-state-change-functions #'image--window-state-change nil t)
(when image-auto-resize-on-window-resize
(add-hook 'window-state-change-functions #'image--window-state-change nil t))
(run-mode-hooks 'image-mode-hook)
(let ((image (image-get-display-property))
@ -768,7 +801,7 @@ was inserted."
filename))
;; If we have a `fit-width' or a `fit-height', don't limit
;; the size of the image to the window size.
(edges (and (null image-transform-resize)
(edges (and (eq image-transform-resize t)
(window-inside-pixel-edges (get-buffer-window))))
(type (if (image--imagemagick-wanted-p filename)
'imagemagick
@ -878,7 +911,9 @@ Otherwise, display the image by calling `image-mode'."
;; image resizing happens later during redisplay. So if those
;; consecutive calls happen without any redisplay between them,
;; the costly operation of image resizing should happen only once.
(run-with-idle-timer 1 nil #'image-fit-to-window window))
(when (numberp image-auto-resize-on-window-resize)
(run-with-idle-timer image-auto-resize-on-window-resize nil
#'image-fit-to-window window)))
(defun image-fit-to-window (window)
"Adjust size of image to display it exactly in WINDOW boundaries."
@ -1282,7 +1317,7 @@ These properties are determined by the Image mode variables
`image-transform-resize' and `image-transform-rotation'. The
return value is suitable for appending to an image spec."
(setq image-transform-scale 1.0)
(when (or image-transform-resize
(when (or (not (memq image-transform-resize '(nil t)))
(/= image-transform-rotation 0.0))
;; Note: `image-size' looks up and thus caches the untransformed
;; image. There's no easy way to prevent that.
@ -1328,6 +1363,12 @@ return value is suitable for appending to an image spec."
(setq image-transform-resize 'fit-width)
(image-toggle-display-image))
(defun image-transform-fit-both ()
"Fit the current image both to the height and width of the current window."
(interactive)
(setq image-transform-resize t)
(image-toggle-display-image))
(defun image-transform-set-rotation (rotation)
"Prompt for an angle ROTATION, and rotate the image by that amount.
ROTATION should be in degrees."
@ -1338,7 +1379,7 @@ ROTATION should be in degrees."
(defun image-transform-reset ()
"Display the current image with the default size and rotation."
(interactive)
(setq image-transform-resize nil
(setq image-transform-resize image-auto-resize
image-transform-rotation 0.0
image-transform-scale 1)
(image-toggle-display-image))

2
lisp/simple.el
View file

@ -4846,7 +4846,7 @@ In Transient Mark mode, deactivate the mark.
If `interprogram-cut-function' is non-nil, also save the text for a window
system cut and paste.
If you want to append the killed line to the last killed text,
If you want to append the killed region to the last killed text,
use \\[append-next-kill] before \\[kill-ring-save].
The copied text is filtered by `filter-buffer-substring' before it is

271
src/xdisp.c
View file

@ -30,8 +30,9 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
Updating the display is triggered by the Lisp interpreter when it
decides it's time to do it. This is done either automatically for
you as part of the interpreter's command loop or as the result of
calling Lisp functions like `sit-for'. The C function `redisplay'
in xdisp.c is the only entry into the inner redisplay code.
calling Lisp functions like `sit-for'. The C function
`redisplay_internal' in xdisp.c is the only entry into the inner
redisplay code.
The following diagram shows how redisplay code is invoked. As you
can see, Lisp calls redisplay and vice versa.
@ -89,7 +90,15 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
second glyph matrix is constructed, the so called `desired glyph
matrix' or short `desired matrix'. Current and desired matrix are
then compared to find a cheap way to update the display, e.g. by
reusing part of the display by scrolling lines.
reusing part of the display by scrolling lines. The actual update
of the display of each window by comparing the desired and the
current matrix is done by `update_window', which calls functions
which draw to the glass (those functions are specific to the type
of the window's frame: X, w32, NS, etc.).
Once the display of a window on the glass has been updated, its
desired matrix is used to update the corresponding rows of the
current matrix, and then the desired matrix is discarded.
You will find a lot of redisplay optimizations when you start
looking at the innards of redisplay. The overall goal of all these
@ -119,13 +128,13 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
. try_window
This function performs the full redisplay of a single window
assuming that its fonts were not changed and that the cursor
will not end up in the scroll margins. (Loading fonts requires
re-adjustment of dimensions of glyph matrices, which makes this
method impossible to use.)
This function performs the full, unoptimized, redisplay of a
single window assuming that its fonts were not changed and that
the cursor will not end up in the scroll margins. (Loading
fonts requires re-adjustment of dimensions of glyph matrices,
which makes this method impossible to use.)
These optimizations are tried in sequence (some can be skipped if
The optimizations are tried in sequence (some can be skipped if
it is known that they are not applicable). If none of the
optimizations were successful, redisplay calls redisplay_windows,
which performs a full redisplay of all windows.
@ -145,38 +154,62 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
Desired matrices.
Desired matrices are always built per Emacs window. The function
`display_line' is the central function to look at if you are
interested. It constructs one row in a desired matrix given an
Desired matrices are always built per Emacs window. It is
important to know that a desired matrix is in general "sparse": it
only has some of the glyph rows "enabled". This is because
redisplay tries to optimize its work, and thus only generates
glyphs for rows that need to be updated on the screen. Rows that
don't need to be updated are left "disabled", and their contents
should be ignored.
The function `display_line' is the central function to look at if
you are interested in how the rows of the desired matrix are
produced. It constructs one row in a desired matrix given an
iterator structure containing both a buffer position and a
description of the environment in which the text is to be
displayed. But this is too early, read on.
Glyph rows.
A glyph row is an array of `struct glyph', where each glyph element
describes a "display element" to be shown on the screen. More
accurately, a glyph row can have up to 3 different arrays of
glyphs: one each for every display margins, and one for the "text
area", where buffer text is displayed. The text-area glyph array
is always present, whereas the arrays for the marginal areas are
present (non-empty) only if the corresponding display margin is
shown in the window. If the glyph array for a marginal area is not
present its beginning and end coincide, i.e. such arrays are
actually empty (they contain no glyphs). Frame glyph matrics, used
on text-mode terminals (see below) never have marginal areas, they
treat the entire frame-wide row of glyphs as a single large "text
area".
Iteration over buffer and strings.
Characters and pixmaps displayed for a range of buffer text depend
on various settings of buffers and windows, on overlays and text
properties, on display tables, on selective display. The good news
is that all this hairy stuff is hidden behind a small set of
interface functions taking an iterator structure (struct it)
interface functions taking an iterator structure (`struct it')
argument.
Iteration over things to be displayed is then simple. It is
started by initializing an iterator with a call to init_iterator,
started by initializing an iterator with a call to `init_iterator',
passing it the buffer position where to start iteration. For
iteration over strings, pass -1 as the position to init_iterator,
and call reseat_to_string when the string is ready, to initialize
iteration over strings, pass -1 as the position to `init_iterator',
and call `reseat_to_string' when the string is ready, to initialize
the iterator for that string. Thereafter, calls to
get_next_display_element fill the iterator structure with relevant
information about the next thing to display. Calls to
set_iterator_to_next move the iterator to the next thing.
`get_next_display_element' fill the iterator structure with
relevant information about the next thing to display. Calls to
`set_iterator_to_next' move the iterator to the next thing.
Besides this, an iterator also contains information about the
display environment in which glyphs for display elements are to be
produced. It has fields for the width and height of the display,
the information whether long lines are truncated or continued, a
current X and Y position, and lots of other stuff you can better
see in dispextern.h.
current X and Y position, the face currently in effect, and lots of
other stuff you can better see in dispextern.h.
The "stop position".
@ -184,57 +217,62 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
infrequently. These include the face of the characters, whether
text is invisible, the object (buffer or display or overlay string)
being iterated, character composition info, etc. For any given
buffer or string position, the sources of information that
affects the display can be determined by calling the appropriate
primitives, such as Fnext_single_property_change, but both these
buffer or string position, the sources of information that affects
the display can be determined by calling the appropriate
primitives, such as `Fnext_single_property_change', but both these
calls and the processing of their return values is relatively
expensive. To optimize redisplay, the display engine checks these
sources of display information only when needed. To that end, it
always maintains the position of the next place where it must stop
and re-examine all those potential sources. This is called "stop
position" and is stored in the stop_charpos field of the iterator.
The stop position is updated by compute_stop_pos, which is called
whenever the iteration reaches the current stop position and
processes it. Processing a stop position is done by handle_stop,
which invokes a series of handlers, one each for every potential
source of display-related information; see the it_props array for
those handlers. For example, one handler is handle_face_prop,
which detects changes in face properties, and supplies the face ID
that the iterator will use for all the glyphs it generates up to
the next stop position; this face ID is the result of realizing the
face specified by the relevant text properties at this position.
Each handler called by handle_stop processes the sources of display
sources of display information only when needed, not for every
character. To that end, it always maintains the position of the
next place where it must stop and re-examine all those potential
sources. This is called "the stop position" and is stored in the
`stop_charpos' field of the iterator. The stop position is updated
by `compute_stop_pos', which is called whenever the iteration
reaches the current stop position and processes it. Processing a
stop position is done by `handle_stop', which invokes a series of
handlers, one each for every potential source of display-related
information; see the `it_props' array for those handlers. For
example, one handler is `handle_face_prop', which detects changes
in face properties, and supplies the face ID that the iterator will
use for all the glyphs it generates up to the next stop position;
this face ID is the result of "realizing" the face specified by the
relevant text properties at this position (see xfaces.c). Each
handler called by `handle_stop' processes the sources of display
information for which it is "responsible", and returns a value
which tells handle_stop what to do next.
which tells `handle_stop' what to do next.
Once handle_stop returns, the information it stores in the iterator
fields will not be refreshed until the iteration reaches the next
stop position, which is computed by compute_stop_pos called at the
end of handle_stop. compute_stop_pos examines the buffer's or
string's interval tree to determine where the text properties
change, finds the next position where overlays and character
composition can change, and stores in stop_charpos the closest
position where any of these factors should be reconsidered.
Once `handle_stop' returns, the information it stores in the
iterator fields will not be refreshed until the iteration reaches
the next stop position, which is computed by `compute_stop_pos'
called at the end of `handle_stop'. `compute_stop_pos' examines
the buffer's or string's interval tree to determine where the text
properties change, finds the next position where overlays and
character composition can change, and stores in `stop_charpos' the
closest position where any of these factors should be reconsidered.
Handling of the stop position is done as part of the code in
`get_next_display_element'.
Producing glyphs.
Glyphs in a desired matrix are normally constructed in a loop
calling get_next_display_element and then PRODUCE_GLYPHS. The call
to PRODUCE_GLYPHS will fill the iterator structure with pixel
information about the element being displayed and at the same time
produce glyphs for it. If the display element fits on the line
being displayed, set_iterator_to_next is called next, otherwise the
glyphs produced are discarded. The function display_line is the
workhorse of filling glyph rows in the desired matrix with glyphs.
In addition to producing glyphs, it also handles line truncation
and continuation, word wrap, and cursor positioning (for the
latter, see also set_cursor_from_row).
calling `get_next_display_element' and then `PRODUCE_GLYPHS'. The
call to `PRODUCE_GLYPHS' will fill the iterator structure with
pixel information about the element being displayed and at the same
time will produce glyphs for it. If the display element fits on
the line being displayed, `set_iterator_to_next' is called next,
otherwise the glyphs produced are discarded, and `display_line'
marks this glyph row as a "continued line". The function
`display_line' is the workhorse of filling glyph rows in the
desired matrix with glyphs. In addition to producing glyphs, it
also handles line truncation and continuation, word wrap, and
cursor positioning (for the latter, see `set_cursor_from_row').
Frame matrices.
That just couldn't be all, could it? What about terminal types not
supporting operations on sub-windows of the screen (a.k.a. "TTY" or
"text-mode terminal")? To update the display on such a terminal,
"text-mode terminals")? To update the display on such a terminal,
window-based glyph matrices are not well suited. To be able to
reuse part of the display (scrolling lines up and down), we must
instead have a view of the whole screen. This is what `frame
@ -252,19 +290,62 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
using the frame matrices, which allows frame-global optimization of
what is actually written to the glass.
To be honest, there is a little bit more done, but not much more.
If you plan to extend that code, take a look at dispnew.c. The
function build_frame_matrix is a good starting point.
Frame matrices don't have marginal areas, only a text area. That
is, the entire row of glyphs that spans the width of a text-mode
frame is treated as a single large "text area" for the purposes of
manipulating and updating a frame glyph matrix.
To be honest, there is a little bit more done for frame matrices,
but not much more. If you plan to extend that code, take a look at
dispnew.c. The function build_frame_matrix is a good starting
point.
Simulating display.
Some of Emacs commands and functions need to take display layout
into consideration. For example, C-n moves to the next screen
line, but to implement that, Emacs needs to find the buffer
position which is directly below the cursor position on display.
This is not trivial when buffer display includes variable-size
elements such as different fonts, tall images, etc.
To solve this problem, the display engine implements several
functions that can move through buffer text in the same manner as
`display_line' and `display_string' do, but without producing any
glyphs for the glyph matrices. The workhorse of this is
`move_it_in_display_line_to'. Its code and logic are very similar
to `display_line', but it differs in two important aspects: it
doesn't produce glyphs for any glyph matrix, and it returns a
status telling the caller how it ended the iteration: whether it
reached the required position, hit the end of line, arrived at the
window edge without exhausting the buffer's line, etc. Since the
glyphs are not produced, the layout information available to the
callers of this function is what is recorded in `struct it' by the
iteration process.
Several higher-level functions call `move_it_in_display_line_to' to
perform more complex tasks: `move_it_by_lines' can move N lines up
or down from a given buffer position and `move_it_to' can move to a
given buffer position or to a given X or Y pixel coordinate.
These functions are called by the display engine itself as well,
when it needs to make layout decisions before producing the glyphs.
For example, one of the first things to decide when redisplaying a
window is where to put the `window-start' position; if the window
is to be recentered (the default), Emacs makes that decision by
starting from the position of point, then moving up the number of
lines corresponding to half the window height using
`move_it_by_lines'.
Bidirectional display.
Bidirectional display adds quite some hair to this already complex
design. The good news are that a large portion of that hairy stuff
is hidden in bidi.c behind only 3 interfaces. bidi.c implements a
reordering engine which is called by set_iterator_to_next and
reordering engine which is called by `set_iterator_to_next' and
returns the next character to display in the visual order. See
commentary on bidi.c for more details. As far as redisplay is
concerned, the effect of calling bidi_move_to_visually_next, the
concerned, the effect of calling `bidi_move_to_visually_next', the
main interface of the reordering engine, is that the iterator gets
magically placed on the buffer or string position that is to be
displayed next in the visual order. In other words, a linear
@ -279,27 +360,27 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
monotonously changing with vertical positions. Also, accounting
for face changes, overlays, etc. becomes more complex because
non-linear iteration could potentially skip many positions with
changes, and then cross them again on the way back (see
handle_stop_backwards)...
such changes, and then cross them again on the way back (see
`handle_stop_backwards')...
One other prominent effect of bidirectional display is that some
paragraphs of text need to be displayed starting at the right
margin of the window---the so-called right-to-left, or R2L
paragraphs. R2L paragraphs are displayed with R2L glyph rows,
which have their reversed_p flag set. The bidi reordering engine
which have their `reversed_p' flag set. The bidi reordering engine
produces characters in such rows starting from the character which
should be the rightmost on display. PRODUCE_GLYPHS then reverses
the order, when it fills up the glyph row whose reversed_p flag is
set, by prepending each new glyph to what is already there, instead
of appending it. When the glyph row is complete, the function
extend_face_to_end_of_line fills the empty space to the left of the
leftmost character with special glyphs, which will display as,
well, empty. On text terminals, these special glyphs are simply
blank characters. On graphics terminals, there's a single stretch
glyph of a suitably computed width. Both the blanks and the
stretch glyph are given the face of the background of the line.
This way, the terminal-specific back-end can still draw the glyphs
left to right, even for R2L lines.
should be the rightmost on display. `PRODUCE_GLYPHS' then reverses
the order, when it fills up the glyph row whose `reversed_p' flag
is set, by prepending each new glyph to what is already there,
instead of appending it. When the glyph row is complete, the
function `extend_face_to_end_of_line' fills the empty space to the
left of the leftmost character with special glyphs, which will
display as, well, empty. On text terminals, these special glyphs
are simply blank characters. On graphics terminals, there's a
single stretch glyph of a suitably computed width. Both the blanks
and the stretch glyph are given the face of the background of the
line. This way, the terminal-specific back-end can still draw the
glyphs left to right, even for R2L lines.
Bidirectional display and character compositions.
@ -310,23 +391,23 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
Emacs display supports this by providing "character compositions",
most of which is implemented in composite.c. During the buffer
scan that delivers characters to PRODUCE_GLYPHS, if the next
scan that delivers characters to `PRODUCE_GLYPHS', if the next
character to be delivered is a composed character, the iteration
calls composition_reseat_it and next_element_from_composition. If
they succeed to compose the character with one or more of the
calls `composition_reseat_it' and `next_element_from_composition'.
If they succeed to compose the character with one or more of the
following characters, the whole sequence of characters that were
composed is recorded in the `struct composition_it' object that is
part of the buffer iterator. The composed sequence could produce
one or more font glyphs (called "grapheme clusters") on the screen.
Each of these grapheme clusters is then delivered to PRODUCE_GLYPHS
in the direction corresponding to the current bidi scan direction
(recorded in the scan_dir member of the `struct bidi_it' object
that is part of the iterator). In particular, if the bidi iterator
currently scans the buffer backwards, the grapheme clusters are
delivered back to front. This reorders the grapheme clusters as
appropriate for the current bidi context. Note that this means
that the grapheme clusters are always stored in the LGSTRING object
(see composite.c) in the logical order.
Each of these grapheme clusters is then delivered to
`PRODUCE_GLYPHS' in the direction corresponding to the current bidi
scan direction (recorded in the `scan_dir' member of the `struct
bidi_it' object that is part of the iterator). In particular, if
the bidi iterator currently scans the buffer backwards, the
grapheme clusters are delivered back to front. This reorders the
grapheme clusters as appropriate for the current bidi context.
Note that this means that the grapheme clusters are always stored
in the `LGSTRING' object (see composite.c) in the logical order.
Moving an iterator in bidirectional text
without producing glyphs.
@ -337,18 +418,18 @@ along with GNU Emacs. If not, see <https://www.gnu.org/licenses/>. */
As far as the iterator is concerned, the geometry of such rows is
still left to right, i.e. the iterator "thinks" the first character
is at the leftmost pixel position. The iterator does not know that
PRODUCE_GLYPHS reverses the order of the glyphs that the iterator
delivers. This is important when functions from the move_it_*
`PRODUCE_GLYPHS' reverses the order of the glyphs that the iterator
delivers. This is important when functions from the `move_it_*'
family are used to get to certain screen position or to match
screen coordinates with buffer coordinates: these functions use the
iterator geometry, which is left to right even in R2L paragraphs.
This works well with most callers of move_it_*, because they need
This works well with most callers of `move_it_*', because they need
to get to a specific column, and columns are still numbered in the
reading order, i.e. the rightmost character in a R2L paragraph is
still column zero. But some callers do not get well with this; a
notable example is mouse clicks that need to find the character
that corresponds to certain pixel coordinates. See
buffer_posn_from_coords in dispnew.c for how this is handled. */
`buffer_posn_from_coords' in dispnew.c for how this is handled. */
#include <config.h>
#include <stdlib.h>