Environment > Setting Preferences > X Window System Graphics Preferences

# X Window System Graphics Preferences

The preferences in this section are specific to versions of IDL that support the X Window System. They do not exist in the Microsoft Windows version of IDL.

## IDL_GR_X_COLORS

The IDL_GR_X_COLORS preference specifies the number of color-table indices to allocate from the shared colormap used by direct graphics. If the value is positive, the specified number of indices are allocated. If the value is negative, all but the specified number are allocated. If the value is 0, all or most of the available color indices are allocated.

Committed changes take effect immediately if IDL has not yet made a connection to the X Window display. Otherwise, changes take effect in future IDL sessions. The default value is 0.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_DEPTH

The IDL_GR_X_DEPTH preference specifies the depth, in bits, of the visual used by IDL.

Committed changes take effect immediately if IDL has not yet made a connection to the X Window display. Otherwise, changes take effect in future IDL sessions. The default value is 0, meaning that IDL selects a visual from those available in the server, using the rules described in the documentation for the X Window device.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_HEIGHT

The IDL_GR_X_HEIGHT preference sets the default height of graphics windows on X Windows systems. Set IDL_GR_X_HEIGHT to a value greater than or equal to 1. Committed changes take effect immediately. The default value is 512. You can set this preference in the IDL Workbench Preferences dialog.

## IDL_GR_X_QSCREEN

If the IDL_GR_X_QSCREEN preference is set to True (1), the IDL_GR_X_HEIGHT and IDL_GR_X_WIDTH preferences are ignored. Instead, the default size of a graphics window created by the X Window System direct graphics device (`'X'`) is one-fourth the size of the screen.

Value | Aliases
0 | False, No, Off
1 | True, Yes, On

Committed changes take effect immediately. The default value is True (1).

This preference can be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_RENDERER

IDL supports two methods of rendering object graphics: with a hardware graphics accelerator or with a software rendering package. The IDL_GR_X_RENDERER preference determines the default method used for volume rendering.

Value | Alias
0 | Hardware
1 | Software

Committed changes take effect immediately. The default value is Hardware (0).

This preference can be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_RETAIN

The IDL_GR_X_RETAIN preference specifies the default type of backing store to use for direct graphics windows. Note that you can override this default using the RETAIN keyword to the WRITE_BMP procedure.

Value | Aliases
0 | None
1 | Server, System
2 | IDLPixmap

Committed changes take effect immediately if IDL has not yet made a connection to the X Window display. Otherwise, changes take effect in future IDL sessions. The default value is Server (1).

This preference can be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_VISUAL

The IDL_GR_X_VISUAL preference specifies the preferred X11 visual class for direct graphics windows.

Value | Alias
0 | None
1 | StaticGray
2 | GrayScale
3 | StaticColor
4 | PseudoColor
5 | TrueColor
6 | DirectColor

Committed changes take effect immediately if IDL has not yet made a connection to the X Window display. Otherwise, changes take effect in future IDL sessions. The default value is None (0), meaning that IDL selects a visual from those available in the server, using the rules described in the documentation for the X Windows device.

This preference cannot be set in the IDL Workbench Preferences dialog.

## IDL_GR_X_WIDTH

The IDL_GR_X_WIDTH preference sets the default width of graphics windows on X Windows systems. Set IDL_GR_X_WIDTH to a value greater than or equal to 1. Committed changes take effect immediately. The default value is 640. You can set this preference in the IDL Workbench Preferences dialog.