[vwnc] Cairo Question regarding text placement

Hi all again.. Another Cairo question..

I've got some sample Cairo "C" code to generate some text to a PDF and
all works great -- the overall PDL is below :

    surface = cairo_pdf_surface_create(...);
    cr = cairo_create(surface);
    draw(cr);
    cairo_surface_destroy(surface);
    cairo_show_page(cr);
    cairo_destroy(cr);

    draw(cairo_t *cr)
    {
       cairo_move_to(cr, 10, 10);
       cairo_set_source_rgb(cr, 1.0, 1.0, 0.0);
       cairo_show_text(cr, "Hello World");
    }


I used the sample code below to try to emulate what was done above..
However, the text in the resulting
PDF has a text bitmap and looks poor IMHO (and the text is not
selectable in your favorite PDF viewer).
The C code above uses cairo_show_text which maps to
CairoContext>>showText: aString.. I didn't find
any code that uses that in the VW examples unfortunately... and it can't
be used by the Layout class.. Is
there a way to make this work closer to that C code above?  Thanks!

Here's the VW code :

surface := ImageSurface format: CairoFormat argb32 extent: 576@216.
surface newCairoContextWhile: [:aCr |

    aCr sourceColorValue: ColorValue black.
    aCr moveTo: 0 @ 10.

    layout := aCr newLayout.
    layout alignCenter.
    "layout compositionWidth: self bounds width - 10."
    "layout fontDescriptionString:'Monaco, 12'."
    layout text: 'the fox is lazy' .   "works OK but is rendered as a
bitmap"
    layout showText: 'this too'.    "doesn't work"
    layout showOn: aCr.
    layout release.
].
pdf := PDFSurface path: '/tmp/sample.pdf'
            pointExtent: 576 @ 216.
pdf newCairoContextWhile: [:cr |
        cr
            source: surface;
            paint;
            showPage].
pdf finish

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Responses inline below (untested, but hopefully enough to get you going).


In general, I find that you can convert C-based Cairo examples almost directly to Smalltalk once you know a couple of the right idioms (like newCairoContextWhile:).  Almost everything else comes straight across; if you have significantly more code in Smalltalk than in C, then you're doing more than you were in C.  Again, not necessarily a bad thing, but definitely a cause of suspicion when you're looking for behavior differences.

Randy
--
Randy Coulman
[hidden email]

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Randy Coulman wrote:
> Responses inline below (untested, but hopefully enough to get you going).
>
Cool!  Thanks Much!  I was able to do some more fiddling around and came
up with
this modified version which seems to work as I was hoping!

pdf := PDFSurface path: '/tmp/sample.pdf' pointExtent: 576 @ 216.
pdf newCairoContextWhile: [: aCr |
    aCr sourceColorValue: ColorValue black.
    aCr moveTo: 0 @ 10.

    layout := aCr newLayout.
    layout alignCenter.
    layout text: 'the fox is lazy' .   "works OK but is rendered as a
bitmap"
    layout showOn: aCr.
    layout release.
    ].
pdf finish

It creates a small PDF that has text that can be cut-n-pasted -- just
what I was
looking for!  Sorry that the code is a bit ugly...


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On Jun 16, 2009, at 11:40 PM, Rick Flower wrote:

You probably need to help it a little Rick. Give the layout a  
fontDescriptionString, something like:

layout fontDescriptionString: 'Arial, 20'.

I would expect that improves things.

--
Travis Griggs
Objologist
"Every institution finally perishes by an excess of its own first  
principle." - Lord Acton



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