content: package com.npi.blureffect;
  
  import android.app.Activity;
  import android.graphics.Bitmap;
  import android.graphics.BitmapFactory;
  import android.os.Bundle;
  import android.view.View;
  import android.view.Window;
  import android.widget.AbsListView;
  import android.widget.AbsListView.LayoutParams;
  import android.widget.AbsListView.OnScrollListener;
  import android.widget.ArrayAdapter;
  import android.widget.CompoundButton;
  import android.widget.CompoundButton.OnCheckedChangeListener;
  import android.widget.ImageView;
  import android.widget.ListView;
  import android.widget.Switch;
  
  import java.io.File;
  
  public class MainActivity extends Activity {
  
  	private static final String BLURRED_IMG_PATH = "blurred_image.png";
  	private static final int TOP_HEIGHT = 700;
  	private ListView mList;
  	private ImageView mBlurredImage;
  	private View headerView;
  	private ImageView mNormalImage;
  	private ScrollableImageView mBlurredImageHeader;
  	private Switch mSwitch;
  	private float alpha;
  
  	@Override
  	protected void onCreate(Bundle savedInstanceState) {
  		super.onCreate(savedInstanceState);
  		requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
  		setContentView(R.layout.activity_main);
  
  		// Get the screen width
  		final int screenWidth = ImageUtils.getScreenWidth(this);
  
  		// Find the view
  		mBlurredImage = (ImageView) findViewById(R.id.blurred_image);
  		mNormalImage = (ImageView) findViewById(R.id.normal_image);
  		mBlurredImageHeader = (ScrollableImageView) findViewById(R.id.blurred_image_header);
  		mSwitch = (Switch) findViewById(R.id.background_switch);
  		mList = (ListView) findViewById(R.id.list);
  
  		// prepare the header ScrollableImageView
  		mBlurredImageHeader.setScreenWidth(screenWidth);
  
  		// Action for the switch
  		mSwitch.setOnCheckedChangeListener(new OnCheckedChangeListener() {
  
  			@Override
  			public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
  				if (isChecked) {
  					mBlurredImage.setAlpha(alpha);
  				} else {
  					mBlurredImage.setAlpha(0f);
  
  				}
  
  			}
  		});
  
  		// Try to find the blurred image
  		final File blurredImage = new File(getFilesDir() + BLURRED_IMG_PATH);
  		if (!blurredImage.exists()) {
  
  			// launch the progressbar in ActionBar
  			setProgressBarIndeterminateVisibility(true);
  
  			new Thread(new Runnable() {
  
  				@Override
  				public void run() {
  
  					// No image found => let's generate it!
  					BitmapFactory.Options options = new BitmapFactory.Options();
  					options.inSampleSize = 2;
  					Bitmap image = BitmapFactory.decodeResource(getResources(), R.drawable.image, options);
  					Bitmap newImg = Blur.fastblur(MainActivity.this, image, 12);
  					ImageUtils.storeImage(newImg, blurredImage);
  					runOnUiThread(new Runnable() {
  
  						@Override
  						public void run() {
  							updateView(screenWidth);
  
  							// And finally stop the progressbar
  							setProgressBarIndeterminateVisibility(false);
  						}
  					});
  
  				}
  			}).start();
  
  		} else {
  
  			// The image has been found. Let's update the view
  			updateView(screenWidth);
  
  		}
  
  		String[] strings = getResources().getStringArray(R.array.list_content);
  
  		// Prepare the header view for our list
  		headerView = new View(this);
  		headerView.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, TOP_HEIGHT));
  		mList.addHeaderView(headerView);
  		mList.setAdapter(new ArrayAdapter<String>(this, R.layout.list_item, strings));
  		mList.setOnScrollListener(new OnScrollListener() {
  
  			@Override
  			public void onScrollStateChanged(AbsListView view, int scrollState) {
  
  			}
  
  			/**
  			 * Listen to the list scroll. This is where magic happens ;)
  			 */
  			@Override
  			public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
  
  				// Calculate the ratio between the scroll amount and the list
  				// header weight to determinate the top picture alpha
  				alpha = (float) -headerView.getTop() / (float) TOP_HEIGHT;
  				// Apply a ceil
  				if (alpha > 1) {
  					alpha = 1;
  				}
  
  				// Apply on the ImageView if needed
  				if (mSwitch.isChecked()) {
  					mBlurredImage.setAlpha(alpha);
  				}
  
  				// Parallax effect : we apply half the scroll amount to our
  				// three views
  				mBlurredImage.setTop(headerView.getTop() / 2);
  				mNormalImage.setTop(headerView.getTop() / 2);
  				mBlurredImageHeader.handleScroll(headerView.getTop() / 2);
  
  			}
  		});
  	}
  
  	private void updateView(final int screenWidth) {
  		Bitmap bmpBlurred = BitmapFactory.decodeFile(getFilesDir() + BLURRED_IMG_PATH);
  		bmpBlurred = Bitmap.createScaledBitmap(bmpBlurred, screenWidth, (int) (bmpBlurred.getHeight() * ((float) screenWidth) / (float) bmpBlurred.getWidth()), false);
  
  		mBlurredImage.setImageBitmap(bmpBlurred);
  
  		mBlurredImageHeader.setoriginalImage(bmpBlurred);
  	}
  }
  