21天学习android开发教程之SurfaceView

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent" android:layout_height="fill_parent"    android:orientation="vertical">    <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="简单绘画">        <button android:id="@+id/Button02" android:layout_width="wrap_content"             android:layout_height="wrap_content" android:text="定时器绘画">        <surfaceview android:id="@+id/SurfaceView01"         android:layout_width="fill_parent" android:layout_height="fill_parent">

package com.testSurfaceView;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 testSurfaceView extends Activity {    /** Called when the activity is first created. */    Button btnSimpleDraw, btnTimerDraw;    SurfaceView sfv;    SurfaceHolder sfh;    private Timer mTimer;    private MyTimerTask mTimerTask;    int Y_axis[],//保存正弦波的Y轴上的点    centerY,//中心线    oldX,oldY,//上一个XY点     currentX;//当前绘制到的X轴上的点    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        btnSimpleDraw = (Button) this.findViewById(R.id.Button01);        btnTimerDraw = (Button) this.findViewById(R.id.Button02);        btnSimpleDraw.setOnClickListener(new ClickEvent());        btnTimerDraw.setOnClickListener(new ClickEvent());        sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);        sfh = sfv.getHolder();        //动态绘制正弦波的定时器        mTimer = new Timer();        mTimerTask = new MyTimerTask();        // 初始化y轴数据        centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv                .getTop()) / 2;        Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()];        for (int i = 1; i < Y_axis.length; i++) {// 计算正弦波            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);//直接绘制正弦波                        } else if (v == btnTimerDraw) {                oldY = centerY;                mTimer.schedule(mTimerTask, 0, 5);//动态绘制正弦波            }        }    }    class MyTimerTask extends TimerTask {        @Override        public void run() {            SimpleDraw(currentX);            currentX++;//往前进            if (currentX == Y_axis.length - 1) {//如果到了终点，则清屏重来                ClearDraw();                currentX = 0;                oldY = centerY;            }        }    }        /*     * 绘制指定区域     */    void SimpleDraw(int length) {        if (length == 0)            oldX = 0;        Canvas canvas = sfh.lockCanvas(new Rect(oldX, 0, oldX + length,                getWindowManager().getDefaultDisplay().getHeight()));// 关键:获取画布        Log.i("Canvas:",                String.valueOf(oldX) + "," + String.valueOf(oldX + length));        Paint mPaint = new Paint();        mPaint.setColor(Color.GREEN);// 画笔为绿色        mPaint.setStrokeWidth(2);// 设置画笔粗细        int y;        for (int i = oldX + 1; i < length; i++) {// 绘画正弦波            y = Y_axis[i - 1];            canvas.drawLine(oldX, oldY, i, y, mPaint);            oldX = i;            oldY = y;        }        sfh.unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像    }    void ClearDraw() {        Canvas canvas = sfh.lockCanvas(null);        canvas.drawColor(Color.BLACK);// 清除画布        sfh.unlockCanvasAndPost(canvas);    }}