using color tables with forms and bitblt?

OK, I'm such a noob here, that I'm not quite sure how to ask my question...


I have a "dwell file" -an array of values generated by a Mandelbrot Set
application, one per pixel, with arbitrary values between 1 and
xxxxxxxxxxx (currently less than 2 billion, and right now far less than
1,000,000)- and I would like to use them, suitably tweaked, as indices
into a ColorMap. The ColorMap need not have 1,000,000 entries. No-one
can see that many color differences in a Mandelbrot set anyway.

I can generate an array of Color (ColorArray?) but I'm not sure how to
use them to create the ColorMap, and I'm not sure how to use the
ColorMap to speedily change what is drawn in the first place.

Right now, I'm creating a color dictionary and drawing via:


1 to: 800 do: [:y|
     1 to: 800 do: [:x| |i|
         i := x+ ((y-1) *800).  aForm colorAt: x@y put:( myDictColors
at:  (myArray at: i )).]
         ].


where myDictColors is a dictionary whose keys are the dwells listed in
the dwell array file and whose values are Color objects from my array of
colors.

Drawing the above takes about 1.5 seconds, which is a bit slow. I'd like
realtime-ish updating as I play with colors in the palette. Can this be
done, at least up to the 4096 color limit that BitBlt has for ColorMaps?

If so, how?  I've been trying to figure out the various classes and I'm
stumped.


Thanks





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Hi Lawson.

I've has a play and something along the following lines might help...

|extent f bm colors colorWords cm originalForm|
extent := 256@192.
originalForm := Display copy: (0@0 extent: extent).
f := Form extent: extent depth: 32.
0 to: 359 by: 1 do: [:h |
 colors := (Color h: h s: 0.9 v: 0.7) wheel: 4096.
 colorWords := colors collect: [:c |
  c pixelWordForDepth: 32].
 bm := colorWords as: Bitmap.
" cm := ColorMap
  shifts: #(-12 -8 -4 0)
  masks: #(16rF00000 16rF000 16rF0 16r00)
  colors: bm."
 (BitBlt current toForm: f)
  colorMap: bm;
  copy: f boundingBox
  from: 0@0 in: originalForm.
 f displayAt: 50@40.
 Display forceDisplayUpdate.
 (Delay forMilliseconds: 10) wait].


Display restore.

---------------
ColorMap stuff commentedd out as BitBlt can automatically adjust based on
colorMap size though a full ColorMap object can give more control.

Your base mandelbrot would be represented as a 32bit form (originalForm),
probably best to stick to the 24bits of RGB values.
The Bitmap provides 4096 color mappings, though I think that 32768 allegedly
works too.
Just using #wheel: to demonstrate, fill your map as you wish!

Runs at around 100 fps (without the delay) on my pc, though that includes
creation of the colour maps on each iteration.
Around 20fps for a fullish screen (1080p) for just the display cycle with
precomputed maps.

Hopefully helpful.

Regards, Gary

----- Original Message -----
From: "Lawson English" <[hidden email]>
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Sent: Saturday, August 04, 2012 12:30 AM
Subject: [Pharo-project] using color tables with forms and bitblt?