Drawing rotated text in CAPI

Hi,

I'm working on a CAPI-based library for drawing scientific graphs.
As part of that, I want to draw some rotated text (e.g. I'd like
the label for the y-axis to be rotated 90 degrees, and I'd like to
have the option of rotating 'tick labels' for the x-axis by 45 degrees).

I can't find any way to do that. Here are some things I've considerd:

- My first idea was to use graphics-port transforms (e.g.
  GP:WITH-GRAPHICS-ROTATION). This works nicely with drawing functions
  like GP:DRAW-RECTANGLE & friends, but does not do what I'd hope
  with GP:DRAW-STRING.

- My second idea was to draw the string to a pixmap, and then copy
  the resulting pixmap to the graphics port that has my graph in it.
  That doesn't work either, because I can't specify a rotation when
  copying a pixmap to a port (which is probably quite understandable,
  but that doesn't help me).

- My third idea is to specify a rotation angle when creating a font.
  Windows, the platform I'm most interested in at the moment, lets
  you create fonts with a rotation angle. But I can't find anything
  in the CAPI documentation that tells me how to specify a rotation
  angle or, alternatively, how I can create a CAPI font based on
  a Windows font that I could create myself (e.g. using the FLI).

- My last resort would be to make this totally Windows-specific and
  use the FLI both to create a font and to draw the string. I'd rather
  not do that, so I'd appreciate any suggestions for a more portable
  solution.

Thanks a lot in advance,

Arthur Lemmens

Re: Drawing rotated text in CAPI

Just in case a *completely* tangential solution would be acceptable - cl-pdf 
seems to do what you seem to  want (except that the output is pdf and not 
interactive).  www.fractalconcept.com.  I guess that the opengl stuff would 
do it too.  I would be interested, too, to know how to do it in capi.
pt

Re: Drawing rotated text in CAPI

> 
> Yes, that may be a better idea; interactivity and integration with the
> rest of my (CAPI-based) programs would be possible in OpenGL, I suppose.
> 
> I'd still prefer to do it in CAPI though.
> 

First, I don't use CAPI.  

If you can get and set a pixel in an image, you can rotate a string
90 degrees counterclockwise in the following brute force approach:

(let ((pixmap (make-pixmap width height ...)))
  (clean-up-junk-bits pixmap ...)
  (draw-string pixmap "vertical" ...)
  (let ((horizontal-image (image-get pixmap 0 0 width height))
	(vertical-image (image-new height width ...)))
    (dotimes (i width)
      (dotimes (j height)
	(image-put-pixel vertical-image
			 j
			 (- width i 1)
			 (image-get-pixel horizontal-image i j))))
    ;; do whatever you want with the vertical image
    ...))

For drawing vertical axis and tic labels, this approach is adequate.

If you can get and set a pixel in a pixmap, that's even better.

Best,

-cph

Re: Drawing rotated text in CAPI

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Re: Drawing rotated text in CAPI

I wrote:

> I'm working on a CAPI-based library for drawing scientific graphs.
> As part of that, I want to draw some rotated text (e.g. I'd like
> the label for the y-axis to be rotated 90 degrees, and I'd like to
> have the option of rotating 'tick labels' for the x-axis by 45 degrees).

Thanks to everyone who replied to this.

I've decided to forget about 45-degrees rotation for the time being,
and to implement 90-degrees rotation by drawing the string horizontally
to a pixmap and then copying the pixels vertically (following Chisheng
Huang's suggestion).

Then I wrapped this up in a function I called DRAW-STRING-IN-RECTANGLE.
You can specify x-alignment (:left, :center or :right), y-alignment (:top,
:center or :bottom) and direction (:left-right, :bottom-top or :top-bottom).

A couple of people expressed interest in this problem, so I've included
my solution (see the attachment). I hope this is useful to someone.

Regards,

Arthur Lemmens