CoverFlow.java

/*
 * Copyright (C) 2003-2014 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 3 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.exoplatform.widget;

import android.content.Context;
import android.graphics.Camera;
import android.graphics.Matrix;
import android.util.AttributeSet;
import android.view.View;
import android.view.animation.Transformation;
import android.widget.Gallery;
import android.widget.ImageView;

public class CoverFlow extends Gallery {

    /**
     * Graphics Camera used for transforming the matrix of ImageViews
     */
    private Camera mCamera = new Camera();

    /**
     * The maximum angle the Child ImageView will be rotated by
     */    
    private int mMaxRotationAngle = 60;
    
    /**
     * The maximum zoom on the centre Child
     */
    private int mMaxZoom = -120;
    
    /**
     * The Centre of the Coverflow 
     */   
    private int mCoveflowCenter;
   
 public CoverFlow(Context context) {
  super(context);
  this.setStaticTransformationsEnabled(true);
 }

 public CoverFlow(Context context, AttributeSet attrs) {
  super(context, attrs);
        this.setStaticTransformationsEnabled(true);
 }
 
  public CoverFlow(Context context, AttributeSet attrs, int defStyle) {
   super(context, attrs, defStyle);
   this.setStaticTransformationsEnabled(true);   
  }
  
    /**
     * Get the max rotational angle of the image
  * @return the mMaxRotationAngle
  */
 public int getMaxRotationAngle() {
  return mMaxRotationAngle;
 }

 /**
  * Set the max rotational angle of each image
  * @param maxRotationAngle the mMaxRotationAngle to set
  */
 public void setMaxRotationAngle(int maxRotationAngle) {
  mMaxRotationAngle = maxRotationAngle;
 }

 /**
  * Get the Max zoom of the centre image
  * @return the mMaxZoom
  */
 public int getMaxZoom() {
  return mMaxZoom;
 }

 /**
  * Set the max zoom of the centre image
  * @param maxZoom the mMaxZoom to set
  */
 public void setMaxZoom(int maxZoom) {
  mMaxZoom = maxZoom;
 }

 /**
     * Get the Centre of the Coverflow
     * @return The centre of this Coverflow.
     */
    private int getCenterOfCoverflow() {
        return (getWidth() - getPaddingLeft() - getPaddingRight()) / 2 + getPaddingLeft();
    }
    
    /**
     * Get the Centre of the View
     * @return The centre of the given view.
     */
    private static int getCenterOfView(View view) {
        return view.getLeft() + view.getWidth() / 2;
    }  
    /**
  * {@inheritDoc}
  *
  * @see #setStaticTransformationsEnabled(boolean) 
  */ 
    protected boolean getChildStaticTransformation(View child, Transformation t) {
  
  final int childCenter = getCenterOfView(child);
  final int childWidth = child.getWidth() ;
  int rotationAngle = 0;
  
  t.clear();
  t.setTransformationType(Transformation.TYPE_MATRIX);
  
        if (childCenter == mCoveflowCenter) {
            transformImageBitmap((ImageView) child, t, 0);
        } else {      
            rotationAngle = (int) (((float) (mCoveflowCenter - childCenter)/ childWidth) *  mMaxRotationAngle);
            if (Math.abs(rotationAngle) > mMaxRotationAngle) {
             rotationAngle = (rotationAngle < 0) ? -mMaxRotationAngle : mMaxRotationAngle;   
            }
            transformImageBitmap((ImageView) child, t, rotationAngle);         
        }    
             
  return true;
 }

 /**
  * This is called during layout when the size of this view has changed. If
  * you were just added to the view hierarchy, you're called with the old
  * values of 0.
  *
  * @param w Current width of this view.
  * @param h Current height of this view.
  * @param oldw Old width of this view.
  * @param oldh Old height of this view.
     */
     protected void onSizeChanged(int w, int h, int oldw, int oldh) {
      mCoveflowCenter = getCenterOfCoverflow();
      super.onSizeChanged(w, h, oldw, oldh);
     }
  
     /**
      * Transform the Image Bitmap by the Angle passed 
      * 
      * @param imageView ImageView the ImageView whose bitmap we want to rotate
      * @param t transformation 
      * @param rotationAngle the Angle by which to rotate the Bitmap
      */
     private void transformImageBitmap(ImageView child, Transformation t, int rotationAngle) {            
      mCamera.save();
      final Matrix imageMatrix = t.getMatrix();;
      final int imageHeight = child.getLayoutParams().height;;
      final int imageWidth = child.getLayoutParams().width;
      final int rotation = Math.abs(rotationAngle);
                     
      mCamera.translate(0.0f, 0.0f, 100.0f);
         
      //As the angle of the view gets less, zoom in     
      if ( rotation < mMaxRotationAngle ) {
       float zoomAmount = (float) (mMaxZoom +  (rotation * 1.5));
       mCamera.translate(0.0f, 0.0f, zoomAmount);          
      } 
      
      mCamera.rotateY(rotationAngle);
      mCamera.getMatrix(imageMatrix);               
      imageMatrix.preTranslate(-(imageWidth/2), -(imageHeight/2)); 
      imageMatrix.postTranslate((imageWidth/2), (imageHeight/2));
      mCamera.restore();
 }
}