Hi,
Carlos Garnacho wrote:
> What are we missing in the current core? What benefits would bring a new
> one?
I certainly have not sat down and exhaustively tried to figure this out.
There is a fair bit of cruft in the core; if you were starting over, I'm
sure you'd want to just kill GdkWindow for example, and many other "Xlib
leakages" such as how some of the events work. You'd want to be
Cairo-only, use interfaces instead of objects for the core APIs (widget,
container), rethink GtkContainer and its common subclasses (as
HippoCanvas does), fix the theme system, blah blah. The list could get
pretty long.
The question is which of these are cosmetic cleanups that aren't really
worth it and which add new capabilities, and how long is the new
capabilities list. Probably not nearly as long as the cosmetic list.
Replacing the core with a more canvas-ish solution would not have to be
done all in one shot, though; the WidgetCanvasItem and CanvasWidget
provide a lot of interoperability. You could also have some of the
existing widgets implement the CanvasItem interface directly, for
example GtkEntry could be both a GtkWidget and a CanvasItem.
There's no real disruption to the current core while building a new
canvas-style core either, in fact I'd suggest evolving the canvas stuff
outside of GTK+ for at least a couple of years. It is probably also true
that certain "heavy" widgets such as TextView and TreeView never benefit
from conversion to a canvas-like model.
New capabilities I can quickly think of, all of which might be possible
to retrofit into GtkWidget/GtkContainer themselves:
- better layout
- overlapping/alpha-blending
- reduced overhead / more lightweight objects (speculative)
- better containers replacing [HV]Box/Misc (see HippoCanvasBox and
xalign, yalign, padding, border properties)
- printing trees of items
- general ability to draw an item to stuff other than the screen
- support for nonrectangular items (e.g. a diagonal line)
- nicer event system (e.g. easier enter/leave tracking, remove
only-useful-for-toplevels stuff from main item interface)
In the end I'm guessing this is just too much work. At the same time,
for some apps already we see that even a simple answer like HippoCanvas
has important advantages over GtkWidget.
Havoc
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