Struct gtk4::LayoutManager [−][src]
pub struct LayoutManager(_);Expand description
Layout managers are delegate classes that handle the preferred size and the allocation of a widget.
You typically subclass LayoutManager if you want to implement a
layout policy for the children of a widget, or if you want to determine
the size of a widget depending on its contents.
Each Widget can only have a LayoutManager instance associated
to it at any given time; it is possible, though, to replace the layout
manager instance using WidgetExt::set_layout_manager().
Layout properties
A layout manager can expose properties for controlling the layout of
each child, by creating an object type derived from LayoutChild
and installing the properties on it as normal GObject properties.
Each LayoutChild instance storing the layout properties for a
specific child is created through the LayoutManagerExt::layout_child()
method; a LayoutManager controls the creation of its LayoutChild
instances by overriding the GtkLayoutManagerClass.create_layout_child()
virtual function. The typical implementation should look like:
⚠️ The following code is in c ⚠️
static GtkLayoutChild *
create_layout_child (GtkLayoutManager *manager,
GtkWidget *container,
GtkWidget *child)
{
return g_object_new (your_layout_child_get_type (),
"layout-manager", manager,
"child-widget", child,
NULL);
}The property::LayoutChild::layout-manager and
property::LayoutChild::child-widget properties
on the newly created LayoutChild instance are mandatory. The
LayoutManager will cache the newly created LayoutChild instance
until the widget is removed from its parent, or the parent removes the
layout manager.
Each LayoutManager instance creating a LayoutChild should use
LayoutManagerExt::layout_child() every time it needs to query
the layout properties; each LayoutChild instance should call
LayoutManagerExt::layout_changed() every time a property is
updated, in order to queue a new size measuring and allocation.
This is an Abstract Base Class, you cannot instantiate it.
Implements
Trait Implementations
This method returns an ordering between self and other values if one exists. Read more
This method tests less than (for self and other) and is used by the < operator. Read more
This method tests less than or equal to (for self and other) and is used by the <=
operator. Read more
This method tests greater than (for self and other) and is used by the > operator. Read more
Returns the type identifier of Self.
Auto Trait Implementations
impl RefUnwindSafe for LayoutManager
impl !Send for LayoutManager
impl !Sync for LayoutManager
impl Unpin for LayoutManager
impl UnwindSafe for LayoutManager
Blanket Implementations
Mutably borrows from an owned value. Read more
Upcasts an object to a superclass or interface T. Read more
Upcasts an object to a reference of its superclass or interface T. Read more
Tries to downcast to a subclass or interface implementor T. Read more
Tries to downcast to a reference of its subclass or interface implementor T. Read more
Tries to cast to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Tries to cast to reference to an object of type T. This handles upcasting, downcasting
and casting between interface and interface implementors. All checks are performed at
runtime, while downcast and upcast will do many checks at compile-time already. Read more
Casts to T unconditionally. Read more
Casts to &T unconditionally. Read more
Returns true if the object is an instance of (can be cast to) T.
pub fn set_property<'a, N, V>(
&self,
property_name: N,
value: V
) -> Result<(), BoolError> where
N: Into<&'a str>,
V: ToValue,
pub fn set_property_from_value<'a, N>(
&self,
property_name: N,
value: &Value
) -> Result<(), BoolError> where
N: Into<&'a str>,
pub fn set_properties_from_value(
&self,
property_values: &[(&str, Value)]
) -> Result<(), BoolError>
pub fn has_property<'a, N>(&self, property_name: N, type_: Option<Type>) -> bool where
N: Into<&'a str>,
pub fn find_property<'a, N>(&self, property_name: N) -> Option<ParamSpec> where
N: Into<&'a str>,
Safety Read more
Safety Read more
Safety Read more
Safety Read more
pub fn connect<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
N: Into<&'a str>,
F: 'static + Fn(&[Value]) -> Option<Value> + Send + Sync,
Same as connect but takes a SignalId instead of a signal name.
pub fn connect_local<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
N: Into<&'a str>,
F: 'static + Fn(&[Value]) -> Option<Value>,
Same as connect_local but takes a SignalId instead of a signal name.
pub unsafe fn connect_unsafe<'a, N, F>(
&self,
signal_name: N,
after: bool,
callback: F
) -> Result<SignalHandlerId, BoolError> where
N: Into<&'a str>,
F: Fn(&[Value]) -> Option<Value>,
Same as connect_unsafe but takes a SignalId instead of a signal name.
Emit signal by signal id.
Same as emit but takes Value for the arguments.
Emit signal by its name.
Same as emit_by_name but takes Value for the arguments.
Emit signal with details by signal id.
Same as emit_with_details but takes Value for the arguments.
pub fn connect_notify<F>(&self, name: Option<&str>, f: F) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec) + Send + Sync,
pub fn connect_notify_local<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: 'static + Fn(&T, &ParamSpec),
pub unsafe fn connect_notify_unsafe<F>(
&self,
name: Option<&str>,
f: F
) -> SignalHandlerId where
F: Fn(&T, &ParamSpec),
pub fn bind_property<'a, O, N, M>(
&'a self,
source_property: N,
target: &'a O,
target_property: M
) -> BindingBuilder<'a> where
O: ObjectType,
N: Into<&'a str>,
M: Into<&'a str>,
Returns a SendValue clone of self.