Last changed at 10 Mar 2009.

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 -- SDL GF driver --

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Here is an additional information about SDL GF driver:

 * 0. Introduction.

 * 1. Environment variables which SDL GF driver supports.

 * 2. Custom video modes.

 * 3. Limitations.

0. Introduction.

   SDL GF driver is a layer between SDL and QNX Graphics Framework (GF). Hardware

accelerated features which SDL could support depends on real hardware capabilities.

1. Environment variables which GF driver supports.

   GF driver supports the following environment variables for QNX GF specific

customization options:

   a) SDL_VIDEO_GF_REFRESH_RATE - refresh rate of video output in Hz. Without

      this environment variable declaration SDL controls refresh rate of your

      display. If this enironment variable is set to 0, SDL will control refresh

      rate of display, otherwise value of SDL_VIDEO_GF_REFRESH_RATE is used for

      all screen resolutions as refresh rate. This example will set 60Hz refresh

      rate as refresh rate for all graphics modes:

      export SDL_VIDEO_GF_REFRESH_RATE=60

2. Custom video modes.

   Since most QNX graphics drivers supports GENERIC video modes, i.e. you could

specify any horizontal and vertical resolution and any refresh rate, SDL GF

driver uses its own fullscreen modes list, which could be incomplete. You could

add any custom video mode, which your QNX graphics driver supports by editing

file ./src/video/qnxgf/SDL_qnxgf.c. Custom graphics mode definition looks like

   {0, 1024, 640, 60, NULL},   /* 1024x640 mode is 60Hz only               */

You must specify horizontal resolution as second parameter, vertical resolution

as third parameter and refresh rate as fourth parameter. Please leave first and

last parameters as 0 and NULL. Then please send me your changes to e-mail address

which is specified in the header of this document.

3. Limitations.

   There are few limitations while using SDL GF driver:

   a) Since GF driver supports fullscreen modes only, when you are not specifing

SDL_WINDOW_FULLSCREEN flag, an SDL GF driver will try to find the fullscreen

graphics mode which corresponds to SDL window size. Refresh rate will be the

lowest available, if SDL_VIDEO_GF_REFRESH_RATE environment variable is not set.