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