Gnome::Gtk4::Constraint
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Description
Gnome::Gtk4::Constraint describes a constraint between attributes of two widgets, expressed as a linear equation.
The typical equation for a constraint is:
Each Gnome::Gtk4::Constraint is part of a system that will be solved by a Gnome::Gtk4::ConstraintLayout in order to allocate and position each child widget or guide.
The source and target, as well as their attributes, of a Gnome::Gtk4::Constraint instance are immutable after creation.
Uml Diagram =for image :src<asset_files/images/plantuml/Constraint.png> :width<70%> :class<inline>
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Class initialization
new
:native-object
Create an object using a native object from an object of the same type found elsewhere. See also Gnome::N::TopLevelSupportClass.
multi method new ( N-Object() :$native-object! )
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new-constraint
Creates a new constraint representing a relation between a layout attribute on a source and a layout attribute on a target.
method new-constraint ( gpointer $target, GtkConstraintAttribute $target-attribute, GtkConstraintRelation $relation, gpointer $source, GtkConstraintAttribute $source-attribute, Num() $multiplier, Num() $constant, Int() $strength --> Gnome::Gtk4::Constraint )
$target; the target of the constraint.
$target-attribute; the attribute of target to be set.
$relation; the relation equivalence between target_attribute and source_attribute.
$source; the source of the constraint.
$source-attribute; the attribute of source to be read.
$multiplier; a multiplication factor to be applied to source_attribute.
$constant; a constant factor to be added to source_attribute.
$strength; the strength of the constraint.
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new-constant
Creates a new constraint representing a relation between a layout attribute on a target and a constant value.
method new-constant ( gpointer $target, GtkConstraintAttribute $target-attribute, GtkConstraintRelation $relation, Num() $constant, Int() $strength --> Gnome::Gtk4::Constraint )
$target; a the target of the constraint.
$target-attribute; the attribute of target to be set.
$relation; the relation equivalence between target_attribute and constant.
$constant; a constant factor to be set on target_attribute.
$strength; the strength of the constraint.
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Methods
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get-constant
Retrieves the constant factor added to the source attributes' value.
method get-constant (--> Num )
Return value; a constant factor.
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get-multiplier
Retrieves the multiplication factor applied to the source attribute's value.
method get-multiplier (--> Num )
Return value; a multiplication factor.
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get-relation
The order relation between the terms of the constraint.
method get-relation (--> GtkConstraintRelation )
Return value; a relation type.
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get-source
Retrieves the Gnome::Gtk4::ConstraintLayout used as the source for the constraint.
If the source is set to undefined at creation, the constraint will use the widget using the Gnome::Gtk4::ConstraintLayout as the source.
method get-source (--> N-Object )
Return value; the source of the constraint.
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get-source-attribute
Retrieves the attribute of the source to be read by the constraint.
method get-source-attribute (--> GtkConstraintAttribute )
Return value; the source's attribute.
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get-strength
Retrieves the strength of the constraint.
method get-strength (--> Int )
Return value; the strength value.
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get-target
Retrieves the Gnome::Gtk4::ConstraintLayout used as the target for the constraint.
If the targe is set to undefined at creation, the constraint will use the widget using the Gnome::Gtk4::ConstraintLayout as the target.
method get-target (--> N-Object )
Return value; a Gnome::Gtk4::R-ConstraintTarget.
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get-target-attribute
Retrieves the attribute of the target to be set by the constraint.
method get-target-attribute (--> GtkConstraintAttribute )
Return value; the target's attribute.
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is-attached
Checks whether the constraint is attached to a Gnome::Gtk4::ConstraintLayout, and it is contributing to the layout.
method is-attached (--> Bool )
Return value; True if the constraint is attached.
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is-constant
Checks whether the constraint describes a relation between an attribute on the target and a constant value.
method is-constant (--> Bool )
Return value; True if the constraint is a constant relation.
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is-required
Checks whether the constraint is a required relation for solving the constraint layout.
method is-required (--> Bool )
Return value; True if the constraint is required.