github.com/sparques/framebuffer

framebuffer

Note: This is work in progress. Use at your own risk.

This library allows a Go application to draw arbitrary graphics to the Linux Framebuffer. This allows one to create graphical applications without the need for a monolithic display manager like X.

This is a pure Go implementation.

Because the framebuffer offers direct access to a chunk of memory mapped pixel data, it is strongly advised to keep all actual drawing operations confined to the thread that initialized the framebuffer.

The framebuffer is usually initialized to a specific display mode by the kernel itself. While this library supplies the means to alter the current display mode, this may not always have any effect as a driver can choose to ignore your requested values. Besides that, it is generally considered safer to use the external fbset command for this purpose. Video modes for the framebuffer require very precise timing values to be supplied along with any desired resolution. Doing this incorrectly can damage the display.

fbset comes with a set of default modes which are stored in the file /etc/fb.modes. We read this file and extract the set of video modes from it. These modes each have a name by which they can be identified. When supplying a new mode to this package, it should come in the form of this name. For example: "1600x1200-76".

New video modes can be added to the /etc/fb.modes file.

The framebuffer obscures the terminal, so any debug or error data written to stdout and/or stderr, will not be visible while it is running. To get access to this data, pipe their outputs to a file:

./myapp 1> stdout.log 2>error.log

Known issues

• Running a program which writes to the Framebuffer, may fail with a permission error. This is likely because your current user is not part of the video group. Add the user to this group and all should be well.

• This library draws directly the raw framebuffer. This means that it may interfere with other applications doing the same thing. This includes X, if it is running. While we take every effort to appropriately handle switching between the various applications, this should always be kept in mind.

• There may be ioctl errors when trying to run a program in a terminal emulator. This happens because the API requires a real tty. Ideally this should be fixed at some point.

Usage

go get github.com/jteeuwen/framebuffer

License

Unless otherwise stated, all of the work in this project is subject to a 1-clause BSD license. Its contents can be found in the enclosed LICENSE file.