自定义类继承ImageView 实现多点图片触碰的拖动和缩放

最近的一个android 项目中，客户要求在查看拍照上传的图片时，可以对图片进行多点触控的拖拽、放大、缩小等操作。网上的范例都不怎么好，实现的效果差强人意。

下面说说我的方案：

步骤一：自定义一个View，该View继承自ImageView。在该View中实现多点触控的拖拽、缩放等功能。

步骤二：像使用ImageView那样，在XML中引入该View。当然也可以动态创建该View然后添加到容器组件中。

 

一、自定义TouchView继承ImageView

package com.hzunitech.xcgk.ui;

import android.content.Context;   
import android.util.AttributeSet;
import android.util.FloatMath;   
import android.view.MotionEvent;   
import android.view.animation.TranslateAnimation;   
import android.widget.ImageView;   
/**  
 * 继承ImageView 实现了多点触碰的拖动和缩放  
 * @author lihua    
 */   
public class TouchView extends ImageView {
	

    static final int NONE = 0;   
    static final int DRAG = 1;     //拖动中    
    static final int ZOOM = 2;     //缩放中    
    static final int BIGGER = 3;   //放大ing    
    static final int SMALLER = 4;  //缩小ing    
    private int mode = NONE;       //当前的事件     
   
    private float beforeLenght;   //两触点距离    
    private float afterLenght;    //两触点距离    
    private float scale = 0.04f;  //缩放的比例 X Y方向都是这个值 越大缩放的越快    
      
    private int screenW;   
    private int screenH;   
       
    /*处理拖动 变量 */   
    private int start_x;   
    private int start_y;   
    private int stop_x ;   
    private int stop_y ;   
       
    private TranslateAnimation trans; //处理超出边界的动画    
    
    /**
     * 默认构造函数
     * @param context
     */
    public TouchView(Context context){
    	super(context);
    }
    /**
     * 该构造方法在静态引入XML文件中是必须的
     * @param context
     * @param paramAttributeSet
     */
    public TouchView(Context context,AttributeSet paramAttributeSet){
    	super(context,paramAttributeSet);
    }
    /**
     * 该构造函数在动态创建时，指定图片的初始高宽
     * @param context
     * @param w
     * @param h
     */
    public TouchView(Context context,int w,int h) {   
        super(context);   
        this.setPadding(0, 0, 0, 0);   
        screenW = w;   
        screenH = h;   
    }   
       
    /**  
     * 就算两点间的距离  
     */   
    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);   
    }   
       
    /**  
     * 处理触碰..  
     */   
    @Override   
    public boolean onTouchEvent(MotionEvent event)   
    {      
        switch (event.getAction() & MotionEvent.ACTION_MASK) {   
        case MotionEvent.ACTION_DOWN:   
                mode = DRAG;   
                stop_x = (int) event.getRawX();   
                stop_y = (int) event.getRawY();   
                start_x = (int) event.getX();   
                start_y = stop_y - this.getTop();   
                if(event.getPointerCount()==2)   
                    beforeLenght = spacing(event);   
                break;   
        case MotionEvent.ACTION_POINTER_DOWN:   
                if (spacing(event) > 10f) {   
                        mode = ZOOM;   
                        beforeLenght = spacing(event);   
                }   
                break;   
        case MotionEvent.ACTION_UP:   
            /*判断是否超出范围     并处理*/   
                int disX = 0;   
                int disY = 0;   
                if(getHeight()<=screenH || this.getTop()<0)   
                {   
                    if(this.getTop()<0 )   
                    {   
                        int dis = getTop();   
                        this.layout(this.getLeft(), 0, this.getRight(), 0 + this.getHeight());   
                        disY = dis - getTop();   
                    }   
                    else if(this.getBottom()>screenH)   
                    {   
                        disY = getHeight()- screenH+getTop();   
                        this.layout(this.getLeft(), screenH-getHeight(), this.getRight(), screenH);   
                    }   
                }   
                if(getWidth()<=screenW)   
                {   
                    if(this.getLeft()<0)   
                    {   
                        disX = getLeft();   
                        this.layout(0, this.getTop(), 0+getWidth(), this.getBottom());   
                    }   
                    else if(this.getRight()>screenW)   
                    {   
                        disX = getWidth()-screenW+getLeft();   
                        this.layout(screenW-getWidth(), this.getTop(), screenW, this.getBottom());   
                    }   
                }   
                if(disX!=0 || disY!=0)   
                {   
                    trans = new TranslateAnimation(disX, 0, disY, 0);   
                    trans.setDuration(500);   
                    this.startAnimation(trans);   
                }   
                mode = NONE;   
                break;   
        case MotionEvent.ACTION_POINTER_UP:   
                mode = NONE;   
                break;   
        case MotionEvent.ACTION_MOVE:   
                /*处理拖动*/   
                if (mode == DRAG) {   
                    if(Math.abs(stop_x-start_x-getLeft())<88 && Math.abs(stop_y - start_y-getTop())<85)   
                    {   
                        this.setPosition(stop_x - start_x, stop_y - start_y, stop_x + this.getWidth() - start_x, stop_y - start_y + this.getHeight());                 
                        stop_x = (int) event.getRawX();   
                        stop_y = (int) event.getRawY();   
                    }   
                }    
                /*处理缩放*/   
                else if (mode == ZOOM) {   
                    if(spacing(event)>10f)   
                    {   
                        afterLenght = spacing(event);   
                        float gapLenght = afterLenght - beforeLenght;                        
                        if(gapLenght == 0) {     
                           break;   
                        }   
                        else if(Math.abs(gapLenght)>5f)   
                        {   
                            if(gapLenght>0) {  
                            	
                                this.setScale(scale,BIGGER);      
                            }else {     
                                this.setScale(scale,SMALLER);      
                            }                                
                            beforeLenght = afterLenght;    
                        }   
                    }   
                }   
                break;   
        }   
        return true;       
    } 
    
    
    /**  
     * 实现处理缩放  
     */   
    private void setScale(float temp,int flag) {      
           
        if(flag==BIGGER) {      
            this.setFrame(this.getLeft()-(int)(temp*this.getWidth()),       
                          this.getTop()-(int)(temp*this.getHeight()),       
                          this.getRight()+(int)(temp*this.getWidth()),       
                          this.getBottom()+(int)(temp*this.getHeight()));         
        }else if(flag==SMALLER){      
            this.setFrame(this.getLeft()+(int)(temp*this.getWidth()),       
                          this.getTop()+(int)(temp*this.getHeight()),       
                          this.getRight()-(int)(temp*this.getWidth()),       
                          this.getBottom()-(int)(temp*this.getHeight()));      
        }      
    }   
       
    /**  
     * 实现处理拖动  
     */   
    private void setPosition(int left,int top,int right,int bottom) {     
        this.layout(left,top,right,bottom);                
    }   
}

 

二、在XML文件中引入TouchView。

在xml中引入TouchView和引入其父类ImageView是一样的。

    	   <ImageView
               android:id="@+id/drawing"
               android:layout_width="fill_parent"
               android:layout_height="fill_parent" >
           </ImageView>

 

   	   <com.hzunitech.xcgk.ui.TouchView
              android:id="@+id/drawing"
              android:layout_width="fill_parent"
              android:layout_height="fill_parent" 
              android:layout_marginTop="50px"
              android:gravity="center">
          </com.hzunitech.xcgk.ui.TouchView>

 在Activity中，为找到该组件，并为其动态设置图片。

TouchView drawing = (TouchView)findViewById(R.id.drawing);
//獲得網絡url上的一個圖片
Bitmap img = AvdUtils.getHttpBitmap(Constants.URL_PREFIX+takan.getFileName());  
drawing.setImageBitmap(img);