Re: Generating a drawable widget

On Jan 9, 2005, at 6:54 PM, Hermann Kaser wrote:

I've spent the past few hours trying to figure out how to create a drawable area, I'm trying to make a little graph area to make a network usage timeline. I have the following code:

$graph = Gtk2::Gdk::Pixmap->new($drawable,200,100,-1);

a GdkPixmap isn't a widget, so it can't be packed into a container.

what you want to do is

a) use a Gtk2::DrawingArea. This is a drawable widget; you could draw directly to the screen or to a Gtk2::Gdk::Pixmap and copy that to the screen in expose (which is how the scribble example does it). With either option you can use the gdk drawing primitives. The drawing area also has its own GdkWindow, so you can handle mouse events and all that, e.g., to make an interactive plot (see the example).

b) draw to a Gtk2::Gdk::Pixbuf, and display that in a Gtk2::Image. This is usually a pretty good option in C, but since a GdkPixbuf is a 24-bit rgb pixel buffer and those aren't too easy to manipulate in perl, and you can't use the gdk drawing primitives, i tend to avoid this one.

But I haven't managed to generate a drawable area using Gtk::GDK::Drawable so that it goes in $drawable and therefore fits Pixmap. The documentation for Gtk::GDK::Pixmap says that ->new accepts either a Gtk2::Gdk::Drawable or a undef, but it always gives me an error when trying undef.

You can use the GdkWindow of the widget as the drawable, like this:

  $pixmap = Gtk2::Gdk::Pixmap->new ($widget->window, $width, $height,
                                 -1);  # same depth as window

She's obviously your child. She looks like you, she talks a lot, and most of it is gibberish.
  -- Elysse, to me, of Zella.

[Date Prev][Date Next]   [Thread Prev][Thread Next]   [Thread Index] [Date Index] [Author Index]