android google map 实现拉框功能

主要的类

package com.activity.control;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.os.Handler;
import android.util.FloatMath;
import android.view.GestureDetector;
import android.view.GestureDetector.OnDoubleTapListener;
import android.view.GestureDetector.OnGestureListener;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;

import com.activity.MyMapActivity;
import com.google.android.maps.GeoPoint;
import com.google.android.maps.MapView;
import com.google.android.maps.Overlay;
import com.google.android.maps.Projection;

/**     
 * <b>类名称：</b>RectangularBoxOverlay<br/>  
 * <b>类描述：</b>矩形框控件<br/>  
 * <b>创建人：</b>ZhengJie<br/>  
 * <b>修改人：</b>ZhengJie<br/>  
 * <b>修改时间：</b>2012-7-11 上午11:41:24<br/>  
 * <b>修改备注：</b><br/>  
 * @version 1.2.0<br/> 
 */
public class RectangularBoxOverlay extends Overlay implements 
	OnTouchListener{
	private static final String TAG = "RectangularBoxOverlay";


	PointF start = new PointF();
	PointF mid = new PointF();
	public float oldDist;
	public static final int NONE = 0;
	public static final int DRAG = 1;
	public static final int ZOOM = 2;
	public int mode = NONE;
	private Handler mHandler;
	public  float x=0;
	public  float y=0;
	public  float end_x=0;
	public  float end_y=0;
	
	public GeoPoint startPoint;
	public GeoPoint endPoint;
	/* 相关变量声明 */
	//private GestureDetector mGestureDetector = new GestureDetector(this);
	private Projection myProject;
	private Context context;
	private final Paint paint;
	private Paint box_paint;
	private Canvas canvas;
	private MapView mapView;
	
	
	//画笔状态 0绘画中 1绘画完成
	private int boxState=0;
	
	
	public RectangularBoxOverlay(Context context,Projection project,MapView mapView){
		this.context=context;
		this.myProject=project;
		this.mapView=mapView;
		 // 设置画笔
        paint = new Paint();
        paint.setColor(Color.RED);
        // 画笔的粗细
        paint.setStrokeWidth(3);
        paint.setAntiAlias(true);
        paint.setStrokeMiter(3);
//        paint.setStyle(Style.STROKE);
        paint.setAlpha(50);
        paint.setStyle(Paint.Style.FILL);//设置填满   
        
        box_paint = new Paint();
        box_paint.setColor(Color.RED);
        box_paint.setStyle(Style.STROKE);
        box_paint.setStrokeWidth(3);
        box_paint.setAntiAlias(true);
        box_paint.setStrokeMiter(3);
        
        
        
        
	}
	@Override
	public void draw(Canvas canvas, MapView mapView, boolean shadow) {
		super.draw(canvas, mapView, shadow);
		// 得到当前屏幕的高*宽
		
		if(shadow) 
        {
            return;
        }
		this.canvas=canvas;
		int width = canvas.getWidth();
        int height = canvas.getHeight();
		//canvas.drawColor(Color.BLACK);
        android.graphics.Point pixelPoint = new android.graphics.Point();
        
        
        if(startPoint!=null){
	        pixelPoint= myProject.toPixels(startPoint,pixelPoint);
	        x=pixelPoint.x;
	        y=pixelPoint.y;
        }
        if(endPoint!=null){
	        pixelPoint= myProject.toPixels(endPoint,pixelPoint);
	        end_x=pixelPoint.x;
	        end_y=pixelPoint.y;
        }
		canvas.save();
		if(boxState==0){
	        canvas.drawRect(0, 0, width, height, paint); 
	        //System.out.println(x+"+"+ y+"+"+ end_x+"+"+ end_y);
	        canvas.drawRect(x, y, end_x, end_y, box_paint);
		}else if(boxState==1){
			paint.setAlpha(0);
			canvas.drawRect(0, 0, width, height, paint); 
			paint.setAlpha(50);
			canvas.drawRect(x+3, y+3, end_x-3, end_y-3, paint); 
			canvas.drawRect(x, y, end_x, end_y, box_paint);
			
		}
		canvas.restore();
		//System.out.println("我在画画");
	}
	@Override
	public boolean onKeyDown(int keyCode, KeyEvent event, MapView mapView) {
		//System.out.println("-------onKeyDown");
		return super.onKeyDown(keyCode, event, mapView);
	}
	
	
	@Override
	public boolean onTouch(View v, MotionEvent event) {
		//System.out.println("-------进入拖拉模式");
		//System.out.println(x+"+"+ y+"+"+ end_x+"+"+ end_y);
		switch (event.getAction() & MotionEvent.ACTION_MASK) {
		// 设置拖拉模式
		case MotionEvent.ACTION_DOWN:
			//start.set(event.getX(), event.getY());
			mode = DRAG;
			x=event.getX();
			y=event.getY();
			//this.canvas=new Canvas();
			//System.out.println("x:"+x+" y:"+y);
			startPoint=myProject.fromPixels(new Double(x).intValue() , new Double(y).intValue());
			break;

		case MotionEvent.ACTION_UP:
		case MotionEvent.ACTION_POINTER_UP:
			//System.out.println("弹起了");
			boxState=1;
			mode = NONE;
			((MyMapActivity)this.context).lock_map=false;
			mapView.invalidate();
			break;
		// 设置多点触摸模式
		case MotionEvent.ACTION_POINTER_DOWN:
			oldDist = spacing(event);
			if (oldDist > 10f) {
				mode = ZOOM;
			}
			break;
		// 若为DRAG模式，则点击移动图片
		case MotionEvent.ACTION_MOVE:
			end_x=event.getX();
			end_y=event.getY();
			endPoint=myProject.fromPixels(new Double(end_x).intValue() , new Double(end_y).intValue());
			canvas.drawRect(x, y, end_x, end_y, box_paint);
			if (mode == DRAG) {
				mapView.invalidate();
				//this.draw(new Canvas(), mapView, true);
				//System.out.println(x+"+"+ y+"+"+ end_x+"+"+ end_y);
			}
			// 若为ZOOM模式，则多点触摸缩放
			else if (mode == ZOOM) {
				
				float newDist = spacing(event);
				if (newDist > 10f) {
					
					
					float scale = newDist / oldDist;
//					System.out.println(scale+"+"+ scale+"+"+ mid.x+"+"+ mid.y);
					// 设置缩放比例和图片中点位置
				}
			}
			break;
		}
		return false;
	}

	
	// 计算移动距离
	private float spacing(MotionEvent event) {
		float x = event.getX(0) - event.getX(1);
		float y = event.getY(0) - event.getY(1);
		return FloatMath.sqrt(x * x + y * y);
	}

	// 计算中点位置
	private void midPoint(PointF point, MotionEvent event) {
		float x = event.getX(0) + event.getX(1);
		float y = event.getY(0) + event.getY(1);
		point.set(x / 2, y / 2);
	}
	

}