ResizeImage class

Instructs Flutter to decode the image at the specified dimensions instead of at its native size.

The width and height parameters refer to logical pixels.

Logical pixels have roughly the same visual size across devices, whereas physical pixels correspond to actual device hardware. The number of physical pixels per logical pixel is described by the ui.FlutterView.devicePixelRatio.

This allows finer control of the size of the image in ImageCache and is generally used to reduce the memory footprint of ImageCache.

The decoded image may still be displayed at sizes other than the cached size provided here.

This example shows how to size the image to half of the screen's width.

   Image(
     image: ResizeImage(
       FileImage(File('path/to/image')),
       width: MediaQuery.sizeOf(context).width ~/ 2, // Half of the screen's width.
     ),
   );

Inheritance

Constructors

ResizeImage(ImageProvider<Object> imageProvider, {int? width, int? height, ResizeImagePolicy policy = ResizeImagePolicy.exact, bool allowUpscaling = false}): Creates an ImageProvider that decodes the image to the specified size.
const

Properties

allowUpscaling → bool: Whether the width and height parameters should be clamped to the intrinsic width and height of the image.
final
hashCode → int: The hash code for this object.
no setterinherited
height → int?: The height the image should decode to and cache.
final
imageProvider → ImageProvider<Object>: The ImageProvider that this class wraps.
final
policy → ResizeImagePolicy: The policy that determines how width and height are interpreted.
final
runtimeType → Type: A representation of the runtime type of the object.
no setterinherited
width → int?: The width the image should decode to and cache.
final

Methods

createStream(ImageConfiguration configuration) → ImageStream: Called by resolve to create the ImageStream it returns.
inherited
evict({ImageCache? cache, ImageConfiguration configuration = ImageConfiguration.empty}) → Future<bool>: Evicts an entry from the image cache.
inherited
loadBuffer(ResizeImageKey key, DecoderBufferCallback decode) → ImageStreamCompleter: Converts a key into an ImageStreamCompleter, and begins fetching the image.
override
loadImage(ResizeImageKey key, ImageDecoderCallback decode) → ImageStreamCompleter: Converts a key into an ImageStreamCompleter, and begins fetching the image.
override
noSuchMethod(Invocation invocation) → dynamic: Invoked when a nonexistent method or property is accessed.
inherited
obtainCacheStatus({required ImageConfiguration configuration, ImageErrorListener? handleError}) → Future<ImageCacheStatus?>: Returns the cache location for the key that this ImageProvider creates.
inherited
obtainKey(ImageConfiguration configuration) → Future<ResizeImageKey>: Converts an ImageProvider's settings plus an ImageConfiguration to a key that describes the precise image to load.
override
resolve(ImageConfiguration configuration) → ImageStream: Resolves this image provider using the given configuration, returning an ImageStream.
inherited
resolveStreamForKey(ImageConfiguration configuration, ImageStream stream, ResizeImageKey key, ImageErrorListener handleError) → void: Called by resolve with the key returned by obtainKey.
inherited
toString() → String: A string representation of this object.
inherited

Operators

operator ==(Object other) → bool: The equality operator.
inherited

Static Methods

resizeIfNeeded(int? cacheWidth, int? cacheHeight, ImageProvider<Object> provider) → ImageProvider<Object>: Composes the provider in a ResizeImage only when cacheWidth and cacheHeight are not both null.