Struct gtk4::TreeModelFilter [−][src]
pub struct TreeModelFilter(_);Expand description
A TreeModel which hides parts of an underlying tree model
A TreeModelFilter is a tree model which wraps another tree model,
and can do the following things:
-
Filter specific rows, based on data from a “visible column”, a column storing booleans indicating whether the row should be filtered or not, or based on the return value of a “visible function”, which gets a model, iter and user_data and returns a boolean indicating whether the row should be filtered or not.
-
Modify the “appearance” of the model, using a modify function. This is extremely powerful and allows for just changing some values and also for creating a completely different model based on the given child model.
-
Set a different root node, also known as a “virtual root”. You can pass in a
TreePathindicating the root node for the filter at construction time.
The basic API is similar to TreeModelSort. For an example on its usage,
see the section on TreeModelSort.
When using TreeModelFilter, it is important to realize that
TreeModelFilter maintains an internal cache of all nodes which are
visible in its clients. The cache is likely to be a subtree of the tree
exposed by the child model. TreeModelFilter will not cache the entire
child model when unnecessary to not compromise the caching mechanism
that is exposed by the reference counting scheme. If the child model
implements reference counting, unnecessary signals may not be emitted
because of reference counting rule 3, see the TreeModel
documentation. (Note that e.g. TreeStore does not implement
reference counting and will always emit all signals, even when
the receiving node is not visible).
Because of this, limitations for possible visible functions do apply.
In general, visible functions should only use data or properties from
the node for which the visibility state must be determined, its siblings
or its parents. Usually, having a dependency on the state of any child
node is not possible, unless references are taken on these explicitly.
When no such reference exists, no signals may be received for these child
nodes (see reference counting rule number 3 in the TreeModel section).
Determining the visibility state of a given node based on the state
of its child nodes is a frequently occurring use case. Therefore,
TreeModelFilter explicitly supports this. For example, when a node
does not have any children, you might not want the node to be visible.
As soon as the first row is added to the node’s child level (or the
last row removed), the node’s visibility should be updated.
This introduces a dependency from the node on its child nodes. In order
to accommodate this, TreeModelFilter must make sure the necessary
signals are received from the child model. This is achieved by building,
for all nodes which are exposed as visible nodes to TreeModelFilter’s
clients, the child level (if any) and take a reference on the first node
in this level. Furthermore, for every row-inserted, row-changed or
row-deleted signal (also these which were not handled because the node
was not cached), TreeModelFilter will check if the visibility state
of any parent node has changed.
Beware, however, that this explicit support is limited to these two
cases. For example, if you want a node to be visible only if two nodes
in a child’s child level (2 levels deeper) are visible, you are on your
own. In this case, either rely on TreeStore to emit all signals
because it does not implement reference counting, or for models that
do implement reference counting, obtain references on these child levels
yourself.
Implements
TreeModelFilterExt, glib::ObjectExt, TreeDragSourceExt, TreeModelExt, TreeModelFilterExtManual, TreeModelExtManual
Implementations
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 TreeModelFilter
impl !Send for TreeModelFilter
impl !Sync for TreeModelFilter
impl Unpin for TreeModelFilter
impl UnwindSafe for TreeModelFilter
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.