Graphics

You can modify the following preferences on the Preferences → IDL → Graphics preferences page:

Option
Description
Default

Default size (pixels):

Set this preference to specify the default width and height of IDL graphics windows in the Width and Height fields. These controls set the values of the IDL_GR_WIN_HEIGHT and IDL_GR_WIN_WIDTH preferences (Windows) and the IDL_GR_X_HEIGHT and IDL_GR_X_WIDTH preferences (UNIX). Check 1/4 screen size box to specify that graphics windows have a default width and height of half the screen width and height. This control sets the value of the IDL_GR_WIN_QSCREEN preference (Windows) and the IDL_GR_X_QSCREEN preference (UNIX).

1/4 screen size checked (on) -— 640 by 512

Direct graphics layout:

Set this preference to specify which layout type to use: Tile (0) or Cascade (1). On Windows systems, you can specify that graphics windows should be created side-by-side, with no overlap by selecting the Tile radio button, or that they should be created overlapping by selecting the Cascade radio button. This control sets the value of the IDL_GR_WIN_LAYOUT preference.

Tile (0)

Backing store method for window contents:

Set this preference to enable backing store so that a copy of each Graphics window is kept in memory; the copy is used to refresh the window when it has been covered and uncovered. IDL's performance may increase when no backing store is used, since the amount of memory required to save copies can affect the speed at which IDL will run. Settings in this section correspond to settings of the RETAIN keyword to the DEVICE procedure; see Backing Store for more information.

  • None (RETAIN = 0): Select this option to refrain from keeping a copy of the window. In some situations, disabling backing store may lead to an increase in IDL's performance.
  • System (RETAIN = 1): Select this option to request backing store from the windowing system. This is the default.
  • IDL (RETAIN = 2): Select this option to specify that IDL should maintain the backing store using its own memory.

Note - Backing Store preference changes do not take effect until the next IDL session.

This control sets the value of the IDL_GR_WIN_RETAIN preference (Windows) and the IDL_GR_X_RETAIN preference (UNIX).

Provided by system (1)

Rendering method for object graphics:

IDL supports two methods of rendering object graphics: via a hardware graphics accelerator or via a software rendering package. Select Hardware rendering if your system has OpenGL graphics accelerator hardware. Select Software rendering otherwise. This control sets the value of the IDL_GR_WIN_RENDERER preference (Windows) and the IDL_GR_X_RENDERER preference (UNIX).

See Hardware vs. Software Rendering for information about the differences between the two rendering systems.

Hardware (0)

Image tiles (mbytes):

Set this preference to specify how much memory (in megabytes) IDL can use for caching image tiles. When the amount of allocated memory reaches the value of IDL_GR_TILECACHESIZE, the least recently viewed tile or tiles are freed to make room for the new tile. Therefore, the amount of memory used for caching tiles will not grow above this value.

256

TrueType fonts (glyphs):

Note - On UNIX systems, this preference is included in the Graphics Attributes section of the dialog, described below.

IDL saves TrueType fonts as a set of glyphs; each glyph represents the triangulation data for drawing one character. The TrueType fonts (glyphs) field allows you to set the number of glyphs to keep in cache memory; keeping glyphs in memory speeds drawing of fonts in IDL graphics windows. The default number of glyphs in cache memory is 256, roughly two TrueType font sets.

Enter the number of TrueType characters for which to save triangulation information. Saving the triangulation information for TrueType characters means that IDL will not have to calculate the polygons to draw the next time a character of the same font and size is rendered. Larger values will use more memory but can increase drawing speed if multiple fonts are used. The default is 256.

This control sets the value of the IDL_GR_TTCACHESIZE preference.

256