When you create a gallery application, you will allow the user to zoom the image in and out through pinch (moving a finger and thumb a part or bringing them together). In this Android tip, I am going show you how to zoom an ImageView when the user makes a pinch on the screen.


<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"

   xmlns:tools="http://schemas.android.com/tools"

   android:layout_width="match_parent"

   android:layout_height="match_parent"  

   android:orientation="vertical"

   tools:context="com.example.inputdialog.MainActivity" >  



	<ImageView

		android:id="@+id/imgview"

		android:layout_width="wrap_content"

		android:layout_height="wrap_content" 

		android:layout_centerInParent="true"

		android:src="@drawable/ic_launcher"	

		

	

		/>



</RelativeLayout>

public class MainActivity extends Activity{

	ImageView imgView;

	ScaleGestureDetector scaleGDetector;

	float scale=1f;

	protected void onCreate(Bundle savedInstanceState) {

      super.onCreate(savedInstanceState);

      setContentView(R.layout.activity_main); 

      imgView=(ImageView)findViewById(R.id.imgview);

      scaleGDetector=new ScaleGestureDetector(this, new ScaleListener());

     

   } 

   @Override

   public boolean onTouchEvent(MotionEvent ev) {

   	scaleGDetector.onTouchEvent(ev);

     return true;

   }

   

   private class ScaleListener implements ScaleGestureDetector.OnScaleGestureListener{

   		public boolean onScaleBegin(ScaleGestureDetector sgd){

   			

   				return true;

			

   		}

   		public void onScaleEnd(ScaleGestureDetector sgd){

   			

   		}

   		public boolean onScale(ScaleGestureDetector sgd){

   			// Multiply scale factor

   			scale*= sgd.getScaleFactor();

   			// Scale or zoom the imageview

   			imgView.setScaleX(scale);

   			imgView.setScaleY(scale);

   			Log.i("Main",String.valueOf(scale));

   			return true;

   		}

   }

}

Posted by: Dara | post date: 01-17-2015 | Subject: Android Apps Development