Issue #862 - Add size_allocate vfunc to gtk::Widget #961
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| @@ -209,6 +210,10 @@ pub trait WidgetImpl: WidgetImplExt + ObjectImpl + 'static { | |||
| fn get_preferred_height_for_width(&self, widget: &Widget, width: i32) -> (i32, i32) { | |||
| self.parent_get_preferred_height_for_width(widget, width) | |||
| } | |||
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| fn size_allocate(&self, widget: &Widget, allocation: &Allocation) { | |||
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The function gtk_widget_size_allocate() says in the docs:
In this function, the allocation may be adjusted. It will be forced to a 1x1 minimum size, and the adjust_size_allocation virtual method on the child will be used to adjust the allocation. Standard adjustments include removing the widget’s margins, and applying the widget’s Widget:halign and Widget:valign properties.
So maybe this needs to be mutable after all and subclasses need to be able to modify it?
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Note that I have no idea how this function is supposed to work, I'm just guessing from the docs :)
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That was my initial guess (see previous PR).
Looking at https://gitlab.gnome.org/GNOME/gtk/blob/gtk-3-24/gtk/gtkwidget.c#L6443
The GtkWidget vfunc doesn't modify it.
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Does any of the subclasses? Maybe worth asking on #gtk :)
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From what I can see they don't. At best they call gtk_widget_set_allocation or the parent class size allocate vfunc.
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Would be useful to get a definite answer from a GTK developer :)
src/subclass/widget.rs
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| let instance = &*(ptr as *mut T::Instance); | ||
| let imp = instance.get_impl(); | ||
| let wrap: Widget = from_glib_borrow(ptr); | ||
| let allocate: Allocation = from_glib_none(allocation); |
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If the allocation should be possible to modify then you need to write it back afterwards.
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The allocation is not an in-out parameter; you're supposed to call gtk_widge_set_allocation() or chain up to the parent class's allocation in your widget implementation, in which case you can tweak the argument for those.
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Thanks, so the allocation should actually be an immutable reference. And new allocations could be passed to childs, etc.
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So as part of this |
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@ebassi Thanks for the clarification. |
This is auto generated. |
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That's true, but it can be fixed like here Lines 680 to 684 in 2fcc486 |
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OK. Added it as a separate commit as this one we might want to skip cherry-picking to to 0.8 |
Both can be backported :) Changing from |
src/subclass/widget.rs
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| unsafe { | ||
| let data = self.get_type_data(); | ||
| let parent_class = data.as_ref().get_parent_class() as *mut gtk_sys::GtkWidgetClass; | ||
| let f = (*parent_class).size_allocate.unwrap(); |
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| let f = (*parent_class).size_allocate.unwrap(); | |
| let f = (*parent_class).size_allocate.expect("No parent class impl for \"size_allocate\""); |
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Otherwise looks good to me, thanks! |
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@GuillaumeGomez please merge :) |
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Thanks! |
Replaces PR #959 (on master this time)