I have this code:

public static String scaleImage(ImageElement imageElement, String mime_type) {
    Canvas canvasTmp = Canvas.createIfSupported();
    Context2d context = canvasTmp.getContext2d();
    canvasTmp.setCoordinateSpaceWidth(imageElement.getWidth());
    canvasTmp.setCoordinateSpaceHeight(imageElement.getHeight());
    context.drawImage(imageElement, 0, 0, imageElement.getWidth(), imageElement.getHeight());
    // How to set quality?
    String tempStr = canvasTmp.toDataUrl(mime_type);
    return tempStr;
}

The problem with this code is the output String tempStr is just data:,