HP Workstation zx2000 HP Graphics Administration Guide for HP-UX 11.X (IPF ver - Page 34

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. Command Line Switches Switch Value Description -screen ScrnNum WxHxD 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. -pixdepths Depth1 Depth2 . . . 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. -fbdir FrameBufferDirectory 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. The file is in xwd format. Capturing a full-screen snapshot can be done with a file copy command. The resulting image contains the cursor image. If this option and the -shmem option are not specified, the frame buffer memory is allocated with malloc(). -shmem NA 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 malloc(). -linebias Bitmask 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. 4-22 Graphics Administration Guide