Android轻松画出触摸轨迹

本文实例介绍了Android如何画出触摸轨迹的方法，分享给大家供大家参考，具体内容如下

效果图：

实现代码：

package com.android.gameview5;

import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceHolder.Callback;
import android.view.SurfaceView;
import android.view.Window;
import android.view.WindowManager;

public class SurfaceViewActivity3 extends Activity {
 public void onCreate(Bundle s){
 super.onCreate(s);
 //全屏显示
 requestWindowFeature(Window.FEATURE_NO_TITLE);
 getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
 WindowManager.LayoutParams.FLAG_FULLSCREEN);
 setContentView(new MyView(this));
 }
 public class MyView extends SurfaceView implements Callback,Runnable{

public static final int TIME_IN_FRAME =50;

Paint mPaint = null;
 Paint mTextPaint = null;
 SurfaceHolder mSurfaceHolder = null;

boolean mRunning = false;

Canvas mCanvas = null;

private Path mPath;

private float mPosX,mPosY;

public MyView(Context context){
super(context);
this.setFocusable(true);
this.setFocusableInTouchMode(true);
 mSurfaceHolder = this.getHolder();
 mSurfaceHolder.addCallback(this);
 mCanvas = new Canvas();

mPaint = new Paint();
 mPaint.setColor(Color.BLACK);

mPaint.setAntiAlias(true);

mPaint.setStyle(Paint.Style.STROKE);

mPaint.setStrokeCap(Paint.Cap.ROUND);

mPaint.setStrokeWidth(6);

mPath = new Path();

mTextPaint = new Paint();

mTextPaint.setColor(Color.BLACK);

mTextPaint.setTextSize(15);

}
public boolean onTouchEvent(MotionEvent event){
 int action = event.getAction();
 float x = event.getX();
 float y = event.getY();
 switch(action){
 case MotionEvent.ACTION_DOWN:
 mPath.moveTo(x, y);
 break;
 case MotionEvent.ACTION_MOVE:
 mPath.quadTo(mPosX, mPosY, x, y);
 break;
 case MotionEvent.ACTION_UP:
 //mPath.reset();
 break;
 }
 //记录当前触摸点得当前得坐标
 mPosX = x;
 mPosY = y;
return true;
}
private void onDraw(){
mCanvas.drawColor(Color.WHITE);
//绘制曲线
mCanvas.drawPath(mPath, mPaint);
mCanvas.drawText("当前触笔X："+mPosX,0,20,mTextPaint);
mCanvas.drawText("当前触笔Y:"+mPosY,0,40,mTextPaint);
}
public void run() {
// TODO Auto-generated method stub
while(mRunning){
long startTime = System.currentTimeMillis();
synchronized(mSurfaceHolder){
mCanvas = mSurfaceHolder.lockCanvas();
onDraw();
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
}
long endTime = System.currentTimeMillis();
int diffTime = (int) (endTime - startTime);
while(diffTime<=TIME_IN_FRAME){
diffTime =(int)(System.currentTimeMillis()-startTime);
Thread.yield();
}
}
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
mRunning = true;
new Thread(this).start();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
mRunning = false;
}

}
}