在SurfaceView中模拟正弦波

在SurfaceView中模拟正弦波

本工程主要实现在SurfaceView中模拟正弦波形，首先把正弦波的Y轴的数据存储在数组里。使用canvas.drawline划线。

有两个问题：Timer和TimerTask的使用和划线区域的锁定

(1)   Timer和TimerTask调用cancel之后，Timer和TimerTask终止，但是Timer还存在，当再次使用使用Time. schedule(TimerTask task,long delay, long period)程序会报错，要解决这个错误首先要调用Timer.cancel()终止定时器，然后给Timer和TimerTask赋值为null。再次使用使用重新声明Timer和TimerTask。

(2)  划线区域的锁定最好是画那一块位置锁定那一块。这样画图效果较好，同时曲线的连接也比较好，不会出现断点。

布局文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:gravity="center"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/button1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginRight="15dp"
            android:text="@string/button1" />

        <Button
            android:id="@+id/button2"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginLeft="15dp"
            android:text="@string/button2" />

    </LinearLayout>

    <SurfaceView
        android:id="@+id/surfaceView1"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</LinearLayout>

主程序：

package com.example.sintest;

import java.util.Timer;
import java.util.TimerTask;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.Rect;
import android.view.Menu;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;

public class Sin1Activity extends Activity {
	
	private Button btnSimpleDraw,btnTimerDraw;
	private SurfaceView sfv;
	private SurfaceHolder sfd;
	
	private Timer mTimer;
	private MyTimerTask mTimerTask;
	
	int arrayY[],oldX,oldY,centerY,currentX;
	
	//设置TimerTask运行标志位
	private boolean taskFlag = false;
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_sin1);
        //获得控件的引用
        btnSimpleDraw = (Button)findViewById(R.id.button1);
        btnTimerDraw = (Button)findViewById(R.id.button2);
        sfv = (SurfaceView)findViewById(R.id.surfaceView1);
        sfd = sfv.getHolder();
        
        //数据初始化
        centerY = (getWindowManager().getDefaultDisplay().getHeight())/2;
        arrayY = new int[getWindowManager().getDefaultDisplay().getWidth()];
        for (int i = 0; i < arrayY.length; i++) {// 计算正弦波
			arrayY[i] = centerY
					- (int) (100 * Math.sin(i * 2 * Math.PI / 180));
		}
        
        btnSimpleDraw.setOnClickListener(new ButtonListener());
        btnTimerDraw.setOnClickListener(new ButtonListener());
    }

    
    public void simpleDraw(int length) {
		length = length - 1;
		
		Canvas canvas = sfd.lockCanvas(new Rect(oldX, 0, oldX + length,
				getWindowManager().getDefaultDisplay().getHeight()));
		
		Paint mPaint = new Paint();
		mPaint.setColor(Color.GREEN);
		mPaint.setStrokeWidth(2);
		
		int y;
		for (int i = oldX + 1; i <= length; i++) {
			y = arrayY[i];
			canvas.drawLine(oldX, oldY, i, y, mPaint);
			oldX = i;
			oldY = y;
		}
		
		sfd.unlockCanvasAndPost(canvas);
	}
    
    //清屏程序
    public void clearScreen() {
    	Canvas canvas = sfd.lockCanvas(null);
    	canvas.drawColor(Color.BLACK);
    	sfd.unlockCanvasAndPost(canvas);
	}
    
    //按键监听器类，实现按键的事件处理
    class ButtonListener implements OnClickListener{

		@Override
		public void onClick(View v) {
			// TODO Auto-generated method stub
			if (v == btnSimpleDraw) {
				//先判断TimerTask是否运行，如果运行就取消
				if (taskFlag) {
					mTimer.cancel();
					mTimer = null;
					mTimerTask = null;
					taskFlag = false;
				}
				//清一下屏幕
				clearScreen();
				//设置画图的起点
				oldX = 0;
				oldY = centerY;
				
				simpleDraw(arrayY.length);
				
			}
			
			if (v == btnTimerDraw) {
				if (taskFlag) {
					mTimer.cancel();
					mTimerTask = null;
					mTimer = null;
				}
				//清屏
				clearScreen();
				//设置画图的起点
				oldX = 0;
				oldY = centerY;
				currentX = 0;
				
				taskFlag = true;
				
				mTimer = new Timer();
				mTimerTask = new MyTimerTask();
				mTimer.schedule(mTimerTask, 0, 10);
				
			}
		}
    	
    }
    
    //定时器任务类，用于实现给定时处理的任务
    class MyTimerTask extends TimerTask{

		@Override
		public void run() {
			// TODO Auto-generated method stub
			simpleDraw(currentX);
			currentX++;
			if (currentX == arrayY.length+1) {
				clearScreen();
				currentX = 0;
				oldX = 0;
				oldY = centerY;
				
			}
		}
    	
    }
    
    
    
    


	@Override
	protected void onPause() {
		// TODO Auto-generated method stub
		super.onPause();
		mTimerTask.cancel();
	}


	@Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_sin1, menu);
        return true;
    }

    
}

 

工程文件：http://download.csdn.net/detail/zhaoshiqing7/4550032