The virtual framebuffer is located in $QTDIR/src/util/qvfb
widgets -qws -display QVFb:0
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, 8 or 32, default: 8).|
|-nocursor||do not display the X11 cursor in the framebuffer window.|
|-qwsdisplay :id||the Qt/Embedded display id to provide (default :0).|
The virtual framebuffer emulates a framebuffer using a shared memory region (the virtual frame buffer) and a utility to display the framebuffer in a window (qvfb). The regions of the display that have changed are 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.
The target refresh rate can be set via the View->Refresh Rate menu item. This will cause qvfb to check for updated regions more quickly. The rate is a target only. If little drawing is being done, the framebuffer will not show any updates between drawing events. If an application is displaying an animation the updates will be frequent, and the application and qvfb will compete for processor time.
Mouse and keyboard events are passed to the Qt/Embedded master process via named pipes.
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 defined in production libraries.
|Copyright © 2000 Trolltech||Trademarks|
Qt version 2.2.1