Qt for Embedded Linux Virtual Framebuffer | |
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The virtual frame buffer allows a Qt for Embedded Linux program to be developed | |
on your desktop machine, without switching between consoles and X11. The virtual | |
framebuffer consists of a shared memory region (the virtual frame buffer) | |
and a utility to display the framebuffer in a window. The display is updated | |
periodically, so you will see discrete snapshots of the framebuffer rather | |
than each individual drawing operation. For this reason drawing problems | |
such as flickering may not be apparent until the program is run using a real | |
framebuffer. | |
To use the virtual framebuffer: | |
1. Ensure QT_NO_QWS_VFB is not set in qconfig.h (when you configure Qt, | |
add the -qvfb option). | |
2. Start qvfb (qvfb should be compiled as a normal Qt for X11 application, | |
NOT as a Qt for Embedded Linux application!). | |
3. Start a Qt for Embedded Linux server (i.e. construct QApplication with | |
QApplication::GuiServer flag, or run a client with the -qws option). | |
qvfb supports the following command line options: | |
[-width width] the width of the virtual framebuffer (default: 240). | |
[-height height] the height of the virtual framebuffer (default: 320). | |
[-depth depth] the depth of the virtual framebuffer (1,4,8 or 32, default: 8). | |
[-nocursor] do not display the X11 cursor in the framebuffer window. | |
[-qwsdisplay] the Qt for Embedded Linux display ID, e.g. -qwsdisplay :1 (default :0). | |
[-skin skinfile] tells qvfb to load a skin file, e.g. -skin pda.skin | |
Please refer to the file "pda.skin" as an example of what a skin file looks like. | |
The format for skin files is: | |
Image filename of skin with buttons in their up positions | |
Image filename of skin with buttons in their down positions | |
X offset of top left corner of the virtual screen on the skin image | |
Y offset of top left corner of the virtual screen on the skin image | |
Width of the virtual screen on the skin image | |
Height of the virtual screen on the skin image | |
Number of defined button regions | |
Then for each button region the format is: | |
Button identifier | |
Qt scan codes to generate for the button | |
Top left X coordinate of the button region | |
Top left Y coordinate of the button region | |
Bottom right X coordinate of the button region | |
Bottom right Y coordinate of the button region | |
The virtual framebuffer is a development tool only. No security issues have | |
been considered in the virtual framebuffer design. It should not be used | |
in a production environment and QT_NO_QWS_VFB should always be in force | |
in production libraries. |