[Resend because it was apparently eaten the first time]
Hi folks,
Currently, there are several concurrent colour maps used by gEDA:
- PostScript colour map
- PNG colour map
- Screen colour map
- "Overlay" screen colour map (what is this even used for?)
- others?
As well as several flags used to effect the colour/transparency of output.
I propose to consolidate these into 2 RGBA colour maps:
1. A print colour map.
2. A screen colour map.
All the other colour maps would be derived from these.
Colours would be specified by #RRGGBB or #RRGGBBAA in hexadecimal.
N.b. that the "colour override" feature would be disabled for the time being.
What was the original motivation behind this feature, anyway?
PNG Output
----------
Would use RGBA values directly. Option to select which colour map to use for
output.
PostScript Output
-----------------
Any alpha level above 0 would result in objects being drawn. Objects whose
colour has alpha = 0 would not be drawn.
Hexadecimal colour codes would be mapped to PostScript colourspace such that:
0x00 --> 0.0
0xff --> 1.0
Screen (GDK)
------------
Any alpha level above 0 would result in objects being drawn. Objects whose
colour has alpha = 0 would not be drawn.
How should "overlay" colours be derived?
Screen (Cairo)
--------------
Would use RGBA values directly.
pcjc2: Does the Cairo renderer use the "overlay" colours?
Scheme API
----------
Two functions: (print-color-map) and (screen-color-map)
With an argument, sets the colour map. Without an argument, returns the
current colour map. The map may contain symbolic or numeric color indices.
Example: to set the print background to be transparent.
(print-color-map '(background "#ffffff00"))
Example: to set the print colour map to be the same as the screen.
(print-color-map (screen-color-map))
Feedback appreciated.
Peter
--
Peter Brett
Electronic Systems Engineer
Integral Informatics Ltd
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