AsyncDrawable.java 文件源码

public void setCallback2(@Nullable Callback callback) {

        this.callback = callback;
        super.setCallback(callback);

        // if not null -> means we are attached
        if (callback != null) {
            loader.load(destination, this);
        } else {
            if (result != null) {

                result.setCallback(null);

                // let's additionally stop if it Animatable
                if (result instanceof Animatable) {
                    ((Animatable) result).stop();
                }
            }
            loader.cancel(destination);
        }
    }