Re: How to use cairo with gtk

[muppet <scott asofyet org>]

On Mar 21, 2008, at 9:59 AM, Ye Wenbin wrote:
> Hi,
> I try a new module VS::Chart which create chart using Cairo.
> I want display the image as a Gtk widget without save the image
> to disk. The problem is VS::Chart using Cairo::ImageSurface
> to draw the chart, I can't find document for that.
> Is it possible convert the Cairo::ImageSurface to Gtk2::Image?
> I am especial appreciate if you can give some document
> about the concepts in Gtk or Cairo, for example,
> Gdk, graphic context, and so on. I'm not good at English,
> so understanding these things is not easy for me.


The lack of a way to display cairo image surfaces directly through gtk 
+ is a known deficiency in gtk+, last i heard.

The documentation for the cairo image surface is here:
http://cairographics.org/manual/cairo-Image-Surfaces.html

The perl API is pretty much the same; $imagesurface->get_data()  
returns you a scalar holding the image data.  If you ensure that the  
cairo image surface is created in cairo's RGB24 format, you can use  
the data directly with Gtk2::Gdk::Pixbuf like this:


    my $width = $surface->get_width;
    my $height = $surface->get_height;
    my $stride = $surface->get_stride;
    my $data = $surface->get_data;

    my $pixbuf = Gtk2::Gdk::Pixbuf->new_from_data ($data, 'rgb',  
FALSE, 8, $wudth, $height, $stride);

    my $image = Gtk2::Image->new_from_pixbuf ($pixbuf);


--
zella (crying):  I want...
us:  What?
zella (still crying):  I want...  something!