Qt/Embedded Virtual Framebuffer

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 frequently. 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, then 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 be avoided in a production environment; QT_NO_QWS_VFB should always be defined in production libraries.