Message-ID: <44EE235F.2050809 at tin.it>
Date: Fri, 25 Aug 2006 00:08:31 +0200
From: Stalkern 2 <stalkern2 at tin.it>
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To: lablgtk at math.nagoya-u.ac.jp
Subject: Re: how to put text in a drawing_area ?
References: <16685.28897.429085.9744 at soggy.deldotd.com> <20040826.165052.74190188.garrigue at kurims.kyoto-u.ac.jp>
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Jacques GARRIGUE wrote:
> From: briand at aracnet.com
> 
>> Seems like a very simple thing and in fact gDraw.mli contains the
>> following comment :
>>
>>
>> (** Functions for drawing points, lines, arcs, and text
>>     at gtkdoc gdk gdk-Drawing-Primitives *)
>>
>>
>> However there is no text method and I can't seem to trace out a link
>> to the regular text widgets, nor can I find anything in the examples
>> directory...
> 
> You need to use the #put_layout method.
> But for that you must first create a layout with:
> 
>   let layout = area#misc#pango_context#create_layout in
> 
> Then you write in the layout, before drawing it:
> 
>   Pango.Layout.set_text layout "my text";
>   drawable#put_layout layout ~x:10 ~y:10
> 
> Hope this helps.
> 
> Jacques
> 
> P.S. maybe we could add a simpler utility method...
> 

Hello to everybody

I'm plotting some stuff and of course I'm attempting to write the name
of the Y values _vertically_ (not very original, is it?).

The Gnome Developers' API says clearly "There is no way to draw scaled
or rotated text with GDK." (http://developer.gnome.org/doc/GGAD/z132.html).

However, a simple "rotation" like the one that I'm looking for can be
done by swapping coords rather simply.

Here is code in GTK/Python, by John Hunter
(http://www.daa.com.au/pipermail/pygtk/2004-September/008660.html)

---->8---->8---->8---->8---->8---->8---->8---->8---->8---->8---->8----
    def draw_text_rotated(self, x=50, y=100):
        """
        Draw the text rotated 90 degrees
        """

        gc = self.drawable.new_gc()

        inkRect, logicalRect = self.layout.get_pixel_extents()
        rect = inkRect
        l, b, w, h = rect

        # save the background
        imageBack = self.drawable.get_image(x, y, w, h)
        imageVert = self.drawable.get_image(x, y, h, w)

        # transform the vertical image, write it onto the renderer,
        # and draw the layout onto it
        imageFlip = gtk.gdk.Image(type=gtk.gdk.IMAGE_NORMAL,
                                  visual=self.drawable.get_visual(),
                                  width=w, height=h)
        if imageFlip is None or imageBack is None or imageVert is None:
            print >> sys.stderr, "Could not renderer vertical text", s
            return
        imageFlip.set_colormap(self.drawable.get_colormap())
        for i in range(w):
            for j in range(h):
                imageFlip.put_pixel(i, j, imageVert.get_pixel(j,w-i-1) )

        self.drawable.draw_image(gc, imageFlip, 0, 0, x, y, w, h)
        self.drawable.draw_layout(gc, x, y-b, self.layout)

        # now get that image and flip it vertical
        imageIn = self.drawable.get_image(x, y, w, h)
        imageOut = gtk.gdk.Image(type=gtk.gdk.IMAGE_NORMAL,
                                 visual=self.drawable.get_visual(),
                                 width=h, height=w)
        imageOut.set_colormap(self.drawable.get_colormap())
        for i in range(w):
            for j in range(h):
                imageOut.put_pixel(j, i, imageIn.get_pixel(w-i-1,j) )

        # draw the old background and the flipped text
        self.drawable.draw_image(gc, imageBack, 0, 0, x, y, w, h)
        self.drawable.draw_image(gc, imageOut, 0, 0, x, y, h, w)

        return True
----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----8<----

I don't see very much Pango here, but I've thought that one could draw
to a temporary Gdk.image by means of a Pango layout, then use the
get_pixel and put_pixel functions available for Gdk.images as the code
above suggests, then put the "pseudo-rotated" image to the drawable with
the plot.

However, I'm in trouble:

	_I'm unable to bring the Pango.layout onto a Gdk.image.

	_if I bring the Pango.layout to a Gdk.pixmap, I'm in trouble with
getting and putting pixel without too much overkill.


Does anybody know what direction should I turn myself to, before getting
sick with this? I've thought about the nice label rotation features
available as of GTK+ 2.6, but I need the whole plot to be an image and
I'm (still?) unable to bring a Gtk.label to a drawable.

I hereby swear that it is not my fault if Y axes are plotted vertically,
but of Mister Descartes AFAIK :-) ...thanks in advance for any hint!

Ernesto