OpenPandora: Using custom cursors in fullscreen X11 SDL windows without touchscreen drifting/grabbing issues.

Note: This is is quick guide aimed at developers/porters looking to fix issues with custom SDL cursors (Cursors made up using an SDL_Surface) and the OpenPandora touchscreen, if your not using SDL then the chances are your not seeing the issue.

Normally I would not put together quick posts with small code snippets (I tend to direct people to code and tell them to work it out ) but as several people pointed out to me recently ScummVM for the OpenPandora works around a ‘feature’ in the SDL build on the device that causes relative screen coordinates to be returned to the event stack when you hit the screen edges with the touchscreen. In essence this is a code fix for the ‘cursor drift’ bug people report.

Nubs, mice, in fact any relative input device are fine, it is absolute input devices like the touchscreen that ‘drift’ and end up offset making some types of application unusable with the touchscreen (ScummVM was one of them).

As the same issue seems to cause problems several other applications on the OpenPandora I thought I would do a quick howto with a work around and give a little background on the issue.

Read the rest of this entry »