AspectRatio 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.
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).
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.
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
Constructors
- AspectRatio({Key key, @required double aspectRatio, Widget child })
-
Creates a widget with a specific aspect ratio. [...]
const
Properties
- aspectRatio → double
-
The aspect ratio to attempt to use. [...]
final
- child → Widget
-
The widget below this widget in the tree. [...]
final, inherited
- hashCode → int
-
The hash code for this object. [...]
read-only, inherited
- key → Key
-
Controls how one widget replaces another widget in the tree. [...]
final, inherited
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Methods
-
createRenderObject(
BuildContext context) → RenderAspectRatio -
Creates an instance of the RenderObject class that this
RenderObjectWidget represents, using the configuration described by this
RenderObjectWidget. [...]
override
-
debugFillProperties(
DiagnosticPropertiesBuilder properties) → void -
Add additional properties associated with the node. [...]
override
-
updateRenderObject(
BuildContext context, covariant RenderAspectRatio renderObject) → void -
Copies the configuration described by this RenderObjectWidget to the
given RenderObject, which will be of the same type as returned by this
object's createRenderObject. [...]
override
-
createElement(
) → SingleChildRenderObjectElement -
RenderObjectWidgets always inflate to a RenderObjectElement subclass.
inherited
-
debugDescribeChildren(
) → List< DiagnosticsNode> -
Returns a list of DiagnosticsNode objects describing this node's
children. [...]
@protected, inherited
-
didUnmountRenderObject(
covariant RenderObject renderObject) → void -
A render object previously associated with this widget has been removed
from the tree. The given RenderObject will be of the same type as
returned by this object's createRenderObject.
@protected, inherited
-
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent 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 toStringDeep. [...]
inherited
-
toString(
{DiagnosticLevel minLevel: DiagnosticLevel.debug }) → String -
Returns a string representation of this object.
inherited
-
toStringDeep(
{String prefixLineOne: '', String prefixOtherLines, DiagnosticLevel minLevel: DiagnosticLevel.debug }) → 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 ==(
dynamic other) → bool -
The equality operator. [...]
inherited