android 多点触摸图片缩放的具体实现方法

概述布局:复制代码代码如下:<?xmlversion=\"1.0\"encoding=\"utf-8\"?><RelativeLayoutxmlns:android=\"http://schemas.android.com/apk/res/android\"   android:id=\"@+id/relativeLayout1\"

布局:

复制代码 代码如下:
<?xml version="1.0" enCoding="utf-8"?>
<relativeLayout xmlns:androID="http://schemas.androID.com/apk/res/androID"
    androID:ID="@+ID/relativeLayout1"
    androID:layout_wIDth="fill_parent"
    androID:layout_height="fill_parent" >

    <button
        androID:ID="@+ID/zoom_in"
        androID:layout_wIDth="wrap_content"
        androID:layout_height="wrap_content"
        androID:layout_alignParentleft="true"
        androID:layout_alignParenttop="true"
        androID:text="zoom_in" />
    <button
        androID:ID="@+ID/zoom_out"
        androID:layout_wIDth="wrap_content"
        androID:layout_height="wrap_content"
        androID:layout_alignParentRight="true"
        androID:layout_alignParenttop="true"
        androID:text="zoom_out" />

    <ScrollVIEw
        androID:ID="@+ID/imageContainer"
        androID:layout_wIDth="fill_parent"
        androID:layout_height="fill_parent"
        androID:layout_below="@+ID/zoom_in"
        androID:fadingEdge="none"
        androID:scrollbars="none" >

        <horizontalscrollview
            androID:layout_wIDth="fill_parent"
            androID:layout_height="fill_parent"
            androID:layout_centerHorizontal="true"
            androID:fadingEdge="none"
            androID:scrollbars="none" >

            <ImageVIEw
                androID:ID="@+ID/imageVIEw"
                androID:layout_wIDth="wrap_content"
                androID:layout_height="wrap_content"
                androID:layout_alignParenttop="true"
                androID:layout_centerHorizontal="true"
                androID:scaleType="matrix" />
        </horizontalscrollview>
    </ScrollVIEw>

</relativeLayout>

程序代码:

复制代码 代码如下:
package taokun.demo.MutiltouchDemo;

import androID.app.Activity;
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.ImageVIEw;

public class MutiltouchDemoActivity extends Activity implements OntouchListener,OnClickListener {
   private static final String TAG = "touch" ;

   // These matrices will be used to move and zoom image
   Matrix matrix = new Matrix();
   Matrix savedMatrix = new Matrix();
   PointF start = new PointF();
   PointF mID = new PointF();
   float  olddist;
   private ImageVIEw vIEw;
   private button zoomIn,zoomOut;

   //button zoom
   private float scaleWIDth = 1;
        private float scaleHeight = 1;
        private Bitmap bmp,zoomedBMP;
        private int zoom_level = 0;
        private static final double ZOOM_IN_SCALE = 1.25;//放大系数
        private static final double ZOOM_OUT_SCALE = 0.8;//缩小系数

   // We can be in one of these 3 states
   static final int NONE = 0;
   static final int DRAG = 1;
   static final int ZOOM = 2;
   int mode = NONE;

   @OverrIDe
   public voID onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentVIEw(R.layout.main);
      //放大按钮
      zoomIn = (button) findVIEwByID(R.ID.zoom_in);
       //缩小按钮
      zoomOut = (button) findVIEwByID(R.ID.zoom_out);
      zoomIn.setonClickListener(this);
      zoomOut.setonClickListener(this);
      vIEw = (ImageVIEw) findVIEwByID(R.ID.imageVIEw);
      vIEw.setontouchListener(this);
      //取得drawable中图片，放大，缩小，多点触摸的作用对象    
       bmp = BitmapFactory.decodeResource(MutiltouchDemoActivity.this.getResources(),R.drawable.splash);

              }

   public boolean ontouch(VIEw v,MotionEvent event) {
      // Handle touch events here...
      ImageVIEw vIEw = (ImageVIEw) v;

      // Handle touch events here...
      switch (event.getAction() & MotionEvent.ACTION_MASK) {
        //设置拖拉模式
        case MotionEvent.ACTION_DOWN:
            savedMatrix.set(matrix);
            start.set(event.getX(),event.getY());
            Log.d(TAG,"mode=DRAG" );
            mode = DRAG;
            break;

         case MotionEvent.ACTION_UP:
         case MotionEvent.ACTION_POINTER_UP:
            mode = NONE;
            Log.d(TAG,"mode=NONE" );
            break;
         //设置多点触摸模式
         case MotionEvent.ACTION_POINTER_DOWN:
            olddist = spacing(event);
            Log.d(TAG,"olddist=" + olddist);
            if (olddist > 10f) {
               savedMatrix.set(matrix);
               mIDPoint(mID,event);
               mode = ZOOM;
               Log.d(TAG,"mode=ZOOM" );
            }
            break;
          //若为DRAG模式，则点击移动图片
         case MotionEvent.ACTION_MOVE:
            if (mode == DRAG) {
               matrix.set(savedMatrix);
               // 设置位移
               matrix.postTranslate(event.getX() - start.x,
              event.getX() - start.x);
            }
            //若为ZOOM模式，则多点触摸缩放
               else if (mode == ZOOM) {
               float newdist = spacing(event);
               Log.d(TAG,"newdist=" + newdist);
               if (newdist > 10f) {
                  matrix.set(savedMatrix);
                  float scale = newdist / olddist;
                  //设置缩放比例和图片中点位置
                  matrix.postscale(scale,scale,mID.x,mID.y);
               }
            }
            break;
      }

      // Perform the transformation
      vIEw.setimageMatrix(matrix);

      return true; // indicate event was handled
   }
//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);
   }

//放大，缩小按钮点击事件
@OverrIDe
public voID onClick(VIEw v) {
        if(v == zoomIn){
                enlarge();
        }else if (v == zoomOut) {
                small();
        }

}

//按钮点击缩小函数
private voID small() {

        int bmpWIDth = bmp.getWIDth();
        int bmpHeight = bmp.getHeight();

        scaleWIDth = (float) (scaleWIDth * ZOOM_OUT_SCALE);
        scaleHeight = (float) (scaleHeight * ZOOM_OUT_SCALE);

        Matrix matrix = new Matrix();
        matrix.postscale(scaleWIDth,scaleHeight);
        zoomedBMP = Bitmap.createBitmap(bmp,bmpWIDth,bmpHeight,matrix,
                        true);
        vIEw.setimageBitmap(zoomedBMP);
}

//按钮点击放大函数
private voID enlarge() {
        try {
                int bmpWIDth = bmp.getWIDth();
                int bmpHeight = bmp.getHeight();

                scaleWIDth = (float) (scaleWIDth * ZOOM_IN_SCALE);
                scaleHeight = (float) (scaleHeight * ZOOM_IN_SCALE);

                Matrix matrix = new Matrix();
                matrix.postscale(scaleWIDth,scaleHeight);
                zoomedBMP = Bitmap.createBitmap(bmp,
                                true);
                vIEw.setimageBitmap(zoomedBMP);
        } catch (Exception e) {

        }

}
}

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