view runtime/doc/scroll.txt @ 32936:c517845bd10e v9.0.1776

patch 9.0.1776: No support for stable Python 3 ABI Commit: https://github.com/vim/vim/commit/c13b3d1350b60b94fe87f0761ea31c0e7fb6ebf3 Author: Yee Cheng Chin <ychin.git@gmail.com> Date: Sun Aug 20 21:18:38 2023 +0200 patch 9.0.1776: No support for stable Python 3 ABI Problem: No support for stable Python 3 ABI Solution: Support Python 3 stable ABI Commits: 1) Support Python 3 stable ABI to allow mixed version interoperatbility Vim currently supports embedding Python for use with plugins, and the "dynamic" linking option allows the user to specify a locally installed version of Python by setting `pythonthreedll`. However, one caveat is that the Python 3 libs are not binary compatible across minor versions, and mixing versions can potentially be dangerous (e.g. let's say Vim was linked against the Python 3.10 SDK, but the user sets `pythonthreedll` to a 3.11 lib). Usually, nothing bad happens, but in theory this could lead to crashes, memory corruption, and other unpredictable behaviors. It's also difficult for the user to tell something is wrong because Vim has no way of reporting what Python 3 version Vim was linked with. For Vim installed via a package manager, this usually isn't an issue because all the dependencies would already be figured out. For prebuilt Vim binaries like MacVim (my motivation for working on this), AppImage, and Win32 installer this could potentially be an issue as usually a single binary is distributed. This is more tricky when a new Python version is released, as there's a chicken-and-egg issue with deciding what Python version to build against and hard to keep in sync when a new Python version just drops and we have a mix of users of different Python versions, and a user just blindly upgrading to a new Python could lead to bad interactions with Vim. Python 3 does have a solution for this problem: stable ABI / limited API (see https://docs.python.org/3/c-api/stable.html). The C SDK limits the API to a set of functions that are promised to be stable across versions. This pull request adds an ifdef config that allows us to turn it on when building Vim. Vim binaries built with this option should be safe to freely link with any Python 3 libraies without having the constraint of having to use the same minor version. Note: Python 2 has no such concept and this doesn't change how Python 2 integration works (not that there is going to be a new version of Python 2 that would cause compatibility issues in the future anyway). --- Technical details: ====== The stable ABI can be accessed when we compile with the Python 3 limited API (by defining `Py_LIMITED_API`). The Python 3 code (in `if_python3.c` and `if_py_both.h`) would now handle this and switch to limited API mode. Without it set, Vim will still use the full API as before so this is an opt-in change. The main difference is that `PyType_Object` is now an opaque struct that we can't directly create "static types" out of, and we have to create type objects as "heap types" instead. This is because the struct is not stable and changes from version to version (e.g. 3.8 added a `tp_vectorcall` field to it). I had to change all the types to be allocated on the heap instead with just a pointer to them. Other functions are also simply missing in limited API, or they are introduced too late (e.g. `PyUnicode_AsUTF8AndSize` in 3.10) to it that we need some other ways to do the same thing, so I had to abstract a few things into macros, and sometimes re-implement functions like `PyObject_NEW`. One caveat is that in limited API, `OutputType` (used for replacing `sys.stdout`) no longer inherits from `PyStdPrinter_Type` which I don't think has any real issue other than minor differences in how they convert to a string and missing a couple functions like `mode()` and `fileno()`. Also fixed an existing bug where `tp_basicsize` was set incorrectly for `BufferObject`, `TabListObject, `WinListObject`. Technically, there could be a small performance drop, there is a little more indirection with accessing type objects, and some APIs like `PyUnicode_AsUTF8AndSize` are missing, but in practice I didn't see any difference, and any well-written Python plugin should try to avoid excessing callbacks to the `vim` module in Python anyway. I only tested limited API mode down to Python 3.7, which seemes to compile and work fine. I haven't tried earlier Python versions. 2) Fix PyIter_Check on older Python vers / type##Ptr unused warning For PyIter_Check, older versions exposed them as either macros (used in full API), or a function (for use in limited API). A previous change exposed PyIter_Check to the dynamic build because Python just moved it to function-only in 3.10 anyway. Because of that, just make sure we always grab the function in dynamic builds in earlier versions since that's what Python eventually did anyway. 3) Move Py_LIMITED_API define to configure script Can now use --with-python-stable-abi flag to customize what stable ABI version to target. Can also use an env var to do so as well. 4) Show +python/dyn-stable in :version, and allow has() feature query Not sure if the "/dyn-stable" suffix would break things, or whether we should do it another way. Or just don't show it in version and rely on has() feature checking. 5) Documentation first draft. Still need to implement v:python3_version 6) Fix PyIter_Check build breaks when compiling against Python 3.8 7) Add CI coverage stable ABI on Linux/Windows / make configurable on Windows This adds configurable options for Windows make files (both MinGW and MSVC). CI will also now exercise both traditional full API and stable ABI for Linux and Windows in the matrix for coverage. Also added a "dynamic" option to Linux matrix as a drive-by change to make other scripting languages like Ruby / Perl testable under both static and dynamic builds. 8) Fix inaccuracy in Windows docs Python's own docs are confusing but you don't actually want to use `python3.dll` for the dynamic linkage. 9) Add generated autoconf file 10) Add v:python3_version support This variable indicates the version of Python3 that Vim was built against (PY_VERSION_HEX), and will be useful to check whether the Python library you are loading in dynamically actually fits it. When built with stable ABI, it will be the limited ABI version instead (`Py_LIMITED_API`), which indicates the minimum version of Python 3 the user should have, rather than the exact match. When stable ABI is used, we won't be exposing PY_VERSION_HEX in this var because it just doesn't seem necessary to do so (the whole point of stable ABI is the promise that it will work across versions), and I don't want to confuse the user with too many variables. Also, cleaned up some documentation, and added help tags. 11) Fix Python 3.7 compat issues Fix a couple issues when using limited API < 3.8 - Crash on exit: In Python 3.7, if a heap-allocated type is destroyed before all instances are, it would cause a crash later. This happens when we destroyed `OptionsType` before calling `Py_Finalize` when using the limited API. To make it worse, later versions changed the semantics and now each instance has a strong reference to its own type and the recommendation has changed to have each instance de-ref its own type and have its type in GC traversal. To avoid dealing with these cross-version variations, we just don't free the heap type. They are static types in non-limited-API anyway and are designed to last through the entirety of the app, and we also don't restart the Python runtime and therefore do not need it to have absolutely 0 leaks. See: - https://docs.python.org/3/whatsnew/3.8.html#changes-in-the-c-api - https://docs.python.org/3/whatsnew/3.9.html#changes-in-the-c-api - PyIter_Check: This function is not provided in limited APIs older than 3.8. Previously I was trying to mock it out using manual PyType_GetSlot() but it was brittle and also does not actually work properly for static types (it will generate a Python error). Just return false. It does mean using limited API < 3.8 is not recommended as you lose the functionality to handle iterators, but from playing with plugins I couldn't find it to be an issue. - Fix loading of PyIter_Check so it will be done when limited API < 3.8. Otherwise loading a 3.7 Python lib will fail even if limited API was specified to use it. 12) Make sure to only load `PyUnicode_AsUTF8AndSize` in needed in limited API We don't use this function unless limited API >= 3.10, but we were loading it regardless. Usually it's ok in Unix-like systems where Python just has a single lib that we load from, but in Windows where there is a separate python3.dll this would not work as the symbol would not have been exposed in this more limited DLL file. This makes it much clearer under what condition is this function needed. closes: #12032 Signed-off-by: Christian Brabandt <cb@256bit.org> Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>
author Christian Brabandt <cb@256bit.org>
date Sun, 20 Aug 2023 21:30:04 +0200
parents eb2638f278bf
children ab758d4eccdb
line wrap: on
line source

*scroll.txt*    For Vim version 9.0.  Last change: 2022 Oct 17


		  VIM REFERENCE MANUAL    by Bram Moolenaar


Scrolling						*scrolling*

These commands move the contents of the window.  If the cursor position is
moved off of the window, the cursor is moved onto the window (with
'scrolloff' screen lines around it).  A page is the number of lines in the
window minus two.  The mnemonics for these commands may be a bit confusing.
Remember that the commands refer to moving the window (the part of the buffer
that you see) upwards or downwards in the buffer.  When the window moves
upwards in the buffer, the text in the window moves downwards on your screen.

See section |03.7| of the user manual for an introduction.

1. Scrolling downwards		|scroll-down|
2. Scrolling upwards		|scroll-up|
3. Scrolling relative to cursor	|scroll-cursor|
4. Scrolling horizontally	|scroll-horizontal|
5. Scrolling synchronously	|scroll-binding|
6. Scrolling with a mouse wheel |scroll-mouse-wheel|

==============================================================================
1. Scrolling downwards					*scroll-down*

The following commands move the edit window (the part of the buffer that you
see) downwards (this means that more lines downwards in the text buffer can be
seen):

							*CTRL-E*
CTRL-E			Scroll window [count] lines downwards in the buffer.
			The text moves upwards on the screen.
			Mnemonic: Extra lines.

							*CTRL-D*
CTRL-D			Scroll window Downwards in the buffer.  The number of
			lines comes from the 'scroll' option (default: half a
			screen).  If [count] given, first set 'scroll' option
			to [count].  The cursor is moved the same number of
			lines down in the file (if possible; when lines wrap
			and when hitting the end of the file there may be a
			difference).  When the cursor is on the last line of
			the buffer nothing happens and a beep is produced.
			See also 'startofline' option.

<S-Down>	or				*<S-Down>* *<kPageDown>*
<PageDown>	or				*<PageDown>* *CTRL-F*
CTRL-F			Scroll window [count] pages Forwards (downwards) in
			the buffer.  See also 'startofline' option.
			When there is only one window the 'window' option
			might be used.

							*z+*
z+			Without [count]: Redraw with the line just below the
			window at the top of the window.  Put the cursor in
			that line, at the first non-blank in the line.
			With [count]: just like "z<CR>".

==============================================================================
2. Scrolling upwards					*scroll-up*

The following commands move the edit window (the part of the buffer that you
see) upwards (this means that more lines upwards in the text buffer can be
seen):

							*CTRL-Y*
CTRL-Y			Scroll window [count] lines upwards in the buffer.
			The text moves downwards on the screen.
			Note: When using the MS-Windows key bindings CTRL-Y is
			remapped to redo.

							*CTRL-U*
CTRL-U			Scroll window Upwards in the buffer.  The number of
			lines comes from the 'scroll' option (default: half a
			screen).  If [count] given, first set the 'scroll'
			option to [count].  The cursor is moved the same
			number of lines up in the file (if possible; when
			lines wrap and when hitting the end of the file there
			may be a difference).  When the cursor is on the first
			line of the buffer nothing happens and a beep is
			produced.  See also 'startofline' option.

<S-Up>		or					*<S-Up>* *<kPageUp>*
<PageUp>	or					*<PageUp>* *CTRL-B*
CTRL-B			Scroll window [count] pages Backwards (upwards) in the
			buffer.  See also 'startofline' option.
			When there is only one window the 'window' option
			might be used.

							*z^*
z^			Without [count]: Redraw with the line just above the
			window at the bottom of the window.  Put the cursor in
			that line, at the first non-blank in the line.
			With [count]: First scroll the text to put the [count]
			line at the bottom of the window, then redraw with the
			line which is now at the top of the window at the
			bottom of the window.  Put the cursor in that line, at
			the first non-blank in the line.

==============================================================================
3. Scrolling relative to cursor				*scroll-cursor*

The following commands reposition the edit window (the part of the buffer that
you see) while keeping the cursor on the same line.  Note that the 'scrolloff'
option may cause context lines to show above and below the cursor.

							*z<CR>*
z<CR>			Redraw, line [count] at top of window (default
			cursor line).  Put cursor at first non-blank in the
			line.

							*zt*
zt			Like "z<CR>", but leave the cursor in the same
			column.

							*zN<CR>*
z{height}<CR>		Redraw, make window {height} lines tall.  This is
			useful to make the number of lines small when screen
			updating is very slow.  Cannot make the height more
			than the physical screen height.

							*z.*
z.			Redraw, line [count] at center of window (default
			cursor line).  Put cursor at first non-blank in the
			line.

							*zz*
zz			Like "z.", but leave the cursor in the same column.
			Careful: If caps-lock is on, this command becomes
			"ZZ": write buffer and exit!

							*z-*
z-			Redraw, line [count] at bottom of window (default
			cursor line).  Put cursor at first non-blank in the
			line.

							*zb*
zb			Like "z-", but leave the cursor in the same column.

==============================================================================
4. Scrolling horizontally				*scroll-horizontal*

For the following four commands the cursor follows the screen.  If the
character that the cursor is on is moved off the screen, the cursor is moved
to the closest character that is on the screen.  The value of 'sidescroll' is
not used.

z<Right>    or						*zl* *z<Right>*
zl			Move the view on the text [count] characters to the
			right, thus scroll the text [count] characters to the
			left.  This only works when 'wrap' is off.

z<Left>      or						*zh* *z<Left>*
zh			Move the view on the text [count] characters to the
			left, thus scroll the text [count] characters to the
			right.  This only works when 'wrap' is off.

							*zL*
zL			Move the view on the text half a screenwidth to the
			right, thus scroll the text half a screenwidth to the
			left.  This only works when 'wrap' is off.

							*zH*
zH			Move the view on the text half a screenwidth to the
			left, thus scroll the text half a screenwidth to the
			right.  This only works when 'wrap' is off.

For the following two commands the cursor is not moved in the text, only the
text scrolls on the screen.

							*zs*
zs			Scroll the text horizontally to position the cursor
			at the start (left side) of the screen.  This only
			works when 'wrap' is off.

							*ze*
ze			Scroll the text horizontally to position the cursor
			at the end (right side) of the screen.  This only
			works when 'wrap' is off.

==============================================================================
5. Scrolling synchronously				*scroll-binding*

Occasionally, it is desirable to bind two or more windows together such that
when one window is scrolled, the other windows are also scrolled.  In Vim,
windows can be given this behavior by setting the (window-specific)
'scrollbind' option.  When a window that has 'scrollbind' set is scrolled, all
other 'scrollbind' windows are scrolled the same amount, if possible.  The
behavior of 'scrollbind' can be modified by the 'scrollopt' option.

When using the scrollbars, the binding only happens when scrolling the window
with focus (where the cursor is).  You can use this to avoid scroll-binding
for a moment without resetting options.

When a window also has the 'diff' option set, the scroll-binding uses the
differences between the two buffers to synchronize the position precisely.
Otherwise the following method is used.

							*scrollbind-relative*
Each 'scrollbind' window keeps track of its "relative offset," which can be
thought of as the difference between the current window's vertical scroll
position and the other window's vertical scroll position.  When one of the
'scrollbind' windows is asked to vertically scroll past the beginning or end
limit of its text, the window no longer scrolls, but remembers how far past
the limit it wishes to be.  The window keeps this information so that it can
maintain the same relative offset, regardless of its being asked to scroll
past its buffer's limits.

However, if a 'scrollbind' window that has a relative offset that is past its
buffer's limits is given the cursor focus, the other 'scrollbind' windows must
jump to a location where the current window's relative offset is valid.  This
behavior can be changed by clearing the "jump" flag from the 'scrollopt'
option.

						*syncbind* *:syncbind* *:sync*
:syncbind		Force all 'scrollbind' windows to have the same
			relative offset.  I.e., when any of the 'scrollbind'
			windows is scrolled to the top of its buffer, all of
			the 'scrollbind' windows will also be at the top of
			their buffers.

							*scrollbind-quickadj*
The 'scrollbind' flag is meaningful when using keyboard commands to vertically
scroll a window, and also meaningful when using the vertical scrollbar of the
window which has the cursor focus.  However, when using the vertical scrollbar
of a window which doesn't have the cursor focus, 'scrollbind' is ignored.
This allows quick adjustment of the relative offset of 'scrollbind' windows.

==============================================================================
6. Scrolling with a mouse wheel				*scroll-mouse-wheel*

When your mouse has a scroll wheel, it should work with Vim in the GUI.  How
it works depends on your system.  It might also work in an xterm
|xterm-mouse-wheel|.  By default only vertical scroll wheels are supported,
but some GUIs also support horizontal scroll wheels.

On MS-Windows, if the scroll action causes input focus -problems, see
|intellimouse-wheel-problems|.

For Win32 and the X11 GUIs (Motif and GTK) scrolling the wheel generates key
presses <ScrollWheelUp>, <ScrollWheelDown>, <ScrollWheelLeft> and
<ScrollWheelRight>.  For example, if you push the scroll wheel upwards a
<ScrollWheelUp> key press is generated causing the window to scroll upwards
(while the text is actually moving downwards).  The default action for these
keys are:
    <ScrollWheelUp>	    scroll N lines up	        *<ScrollWheelUp>*
    <S-ScrollWheelUp>	    scroll one page up		*<S-ScrollWheelUp>*
    <C-ScrollWheelUp>	    scroll one page up		*<C-ScrollWheelUp>*
    <ScrollWheelDown>	    scroll N lines down	        *<ScrollWheelDown>*
    <S-ScrollWheelDown>	    scroll one page down	*<S-ScrollWheelDown>*
    <C-ScrollWheelDown>	    scroll one page down	*<C-ScrollWheelDown>*
    <ScrollWheelLeft>	    scroll N columns left	*<ScrollWheelLeft>*
    <S-ScrollWheelLeft>	    scroll one page left	*<S-ScrollWheelLeft>*
    <C-ScrollWheelLeft>	    scroll one page left	*<C-ScrollWheelLeft>*
    <ScrollWheelRight>	    scroll N columns right	*<ScrollWheelRight>*
    <S-ScrollWheelRight>    scroll one page right	*<S-ScrollWheelRight>*
    <C-ScrollWheelRight>    scroll one page right	*<C-ScrollWheelRight>*
This should work in all modes, except when editing the command line.

The value of N depends on the system.  By default Vim scrolls three lines when
moving vertically, and six columns when moving horizontally.  On MS-Windows
the amount of lines and columns for each scroll action is taken from the
system-wide settings.

Note that horizontal scrolling only works if 'nowrap' is set.  Also, unless
the "h" flag in 'guioptions' is set, the cursor moves to the longest visible
line if the cursor line is about to be scrolled off the screen (similarly to
how the horizontal scrollbar works).

You can modify the default behavior by mapping the keys.  For example, to make
the scroll wheel move one line or half a page in Normal mode: >
   :map <ScrollWheelUp> <C-Y>
   :map <S-ScrollWheelUp> <C-U>
   :map <ScrollWheelDown> <C-E>
   :map <S-ScrollWheelDown> <C-D>
You can also use Alt and Ctrl modifiers.

This only works when Vim gets the scroll wheel events, of course.  You can
check if this works with the "xev" program.
							*mouse-scrolling-off*
If you do not want the mouse to cause scrolling (e.g. because resting your
palm on the touchpad causes scroll events), you can disable that with: >
	:map <ScrollWheelDown> <Nop>
	:map! <ScrollWheelDown> <Nop>
	:map <ScrollWheelUp> <Nop>
	:map! <ScrollWheelUp> <Nop>
	:map <ScrollWheelLeft> <Nop>
	:map! <ScrollWheelLeft> <Nop>
	:map <ScrollWheelRight> <Nop>
	:map! <ScrollWheelRight> <Nop>

When using XFree86, the /etc/XF86Config file should have the correct entry for
your mouse.  For FreeBSD, this entry works for a Logitech scrollmouse: >
    Protocol     "MouseMan"
    Device       "/dev/psm0"
    ZAxisMapping 4 5
See the XFree86 documentation for information.

						*<MouseDown>* *<MouseUp>*
The keys <MouseDown> and <MouseUp> have been deprecated.  Use <ScrollWheelUp>
instead of <MouseDown> and use <ScrollWheelDown> instead of <MouseUp>.

							*xterm-mouse-wheel*
To use the mouse wheel in a new xterm you only have to make the scroll wheel
work in your Xserver, as mentioned above.

To use the mouse wheel in an older xterm you must do this:
1. Make it work in your Xserver, as mentioned above.
2. Add translations for the xterm, so that the xterm will pass a scroll event
   to Vim as an escape sequence.
3. Add mappings in Vim, to interpret the escape sequences as <ScrollWheelDown>
   or <ScrollWheelUp> keys.

You can do the translations by adding this to your ~.Xdefaults file (or other
file where your X resources are kept): >

  XTerm*VT100.Translations:		#override \n\
		s<Btn4Down>: string("0x9b") string("[64~") \n\
		s<Btn5Down>: string("0x9b") string("[65~") \n\
		<Btn4Down>: string("0x9b") string("[62~") \n\
		<Btn5Down>: string("0x9b") string("[63~") \n\
		<Btn4Up>: \n\
		<Btn5Up>:

Add these mappings to your vimrc file: >
	:map <M-Esc>[62~ <ScrollWheelUp>
	:map! <M-Esc>[62~ <ScrollWheelUp>
	:map <M-Esc>[63~ <ScrollWheelDown>
	:map! <M-Esc>[63~ <ScrollWheelDown>
	:map <M-Esc>[64~ <S-ScrollWheelUp>
	:map! <M-Esc>[64~ <S-ScrollWheelUp>
	:map <M-Esc>[65~ <S-ScrollWheelDown>
	:map! <M-Esc>[65~ <S-ScrollWheelDown>
<
 vim:tw=78:ts=8:noet:ft=help:norl: