ImageExt class
A widget that displays an image.
Several constructors are provided for the various ways that an image can be specified:
new Image, for obtaining an image from an ImageProvider.new Image.asset, for obtaining an image from an AssetBundle using a key.new Image.network, for obtaining an image from a URL.new Image.file, for obtaining an image from a File.new Image.memory, for obtaining an image from a Uint8List.
The following image formats are supported:
To automatically perform pixel-density-aware asset resolution, specify the image using an AssetImage and make sure that a MaterialApp, WidgetsApp, or MediaQuery widget exists above the Image widget in the widget tree.
The image is painted using paintImage, which describes the meanings of the various fields on this class in more detail.
{@tool snippet} The default constructor can be used with any ImageProvider, such as a NetworkImage, to display an image from the internet.
const Image(
image: NetworkImage('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl.jpg'),
)
{@end-tool}
{@tool snippet} The Image Widget also provides several constructors to display different types of images for convenience. In this example, use the Image.network constructor to display an image from the internet.
Image.network('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl-2.jpg')
{@end-tool}
The Image.asset, Image.network, Image.file, and Image.memory
constructors allow a custom decode size to be specified through
cacheWidth and cacheHeight parameters. The engine will decode the
image to the specified size, which is primarily intended to reduce the
memory usage of ImageCache.
In the case where a network image is used on the Web platform, the
cacheWidth and cacheHeight parameters are ignored as the Web engine
delegates image decoding of network images to the Web, which does not support
custom decode sizes.
See also:
- Icon, which shows an image from a font.
new Ink.image, which is the preferred way to show an image in a material application (especially if the image is in a Material and will have an InkWell on top of it).- Image, the class in the dart:ui library.
- Cookbook: Display images from the internet
- Cookbook: Work with cached images
- Cookbook: Fade in images with a placeholder
- Inheritance
-
- Object
- DiagnosticableTree
- Widget
- StatefulWidget
- ImageExt
Constructors
-
ImageExt({Key? key, required ImageProvider<
Object> image, CustomImageBuilder? imageBuilder, ImageFrameBuilder? frameBuilder, ImageLoadingBuilder? loadingBuilder, ImageErrorWidgetBuilder? errorBuilder, String? semanticLabel, bool excludeFromSemantics = false, double? width, double? height, Color? color, Animation<double> ? opacity, BlendMode? colorBlendMode, BoxFit? fit, AlignmentGeometry alignment = Alignment.center, ImageRepeat repeat = ImageRepeat.noRepeat, Rect? centerSlice, bool matchTextDirection = false, bool gaplessPlayback = false, bool isAntiAlias = false, bool scrollAwareEnable = false, FilterQuality filterQuality = FilterQuality.low}) -
Creates a widget that displays an image.
const
Properties
- alignment → AlignmentGeometry
-
How to align the image within its bounds.
final
- centerSlice → Rect?
-
The center slice for a nine-patch image.
final
- color → Color?
-
If non-null, this color is blended with each image pixel using colorBlendMode.
final
- colorBlendMode → BlendMode?
-
Used to combine color with this image.
final
- errorBuilder → ImageErrorWidgetBuilder?
-
A builder function that is called if an error occurs during image loading.
final
- excludeFromSemantics → bool
-
Whether to exclude this image from semantics.
final
- filterQuality → FilterQuality
-
The rendering quality of the image.
final
- fit → BoxFit?
-
How to inscribe the image into the space allocated during layout.
final
- frameBuilder → ImageFrameBuilder?
-
A builder function responsible for creating the widget that represents
this image.
final
- gaplessPlayback → bool
-
Whether to continue showing the old image (true), or briefly show nothing
(false), when the image provider changes. The default value is false.
final
- hashCode → int
-
The hash code for this object.
no setterinherited
- height → double?
-
If non-null, require the image to have this height.
final
-
image
→ ImageProvider<
Object> -
The image to display.
final
- imageBuilder → CustomImageBuilder?
-
final
- isAntiAlias → bool
-
Whether to paint the image with anti-aliasing.
final
- key → Key?
-
Controls how one widget replaces another widget in the tree.
finalinherited
- loadingBuilder → ImageLoadingBuilder?
-
A builder that specifies the widget to display to the user while an image
is still loading.
final
- matchTextDirection → bool
-
Whether to paint the image in the direction of the TextDirection.
final
-
opacity
→ Animation<
double> ? -
If non-null, the value from the Animation is multiplied with the opacity
of each image pixel before painting onto the canvas.
final
- repeat → ImageRepeat
-
How to paint any portions of the layout bounds not covered by the image.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
no setterinherited
- scrollAwareEnable → bool
-
Whether to avoid loading images when rapidly scrolling.
final
- semanticLabel → String?
-
A Semantic description of the image.
final
- width → double?
-
If non-null, require the image to have this width.
final
Methods
-
createElement(
) → StatefulElement -
Creates a StatefulElement to manage this widget's location in the tree.
inherited
-
createState(
) → State< ImageExt> -
Creates the mutable state for this widget at a given location in the tree.
override
-
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.
override
-
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}) → 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