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Setting container width
To specify the width of a Container
widget, use its width property.
This is a fixed width, unlike the CSS max-width property
that adjusts the container width up to a maximum value.
To mimic that effect in Flutter,
use the constraints property of the Container.
Create a new BoxConstraints widget with a minWidth or maxWidth.For nested Containers, if the parent’s width is less than the child’s width,
the child Container sizes itself to match the parent.<topic_end>
<topic_start>
Manipulating position and size
The following examples show how to perform more complex operations
on widget position, size, and background.<topic_end>
<topic_start>
Setting absolute position
By default, widgets are positioned relative to their parent.To specify an absolute position for a widget as x-y coordinates,
nest it in a Positioned widget that is,
in turn, nested in a Stack widget.<topic_end>
<topic_start>
Rotating components
To rotate a widget, nest it in a Transform widget.
Use the Transform widget’s alignment and origin properties
to specify the transform origin (fulcrum) in relative and absolute terms,
respectively.For a simple 2D rotation, in which the widget is rotated on the Z axis,
create a new Matrix4 identity object
and use its rotateZ() method to specify the rotation factor
using radians (degrees × π / 180).<topic_end>
<topic_start>
Scaling components
To scale a widget up or down, nest it in a Transform widget.
Use the Transform widget’s alignment and origin properties
to specify the transform origin (fulcrum) in relative or absolute terms,
respectively.For a simple scaling operation along the x-axis,
create a new Matrix4 identity object
and use its scale() method to specify the scaling factor.When you scale a parent widget,
its child widgets are scaled accordingly.<topic_end>
<topic_start>
Applying a linear gradient
To apply a linear gradient to a widget’s background,
nest it in a Container widget.
Then use the Container widget’s decoration property to create a
BoxDecoration object, and use BoxDecoration’s gradient
property to transform the background fill.The gradient “angle” is based on the Alignment (x, y) values:<topic_end>
<topic_start>Vertical gradient
<topic_end>
<topic_start>Horizontal gradient
<topic_end>
<topic_start>
Manipulating shapes
The following examples show how to make and customize shapes.<topic_end>
<topic_start>
Rounding corners
To round the corners of a rectangular shape,
use the borderRadius property of a BoxDecoration object.
Create a new BorderRadius
object that specifies the radius for rounding each corner.<topic_end>
<topic_start>
Adding box shadows
In CSS you can specify shadow offset and blur in shorthand,
using the box-shadow property. This example shows two box shadows,
with properties:In Flutter, each property and value is specified separately.
Use the boxShadow property of BoxDecoration to create a list of
BoxShadow widgets. You can define one or multiple
BoxShadow widgets, which can be stacked
to customize the shadow depth, color, and so on.<topic_end>
<topic_start>
Making circles and ellipses
Making a circle in CSS requires a workaround of applying a
border-radius of 50% to all four sides of a rectangle,
though there are basic shapes.While this approach is supported
with the borderRadius property of BoxDecoration,
Flutter provides a shape property
with BoxShape enum for this purpose.<topic_end>
<topic_start>
Manipulating text
The following examples show how to specify fonts and other
text attributes. They also show how to transform text strings,
customize spacing, and create excerpts.<topic_end>
<topic_start>
Adjusting text spacing
In CSS, you specify the amount of white space
between each letter or word by giving a length value
for the letter-spacing and word-spacing properties, respectively.
The amount of space can be in px, pt, cm, em, etc.In Flutter, you specify white space as logical pixels
(negative values are allowed)
for the letterSpacing and wordSpacing properties
of a TextStyle child of a Text widget.<topic_end>
<topic_start>
Making inline formatting changes
A Text widget lets you display text
with some formatting characteristics.
To display text that uses multiple styles
(in this example, a single word with emphasis),
use a RichText widget instead.
Its text property can specify one or more
TextSpan objects that can be individually styled.In the following example, “Lorem” is in a TextSpan
with the default (inherited) text styling,
and “ipsum” is in a separate TextSpan with custom styling.<topic_end>
<topic_start>
Creating text excerpts