6. Backdrops, Palettes and Fonts

Together with Workspace Manager, Backdrops and Palettes are probably most known things in CDE by which it is visually recognized.

Backdrops, as many probably know are relatively simple XPM textures and pictures consisting usualy from 2-5 base colors: background, foreground, selectColor, topShadowColor, and bottomShadowColor. This colors are taken from the current (or custom) palette and applied to the symbolic definition of colors in XPM templates. Backdrop is then generated, tiled and applied to the root window. Every workspace can have it's own backdrop texture. In 4 colors mode of the palette theme, they are all colored in the same pattern, while in 8 colors mode, every workspace from 1-4 has it's own color variant from the current palette. If there are more that four desks defined, fifth is repeated color of the first, sixth of the second and so on.

Here, in addition to original CDE textures, there are some 100 new and custom textures created from (free and public) textures which were convenient for this customization. In other words, NsCDE implements more than 100 backdrops, and with Backdrop Style Manager user can import to it's $FVWM_USERDIR/backdrops it's own backdrops, or put them there with terminal or file manager.

Backdrops must have alternative extension for X Pixmaps: that is, not .xpm, but .pm.

If one wants their custom backdrop to be dynamic with palette/theme of NsCDE, one must edit them to set symbolic names of the colors described above. See existing backdrops to get an idea. Apart from symbolic names, backdrops also have a real color defined to be compatible with XPM specification, but values of this colors can be arbitrary, since they are not used if symbolic name on the same line is set.

Default backdrops are set from the /usr/local/share/nscde/defaults/backer until user does not redefine/set his own with Backdrop Style Manager. Default palette is Broica in 8 colors variant.

Backdrops generated by Backdrop Style manager are put in user's $FVWM_USERDIR/backer/DeskN-<backdropname>.pm and defined in $FVWM_USERDIR/NsCDE-Backdrops.conf as colorsets of TiledPixmap type. NsCDE reserved FVWM colorsets numbers for backdrops are from 31-38 for all eight possible desktops. This file is read by FvwmBacker(1) FVWM module. It is automatically generated when user makes first change with Backdrop Style Manager.

Until then, file /usr/local/etc/nscde/NsCDE-Backdrops.conf is read, which itself reads pre-generated and pre-defined backdrops from the /usr/local/share/nscde/defaults/backer directory.

We can conclude that backdrops are source form or template file, and when processed with color values from the palette, this backdrop's final form is, ready to be set by FvwmBacker(1).

When NsCDE is used with FVWM3 and per-monitor or shared DekstopConfiguration monitor modes, FvwmBacker(1) is not in use, because it cannot treat different physical (and virtual) monitors separately. Functions driven by the new_desk FvwmEvent(1) event are called in that case, which will be loaded from the cache directory $FVWM_USERDIR/backer/bgcache if found, or automatically generated with the help of ImageMagick's convert(1) tool if they do not exist, and then loaded. This mechanism automatically calculates screen width, height, X and Y coordinates, desks and backdrops to produce cjoined backdrops as one big PNG file which is then loaded to show correct background for desks on different monitors.