instantiateImageCodec function
Instantiates an image Codec.
The list
parameter is the binary image data (e.g a PNG or GIF binary data).
The data can be for either static or animated images. The following image
formats are supported: JPEG, PNG, GIF, Animated GIF, WebP, Animated WebP, BMP, and WBMP
The targetWidth
and targetHeight
arguments specify the size of the
output image, in image pixels. If they are not equal to the intrinsic
dimensions of the image, then the image will be scaled after being decoded.
If the allowUpscaling
parameter is not set to true, both dimensions will
be capped at the intrinsic dimensions of the image, even if only one of
them would have exceeded those intrinsic dimensions. If exactly one of these
two arguments is specified, then the aspect ratio will be maintained while
forcing the image to match the other given dimension. If neither is
specified, then the image maintains its intrinsic size.
Scaling the image to larger than its intrinsic size should usually be
avoided, since it causes the image to use more memory than necessary.
Instead, prefer scaling the Canvas transform. If the image must be scaled
up, the allowUpscaling
parameter must be set to true.
The returned future can complete with an error if the image decoding has failed.
Implementation
Future<Codec> instantiateImageCodec(
Uint8List list, {
int? targetWidth,
int? targetHeight,
bool allowUpscaling = true,
}) {
return _futurize((_Callback<Codec> callback) {
return _instantiateImageCodec(
list,
callback,
null,
targetWidth ?? _kDoNotResizeDimension,
targetHeight ?? _kDoNotResizeDimension,
allowUpscaling,
);
});
}