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1 Qt for Embedded Linux Virtual Framebuffer |
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2 =============================== |
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3 |
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4 The virtual frame buffer allows a Qt for Embedded Linux program to be developed |
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5 on your desktop machine, without switching between consoles and X11. The virtual |
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6 framebuffer consists of a shared memory region (the virtual frame buffer) |
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7 and a utility to display the framebuffer in a window. The display is updated |
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8 periodically, so you will see discrete snapshots of the framebuffer rather |
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9 than each individual drawing operation. For this reason drawing problems |
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10 such as flickering may not be apparent until the program is run using a real |
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11 framebuffer. |
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12 |
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13 To use the virtual framebuffer: |
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14 |
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15 1. Ensure QT_NO_QWS_VFB is not set in qconfig.h (when you configure Qt, |
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16 add the -qvfb option). |
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17 2. Start qvfb (qvfb should be compiled as a normal Qt for X11 application, |
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18 NOT as a Qt for Embedded Linux application!). |
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19 3. Start a Qt for Embedded Linux server (i.e. construct QApplication with |
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20 QApplication::GuiServer flag, or run a client with the -qws option). |
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21 |
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22 qvfb supports the following command line options: |
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23 |
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24 [-width width] the width of the virtual framebuffer (default: 240). |
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25 [-height height] the height of the virtual framebuffer (default: 320). |
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26 [-depth depth] the depth of the virtual framebuffer (1,4,8 or 32, default: 8). |
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27 [-nocursor] do not display the X11 cursor in the framebuffer window. |
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28 [-qwsdisplay] the Qt for Embedded Linux display ID, e.g. -qwsdisplay :1 (default :0). |
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29 [-skin skinfile] tells qvfb to load a skin file, e.g. -skin pda.skin |
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30 |
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31 Please refer to the file "pda.skin" as an example of what a skin file looks like. |
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32 The format for skin files is: |
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33 Image filename of skin with buttons in their up positions |
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34 Image filename of skin with buttons in their down positions |
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35 X offset of top left corner of the virtual screen on the skin image |
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36 Y offset of top left corner of the virtual screen on the skin image |
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37 Width of the virtual screen on the skin image |
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38 Height of the virtual screen on the skin image |
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39 Number of defined button regions |
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40 Then for each button region the format is: |
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41 Button identifier |
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42 Qt scan codes to generate for the button |
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43 Top left X coordinate of the button region |
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44 Top left Y coordinate of the button region |
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45 Bottom right X coordinate of the button region |
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46 Bottom right Y coordinate of the button region |
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47 |
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48 The virtual framebuffer is a development tool only. No security issues have |
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49 been considered in the virtual framebuffer design. It should not be used |
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50 in a production environment and QT_NO_QWS_VFB should always be in force |
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51 in production libraries. |