Hi Edi,
I'm using CL-GD with both LispWorks 5.0 on OS X and CMUCL 19b on
FreeBSD to plot some graphs, and I'm very grateful for your work
here. CL-GD is slick to use and more than fast enough for
generating sparklines on an interactive web-based dashboard.
I'm using WITH-TRANSFORMATION to simplify the graph plotting, and
it's not behaving the way I would expect. As I read it in the
documentation, this...
(with-transformation (:x1 0
:width width
:y1 0
:height height)
...)
... should transform the coordinate system from this...
0,0 -----> width - 1
|
|
|
V
height - 1
... to this...
height - 1
^
|
|
|
0,0 -----> width - 1
Instead, I get this...
height
^
|
|
|
0,1 -----> width - 1
The y-axis transformation isn't consistent with that of the x-axis.
What's even more confusing, is that if the x-axis transformation
does work then the following should only complain about y1, y2, and
height, and not about x1, x2, and width, but that's not the case:
(let ((height 100)
(width 100))
(with-transformation (:x1 0
:x2 (1- width)
:width width
:y1 0
:y2 (1- height)
:height height)
...))
Indeed, when I checked the macroexpansion, I see...
(UNLESS #:X154021 (SETQ #:X154021 (- #:X254022 #:WIDTH54023)))
(UNLESS #:X254022 (SETQ #:X254022 (+ #:X154021 #:WIDTH54023)))
(UNLESS #:WIDTH54023 (SETQ #:WIDTH54023 (- #:X254022 #:X154021)))
(UNLESS #:Y154024 (SETQ #:Y154024 (- #:Y254025 #:HEIGHT54026)))
(UNLESS #:Y254025 (SETQ #:Y254025 (+ #:Y154024 #:HEIGHT54026)))
(UNLESS #:HEIGHT54026 (SETQ #:HEIGHT54026 (- #:Y254025 #:Y154024)))
Again, I would have thought, instead, that...
width = (x2 - x1) + 1
height = (y2 - y1) + 1
So, the y-axis transformation isn't what I expected, but the
macroexpansion suggests that the x-axis transformation should be
off by one as well, yet it isn't.
Am I nuts?
Below is the snippet I was running to grok WITH-TRANSFORMATION.
I can mail you the images I got, if you like.
Thanks in advance,
Mike
(let* ((height 100)
(width 100)
(origin+1 (list 1 1))
(x-axis+1 (list 10 1 20 1 30 1 40 1 50 1 60 1 70 1 80 1 90 1
width 1))
(y-axis+1 (list 1 10 1 20 1 30 1 40 1 50 1 60 1 70 1 80 1 90
1 height))
(x-axis-end+1 (list (1- width) 1))
(y-axis-end+1 (list 1 (1- height))))
(cl-gd:with-image* (width height)
(allocate-color 255 255 255)
(let ((black (allocate-color 0 0 0))
(red (allocate-color 255 0 0))
(green (allocate-color 0 255 0))
(blue (allocate-color 0 0 255))
(yellow (allocate-color 255 255 0)))
(draw-rectangle* 0
(1- height) ; or 0 and ...
(1- width)
0 ; (1- height), doesn't matter
:color yellow)
(draw-rectangle* 0
height ; or 0 and ...
width
0 ; ... height, doesn't matter
:color black)
(set-pixels origin+1 :color red)
(set-pixels x-axis+1 :color green)
(set-pixels x-axis-end+1 :color blue)
(set-pixels y-axis+1 :color green)
(set-pixels y-axis-end+1 :color blue))
(write-image-to-file "/tmp/test1.png"
:if-exists :supersede))
(cl-gd:with-image* (width height)
(allocate-color 255 255 255)
(let ((black (allocate-color 0 0 0))
(red (allocate-color 255 0 0))
(green (allocate-color 0 255 0))
(blue (allocate-color 0 0 255))
(yellow (allocate-color 255 255 0)))
(with-transformation (:x1 0
;;:x2 99
:width width
:y1 0
;;:y2 99
:height height
)
(draw-rectangle* 0
(1- height) ; or 0 and ...
(1- width)
0 ; (1- height), doesn't matter
:color yellow)
(draw-rectangle* 0
height ; or 0 and ...
width
0 ; ... height, doesn't matter
:color black)
(set-pixels origin+1 :color red)
(set-pixels x-axis+1 :color green)
(set-pixels x-axis-end+1 :color blue)
(set-pixels y-axis+1 :color green)
(set-pixels y-axis-end+1 :color blue))
(write-image-to-file "/tmp/test2.png"
:if-exists :supersede))))
--
Michael J. Forster <mike(a)sharedlogic.ca>
