android绘图 自定义组件

package org.touch.cn; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import android.app.ListActivity; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Point; import android.util.AttributeSet; import android.view.MotionEvent; import android.view.View; public class MyPaintView extends View{ private List<Point> allpoint = new ArrayList<Point>();//保存所以的操作坐标 public MyPaintView(Context context, AttributeSet attrs) {//接收context，同时接收属性集合。 super(context, attrs);//调用父类的构造 super.setOnTouchListener(new OnTouchListenerimpl()); } private class OnTouchListenerimpl implements OnTouchListener{ @Override public boolean onTouch(View v, MotionEvent event) { Point p = new Point((int)event.getX(),(int)event.getY());//将坐标保存在Point类 if(event.getAction()==MotionEvent.ACTION_DOWN){ //用户按下 MyPaintView.this.allpoint=new ArrayList<Point>();//重绘 MyPaintView.this.allpoint.add(p);//保存坐标点 }else if(event.getAction()==MotionEvent.ACTION_MOVE){//用户移动 MyPaintView.this.allpoint.add(p);//记录坐标点 MyPaintView.this.postInvalidate();//重绘图形 }else if(event.getAction()==MotionEvent.ACTION_UP){//用户松开 MyPaintView.this.allpoint.add(p);//记录坐标点 MyPaintView.this.postInvalidate();//重绘图形 } return true; //表示下面的操作不在执行了。 } } @Override protected void onDraw(Canvas canvas) { //进行绘图 Paint paint = new Paint();//依靠此类开始画线 paint.setColor(Color.RED); if(MyPaintView.this.allpoint.size()>0)//有坐标点保存的时候开始进行绘图 { Iterator<Point> iterator = MyPaintView.this.allpoint.iterator(); Point first=null; Point last=null; while(iterator.hasNext()){ if(first==null) { first= (Point)iterator.next();//取出坐标 }else { if(last!=null){//前一阶段已经完成 first = last;//重新开始下一阶段 } last=(Point)iterator.next();//结果点坐标 canvas.drawLine(first.x, first.y, last.x, last.y, paint); } } } } }