On Tue, 4 Sep 2018 at 00:09, c.buhtz--- via gtk-app-devel-list <
gtk-app-devel-list@gnome.org> wrote:
> Dear Emmanuele,
>
> you describe how to set a drag icon. I know how to do this.
> https://stackoverflow.com/q/51975256/4865723
>
> But the question is how do I create my icon?
>
That's what I wrote in my email:
> If you want to override that, you should call
> gtk_drag_set_icon_surface(), using a Cairo surface you created:
>
>
https://developer.gnome.org/gtk3/stable/gtk3-Drag-and-Drop.html#gtk-drag-set-icon-surface
>
> The GtkTreeView uses the default handler of the GtkWidget::drag-begin
> signal to set the drag icon; you want your own handler to be called
> after that, so you can override the drag icon with your own.
Icons are Cairo surfaces; this means you need to create a Cairo surface and
render on it using the Cairo API.
> e.g. TreeView create it's own one, too. It is based on the row content.
> I can I do the same? e.g. I only want the content of the second
> column/cell and not the complete row?
>
You can get the contents of the model and render them as you wish, using
the gtk_render_* API.
Ciao,
Emmanuele.
On 2018-09-02 02:33 Emmanuele Bassi
> wrote:
> > On Sat, 1 Sep 2018 at 22:20, c.buhtz--- via gtk-app-devel-list <
> > gtk-app-devel-list@gnome.org> wrote:
> >
> > > I want to use my own drag-icon in a Gtk.TreeView where this is set
> > > as an instance of GdkPixbuf.Pixbuf.
> > >
> > > I can I create/draw a pixbuf and create Text, background and border
> > > color in it?
> > >
> >
> > Typically, GtkTreeView will call gtk_tree_view_create_row_drag_icon()
> > for the default drag surface — a box with the contents of the row.
> >
> >
> https://developer.gnome.org/gtk3/stable/GtkTreeView.html#gtk-tree-view-create-row-drag-icon
> >
> > If you want to override that, you should call
> > gtk_drag_set_icon_surface(), using a Cairo surface you created:
> >
> >
> https://developer.gnome.org/gtk3/stable/gtk3-Drag-and-Drop.html#gtk-drag-set-icon-surface
> >
> > The GtkTreeView uses the default handler of the GtkWidget::drag-begin
> > signal to set the drag icon; you want your own handler to be called
> > after that, so you can override the drag icon with your own. To do
> > that, you can:
> >
> > - call gtk_tree_view_unset_model_drag_source() or
> > gtk_tree_view_unset_model_drag_dest() and implement your own drag and
> > drop handling
> > - call g_signal_stop_emission_by_name() in your drag-begin callback
> > to stop the signal emission chain, and prevent the default handler
> > from running
> > - use g_signal_connect_after() to connect your callback, and have
> > your handler run after the default one
> > - subclass GtkTreeView and override the drag_begin() virtual function
> > without chaining up, to implement your own handler
> >
> > Ciao,
> > Emmanuele.
> >
>
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--
https://www.bassi.io
[@] ebassi [@gmail.com]
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