[cl-gd-devel] Re: Drawing anti-aliased text with transparent background

[Andrei Stebakov]

I got some help from libgd mailing list, so when I put Pierre's sample to
lisp here is what I got (solves my problem):

    (with-image (new width height t)
      (setf (alpha-blending-p new) nil)
      (draw-rectangle* 0 0 width height :image new :filled t :color
(allocate-color 0 0 0 :image new :alpha 127))
      (draw-freetype-string 0 0
                text
                :image new
                :anti-aliased t
                :font-name font
                :angle 0
                :point-size font-size
                :color (allocate-color 0 0 255 :image new))
      (setf (save-alpha-p :image new) t)
      (write-image-to-file file-name :image new :if-exists :supersede)))

Thank you,
Andrew

On 3/17/07, Andrei Stebakov <lispercat at gmail.com> wrote:
>
> Ah, it looks like make-anti-aliased is only for brushes, for drawing
> lines... I wonder what technique works for the text?
>
> Thanks!
> Andrew
>
> On 3/17/07, Andrei Stebakov <lispercat at gmail.com> wrote:
> >
> > I tred to use the (make-anti-aliased) function:
> >     (draw-freetype-string 0 0
> >                   text
> >                   :anti-aliased t
> >                   :font-name font
> >                   :angle 0
> >                   :point-size font-size
> >                   :color (make-anti-aliased (allocate-color 0 0 255)))
> >
> > But the lisp gives me the error:
> >
> > The value of CL-GD::COLOR is #S(CL-GD::ANTI-ALIASED-COLOR
> >                                   :COLOR 255
> >                                   :DO-NOT-BLEND NIL), which is not of
> > type INTEGER.
> >    [Condition of type SIMPLE-TYPE-ERROR]
> >
> > Restarts:
> >  0: [STORE-VALUE] Supply a new value of CL-GD::COLOR.
> >  1: [ABORT] Return to SLIME's top level.
> >  2: [ABORT] Return to Top-Level.
> >
> > Backtrace:
> >   0: (LISP::CHECK-TYPE-ERROR CL-GD::COLOR
> >                              #S(CL-GD::ANTI-ALIASED-COLOR
> >                                   :COLOR 255
> >                                   :DO-NOT-BLEND NIL)
> >                              INTEGER
> >                              NIL)
> >
> > Thank you,
> > Andrew
> >
> > On 3/17/07, Andrei Stebakov < lispercat at gmail.com> wrote:
> > >
> > > Here is what I've got:
> > > http://www.greenpixeldesign.com/cphandler/tmp-img/test.png
> > > I'd like to remove the black outline from the anti-aliased text (I
> > > need RGB true color image). I know I am missing some stupid thing, but I
> > > experimented with different backgrounds, just doesn't make it right. My
> > > current setup is gdlib 2.0.33 on debian, and here is the code;
> > >
> > > (defun create-text-image (text font font-size file-name)
> > >   (multiple-value-bind (width height horizont-shift vertical-shift)
> > >       (get-bounding-rect text font font-size)
> > >     (with-image* (width height t)
> > >       (let* ((white (allocate-color 255 255 255))
> > >          (black (allocate-color 0 0 0))
> > >          (red (allocate-color 255 0 0))
> > >          (green (allocate-color 0 255 0))
> > >          (blue (allocate-color 0 0 255)))
> > >     (setf (transparent-color) black)
> > >     (draw-freetype-string (- 0 horizont-shift) (- height
> > > vertical-shift)
> > >                   text
> > >                   :anti-aliased t
> > >                   :font-name font
> > >                   :angle 0
> > >                   :point-size font-size
> > >                   :color (allocate-color 0 0 255))
> > >
> > >     ;;(true-color-to-palette)
> > >     (write-image-to-file file-name :if-exists :supersede)))))
> > >
> >
> >
>
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