Image class

A widget that displays an image.

Several constructors are provided for the various ways that an image can be specified:

The following image formats are supported: JPEG, PNG, GIF, Animated GIF, WebP, Animated WebP, BMP, and WBMP. Additional formats may be supported by the underlying platform. Flutter will attempt to call platform API to decode unrecognized formats, and if the platform API supports decoding the image Flutter will be able to render it.

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.

An image of an owl displayed by the image widget

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.

An image of an owl displayed by the image widget using the shortcut constructor

Image.network('https://flutter.github.io/assets-for-api-docs/assets/widgets/owl-2.jpg')

{@end-tool}

Memory usage

The image is stored in memory in uncompressed form (so that it can be rendered). Large images will use a lot of memory: a 4K image (3840×2160) will use over 30MB of RAM (assuming 32 bits per pixel).

This problem is exacerbated by the images being cached in the ImageCache, so large images can use memory for even longer than they are displayed.

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 then decode and store the image at the specified size, instead of the image's natural size.

This can significantly reduce the memory usage. For example, a 4K image that will be rendered at only 384×216 pixels (one-tenth the horizontal and vertical dimensions) would only use 330KB if those dimensions are specified using the cacheWidth and cacheHeight parameters, a 100-fold reduction in memory usage.

Web considerations

In the case where a network image is used on the Web platform, the cacheWidth and cacheHeight parameters are only supported when the application is running with the CanvasKit renderer. When the application is using the HTML renderer, the web engine delegates image decoding of network images to the Web, which does not support custom decode sizes.

Custom image providers

{@tool dartpad} In this example, a variant of NetworkImage is created that passes all the ImageConfiguration information (locale, platform, size, etc) to the server using query arguments in the image URL.

** See code in examples/api/lib/painting/image_provider/image_provider.0.dart ** {@end-tool}

See also:

Inheritance

Constructors

Image({Key? key, required ImageProvider<Object> image, 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, FilterQuality filterQuality = FilterQuality.low})
Creates a widget that displays an image.
const
Image.asset(String name, {Key? key, AssetBundle? bundle, ImageFrameBuilder? frameBuilder, ImageErrorWidgetBuilder? errorBuilder, String? semanticLabel, bool excludeFromSemantics = false, double? scale, 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, String? package, FilterQuality filterQuality = FilterQuality.low, int? cacheWidth, int? cacheHeight})
Creates a widget that displays an ImageStream obtained from an asset bundle. The key for the image is given by the name argument.
Image.file(File file, {Key? key, double scale = 1.0, ImageFrameBuilder? frameBuilder, 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, FilterQuality filterQuality = FilterQuality.low, int? cacheWidth, int? cacheHeight})
Creates a widget that displays an ImageStream obtained from a File.
Image.memory(Uint8List bytes, {Key? key, double scale = 1.0, ImageFrameBuilder? frameBuilder, 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, FilterQuality filterQuality = FilterQuality.low, int? cacheWidth, int? cacheHeight})
Creates a widget that displays an ImageStream obtained from a Uint8List.
Image.network(String src, {Key? key, double scale = 1.0, 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, FilterQuality filterQuality = FilterQuality.low, bool isAntiAlias = false, Map<String, String>? headers, int? cacheWidth, int? cacheHeight})
Creates a widget that displays an ImageStream obtained from the network.

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 (in logical pixels).
final
image → ImageProvider<Object>
The image to display.
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
semanticLabel → String?
A Semantic description of the image.
final
width → double?
If non-null, require the image to have this width (in logical pixels).
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<Image>
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, 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