Image.file constructor
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 change the quality when scaling an image.
Use the FilterQuality.low quality setting to scale the image,
which corresponds to bilinear interpolation, rather than the default
FilterQuality.none which corresponds to nearest-neighbor.
If excludeFromSemantics is true, then semanticLabel will be ignored.
Implementation
Image.file(File file, {
  Key key,
  double scale = 1.0,
  this.semanticLabel,
  this.excludeFromSemantics = false,
  this.width,
  this.height,
  this.color,
  this.colorBlendMode,
  this.fit,
  this.alignment = Alignment.center,
  this.repeat = ImageRepeat.noRepeat,
  this.centerSlice,
  this.matchTextDirection = false,
  this.gaplessPlayback = false,
  this.filterQuality = FilterQuality.low,
}) : image = FileImage(file, scale: scale),
     assert(alignment != null),
     assert(repeat != null),
     assert(filterQuality != null),
     assert(matchTextDirection != null),
     super(key: key);