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【移动开发】Android中图片的多点触控和缩放

2017-11-07 697

   前几天做项目用到相机拍照，之后能对图片进行缩放，拖拽，在此我将其单独抽取出来，后面用到时直接拿来用就行了！

效果图：

174133817.png

  注：这里不仅能按钮缩放，还能多点触摸缩放和拖拽功能！

1.布局：

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<? xml  version = "1.0"  encoding = "UTF-8" ?>
< FrameLayout  xmlns:android = "http://schemas.android.com/apk/res/android"
     android:id = "@+id/flayout_img_display"
     android:layout_width = "fill_parent"
     android:layout_height = "fill_parent"
     android:orientation = "vertical"  >
     < LinearLayout
         android:id = "@+id/linearLayout_img_display"
         android:layout_width = "fill_parent"
         android:layout_height = "fill_parent"
         android:layout_gravity = "center"
         android:gravity = "center"  >
         < ImageView
             android:id = "@+id/img_display"
             android:layout_width = "fill_parent"
             android:layout_height = "wrap_content"
             android:paddingBottom = "5.0dip"
             android:paddingTop = "5.0dip"
             android:scaleType = "matrix"  />
     </ LinearLayout >
     < RelativeLayout
         android:id = "@+id/relativeLayout1"
         android:layout_width = "fill_parent"
         android:layout_height = "wrap_content"  >
         < Button
             android:id = "@+id/btn_min"
             android:layout_width = "wrap_content"
             android:layout_height = "wrap_content"
             android:layout_alignParentBottom = "true"
             android:layout_alignParentLeft = "true"
             android:enabled = "false"
             android:text = "缩小"  />
         < Button
             android:id = "@+id/btn_out"
             android:layout_width = "wrap_content"
             android:layout_height = "wrap_content"
             android:layout_alignParentBottom = "true"
             android:layout_alignParentRight = "true"
             android:text = "放大"  />
     </ RelativeLayout >
</ FrameLayout >

2.就一个类：

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import  android.app.Activity;
import  android.content.Intent;
import  android.graphics.Bitmap;
import  android.graphics.BitmapFactory;
import  android.graphics.Matrix;
import  android.graphics.PointF;
import  android.os.Bundle;
import  android.util.FloatMath;
import  android.util.Log;
import  android.view.MotionEvent;
import  android.view.View;
import  android.view.View.OnClickListener;
import  android.view.View.OnTouchListener;
import  android.widget.Button;
import  android.widget.FrameLayout;
import  android.widget.ImageView;
import  android.widget.LinearLayout;
/**
  * 缩放图片界面
  * @author ZHF
  *
  */
public  class  MainActivity  extends  Activity {
     public  static  final  String TAG =  "ImgDisplayActivity" ;
     //控件声明
     private  Button btnZoomin, btnZoomout;
     private  ImageView imgDisPlay;
     private  LinearLayout lLayoutDisplay;
     private  FrameLayout fLayoutDisplay;
                                                                                                            
     private  Bitmap bitmap;
                                                                                                            
     private  int  imgId =  0 ;
     private  double  scale_in =  0.8 ; //缩小比例
     private  double  scale_out =  1.25 ; //放大比例
                                                                                                            
     private  float  scaleWidth =  1 ;
     private  float  scaleHeight =  1 ;
     //模式：0：什么都不干；1：拖拽； 2：缩放
     public  static  final  int  NONE =  0 ;
     public  static  final  int  DRAG =  1 ;
     public  static  final  int  ZOOM =  2 ;
     //声明触发的事件模式
     private  int  mode = NONE;
                                                                                                            
     private  Matrix matrix;    //矩阵
     private  Matrix currMatrix;  //当前矩阵
                                                                                                            
     private  PointF starPoint;
     private  PointF midPoint;
                                                                                                            
     private  float  startDistance;
                                                                                                            
     @Override
     protected  void  onCreate(Bundle savedInstanceState) {
         super .onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         //初始化
         fLayoutDisplay = (FrameLayout) findViewById(R.id.flayout_img_display);
         lLayoutDisplay = (LinearLayout) findViewById(R.id.linearLayout_img_display);
         imgDisPlay = (ImageView) findViewById(R.id.img_display);
         btnZoomin = (Button) findViewById(R.id.btn_min);
         btnZoomout = (Button) findViewById(R.id.btn_out);
                                                                                                                
                                                                                                                
         matrix =  new  Matrix();  //保存拖拽变化
         currMatrix =  new  Matrix(); // 当前的
         starPoint =  new  PointF(); //开始点的位置
                                                                                                                
                                                                                                                
         btnZoomin.setOnClickListener( new  OnClickListener() {
             @Override
             public  void  onClick(View v) {
                 zoomIn();
             }
         });
         btnZoomout.setOnClickListener( new  OnClickListener() {
             @Override
             public  void  onClick(View v) {
                 zoomOut(); //放大
             }
         });
                                                                                                                
         imgDisPlay.setImageResource(R.drawable.img);
         //给图片绑定监听器哦
         imgDisPlay.setOnTouchListener( new  ImageViewOnTouchListener());
                                                                                                                
     }
                                                                                                            
     /**放大操作**/
     private  void  zoomOut() {
         reSizeBmp(scale_out);
         btnZoomin.setEnabled( true );
     }
                                                                                                            
     /**缩小操作**/
     private  void  zoomIn() {
         reSizeBmp(scale_in);
     }
                                                                                                            
     /**接收传入的缩放比例实现缩放**/
     private  void  reSizeBmp( double  scale) {
         //缩放比例
         scaleWidth = ( float ) (scaleWidth * scale);
         scaleHeight = ( float ) (scaleHeight * scale);
                                                                                                                
         Matrix matrix =  new  Matrix();
         matrix.postScale(scaleWidth, scaleHeight);  //设计缩放比例
                                                                                                                
         imgDisPlay.setImageMatrix(matrix);
     }
                                                                                                            
     /**计算触摸实现缩放**/
     final  class  ImageViewOnTouchListener  implements  OnTouchListener{
         @Override
         public  boolean  onTouch(View v, MotionEvent event) {
                                                                                                                    
             switch  (event.getAction() & MotionEvent.ACTION_MASK) {
             case  MotionEvent.ACTION_DOWN:   //一只手指按下
                 Log.i(TAG, "一只手指按下" );
                 currMatrix.set(matrix);
                 starPoint.set(event.getX(), event.getY());
                                                                                                                        
                 mode = DRAG;
                 break ;
             case  MotionEvent.ACTION_POINTER_DOWN:  //如果有一只手指按下屏幕，后续又有一个手指按下     // 两只手指按下
                 Log.i(TAG, "又有一只手指按下" );
                                                                                                                        
                 startDistance = distance(event); //记下两点的距离
                 Log.i(TAG, startDistance+ "" );
                                                                                                                        
                 if (startDistance > 5f) {   //两个手指之间的最小距离像素大于5，认为是多点触摸
                     mode = ZOOM;
                     currMatrix.set(matrix);
                                                                                                                            
                     midPoint = getMidPoint(event);  //记下两个点之间的中心点
                                                                                                                            
                 }
                                                                                                                        
                 break ;
                                                                                                                        
             case  MotionEvent.ACTION_MOVE:
                                                                                                                        
                 if (mode == DRAG) {   //拖拽模式
                     Log.i(TAG, "一只手指在拖拽" );
                                                                                                                            
                     //开始--》结束点的距离
                     float  dx = event.getX() - starPoint.x;
                     float  dy = event.getY() - starPoint.y;
                                                                                                                            
                     matrix.set(currMatrix);
                     matrix.postTranslate(dx, dy); //移动到指定点：矩阵移动比例；eg:缩放有缩放比例
                 }  else  if (mode == ZOOM) {   //缩放模式
                     Log.i(TAG, "正在缩放" );
                                                                                                                            
                     float  distance = distance(event);   //两点之间的距离
                     if (distance > 5f) {
                         matrix.set(currMatrix);
                         float  cale = distance / startDistance;
                         matrix.preScale(cale, cale, midPoint.x, midPoint.y);   //进行比例缩放
                     }
                 }
                 break ;
                                                                                                                        
             case  MotionEvent.ACTION_UP:  //最后一只手指离开屏幕后触发此事件
             case  MotionEvent.ACTION_POINTER_UP:  //一只手指离开屏幕，但还有一只手指在上面会触此事件
                 //什么都没做
                 mode = NONE;
                 break ;
             default :
                 break ;
             }
                                                                                                                    
             imgDisPlay.setImageMatrix(matrix);
                                                                                                                    
             //两只手指的缩放
             return  true ;
         }
     }
                                                                                                            
     /**计算两点之间的距离像素**/
     private  float  distance(MotionEvent e) {
                                                                                                                
         float  eX = e.getX( 1 ) - e.getX( 0 );   //后面的点坐标 - 前面点的坐标
         float  eY = e.getY( 1 ) - e.getY( 0 );
         return  FloatMath.sqrt(eX * eX + eY * eY);
     }
                                                                                                            
     /**计算两点之间的中心点**/
     private  PointF getMidPoint(MotionEvent event) {
                                                                                                                
         float  x = (event.getX( 1 ) - event.getX( 0 )) /  2 ;
         float  y = (event.getY( 1 ) - event.getY( 0 )) /  2 ;
         return  new  PointF(x,y);
     }
}


    ok！主要的算法就在ImageViewOnTouchListener监听器当中，要考虑那三种情况（缩放、拖拽、什么都不干），另外需要注意的就是，单个手指和两个以上手指的情况。


源码下载:http://down.51cto.com/data/876165





     本文转自zhf651555765 51CTO博客，原文链接：http://blog.51cto.com/smallwoniu/1252191，如需转载请自行联系原作者




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