Image.file constructor Null safety

Image.file(
  1. File file,
  2. {Key? key,
  3. double scale = 1.0,
  4. ImageFrameBuilder? frameBuilder,
  5. ImageErrorWidgetBuilder? errorBuilder,
  6. String? semanticLabel,
  7. bool excludeFromSemantics,
  8. double? width,
  9. double? height,
  10. Color? color,
  11. Animation<double>? opacity,
  12. BlendMode? colorBlendMode,
  13. BoxFit? fit,
  14. AlignmentGeometry alignment,
  15. ImageRepeat repeat,
  16. Rect? centerSlice,
  17. bool matchTextDirection,
  18. bool gaplessPlayback,
  19. bool isAntiAlias,
  20. FilterQuality filterQuality,
  21. int? cacheWidth,
  22. int? cacheHeight}
)

Creates a widget that displays an ImageStream obtained from a File.

The file, scale, and repeat arguments must not be null.

Either the width and height arguments should be specified, or the widget should be placed in a context that sets tight layout constraints. Otherwise, the image dimensions will change as the image is loaded, which will result in ugly layout changes.

On Android, this may require the android.permission.READ_EXTERNAL_STORAGE permission.

Use filterQuality to specify the rendering quality of the image.

If excludeFromSemantics is true, then semanticLabel will be ignored.

If cacheWidth or cacheHeight are provided, it indicates to the engine that the image must be decoded at the specified size. The image will be rendered to the constraints of the layout or width and height regardless of these parameters. These parameters are primarily intended to reduce the memory usage of ImageCache.

Loading an image from a file creates an in memory copy of the file, which is retained in the ImageCache. The underlying file is not monitored for changes. If it does change, the application should evict the entry from the ImageCache.

See also:

  • FileImage provider for evicting the underlying file easily.

Implementation

Image.file(
  File file, {
  Key? key,
  double scale = 1.0,
  this.frameBuilder,
  this.errorBuilder,
  this.semanticLabel,
  this.excludeFromSemantics = false,
  this.width,
  this.height,
  this.color,
  this.opacity,
  this.colorBlendMode,
  this.fit,
  this.alignment = Alignment.center,
  this.repeat = ImageRepeat.noRepeat,
  this.centerSlice,
  this.matchTextDirection = false,
  this.gaplessPlayback = false,
  this.isAntiAlias = false,
  this.filterQuality = FilterQuality.low,
  int? cacheWidth,
  int? cacheHeight,
}) : image = ResizeImage.resizeIfNeeded(cacheWidth, cacheHeight, FileImage(file, scale: scale)),
     loadingBuilder = null,
     assert(alignment != null),
     assert(repeat != null),
     assert(filterQuality != null),
     assert(matchTextDirection != null),
     assert(cacheWidth == null || cacheWidth > 0),
     assert(cacheHeight == null || cacheHeight > 0),
     assert(isAntiAlias != null),
     super(key: key);