Re: [gedit-list] GtkSourceView, highlight lines with errors

[Sébastien Wilmet <swilmet gnome org>]

On Fri, May 20, 2016 at 01:22:57PM +0200, Stefan Salewski wrote:
> Some days ago I started writing a simple editor for Nim language, using
> Nims advanced idetools/nimsuggest service for error locating and source
> completion.
>
> I found no way to highlight lines with errors in a clean way. test-
> widget.c example uses this code
>
> gdk_rgba_parse (&color, "lightgreen");
> gtk_source_mark_attributes_set_background (attrs, &color);
>
> That works fine, but using a fixed color makes not too much sense for
> applications using arbitrary color schemes with syntax highlight. What
> would one do to highlight background, when color schemes are used? No
> idea still after some hour of googling and testing. What we would need
> is a way to ask current background color, so that we can change that
> color.
>
> For ordinary widgets this is available
>
> https://developer.gnome.org/gtk3/stable/GtkStyleContext.html#gtk-style-
> context-get-background-color
>
> but it is already deprecated.
>
> So we need access to the general background color, so that we can
> modify it, or access to a highlighted background color variant, which
> we can set.
>
> I think there is a "highlight current line" function somewhere hidden
> in the code -- it is possible to apply that method to lines with
> compiler errors?

Good question.

Some applications have a function to choose a color in a smart way:
choose the best color depending on some other colors. But GtkSourceView
doesn't have such function, unfortunately.

The style schemes have a list of colors. Maybe you can use one of them.

There are some code in GtkSourceView that do:

gtk_style_context_get (style_context,
                       gtk_style_context_get_state (style_context),
                       "background-color", &background_color,
                       NULL);

So it is still possible to retrieve the background color.

The highlight current line implementation is in gtksourceview.c. See
gtk_source_view_draw_layer() (it overrides the GtkTextView draw_layer
virtual function).

Hope that helps.

--
Sébastien