decodeIsolate function
Implementation
void decodeIsolate(DecodeParam param) {
if (param.bytes == null) {
param.sendPort?.send(null);
return;
}
// Read an image from file (webp in this case).
// decodeImage will identify the format of the image and use the appropriate
// decoder.
var image2 = imageProcess2(param);
param.sendPort?.send(image2);
}