Scale bitmap according to ScaleGestureDetector

In the last exercise, "Detect pinch zoom using ScaleGestureDetector" was shown. it's modified to scale a bitmap accordingly. (It's for demonstration only, may be not practical in real use.

package com.exercise.AndroidPinchZoom;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.ScaleGestureDetector.SimpleOnScaleGestureListener;
import android.widget.ImageView;
import android.widget.TextView;

public class AndroidPinchZoomActivity extends Activity {
 
 TextView scaleGesture;
 ImageView myImageView;
 float curScale = 1F;
 Bitmap bitmap;
 int bmpWidth, bmpHeight;
 
 ScaleGestureDetector scaleGestureDetector;
 
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
       scaleGesture = (TextView)findViewById(R.id.ScaleGesture);
       myImageView = (ImageView)findViewById(R.id.imageview);
      
       bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
       bmpWidth = bitmap.getWidth();
       bmpHeight = bitmap.getHeight();
       drawMatrix();
      
       scaleGestureDetector = new ScaleGestureDetector(this, new simpleOnScaleGestureListener());
   }
  
   private void drawMatrix(){
    
    curScale = ((curScale - 1) * 10) + 1;
    if (curScale < 0.1){
     curScale = 0.1f;
    }
    
    Bitmap resizedBitmap;    
       int newHeight = (int) (bmpHeight * curScale);
       int newWidth = (int) (bmpWidth * curScale);
       resizedBitmap = Bitmap.createScaledBitmap(bitmap, newWidth, newHeight, false);
       myImageView.setImageBitmap(resizedBitmap);
   }
  
   @Override
 public boolean onTouchEvent(MotionEvent event) {
  // TODO Auto-generated method stub
    scaleGestureDetector.onTouchEvent(event);
  return true;
 }

 public class simpleOnScaleGestureListener extends SimpleOnScaleGestureListener {

  @Override
  public boolean onScale(ScaleGestureDetector detector) {
   // TODO Auto-generated method stub
   curScale = detector.getScaleFactor();
   scaleGesture.setText(String.valueOf(curScale));
   drawMatrix();
   return true;
  }

  @Override
  public boolean onScaleBegin(ScaleGestureDetector detector) {
   // TODO Auto-generated method stub
   return true;
  }

  @Override
  public void onScaleEnd(ScaleGestureDetector detector) {
   // TODO Auto-generated method stub
   super.onScaleEnd(detector);
  }

   }
}

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   android:orientation="vertical" >

   <TextView
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"
       android:text="@string/hello" />
   <TextView
       android:id="@+id/ScaleGesture"
       android:layout_width="fill_parent"
       android:layout_height="wrap_content"/>
   <ImageView
       android:id="@+id/imageview"
       android:layout_gravity="center"
       android:layout_width="fill_parent"
       android:layout_height="fill_parent"
       android:scaleType="center" />
</LinearLayout>

Download the files.

Related article:
- Implement Pinch Zoom in OnTouchListener