ExactAssetImage class
Fetches an image from an AssetBundle, associating it with the given scale.
This implementation requires an explicit final assetName and scale on construction, and ignores the device pixel ratio and size in the configuration passed into resolve. For a resolution-aware variant that uses the configuration to pick an appropriate image based on the device pixel ratio and size, see AssetImage.
Fetching assets
When fetching an image provided by the app itself, use the assetName
argument to name the asset to choose. For instance, consider a directory
icons
with an image heart.png
. First, the pubspec.yaml
of the project
should specify its assets in the flutter
section:
flutter:
assets:
- icons/heart.png
Then, to fetch the image and associate it with scale 1.5
, use
AssetImage('icons/heart.png', scale: 1.5)
Assets in packages
To fetch an asset from a package, the package argument must be provided.
For instance, suppose the structure above is inside a package called
my_icons
. Then to fetch the image, use:
AssetImage('icons/heart.png', scale: 1.5, package: 'my_icons')
Assets used by the package itself should also be fetched using the package argument as above.
If the desired asset is specified in the pubspec.yaml
of the package, it
is bundled automatically with the app. In particular, assets used by the
package itself must be specified in its pubspec.yaml
.
A package can also choose to have assets in its 'lib/' folder that are not
specified in its pubspec.yaml
. In this case for those images to be
bundled, the app has to specify which ones to include. For instance a
package named fancy_backgrounds
could have:
lib/backgrounds/background1.png
lib/backgrounds/background2.png
lib/backgrounds/background3.png
To include, say the first image, the pubspec.yaml
of the app should specify
it in the assets
section:
assets:
- packages/fancy_backgrounds/backgrounds/background1.png
The lib/
is implied, so it should not be included in the asset path.
See also:
- Image.asset for a shorthand of an Image widget backed by ExactAssetImage when using a scale.
- Inheritance
- Object
- ImageProvider<
AssetBundleImageKey> - AssetBundleImageProvider
- ExactAssetImage
Constructors
- ExactAssetImage(String assetName, { double scale: 1.0, AssetBundle bundle, String package })
-
Creates an object that fetches the given image from an asset bundle. [...]
const
Properties
- assetName → String
-
The name of the asset.
final
- bundle → AssetBundle
-
The bundle from which the image will be obtained. [...]
final
- hashCode → int
-
The hash code for this object. [...]
read-only, override
- keyName → String
-
The key to use to obtain the resource from the bundle. This is the
argument passed to AssetBundle.load.
read-only
- package → String
-
The name of the package from which the image is included. See the
documentation for the ExactAssetImage class itself for details.
final
- scale → double
-
The scale to place in the ImageInfo object of the image.
final
- runtimeType → Type
-
A representation of the runtime type of the object.
read-only, inherited
Methods
-
obtainKey(
ImageConfiguration configuration) → Future< AssetBundleImageKey> -
Converts an ImageProvider's settings plus an ImageConfiguration to a key
that describes the precise image to load. [...]
override
-
toString(
) → String -
Returns a string representation of this object.
override
-
evict(
{ImageCache cache, ImageConfiguration configuration: ImageConfiguration.empty }) → Future< bool> -
Evicts an entry from the image cache. [...]
inherited
-
load(
AssetBundleImageKey key) → ImageStreamCompleter -
Converts a key into an ImageStreamCompleter, and begins fetching the
image using
loadAsync
.inherited -
noSuchMethod(
Invocation invocation) → dynamic -
Invoked when a non-existent method or property is accessed. [...]
inherited
-
resolve(
ImageConfiguration configuration) → ImageStream -
Resolves this image provider using the given
configuration
, returning an ImageStream. [...]inherited
Operators
-
operator ==(
dynamic other) → bool -
The equality operator. [...]
override