NAME
qvfb - Virtual framebuffer for Qt
DESCRIPTION
The virtual framebuffer allows Qt/Embedded programs to be developed on
your desktop machine, without switching between consoles and X11.
Start a Qt/Embedded master application (i.e., construct QApplication
with QApplication::GuiServer flag or use the -qws command line
parameter). You will need to specify to the server that you wish to use
the virtual framebuffer driver, e.g.:
widgets -qws -display QVFb:0
You may prefer to set the QWS_DISPLAY environment variable to be
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).
Virtual Framebuffer Design
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 be
avoided in a production environment; QT_NO_QWS_VFB should always be
defined in production libraries.
AUTHORS
TrollTech <http://www.trolltech.com/>