Android的自定义视图与处理程序 [英] Android Custom View with Handler

问题描述

我要寻找一个简单的方法在Android的动画自定义视图。我试图避免使用动画对象，但要与原纱一起工作。我已经通过创建一类来完成创建一个自定义视图扩展 android.view.View。然后，我重写的onDraw 方式和使用画布绘制一个矩形。我想是缩小矩形，所以我保持这种重新presents矩形的右侧的x值的变量。然后我会像矩形的右边缘收缩在一段时间。我也喜欢做的就是创建一个新的线程，启动它，并让它改变矩形的值。 ，除了该视图的所有作品没有得到更新，直到你调用 View.invalidate 。问题是，因为它不是UI线程我不能调用从我催生了线程。我使用的处理程序阅读解决方案...但我仍然不能确定，如果这是正确的解决方案，以及如何使用它们。

 包com.example.practicum;进口android.content.Context;
进口android.graphics.Canvas;
进口android.graphics.Color;
进口android.graphics.Paint;
进口android.graphics.Rect;
进口android.os.Handler;
进口android.os.Message;
进口android.util.AttributeSet;
进口android.view.View;公共类TimerControl扩展视​​图实现Runnable，Handler.Callback
{
    私人涂料粉刷;
    私人矩形RECT;
    私人线程t;
    私人处理程序H;    公共TimerControl（上下文的背景下，ATTRS的AttributeSet）
    {
        超（背景下，ATTRS）;
        // TODO自动生成构造函数存根        油漆=新的油漆（）;
        paint.setColor（Color.BLUE）;
        RECT =新的矩形（0,0,60,60）;
        T =新的Thread（本）;
        t.start（）;
        H =新的处理程序（本）;
        //h.post(this）;
    }    @覆盖
    公共无效的onDraw（帆布油画）
    {
        canvas.drawRect（RECT，油漆）;
    }    @覆盖
    公共无效的run（）
    {
        rect.right = rect.right-1;
        而（真）
        {
            rect.right = rect.right-1;
            this.invalidate（）;
            尝试
            {
                视频下载（5000）;
                h.sendEmptyMessage（0）;
            }
            赶上（InterruptedException的E）
            {
                // TODO自动生成catch块
                e.printStackTrace（）;
            }
        }
    }    @覆盖
    公共布尔的handleMessage（消息MSG）
    {        返回false;
    }}
 

解决方案

您可以定义一个全局处理程序（在UI线程）：

 处理程序mHandler =新的处理程序（）;
 

那么，从你的线程，请致电：

  mHandler.post（新的Runnable（）{
    公共无效的run（）{
        //调用UI线程上的一些方法
    }
}）;
 

I am looking for an easy way to animate custom views in Android. I am trying to avoid using the animator object but want to work with raw threads. What I have done is created a custom view by creating a class that extends android.view.View. I then override the onDraw method and use the canvas to draw a rect. What I would like is the rect to shrink, so I keep a variable that represents the x value of the right hand side of the rectangle. I would then like the the rectangle's right edge shrink in over time. What I would have liked to do is create a new thread, start it and have it change the value of the rectangle. That all works except the view doesn't get updated until you call View.invalidate. The problem is that I can't call that from the thread that I spawned because it is not the UI thread. I read solutions on using Handlers... but I am still unsure if that is the correct solution and then how to use them.

package com.example.practicum;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;

public class TimerControl extends View implements Runnable, Handler.Callback
{
    private Paint paint;
    private Rect rect;
    private Thread t;
    private Handler h;

    public TimerControl(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        // TODO Auto-generated constructor stub



        paint = new Paint();
        paint.setColor(Color.BLUE);
        rect = new Rect(0,0,60,60);
        t = new Thread(this);
        t.start();


        h = new Handler(this);
        //h.post(this);
    }

    @Override
    public void onDraw(Canvas canvas)
    {
        canvas.drawRect(rect, paint);
    }

    @Override
    public void run()
    {
        rect.right = rect.right-1;
        while(true)
        {
            rect.right = rect.right-1;
            this.invalidate();
            try
            {
                Thread.sleep(5000);
                h.sendEmptyMessage(0);
            } 
            catch (InterruptedException e)
            {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    @Override
    public boolean handleMessage(Message msg)
    {

        return false;
    }

}

解决方案

you can define a global Handler (in the UI thread):

Handler mHandler = new Handler();

then, from your thread, call:

mHandler.post(new Runnable() {
    public void run() {             
        // call some method on the UI thread
    }
});

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