Freelog Special Edition 1: Linux/CD1.iso/doc/HOWTO/mini/X-Big-Cursor

Text File | 1998-10-14 | 10KB | 331 lines

  X11-big-cursor MINIHOWTO
  How to use enlarged mouse cursors with the X window system
  J÷rg Schneider <mailto:[e-mail]>
  v2, 11 August 1997

  This document describes how to use enlarged mouse cursors with the X
  window system.
  ______________________________________________________________________

  Table of Contents


  1. Introduction

  2. About this document

  3. How to do it

  4. Notes and limitations

  5. Technical discussion

  6. Other ideas how to make the mouse cursor more visible

  7. Related info

     7.1 How to use a font server
        7.1.1 Setting up a font server
     7.2 How to get the bdf source for some font


  ______________________________________________________________________

  1.  Introduction

  There are several reasons why the standard X mouse cursors are hard to
  track for some people:

  ╖  when running X on a notebook with low contrast LCD

  ╖  on normal screens when using high resolution, 1600x1280 e. g.

  ╖  for visually impaired persons even on normal hardware

  In all cases it might help to use enlarged mouse cursors. Ideally this
  job should be done by a single X program that automatically enlarges
  every mouse cursor.

  To my knowledge there is no simple way to write a utility like this,
  because the X protocol has no provision to query mouse cursors. For
  more details see section ``Technical discussion'' below.

  If we aim for a less general goal, though, something can be done:

  There is a set of standard mouse cursors that can be found in the
  cursor font (try xfd -fn cursor to look at it). Most programs use
  these mouse cursors and the key idea is to replace the standard cursor
  font with an enlarged version.


  2.  About this document

  The motivation for this MINIHOWTO was a visually impaired co-student
  who asked me how to enlarge the mouse cursor under X. After I found
  out how this can be done, I wrote an initial version of this document.
  The knowledge about the method described here does not seem to be
  common, so I decided to share it and submitted this document as a
  Linux MINIHOWTO, despite the fact that it is not specific to Linux at
  all. As all other MINIHOWTOs it can be found in the home of of the
  Linux Documentation Project (LDP) <http://sunsite.unc.edu/LDP/HOWTO/>.

  The master <http://i11www.ira.uka.de/~schneid/X11-big-cursor/master/>
  of this document is maintained in the SGML/linuxdoc format. This makes
  it possible to automatically provide versions in the following formats
  (which can be found in the same place as the master): html, text,
  LaTeX, DVI, PostScript, GNU info.

  Shinobu Miyata <mailto:[e-mail]> has done a Japanese
  translation of this MINIHOWTO. It can be found in
  <http://i11www.ira.uka.de/~schneid/jp/X11-big-cursor/>.


  3.  How to do it

  Follow the steps detailed below. If you don't want to get and compile
  the bdfresize package yourself, you can skip to step 3 and download a
  magnified font instead of creating it.

  1. get cursor.bdf, the source of the cursor font, from some X
     distribution, e. g. from
     <ftp://ftp.x.org/pub/R6.3/xc/fonts/bdf/misc/cursor.bdf> (if you
     don't find it there try an archie search or get it from my copy
     <http://i11www.ira.uka.de/~schneid/X11-big-cursor/cursor.bdf>).

  2. get, compile and install the bdfresize package from
     <ftp://ftp.cs.titech.ac.jp/X11/contrib/Local/bdfresize-1.4.tar.Z>
     (or from my copy <http://i11www.ira.uka.de/~schneid/X11-big-
     cursor/bdfresize-1.4.tar.gz>):

          zcat bdfresize-1.4.tar.Z  | tar xf -
          cd bdfresize-1.4
          xmkmf
          make



  On Linux you probably have to use:

       make CCOPTIONS='-include /usr/include/bsd/bsd.h' clean all




  3. create a directory and install a magnified cursor font in it
     (magnification factor 2 in this example):


          mkdir $HOME/fonts
          bdfresize -f 2 cursor.bdf | bdftopcf >$HOME/fonts/cursor2.pcf
          mkfontdir $HOME/fonts




  I have prepared some cursor fonts
  <http://i11www.ira.uka.de/~schneid/X11-big-cursor/fonts/> with the
  following magnification factors: 1.5, 2, 2.5, 3, 4, 5, 6, 7, 8 and 16.
  You can download one of them an copy it to $HOME/fonts if you don't
  want to use bdfresize.

  4. modify your .xinitrc or .xsession file: before any X client (that
     uses cursors) is started the following commands must  be executed:
          xset +fp $HOME/fonts
          xsetroot -cursor_name X_cursor




  5. leave your X session and restart.

  That's it--now all mouse cursors should have doubled in size.



  4.  Notes and limitations


  ╖  X servers may have a limit for the maximum cursor size, especially
     if they use a hardware implementation for the mouse cursor. Others
     do not have such a limit. E. g. XF86_S3 3.3 works even with a
     512x512 mouse cursor (rather slowly).

  ╖  The magnified cursor font must have the same name as the original
     font (the font name must be cursor, file name does not
     matter)--that is no problem as bdfresize does not change the font
     name.

  ╖  The directory with the new cursor font must be placed before the
     directory with the standard cursor font in the the font path--this
     is accomplished with xset +fp (as opposed to xset fp+).

  ╖  Changes in $HOME/fonts/ will be visible only after the command
     mkfontdir $HOME/fonts; xset fp rehash and only in newly started X
     clients (more exactly: for newly created cursors).

  ╖  xset +fp path may not work on a X-Terminal. In this case a font
     server (see the section ``How to use a fontserver'') can be used if
     supported by the X-Terminal or some other method to install the
     font on the X-Terminal (this can generally only be done by your
     system administrator).

  ╖  The same approach can be used for olcursor and decw$cursor fonts
     and any other cursor font you may encounter.

  ╖  Cursor fonts produced by bdfresize don't look smooth, especially at
     larger magnification factors. It would be nice if someone could
     create better looking handcrafted version at some common sizes.


  5.  Technical discussion

  Is it possible to write a X program that enlarges cursors
  automatically?


     (Partial) solution 1
        Use the XTestCompareCursor from the XTEST extension. For all
        windows that the mouse pointer enters compare the cursor of this
        window with a set of `known' cursors (e. g. from the cursor
        font). If the cursor is found, replace it with an enlarged
        version, otherwise either leave it alone or substitute a
        standard cursor. This will only work where the XTest extension
        is available.


     Solution 2
        Write a proxy X server that relays all client requests unchanged
        to the real X server, except that it intercepts all requests
        corresponing to the XCreate*Cursor Xlib functions.
        XCreate*Cursor requests should be modified to use an enlarged
        cursor.

        This proxy server simulates a new display, e. g. :1. All clients
        that connect to this display (e. g. xterm -display :1) are
        displayed on the real server (normally :0) and their mouse
        cursors are enlarged automatically. The mouse cursors of clients
        that connect to :0 will remain unchanged.


  6.  Other ideas how to make the mouse cursor more visible

  Here are some ideas for rather simple X programs that might make mouse
  cursors easier to track.


  ╖  When a hot key is pressed display something (big cursor, small
     window, shaped window) at pointer position for 0.5s.

  ╖  use XRecolorCursor to change the mouse cursor color every 0.1s

  A more demanding project would be mouse trails α la windoze, i. e.
  when the mouse is moved and the mouse cursor needs to be drawn in a
  different position, then the old mouse cursor does not disappear at
  once, but after a short delay. Mouse trails would be probably best
  implemented in a X server, but it might be feasible to do it as a X
  client, or better as a proxy server (see section ``Technical
  discussion'' for details).


  7.  Related info

  7.1.  How to use a font server

  A font server is a net service that provides a set of X11 fonts with a
  simple protocol. It can be queried which fonts it provides and will
  supply the font bitmap data on request.

  You might want to use a font server to provide the X server with a
  modified cursor font, instead of telling it where to find the font on
  the file system.

  This method is especially handy if you use several machines that don't
  share a common file system or if you use X terminals that support the
  font server protocol.

  A font server program and associated tools comes with the X11R5+
  distribution (AFAIK).


  7.1.1.  Setting up a font server

  Read the manual pages fs(1), fslsfonts(1) (or xfs(1), xfslsfonts(1)
  under X11R6) and try it--it isn't hard. Say, you are running the
  server on host some.host.edu on port 7100. You can test the setup with
  the command

  fslsfonts -server some.host.edu:7100

  To actually use the server issue the command

  xset +fp tcp/some.host.edu:7100

  which should return without an error message.

  7.2.  How to get the bdf source for some font

  If you have set up a font server simply use fstobdf which comes with
  the font server.

  Alternatively you may try getbdf which can dump any installed X11 font
  to a bdf file.