Pixel-vector optimising for lisp-font?

[HPW]

I am thinking about a converter from bitmaps fonts to a lisp-format describing the needed Pixelgrid



Example letter bitmap 7 x 15 (zoomed):

http://hpwsoft.de/anmeldung/html1/newLISP/CharGrid.png">



I scan the bitmap vertical and horzontal and get 2 vector lists.

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Bitmap: 7 x 15 Pixel

Vertical scan:

;     X1 Y1 X2 Y2       Length
(list  0 10  0 11)      ;2
(list  1  7  1  9)      ;3
(list  2  1  2  1)      ;1
(list  2  4  2  6)      ;3
(list  2  8  2  8)      ;1
(list  3  3  3  3)      ;1
(list  3  8  3  8)      ;1
(list  4  1  4  1)      ;1
(list  4  4  4  6)      ;3
(list  4  8  4  8)      ;1
(list  5  7  5  9)      ;3
(list  6 10  6 11)      ;2


Horizontal scan:

;     X1 Y1 X2 Y2       Length
(list  2  1  2  1)      ;1
(list  4  1  4  1)      ;1
(list  3  3  3  3)      ;1
(list  2  4  2  4)      ;1
(list  4  4  4  4)      ;1
(list  2  5  2  5)      ;1
(list  4  5  4  5)      ;1
(list  2  6  2  6)      ;1
(list  4  6  4  6)      ;1
(list  1  7  1  7)      ;1
(list  5  7  5  7)      ;1
(list  1  8  5  8)      ;5
(list  1  9  1  9)      ;1
(list  5  9  5  9)      ;1
(list  0 10  0 10)      ;1
(list  6 10  6 10)      ;1
(list  0 11  0 11)      ;1
(list  6 11  6 11)      ;1


So I want to draw the pixels with the vectors with the largest length and want to avoid double vectors.

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Wanted Result:

(list  0 10  0 11)      ;2
(list  1  7  1  9)      ;3
(list  2  1  2  1)      ;1
(list  2  4  2  6)      ;3
(list  3  3  3  3)      ;1
(list  4  1  4  1)      ;1
(list  4  4  4  6)      ;3
(list  5  7  5  9)      ;3
(list  6 10  6 11)      ;2
(list  1  8  5  8)      ;5


Any lispish ideas?

[HPW]

After thinking about it my first idea is:



I build a list with all vectors and sort it after the vector lenght.

Then I start with the longest vectors and build a second list

with the setted single pixels. Every new vector is checked if it will set any new pixel.

If not it will be dropped from the result-vector list.



I will try this out.

[cormullion]

How about a list of coordinate pairs:



'((0 10) (0 11))



I can see this being useful sometimes...

[HPW]

My current implementation of the optimising part:

(The sublists in resultlist have now an additional value for the vector direction)

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(setq pixellist '()
resultlist2 '()
 )
 (dolist (vlst resultlist)
(setq vectordir(nth 1 vlst)
vectorstart(nth 0(nth 2 vlst))
vectorend(nth 1(nth 2 vlst))
)
(if (= vectordir 0) ;X
(begin
 ;Check if vector is needed
 (setq VectorIsNeeded nil)
 (for (x(first vectorstart)(first vectorend)1)
(if (not(member (list x (last vectorstart)) pixellist))
(setq VectorIsNeeded true)
)
 )
 (if VectorIsNeeded
  (begin
  (setq resultlist2 (append resultlist2 (list vlst)))
  ;Add all pixel to pixellist
  (for (x(first vectorstart)(first vectorend)1)
(if (not(member (list x (last vectorstart)) pixellist))
(setq pixellist (append pixellist (list (list x (last vectorstart)))))
)
  )
  )
 )
)
)
(if (= vectordir 1) ;Y
(begin
 ;Check if vector is needed
 (setq VectorIsNeeded nil)
 (for (y(last vectorstart)(last vectorend)1)
(if (not(member (list (first vectorstart) y) pixellist))
(setq VectorIsNeeded true)
)
 )
 (if VectorIsNeeded
  (begin
  (setq resultlist2 (append resultlist2 (list vlst)))
  ;Add all pixel to pixellist
  (for (y(last vectorstart)(last vectorend)1)
(if (not(member (list (first vectorstart) y) pixellist))
(setq pixellist (append pixellist (list (list (first vectorstart) y))))
)
  )
  )
 )
)
)
 )