VIM: usr_06

## USR_06

    *usr_06.txt*	For Vim version 9.1.  Last change: 2025 Aug 06

    		     VIM USER MANUAL - by Bram Moolenaar

    			  Using syntax highlighting

    Black and white text is boring.  With colors your file comes to life.  This
    not only looks nice, it also speeds up your work.  Change the colors used for
    the different sorts of text.  Print your text, with the colors you see on the
    screen.

    |06.1|	Switching it on
    |06.2|	No or wrong colors?
    |06.3|	Different colors
    |06.4|	With colors or without colors
    |06.5|	Printing with colors
    |06.6|	Further reading

         Next chapter: |usr_07|  Editing more than one file
     Previous chapter: |usr_05|  Set your settings
    Table of contents: |usr_toc|

    *06.1*	Switching it on

    It all starts with one simple command:

    	:syntax enable

    That should work in most situations to get color in your files.  Vim will
    automagically detect the type of file and load the right syntax highlighting.
    Suddenly comments are blue, keywords brown and strings red.  This makes it
    easy to overview the file.  After a while you will find that black&white text
    slows you down!

    If you always want to use syntax highlighting, put the ":syntax enable"
    command in your |vimrc| file.

    If you want syntax highlighting only when the terminal supports colors, you
    can put this in your |vimrc| file:

    	if &t_Co > 1
    	   syntax enable
    	endif

    If you want syntax highlighting only in the GUI version, put the ":syntax
    enable" command in your |gvimrc| file.

    *06.2*	No or wrong colors?

    There can be a number of reasons why you don't see colors:

    - Your terminal does not support colors.
    	Vim will use bold, italic and underlined text, but this doesn't look
    	very nice.  You probably will want to try to get a terminal with
    	colors.  For Unix, I recommend the xterm from the XFree86 project:
    	|xfree-xterm|.

    - Your terminal does support colors, but Vim doesn't know this.
    	Make sure your $TERM setting is correct.  For example, when using an
    	xterm that supports colors:

    		setenv TERM xterm-color

    	or (depending on your shell):

    		TERM=xterm-color; export TERM

    	The terminal name must match the terminal you are using.  If it
    	still doesn't work, have a look at |xterm-color|, which shows a few
    	ways to make Vim display colors (not only for an xterm).

    - The file type is not recognized.
    	Vim doesn't know all file types, and sometimes it's near to impossible
    	to tell what language a file uses.  Try this command:

    		:set filetype

    	If the result is "filetype=" then the problem is indeed that Vim
    	doesn't know what type of file this is.  You can set the type
    	manually:

    		:set filetype=fortran

    	To see which types are available, look in the directory
    	$VIMRUNTIME/syntax.  For the GUI you can use the Syntax menu.
    	Setting the filetype can also be done with a |modeline|, so that the
    	file will be highlighted each time you edit it.  For example, this
    	line can be used in a Makefile (put it near the start or end of the
    	file):

    		# vim: syntax=make

    	You might know how to detect the file type yourself.  Often the file
    	name extension (after the dot) can be used.
    	See |new-filetype| for how to tell Vim to detect that file type.

    - There is no highlighting for your file type.
    	You could try using a similar file type by manually setting it as
    	mentioned above.  If that isn't good enough, you can write your own
    	syntax file, see |mysyntaxfile|.

    Or the colors could be wrong:

    - The colored text is very hard to read.
    	Vim guesses the background color that you are using.  If it is black
    	(or another dark color) it will use light colors for text.  If it is
    	white (or another light color) it will use dark colors for text.  If
    	Vim guessed wrong the text will be hard to read.  To solve this, set
    	the 'background' option.  For a dark background:

    		:set background=dark

    <	And for a light background:

    		:set background=light

    	Make sure you put this _before_ the ":syntax enable" command,
    	otherwise the colors will already have been set.  You could do
    	":syntax reset" after setting 'background' to make Vim set the default
    	colors again.

    - The colors are wrong when scrolling bottom to top.
    	Vim doesn't read the whole file to parse the text.  It starts parsing
    	wherever you are viewing the file.  That saves a lot of time, but
    	sometimes the colors are wrong.  A simple fix is hitting CTRL-L.  Or
    	scroll back a bit and then forward again.
    	For a real fix, see |:syn-sync|.  Some syntax files have a way to make
    	it look further back, see the help for the specific syntax file.  For
    	example, |tex.vim| for the TeX syntax.

    *06.3*	Different colors				*:syn-default-override*

    If you don't like the default colors, you can select another color scheme.  In
    the GUI use the Edit/Color Scheme menu.  You can also type the command:

    	:colorscheme evening

    "evening" is the name of the color scheme.  There are several others you might
    want to try out.  Look in the directory $VIMRUNTIME/colors.

    When you found the color scheme that you like, add the ":colorscheme" command
    to your |vimrc| file.

    You could also write your own color scheme.  This is how you do it:

    1. Select a color scheme that comes close.  Copy this file to your own Vim
       directory.  For Unix, this should work:

    	!mkdir ~/.vim/colors
    	!cp $VIMRUNTIME/colors/morning.vim ~/.vim/colors/mine.vim

       This is done from Vim, because it knows the value of $VIMRUNTIME.

    2. Edit the color scheme file.  These entries are useful:

    	term		attributes in a B&W terminal
    	cterm		attributes in a color terminal
    	ctermfg		foreground color in a color terminal
    	ctermbg		background color in a color terminal
    	gui		attributes in the GUI
    	guifg		foreground color in the GUI
    	guibg		background color in the GUI

       For example, to make comments green:

    	:highlight Comment ctermfg=green guifg=green

       Attributes you can use for "cterm" and "gui" are "bold" and "underline".
       If you want both, use "bold,underline".  For details see the |:highlight|
       command.

    3. Tell Vim to always use your color scheme.  Put this line in your |vimrc|:

    	colorscheme mine

    If you want to see what the most often used color combinations look like, use
    this command:

    	:runtime syntax/colortest.vim

    You will see text in various color combinations.  You can check which ones are
    readable and look nice.  These aren't the only colors available to you though.
    You can specify #rrggbb hex colors and you can define new names for hex
    colors in |v:colornames| like so:

    	let v:colornames['mine_red'] = '#aa0000'

    If you are authoring a color scheme for others to use, it is important
    to define these colors only when they do not exist:

    	call extend(v:colornames, {'mine_red': '#aa0000'}, 'keep')

    This allows users of the color scheme to override the precise definition of
    that color prior to loading your color scheme.  For example, in a |.vimrc|
    file:

    	runtime colors/lists/css_colors.vim
    	let v:colornames['your_red'] = v:colornames['css_red']
    	colorscheme yourscheme

    As a color scheme author, you should be able to rely on some color names for
    GUI colors.  These are defined in `colors/lists/default.vim`.  All such files
    found on the 'runtimepath' are loaded each time the colorscheme command is
    run. A canonical list is provided by the vim distribution, which should
    include all X11 colors (previously defined in rgb.txt).

    *06.4*	With colors or without colors

    Displaying text in color takes a lot of effort.  If you find the displaying
    too slow, you might want to disable syntax highlighting for a moment:

    	:syntax clear

    When editing another file (or the same one) the colors will come back.

    If you want to stop highlighting completely use:

    	:syntax off

    This will completely disable syntax highlighting and remove it immediately for
    all buffers.  See |:syntax-off| for more details.

    							*:syn-manual*
    If you want syntax highlighting only for specific files, use this:

    	:syntax manual

    This will enable the syntax highlighting, but not switch it on automatically
    when starting to edit a buffer.  To switch highlighting on for the current
    buffer, set the 'syntax' option:

    	:set syntax=ON

    *06.5*	Printing with colors				*syntax-printing*

    In the MS-Windows version you can print the current file with this command:

    	:hardcopy

    You will get the usual printer dialog, where you can select the printer and a
    few settings.  If you have a color printer, the paper output should look the
    same as what you see inside Vim.  But when you use a dark background the
    colors will be adjusted to look good on white paper.

    There are several options that change the way Vim prints:
    	'printdevice'
    	'printheader'
    	'printfont'
    	'printoptions'

    To print only a range of lines,  use Visual mode to select the lines and then
    type the command:

    	v100j:hardcopy

    "v" starts Visual mode.  "100j" moves a hundred lines down, they will be
    highlighted.  Then ":hardcopy" will print those lines.  You can use other
    commands to move in Visual mode, of course.

    This also works on Unix, if you have a PostScript printer.  Otherwise, you
    will have to do a bit more work.  You need to convert the text to HTML first,
    and then print it from a web browser.

    Convert the current file to HTML with this command:

    	:TOhtml

    In case that doesn't work:

    	:source $VIMRUNTIME/syntax/2html.vim

    You will see it crunching away, this can take quite a while for a large file.
    Some time later another window shows the HTML code.  Now write this somewhere
    (doesn't matter where, you throw it away later):

    	:write main.c.html

    Open this file in your favorite browser and print it from there.  If all goes
    well, the output should look exactly as it does in Vim.  See |2html.vim| for
    details.  Don't forget to delete the HTML file when you are done with it.

    Instead of printing, you could also put the HTML file on a web server, and let
    others look at the colored text.

    *06.6*	Further reading

    |usr_44|  Your own syntax highlighted.
    |syntax|      All the details.

    Next chapter: |usr_07|  Editing more than one file

    Copyright: see |manual-copyright|  vim:tw=78:ts=8:noet:ft=help:norl:

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