
== CONFIG/bg ==

In this directory, you may add images to display in the background of radar
screens or loose strip bays, sorting them in subdirectories as desired.

Background images come in two flavours:
 - pixmap file: regular image file (e.g. PNG) import with possible transparency;
 - text drawing: text file containing drawing specifications (only for radars).

To make an image selectable at an airport or CTR location, say with code XYZ,
it must be listed in a menu file named "XYZ.lst" placed here. Menu files can
contain any number of images, and images can appear in multiple menu files.

Menu (.lst) and text drawing file formats are described in the sections below.
Both file types allow line comments after a '#' character.


*** MENU FILES ***

Spec lines in menu files take either of the following forms:
 path/to/pixmap.png         NW:SE        Title shown in radar scope menu
 path/to/text-drawing-file  DRAW         Title shown in radar scope menu
 path/to/pixmap.png         LOOSE scale  Title shown in loose strip bay menu

where:
 - file paths are all relative to this directory and must not contain spaces;
 - NW and SE are the North-West and South-East corners for the imported pixmap
   on the radar (see syntax for point specification in the quick reference);
 - "DRAW" is a fixed token, indicating that the file is a text drawing file,
   formatted as described below;
 - "LOOSE" is a fixed token, indicating that the pixmap is for loose strip bays;
 - scale is a multiplying factor for the image width, where 1 corresponds to the
   width of a full-size strip drawn in the bay.

Pixmap images stretch or shrink to meet their specified scale or corners. On
radars, you can start with approximate corners and later adjust them manually
using the positioning helper tool available from the application system menu.


*** TEXT DRAWINGS ***

A text drawing spec file contains a number of drawing sections separated by at
least one empty line. Each one is of the form:
colour
point1  [optional text label]
point2  [optional text label]
...

where:
 - colour is an SVG colour keyword name like "white" or an "RRGGBB" hex spec;
 - points follow the "point specification" syntax given in the quick reference;
 - text labels are optional and may contain spaces.

If a drawing section only contains one point under the colour spec line, a mark
will be drawn to make the single point visible. More points in the section will
result in a broken line path between the listed points. A text label appears
near its corresponding point, whether single or in a line.

If you have sector files such as those used in Euroscope or IvAc, you should
try the integrated "extract from sector file" system tool to convert their
contents into ATC-pie native drawings. You will certainly have to refactor the
resulting files, but you save yourself the trouble of drawing everything
yourself and translating between coordinate formats.

