Using GTK+ on the Framebuffer

Using GTK+ on the Framebuffer — Linux framebuffer aspects of using GTK+

GTK+ for the Linux Framebuffer

Note

The linux-fb GDK target is unmaintained and may not work or even compile. The information below may still be helpful; also there are several patches in bugzilla which may help with making the linux-fb code compilable.

The linux-fb port of GTK+, also known as GtkFB is an implementation of GDK (and therefore GTK+) that runs on the Linux framebuffer. It runs in a single process that doesn't need X. It should run most GTK+ programs without any changes to the source.

Build requirements

You need GTK+ 2.0; the 1.2.x series does not have framebuffer support. To compile GTK+ with framebuffer support you will need FreeType 2; we recommend FreeType 2.0.1 or later, as there was some problems with freetype-config in 2.0. Make sure that you install FreeType before Pango, since Pango also needs it. FreeType can be found at ftp://ftp.freetype.org. You also need fontconfig in order to properly use the FreeType 2 backend in Pango. Fontconfig depends on FreeType as well. Fontconfig can be found at http://fontconfig.org.

Hardware requirements

You need a graphics card with an available framebuffer driver that can run in 8, 16, 24 or 32 bpp, such as matroxfb or vesafb. You also need a supported mouse. GTK+ currently supports the ps2 mouse, ms serial mouse and fidmour touchscreen. Additional hardware support should be simple to add.

Building and installing

First build and install GLib, ATK and Pango as usual, in that order. Then configure GTK+ by running configure (or autogen.sh if running from CVS) with --with-gdktarget=linux-fb.

Then compile as usual: make; make install

Fonts

Since GtkFB uses FreeType 2 to render fonts it can render TrueType and Postscript type 1 antialiased fonts.

GtkFB uses fontconfig for configuration of font information, including directories and aliases. Make sure that you have your fonts.conf file configured with where your TrueType and Type1 fonts are. Please refer to the fontconfig documentation for more information.

Running

To run a program you should only need to start it, but there are some things that can cause problems, and some things that can be controlled by environment variables. Try gtk-demo distributed with GTK+ to test if things work.

If you use a ps2 mouse, make sure that /dev/psaux is readable and writable.

Make sure gpm is not running.

If you don't specify anything GtkFB will start up in the current virtual console in the current resolution and bit-depth. This can be changed by specifying environment variables: 

GDK_VT:
 unset means open on the current VT.
 0-9: open on the specified VT. Make sure you have read/write rights
      there.
 new: Allocate a new VT after the last currently used one.

GDK_DISPLAY_MODE:
 Specifies the name of a mode in /etc/fb.modes that you 
 want to use.

GDK_DISPLAY_DEPTH:
 Specify the desired bit depth of the framebuffer.
 
GDK_DISPLAY_WIDTH:
 Specify the desired width of the framebuffer.
 
GDK_DISPLAY_HEIGHT:
 Specify the desired height of the framebuffer.

GDK_DISPLAY:
 Specify the framebuffer device to use. Default is /dev/fb0.

GDK_MOUSE_TYPE:
 Specify mouse type. Currently supported is:
  ps2 - PS/2 mouse
  imps2 - PS/2 intellimouse (wheelmouse)
  ms - Microsoft serial mouse
  fidmour - touch screen
 Default is ps2.

GDK_KEYBOARD_TYPE:
 Specify keyboard type. Currently supported is
  xlate - normal tty mode keyboard.
    Quite limited, cannot detect key up/key down events. Doesn't
    handle ctrl/alt/shift for all keys. This is the default driver,
    but should not be used in "production" use.
  raw - read from the tty in RAW mode.
    Sets the keyboard in RAW mode and handles all the keycodes. This
    gives correct handling of modifiers and key up/down events. You
    must be root to use this. If you use this for development or
    debugging it is recommended to enable magic sysrq handling in the
    kernel. Then you can use ALT-SysRQ-r to turn the keyboard back to
    normal mode.
 Default is xlate.

Debug features

Pressing Ctrl-Alt-Return repaints the whole screen. Unfortunately this cannot be pressed when using the xlate keyboard driver, so instead you can use shift-F1 instead when using this driver.

Pressing Ctrl-Alt-BackSpace kills the GtkFB program. (This can't be pressed in the xlate driver, so instead you can use shift-F8.)