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Introduce an option which controls touch screen hscroll

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* doc/emacs/input.texi (Touchscreens): Document this new
function and revise this node for clarity and pithiness.

* lisp/touch-screen.el (touch-screen): New custom group.
(touch-screen-display-keyboard, touch-screen-delay)
(touch-screen-precision-scroll, touch-screen-word-select)
(touch-screen-extend-selection, touch-screen-preview-select):
Move such options to that group.
(touch-screen-enable-hscroll): New user option.
(touch-screen-handle-scroll): If it is disabled, maintain the
hscroll accumulators but refrain from scrolling the window.
This commit is contained in:
Po Lu 2023-10-24 21:12:32 +08:00
parent 408c904d66
commit 4bf6f8d997
2 changed files with 68 additions and 51 deletions
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84
doc/emacs/input.texi
View file

@ -23,56 +23,56 @@ which is detailed here.
@section Using Emacs on Touchscreens
@cindex touchscreen input
Touchscreen input works by pressing and moving tools (which include
fingers and some pointing devices--styluses, for example) onto a frame
in order to manipulate its contents.
Touchscreen input is the manipulation of a frame's contents by the
placement and motion of tools (instanced by fingers and such pointing
devices as styluses) on a monitor or computer terminal where a frame
is displayed.
When running under the X Window System or Android, Emacs
automatically detects and maps the following sequences of movements
(``gestures'') to common actions:
Under the X Window System or Android, Emacs detects and maps the
following sequences of movements (``gestures'') to common actions:
@itemize @bullet
@item
@cindex tapping, touchscreens
``Tapping'', briefly placing and lifting a tool from the display,
will result in Emacs selecting the window that was tapped, and
executing any command bound to @code{mouse-1} at that location in the
window. If the tap happened on top of a link (@pxref{Mouse
References}), then Emacs will follow the link instead.
If a command bound to @code{down-mouse-1} is bound to the location
where the tap took place, Emacs will execute that command as well.
@dfn{Tapping}, briefly placing and lifting a tool from the display,
will select the window that was tapped, and execute any command bound
to @code{mouse-1} at that location in the window. If a link
(@pxref{Mouse References}) exists there, then Emacs will follow that
link instead (insofar as such action differs from that taken upon the
simulation of a @code{mouse-1} event).
@item
@cindex scrolling, touchscreens
``Scrolling'', meaning to place a tool on the display and move it up
or down, will result in Emacs scrolling the window contents in the
direction where the tool moves.
If the tool is moved left or right, Emacs additionally scrolls the
window horizontally to follow (@pxref{Horizontal Scrolling}.)
@vindex touch-screen-enable-hscroll
@dfn{Scrolling}, which is continuous vertical or horizontal motion
on the screen, will scroll the contents of the window beneath the
tool's initial location in the direction of movement. The user option
@code{touch-screen-enable-hscroll} governs whether horizontal
scrolling (@pxref{Horizontal Scrolling}) is performed in reaction to
this gesture.
@item
@cindex dragging, touchscreens
@cindex long-press, touchscreens
``Dragging'', which is performing a @dfn{long-press} by placing a
tool on the display and leaving it there for a while prior to moving
the tool around will make Emacs set the point to where the tool was
and begin selecting text under the tool as it moves around, as if
@code{mouse-1} were to be held down. @xref{Mouse Commands}.
@dfn{Dragging}, which is performing a @dfn{long-press} by placing a
tool on the display and leaving it there awhile before moving it to
another position, will move point to the tool's initial position, and
commence selecting text under the tool as it continues its motion, as
if @code{mouse-1} were to be held down and a mouse moved anologously.
@xref{Mouse Commands}.
@vindex touch-screen-word-select
@cindex word selection mode, touchscreens
Some people find it difficult to position a tool accurately on a
touch screen display, to the detriment of text selection. The user
option @code{touch-screen-word-select} enables ``word selection
mode'', causing dragging to select the complete word, not only the
character containing the position of the tool.
To the detriment of text selection, it can prove challenging to
position a tool accurately on a touch screen display. The user option
@code{touch-screen-word-select}, which when enabled, prompts dragging
to select the complete word under the tool. (Normally, the selection
is only extended to encompass the character beneath the tool.)
@vindex touch-screen-extend-selection
@cindex extending the selection, touchscreens
Similarly, it may be difficult to select all of the text intended
within a single gesture. If the user option
In the same vein, it may be difficult to select all of the text
intended within a single gesture. If the user option
@code{touch-screen-extend-selection} is enabled, taps on the locations
of the point or the mark within a window will begin a new ``drag''
gesture, where the region will be extended in the direction of any
@ -80,21 +80,19 @@ subsequent movement.
@vindex touch-screen-preview-select
@cindex previewing the region during selection, touchscreens
Difficulties in making accurate adjustments to the region can also
be alleviated by indicating the position of the point relative to its
containing line within the echo area, since the window cursor may be
physically obscured by the tool. If
Difficulties in making accurate adjustments to the region from the
cursor being physically obscured by the tool can be mitigated by
indicating the position of the point within the echo area. If
@code{touch-screen-preview-select} is non-@code{nil}, the line
containing point is displayed in the echo area (@pxref{Echo Area})
during the motion of the tool, followed by another line indicating the
position of point within the first line.
surrounding point is displayed in the echo area (@pxref{Echo Area})
during the motion of the tool, below which is another line indicating
the position of point relative to the first.
@end itemize
@vindex touch-screen-delay
By default, Emacs considers a tool as having been left on the
display long enough to trigger a ``long-press'' after 0.7 seconds, but
this can be changed by customizing the variable
@code{touch-screen-delay}.
Emacs registers a long-press after the time a tool has been placed
upon the screen exceeds 0.7 seconds. This delay can be adjusted
through customizing the variable @code{touch-screen-delay}.
@node On-Screen Keyboards
@section Using Emacs with Virtual Keyboards

35
lisp/touch-screen.el
View file

@ -58,25 +58,30 @@ This is always cleared upon any significant state change.")
If non-nil, the touch screen key event translation machinery
is being called from `read-sequence' or some similar function.")
(defgroup touch-screen nil
"Interact with Emacs from touch screen devices."
:group 'mouse
:version "30.0")
(defcustom touch-screen-display-keyboard nil
"If non-nil, always display the on screen keyboard.
A buffer local value means to always display the on screen
keyboard when the buffer is selected."
:type 'boolean
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-delay 0.7
"Delay in seconds before Emacs considers a touch to be a long-press."
:type 'number
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-precision-scroll nil
"Whether or not to use precision scrolling for touch screens.
See `pixel-scroll-precision-mode' for more details."
:type 'boolean
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-word-select nil
@ -84,7 +89,7 @@ See `pixel-scroll-precision-mode' for more details."
If non-nil, long-press events (see `touch-screen-delay') followed
by dragging will try to select entire words."
:type 'boolean
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-extend-selection nil
@ -93,7 +98,7 @@ When enabled, tapping on the character containing the point or
mark will resume dragging where it left off while the region is
active."
:type 'boolean
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-preview-select nil
@ -102,7 +107,15 @@ When enabled, a preview of the visible line within the window
will be displayed in the echo area while dragging combined with
an indication of the position of point within that line."
:type 'boolean
:group 'mouse
:group 'touch-screen
:version "30.1")
(defcustom touch-screen-enable-hscroll t
"If non-nil, hscroll can be changed from the touch screen.
When enabled, tapping on a window and dragging your finger left
or right will scroll that window horizontally."
:type 'boolean
:group 'touch-screen
:version "30.1")
(defvar-local touch-screen-word-select-bounds nil
@ -229,7 +242,12 @@ horizontal scrolling according to the movement in DX."
(>= (- accumulator) column-width))
(progn
(setq accumulator (+ accumulator column-width))
(scroll-right 1)
;; Maintain both hscroll counters even when
;; it's disabled to prevent unintentional or
;; patently horizontal gestures from
;; scrolling the window vertically.
(when touch-screen-enable-hscroll
(scroll-right 1))
(setq lines-hscrolled (1+ lines-hscrolled))
(when (not (zerop accumulator))
;; If there is still an outstanding amount
@ -238,7 +256,8 @@ horizontal scrolling according to the movement in DX."
(when (and (> accumulator 0)
(>= accumulator column-width))
(setq accumulator (- accumulator column-width))
(scroll-left 1)
(when touch-screen-enable-hscroll
(scroll-left 1))
(setq lines-hscrolled (1+ lines-hscrolled))
(when (not (zerop accumulator))
;; If there is still an outstanding amount to