android 定时器与Canvas结合使用

最新推荐文章于 2025-04-17 11:42:57 发布

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最新推荐文章于 2025-04-17 11:42:57 发布

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文章标签：移动开发 java

原文链接：http://www.cnblogs.com/rollrock/archive/2012/03/02/2377130.html

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根据别人的例子自己写了，并理解了下

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    >

    <LinearLayout android:id="@+id/LinearLayout01"
         android:layout_width="wrap_content"
         android:layout_height="wrap_content">

  <Button android:id="@+id/Button01"
    android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Button1"
    />

    <Button android:id="@+id/Button02"
    android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Button2"
    />

    </LinearLayout>

        <SurfaceView android:id="@+id/SurfaceView01"
      android:layout_width="fill_parent"
         android:layout_height="fill_parent"
  />
</LinearLayout>

package MyTestSurfaceView.code;

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

import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.util.Log;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;

public class MainActivity extends Activity {
/** Called when the activity is first created. */

private Button btnSimpleDraw;
private Button btnTimerDraw;
private SurfaceView sfv;
private SurfaceHolder sfh;

private Timer mTimer;
private MyTimerTask mTimerTask;
int Y_axis[],centerY,oldX,oldY,currentX;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        btnSimpleDraw = (Button)findViewById(R.id.Button01);
        btnTimerDraw = (Button)findViewById(R.id.Button02);
        btnSimpleDraw.setOnClickListener(new ClickEvent());
        btnTimerDraw.setOnClickListener(new ClickEvent());

        sfv = (SurfaceView)findViewById(R.id.SurfaceView01);
        sfh = sfv.getHolder();

        mTimer = new Timer();
        mTimerTask = new MyTimerTask();

        centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv.getTop())/ 2 ;
        Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()];
        oldX = 0;
        oldY = 0;

        for( int i = 1; i < Y_axis.length; ++ i )
        {
        Y_axis[i-1] = centerY - (int)(100*Math.sin(i*2*Math.PI/180));
        }
    }

    class ClickEvent implements View.OnClickListener
    {
    @Override
    public void onClick(View v )
    {
      if( v == btnSimpleDraw )
      {
       SimpleDraw(Y_axis.length - 1 );
      }
      else if( v == btnTimerDraw )
      {
       oldY = centerY;
       mTimer.schedule(mTimerTask,0,50);
      }
    }
    }


    class MyTimerTask extends TimerTask
    {
    @Override
    public void run()
    {
      SimpleDraw(currentX);
      ++currentX;

      if( currentX == Y_axis.length - 1 )
      {
       ClearDraw();
       currentX = 0;
       oldY = centerY;
      }
    }
    }


    void SimpleDraw( int length )
    {
    if( length == 0 )
    {
      oldX = 0;
    }

    Canvas canvas = sfh.lockCanvas( new Rect(oldX,0,oldX + length , getWindowManager().getDefaultDisplay().getHeight()));

    Paint paint = new Paint();
    paint.setColor(Color.GREEN);
    paint.setStrokeWidth(2);

    int y;
    for( int i = oldX + 1; i < length; ++ i )
    {
      y = Y_axis[i-1];
      canvas.drawLine(oldX,oldY,i,y,paint);
      Log.i("Rollrock" , "Line:" + oldX + " " + oldY + " " + i + " " + y );
      oldX = i;
      oldY = y;
    }

　　

     sfh.unlockCanvasAndPost(canvas);
    }

    private void ClearDraw()
    {
    Canvas canvas = sfh.lockCanvas(null);
    canvas.drawColor(Color.BLACK);
    sfh.unlockCanvasAndPost(canvas);
    }
}

附: 虽然在 xml里面我们可以看到 SurfaceView01 android:layout_height="fill_parent" ，但是通过实际的数据发现，canvas的y坐标的0点再button的下方。

转载于:https://www.cnblogs.com/rollrock/archive/2012/03/02/2377130.html