Android-在invalidate()上重绘后的侦听器 [英] Android - listener after redrawing on invalidate()

问题描述

在我要求视图无效后，我希望在视图完成重绘后收到通知.如此答案中所述，invalidate()方法不会立即调用视图的onDraw() UI，而是安排在主线程空闲后执行的消息队列中重画.

I'd like to be notified after the view finishes redrawing after I ask it to invalidate. As said in this answer, the invalidate() method doesn't call a View's onDraw() the UI immediately, but schedules the repaint in a message queue which is executed after when the main thread is idle.

我想显示一个进度对话框，进行一些UI修改，然后在正确绘制视图时关闭该对话框.有什么技巧可以知道何时绘制视图?也许是通过子类化视图，覆盖onDraw()方法?

I'd like to show a progress dialog, do some UI modifications and then dismiss the dialog when the view is drawn properly. Is there some trick that I can do to know when the View was drawn? Maybe by subclassing the view, overriding the onDraw() method?

推荐答案

我认为您已经回答了自己的问题.为什么不呢?

I think you answered your question yourself. Why not:

public class DrawListenerView extends View{
    private Callback callback;
    public DrawListenerView(Callback callback){
        this.callback = callback;
    }

    @Override
    protected void onDraw (Canvas canvas){
        super.onDraw(canvas);

        //add your method here you want to call
        //Or use a Callback-pattern 
        callback.finish();
    } 
}

public interface Callback(){
    public void finish();
}

如果您查看来源:

上面的评论说

使整个视图无效.如果该视图可见，则将来会在某个时候调用onDraw(android.graphics.Canvas).必须从UI线程调用此方法.要从非UI线程进行调用，请调用postInvalidate().

Invalidate the whole view. If the view is visible, onDraw(android.graphics.Canvas) will >be called at some point in the future. This must be called from a UI thread. To call from >a non-UI thread, call postInvalidate().

尝试一下:)

可能您想使用回调来处理此问题.

probably you want to use a Callback to handle this.

这篇关于Android-在invalidate()上重绘后的侦听器的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！