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# Qt for Embedded Linux Environment Variables

These environment variables are relevant to Qt for Embedded Linux users.

Variable | Description
--- | ---
POINTERCAL_FILE | Specifies the file containing the data used to calibrate the pointer device. See also QWSCalibratedMouseHandler and Qt for Embedded Linux Pointer Handling.

QT_ONSCREEN_PAINT

If defined, the application will render its widgets directly on screen. The affected regions of the screen will not be modified by the screen driver unless another window with a higher focus requests (parts of) the same region.

Setting this environment variable is equivalent to setting the Qt::WA_PaintOnScreen attribute for all the widgets in the application.

See also the Qt for Embedded Linux graphics rendering documentation.

QWS_SW_CURSOR | If defined, the software mouse cursor is always used (even when using an accelerated driver that supports a hardware cursor).

QWS_DISPLAY

Specifies the display type and framebuffer. For example, if the current shell is bash, ksh, zsh or sh:

     export QWS_DISPLAY=<driver>[:<driver specific options>]...
             [:<display num>]

The valid values for the `<driver>` argument are `LinuxFb`, `QVFb`, `VNC`, `Transformed`, `Multi` and keys identifying custom drivers, and the `<display num>` argument is used to separate screens that are using the same screen driver and to enable multiple displays (see the Running Qt for Embedded Linux Applications documentation for more details).

The driver specific options are described in the display management documentation.

QWS_SIZE

Specifies the size of the Qt for Embedded Linux window which is centered within the screen. For example, if the current shell is bash, ksh, zsh or sh:

     export QWS_SIZE=<width>x<height>

QWS_MOUSE_PROTO

Specifies the driver for pointer handling. For example, if the current shell is bash, ksh, zsh or sh:

     export QWS_MOUSE_PROTO=<driver>[:<driver specific options>]

The valid values for the `<driver>` argument are `MouseMan`, `IntelliMouse`, `Microsoft`, `VR41xx`, `LinuxTP`, `Yopy`. `Tslib` and keys identifying custom drivers, and the driver specific options are typically a device, e.g., `/dev/mouse` for mouse devices and `/dev/ts` for touch panels.

Multiple keyboard drivers can be specified in one go:

     export QWS_MOUSE_PROTO="<driver>[:<driver specific options>]
             <driver>[:<driver specific options>]
             <driver>[:<driver specific options>]"

Input will be read from all specified drivers. Note that the `Vr41xx` driver also accepts two optional arguments: `press=<value>` defining a mouseclick (the default value is 750) and `filter=<value>` specifying the length of the filter used to eliminate noise (the default length is 3). For example:

     export QWS_MOUSE_PROTO="Vr41xx:press=500:/dev/misc/ts"

See also Qt for Embedded Linux Pointer Handling.

QWS_KEYBOARD

Specifies the driver and device for character input. For example, if the current shell is bash, ksh, zsh or sh:

     export QWS_KEYBOARD=<driver>[:<driver specific options>]

The valid values for the `<driver>` argument are `SL5000`, `Yopy`, `VR41xx`, `TTY`, `USB` and keys identifying custom drivers, and the driver specific options are typically a device, e.g., `/dev/tty0`.

Multiple keyboard drivers can be specified in one go:

     export QWS_KEYBOARD="<driver>[:<driver specific options>]
             <driver>[:<driver specific options>]
             <driver>[:<driver specific options>]"

Input will be read from all specified drivers.

See also Qt for Embedded Linux Character Input.