AspectRatioModifier class
A widget that attempts to size the child to a specific aspect ratio.
The widget first tries the largest width permitted by the layout constraints. The height of the widget is determined by applying the given aspect ratio to the width, expressed as a ratio of width to height.
For example, a 16:9 width:height aspect ratio would have a value of 16.0/9.0. If the maximum width is infinite, the initial width is determined by applying the aspect ratio to the maximum height.
{@tool dartpad} This examples shows how AspectRatio sets width when its parent's width constraint is infinite. Since its parent's allowed height is a fixed value, the actual width is determined via the given AspectRatio.
Since the height is fixed at 100.0 in this example and the aspect ratio is set to 16 / 9, the width should then be 100.0 / 9 * 16.
** See code in examples/api/lib/widgets/basic/aspect_ratio.0.dart ** {@end-tool}
Now consider a second example, this time with an aspect ratio of 2.0 and layout constraints that require the width to be between 0.0 and 100.0 and the height to be between 0.0 and 100.0. We'll select a width of 100.0 (the biggest allowed) and a height of 50.0 (to match the aspect ratio).
{@tool dartpad}
** See code in examples/api/lib/widgets/basic/aspect_ratio.1.dart ** {@end-tool}
In that same situation, if the aspect ratio is 0.5, we'll also select a width of 100.0 (still the biggest allowed) and we'll attempt to use a height of 200.0. Unfortunately, that violates the constraints because the child can be at most 100.0 pixels tall. The widget will then take that value and apply the aspect ratio again to obtain a width of 50.0. That width is permitted by the constraints and the child receives a width of 50.0 and a height of 100.0. If the width were not permitted, the widget would continue iterating through the constraints. If the widget does not find a feasible size after consulting each constraint, the widget will eventually select a size for the child that meets the layout constraints but fails to meet the aspect ratio constraints.
{@tool dartpad}
** See code in examples/api/lib/widgets/basic/aspect_ratio.2.dart ** {@end-tool}
See also:
- Align, a widget that aligns its child within itself and optionally sizes itself based on the child's size.
- ConstrainedBox, a widget that imposes additional constraints on its child.
- UnconstrainedBox, a container that tries to let its child draw without constraints.
- The catalog of layout widgets.
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatelessWidget
- SingleChildStatelessModifier
- AspectRatioModifier
- Available extensions
Constructors
- AspectRatioModifier({Key? key, Widget? child, Key? modifierKey, required double aspectRatio})
-
Creates a widget with a specific aspect ratio.
const
Properties
- aspectRatio → double
-
The aspect ratio to attempt to use.
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- modifierKey → Key?
-
The actual key of the widget, which Modifier wrapped
finalinherited
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
Methods
-
build(
BuildContext context) → Widget -
Describes the part of the user interface represented by this widget.
inherited
-
buildWithChild(
BuildContext context, Widget? child) → Widget -
A build method that receives an extra
childparameter.override -
createElement(
) → SingleChildStatelessElement -
Create a SingleChildStatelessElement
inherited
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of DiagnosticsNode objects describing this node's
children.
inherited
-
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node.
inherited
-
modified(
) → Modifier -
Available on Widget, provided by the ModifierTransformer extension
Transform normal widget to Modifier -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a nonexistent method or property is accessed.
inherited
-
toDiagnosticsNode(
{String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode -
Returns a debug representation of the object that is used by debugging
tools and by DiagnosticsNode.toStringDeep.
inherited
-
toString(
{DiagnosticLevel minLevel = DiagnosticLevel.info}) → String -
A string representation of this object.
inherited
-
toStringDeep(
{String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug, int wrapWidth = 65}) → String -
Returns a string representation of this node and its descendants.
inherited
-
toStringShallow(
{String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String -
Returns a one-line detailed description of the object.
inherited
-
toStringShort(
) → String -
A short, textual description of this widget.
inherited
Operators
-
operator ==(
Object other) → bool -
The equality operator.
inherited