Re: [Vala] How to draw on a pixbuf

[Nor Jaidi Tuah]

Doing this

> Gdk.Pixbuf result= Gdk.pixbuf_get_from_surface(
> surface, 0, 0, 100, 100);

and then this

> Gdk.cairo_set_source_pixbuf (context, result, 0, 0);
> context.paint ();

can be replaced with the more direct code:

   context.set_source_surface (surface, ...)
   context.paint ();


hand
Nor Jaidi Tuah



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Re: [Vala] How to draw on a pixbuf

[raum]

Hello,

I think I've found a solution :)
- create a Surface and get the context of this surface
- draw on the surface
- create a pixbuf from the surface
- copy pixbuf into my drawingarea !

SOURCE CODE :

using Gtk;
using Cairo;

public static int main (string[] args) {
Cairo.ImageSurface surface;
Cairo.Context cr;

surface = new Cairo.ImageSurface (Cairo.Format.RGB24, 100, 100);

cr = new Cairo.Context (surface);

cr.paint();
cr.set_source_rgb (1, 1, 1);
cr.rectangle (0, 0, 100, 100);
cr.fill ();

cr.set_source_rgb (1, 0, 0);
cr.rectangle (10, 10, 40, 40);
cr.fill ();
cr.move_to(0, 0);
cr.line_to(100, 100);
cr.stroke();

Gdk.Pixbuf result= Gdk.pixbuf_get_from_surface(
surface, 0, 0, 100, 100);

Gtk.init (ref args);
var window = new Window();
window.title = "First GTK+ Program";
window.border_width = 10;
window.window_position = WindowPosition.CENTER;
window.set_default_size (400, 400);
window.destroy.connect (Gtk.main_quit);

DrawingArea da = new DrawingArea();

window.add(da);

da.draw.connect ((context) => {
Gdk.cairo_set_source_pixbuf (context, result, 0, 0);
context.paint ();
return true;
});

window.show_all ();

Gtk.main ();


return 0;

}


> Hello everyone,
>
> I want to prepare a picture and paste in a drawingarea, so I thought I
> should draw on a pixbuf, then copy it to my drawingarea
>
> I've create a drawing area (500x500) and I've tried this code in "on_draw"
> :
> public bool on_draw(Widget da, Context context) {
> (...)
>   var pixbuf = new Gdk.Pixbuf (Gdk.Colorspace.RGB, false, 8, 100, 100);
> Surface s = Gdk.cairo_surface_create_from_pixbuf (pixbuf, 1,
> null);
> Context c = new Context (s);
> c.move_to(0, 0);
> c.line_to(50, 50);
> c.stroke();
>
> Gdk.cairo_set_source_pixbuf (context, pixbuf, 0, 0);
>
> context.paint ();
> (...)
>
> But the result is a partially black rectangle with some with points
>
> Have you some advices ? :)
>
> Thanks.
>
> Regards
>
> Raum
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[Vala] How to draw on a pixbuf

[raum]

Hello everyone,

I want to prepare a picture and paste in a drawingarea, so I thought I
should draw on a pixbuf, then copy it to my drawingarea

I've create a drawing area (500x500) and I've tried this code in "on_draw" :
public bool on_draw(Widget da, Context context) {
(...)
var pixbuf = new Gdk.Pixbuf (Gdk.Colorspace.RGB, false, 8, 100, 100);
Surface s = Gdk.cairo_surface_create_from_pixbuf (pixbuf, 1, null);
Context c = new Context (s);
c.move_to(0, 0);
c.line_to(50, 50);
c.stroke();

Gdk.cairo_set_source_pixbuf (context, pixbuf, 0, 0);

context.paint ();
(...)

But the result is a partially black rectangle with some with points

Have you some advices ? :)

Thanks.

Regards

Raum
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