Android之关于手势操作图片的缩放与移动

在Android中实现手势对于图片的操作，首先需要对MotionEvent以及Matrix两个类有所了解实现对手势的识别以及图片变动的操作。具体介绍可见在下其他两篇博文..

在实现该功能时候需要在xml中要将图片的缩放格式改成Matrix才行.

下面代码主要实现两个demo，一个是关于matrix的简单测试以及图片的手势缩放与移动demo.。。

XML代码如下：

实现代码：

package hfut.gmm;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PointF;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.util.FloatMath;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View;
import android.view.GestureDetector.OnGestureListener;
import android.view.View.OnTouchListener;
import android.view.animation.AnimationUtils;
import android.widget.ImageView;

public class Img_control extends Activity implements OnTouchListener {//implements OnTouchListener {
    private ImageView imgview;
    private ImageView img;
 
    
    private Matrix matrix=new Matrix();
    private Matrix savedMatrix=new Matrix();
    
    static final int NONE = 0;  
    static final int DRAG = 1;  
    static final int ZOOM = 2;  
    int mode = NONE;  

    // Remember some things for zooming  
    PointF start = new PointF();  
    PointF mid = new PointF();  
    float oldDist = 1f;  
    
    //private GestureDetector gesture;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		this.setContentView(R.layout.img_control);
		imgview=(ImageView)this.findViewById(R.id.imag1);
		imgview.setAnimation(AnimationUtils.loadAnimation(this, R.anim.newanim));
		
		
		img=(ImageView)this.findViewById(R.id.imag);
		Matrix mt=img.getImageMatrix();	
		//mt.postRotate(30);
		mt.postScale(0.5f,0.5f);mt.postScale(1.5f,1.5f);
		mt.postRotate(30, 130, 100);
	    mt.postTranslate(100, 10);
		
		img.setImageMatrix(mt);
		
	
		//imgview.setLongClickable(true);
		
		imgview.setImageBitmap(BitmapFactory.decodeResource(this.getResources(), R.drawable.a));
		imgview.setOnTouchListener(this);
		imgview.setLongClickable(true);
		
	}
	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);  
}  

 
      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);  
}  
	@Override
	public boolean onTouch(View v, MotionEvent event) {
		// TODO Auto-generated method stub
		/*
		Log.d("Infor", "类别:"+event.getAction());
		Log.d("Infor", "mask:"+event.getActionMasked());
		Log.d("Infor", "index:"+event.getActionIndex());
		Log.d("Infor", "points:"+event.getPointerCount());*/
	    Log.d("Infor", "size:"+event.getSize());
	    if(event.getActionMasked()==MotionEvent.ACTION_POINTER_UP)
	    	Log.d("Infor", "多点操作");
	    switch(event.getActionMasked()){
	    case MotionEvent.ACTION_DOWN:
	    	  matrix.set(imgview.getImageMatrix());
	    	  savedMatrix.set(matrix);
	    	  start.set(event.getX(),event.getY());
	    	  Log.d("Infor", "触摸了...");
	    	  mode=DRAG;
	          break;
	    case MotionEvent.ACTION_POINTER_DOWN:  //多点触控
	    	 oldDist=this.spacing(event);
	        if(oldDist>10f){
	    	 Log.d("Infor", "oldDist"+oldDist);
	         savedMatrix.set(matrix);
	    	 midPoint(mid,event);
	    	 mode=ZOOM;
	        }
	        break;
	    case MotionEvent.ACTION_POINTER_UP:
	    	mode=NONE;
	        break;
	    case MotionEvent.ACTION_MOVE:
	    	if(mode==DRAG){         //此实现图片的拖动功能...
	    		matrix.set(savedMatrix);
	    	    matrix.postTranslate(event.getX()-start.x, event.getY()-start.y);
	    	}
	    	    else if(mode==ZOOM){// 此实现图片的缩放功能...
	    	 float newDist=spacing(event);
	    	 if(newDist>10){
	    		 matrix.set(savedMatrix);
	    		 float scale=newDist/oldDist;
	    		 matrix.postScale(scale, scale, mid.x, mid.y);	    		 
	    	 }
	    	    }
	    	break;
	    }
	    imgview.setImageMatrix(matrix);
		return false;
	}	
}

运行结果如下：

美女图片很养眼哈...