Virtual Frame Buffer (Xvfb) - HP zx2000 Supplementary Manual

configuring an X Server on HP-UX

virtual frame buffer (Xvfb)

Xvfb(1) is an X Server that does not require display hardware or input devices. It emulates a
video frame buffer by using the system's virtual memory.
Xvfb may be used for: rendering with non-standard depths and screen configurations, software
rendering, providing a way to run applications that don't need an X Server but for some reason
insist on having one, etc.
Generally the user application must use functions such as XGetImage(3) in order to see what
was rendered.
Most of the content in this section is based on the Xvfb(1) manual page provided by XFree86.
configuring the virtual frame buffer
No configuration file is required to use the virtual frame buffer.
using the virtual frame buffer
In addition to the normal server options described in "Starting the X Server From the Command
Line", Xvfb accepts the following command line switches.
Switch
-screen
-pixdepths
-fbdir
-shmem
-linebias
4–22
Command Line Switches
Value
ScrnNum WxHxD
Depth1 Depth2 . . .
FrameBufferDirectory
NA
Bitmask
Description
Creates a screen and sets its width, height, and depth to
W, H, and D respectively. By default ScrnNum is 0 and the
default dimensions are: 1280x1024x8.
Specifies a list of pixmap depths that the server should
support in addition to the depths implied by the supported
screens. The option is a space delimited list of integers
ranging in value from 1 to 32.
Specifies the directory in which the memory mapped file
containing the frame buffer memory should be created.
The created file is located at
/FramebufferDirectory/Xvfb_screen<Scrn
The file is in xwd format. Capturing a full-screen
Num>.
snapshot can be done with a file copy command. The
resulting image contains the cursor image. If this option
and the option are not specified, the frame buffer
–shmem
memory is allocated with
Specifies that the frame buffer should be put in shared
memory. The shared memory ID for each screen is printed
by the server. The shared memory image is in xwd format.
If this option and the –fbdir option are not specified, the
frame buffer memory is allocated with
This option specifies how to adjust the pixelization of thin
lines. The Bitmask value is interpreted to be in octants. The
value represents the direction in which it is preferred to
take an axial step when the Bresenham error term is
exactly zero.
.
malloc()
malloc()
Graphics Administration Guide
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