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Diffstat (limited to 'src/plugins/gfxdrivers/eglnullws/README')
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diff --git a/src/plugins/gfxdrivers/eglnullws/README b/src/plugins/gfxdrivers/eglnullws/README new file mode 100644 index 0000000000..80b88c7e01 --- /dev/null +++ b/src/plugins/gfxdrivers/eglnullws/README @@ -0,0 +1,48 @@ +EGL NullWS QScreen Driver +========================= + +If your application draws everything within a single full-screen QGLWidget then +you may wish to use this QScreen plugin driver. This driver simply returns 0 +(as a EGLNativeWindowType value) when asked by the QtOpenGl module to create a +native window. Some OpenGL ES implementations (including PowerVR) interpret this +to mean that a full-screen OpenGL context is desired without any windowing +support (NullWS). + +To tell a Qt/Embedded application to use this driver use the -display command +line option or the QWS_DISPLAY environment variable. The following driver +options are supported: + +size=WIDTHxHEIGHT Screen size reported by the driver +format=FORMAT Screen format + +Run with '-display eglnullws:help' to get a full list of options (including a +list of supported format strings). + +If you choose a screen format that is not supported by the hardware then the +QtOpenGl module will write out a list of supported EGL configurations. Use +one of the supported screen formats from this list. + +Using this driver with PowerVR hardware +--------------------------------------- + +Using this plugin with PowerVR hardware should give a significant speedup +compared to running with the Qt powervr driver (with a full-screen QGLWidget). +This is because sacrificing the window system allows less work to be done in +order to get graphics on the screen. Using this driver also avoids the memory +fragmentation issues present in the powervr driver and avoids any direct +dependencies on the deprecated PVR2D API from Imagination Technologies. + +To use this driver ensure you have /etc/powervr.ini with contents similar to +this: + +[default] +WindowSystem=libpvrPVR2D_FLIPWSEGL.so + +This driver will also function with libpvrPVR2D_FRONTWSEGL.so, but that draws +straight into the framebuffer and will therefore cause flickering (it can be +useful for performance testing though). The flip plugin uses triple buffering, +so you will need to set the virtual vertical resolution of your framebuffer to +be three times the physical vertical resolution of your screen. This can be +done with 'fbset -vyres'. Failure to do this can cause system crashes. You +should also ensure that the plugin you choose in powervr.ini is in your library +path (it may just silently default to the flip plugin if not). |