performLayout method
布局
Implementation
performLayout(PrinterConstraints constraints, PrinterCanvas canvas) {
super.performLayout(constraints, canvas);
List<List<bool>>? image = this.getValue(dataSource);
if (image != null && image.length > 0) {
double imageWidth = image[0].length.toDouble();
actualSize = PrinterSize(imageWidth, image.length.toDouble());
}
}