Re: wip/baedert/drawing branch

[Matthias Clasen <matthias clasen gmail com>]

On Thu, May 18, 2017 at 11:52 AM, Timm Bäder <mail baedert org> wrote:

Hi,

I've collected a whole bunch of changes in th wip/baedert/drawing branch.
Here's a little overview of how things work in there, so we can decide
if it's the right way forward.

Hey Tim, thanks for writing this up.

Let me ask a few questions that are unclear to me, before we discuss the individual things:

- What are the overall goals here ? That would be good to know. My guess would be:
  1) Get rid of gadgets

  2) Full css drawing for all widgets

  anything else ?

 

  - gtk_widget_real_snapshot calls gtk_widget_snapshot_child on all the
   child widgets of the given GtkWidget instance. This makes sense to me
   but it's already been problematic when porting GtkScale and GtkRange
   away from gadgets because GtkRange didn't override ::snapshot so
   GtkScale couldn't just subclass it and chain up, since it would cause
   all child widgets to be drawn twice.

Iirc, we've had this kind of issue with containers in the past. You can't chain up without knowing
details about the parents implementation, and ordering becomes really tricky to get right.

Remaining problems/open questions:
 - Both GtkWindow and GtkPopover are special-cased in
   gtk_widget_snapshot to not draw the CSS background and border for
   them, since they are just too special. Getting rid of that special
   case would require porting them away from manual background drawing.
 - There are lots of CSS problems now of course, e.g. GtkRevealer does
   not hide its padding anymore so GtkSearchBar always leaves a few
   pixels of space around, or the 4px margin around GtkMenu which is not
   applied inside the toplevel instead of outside. Also GtkCheckButton
   obviously.

So this is a case where we deviate from gtk3 theming and introduce Adwaigtk-4.0
 

 - Focus outlines work out pretty badly the way they are currently done
   in the branch. Wit gadgets, widgets had pretty fine-grained control
   over which gadget draws the focus outline.

How _are_ they done now ?