玩转Android---UI篇---ZoomControls放大缩小图片

ZoomControls控件是一个可以缩放但控件，效果如下图

以下是它但一些主要但方法

hasFocus ()：判断焦点

hide ()：隐藏

onTouchEvent (MotionEvent event)：现这个方法来处理触摸屏移动事件

setIsZoomInEnabled (boolean isEnabled)：是否允许放大

setIsZoomOutEnabled (boolean isEnabled)：是否允许缩小

setOnZoomInClickListener (View.OnClickListener listener)：注册放大监听器

setOnZoomOutClickListener (View.OnClickListener listener)：注册缩小监听器

setZoomSpeed (long speed)：设置缩放速度

show ()：显示

 

这里面，如果将setIsZoomInEnabled()方法设置为false，那么这个放大的按钮就变成了灰色，不能用了，其实这个控件就是两个按钮而已，只是有外观，没有功能，如果你要放大图片或者缩小图片，还是要在监听事件中实现

开始看代码

main.xml

 <?xml version= "1.0"  encoding= "utf-8" ?>
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:orientation="vertical"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:id="@+id/layout1"
     >
 <ImageView
     android:id="@+id/imgview"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
     android:src="@drawable/yuanyuan"
     />

 <ZoomControls
     android:id="@+id/zoomcontrol"
     android:layout_gravity="bottom"
     android:layout_width="wrap_content"
     android:layout_height="wrap_content"
 />
 </LinearLayout>

 

ZoomExampleActivity.java

 package  com.loulijun.zoomcontroltest;

 import  android.app.Activity;
 import  android.graphics.Bitmap;
 import  android.graphics.BitmapFactory;
 import  android.graphics.Matrix;
 import  android.os.Bundle;
 import  android.util.DisplayMetrics;
 import  android.view.View;
 import  android.view.View.OnClickListener;
 import  android.widget.ImageView;
 import  android.widget.LinearLayout;
 import  android.widget.ZoomControls;

 public   class  ZoomExampleActivity  extends  Activity {
     private  LinearLayout layout1;
     private  ZoomControls zoom;
     private  ImageView img;
     private   int  id= 0 ;
     private   int  displayWidth;
     private   int  displayHeight;
     private   float  scaleWidth =  1 ;
     private   float  scaleHeight =  1 ;
     private  Bitmap bmp;
     @Override
     public   void  onCreate(Bundle savedInstanceState) {
         super .onCreate(savedInstanceState);
         setContentView(R.layout.main);

         layout1 = (LinearLayout)findViewById(R.id.layout1);
         //取得屏幕分辨率大小
         DisplayMetrics dm = new  DisplayMetrics();
         getWindowManager().getDefaultDisplay().getMetrics(dm);
         displayWidth = dm.widthPixels;
         //屏幕高度减去zoomControls的高度
         displayHeight = dm.heightPixels;
         bmp = BitmapFactory.decodeResource(getResources(), R.drawable.yuanyuan);
         img = (ImageView)findViewById(R.id.imgview);
         //zoom.hide();隐藏zoomControls
         //zoom.show();显示zoomCOntrols

         zoom = (ZoomControls)findViewById(R.id.zoomcontrol);
         img = (ImageView)findViewById(R.id.imgview);
         zoom.setIsZoomInEnabled(true );
         zoom.setIsZoomOutEnabled(true );
         //图片放大
         zoom.setOnZoomInClickListener(new  OnClickListener()
         {
             public   void  onClick(View v)
             {
                 int  bmpWidth = bmp.getWidth();
                 int  bmpHeight = bmp.getHeight();
                 //设置图片放大但比例
                 double  scale =  1.25 ;
                 //计算这次要放大的比例
                 scaleWidth = (float )(scaleWidth*scale);
                 scaleHeight = (float )(scaleHeight*scale);
                 //产生新的大小但Bitmap对象
                 Matrix matrix = new  Matrix();
                 matrix.postScale(scaleWidth, scaleHeight);
                 Bitmap resizeBmp = Bitmap.createBitmap(bmp,0 , 0 ,bmpWidth,bmpHeight,matrix, true );
                 img.setImageBitmap(resizeBmp);

             }
         });
         //图片减小
         zoom.setOnZoomOutClickListener(new  OnClickListener()
         {

             public   void  onClick(View v) {
                 int  bmpWidth = bmp.getWidth();
                 int  bmpHeight = bmp.getHeight();
                 //设置图片放大但比例
                 double  scale =  0.8 ;
                 //计算这次要放大的比例
                 scaleWidth = (float )(scaleWidth*scale);
                 scaleHeight = (float )(scaleHeight*scale);
                 //产生新的大小但Bitmap对象
                 Matrix matrix = new  Matrix();
                 matrix.postScale(scaleWidth, scaleHeight);
                 Bitmap resizeBmp = Bitmap.createBitmap(bmp,0 , 0 ,bmpWidth,bmpHeight,matrix, true );
                 img.setImageBitmap(resizeBmp);
             }

         });
     }
 }

 效果如下：