This commit adds the GtkTextTag:underline-rgba and :strikethrough-rgba
properties and the necessary plumbing to apply these colors in GtkTextLayout.
With this change, you can alter the color of underlines including those
of type PANGO_UNDERLINE_ERROR.
You might want to alter the underline color to differentiate between
spelling and grammer mistakes. In code editors, it is convenient to
differentiate between errors and warnings.
Note that the GtkTextAppearance struct is public ABI and has no spare
room for new fields, so we are resorting to some tricky packing to store
the colors in the unused pixel field of the fg_color and bg_color structs.
This packing is accomplished by the macros in gtktextattributesprivate.h.
Signed-off-by: Christian Hergert <christian@hergert.me>
https://bugzilla.gnome.org/show_bug.cgi?id=402168
This now allows text view to render text with alpha values in
the text foreground and backgrounds, the work is almost complete,
currently the error-underline-color is still a GdkColor style property
and since we use only GdkRGBA for rendering it needs to be converted
and applied, probably a new rgba version of the style property should
also be introduced.
This commit adds tests/testtextview that must be run from the tests/
directory to show translucent text in action.
