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转自：http://www.inter-fuser.com/2010/02/android-coverflow-widget-v2.html

/* * Copyright (C) 2010 Neil Davies * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *  * This code is base on the Android Gallery widget and was Created  * by Neil Davies neild001 'at' gmail dot com to be a Coverflow widget *  * @author Neil Davies */package com.example.coverflow;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(); }}

/* * Copyright (C) 2010 Neil Davies * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *      http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. *  * This code is base on the Android Gallery widget and was Created  * by Neil Davies neild001 'at' gmail dot com to be a Coverflow widget *  * @author Neil Davies */package com.example.coverflow;import java.io.FileInputStream;import android.app.Activity;import android.content.Context;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.graphics.Canvas;import android.graphics.LinearGradient;import android.graphics.Matrix;import android.graphics.Paint;import android.graphics.PorterDuffXfermode;import android.graphics.Bitmap.Config;import android.graphics.PorterDuff.Mode;import android.graphics.Shader.TileMode;import android.graphics.drawable.BitmapDrawable;import android.os.Bundle;import android.view.View;import android.view.ViewGroup;import android.widget.BaseAdapter;import android.widget.ImageView;import android.widget.ImageView.ScaleType;public class CoverFlowExample extends Activity {    /** Called when the activity is first created. */    @Override    public void onCreate(Bundle savedInstanceState) {     super.onCreate(savedInstanceState);          CoverFlow coverFlow;     coverFlow = new CoverFlow(this);          coverFlow.setAdapter(new ImageAdapter(this));     ImageAdapter coverImageAdapter =  new ImageAdapter(this);          //coverImageAdapter.createReflectedImages();          coverFlow.setAdapter(coverImageAdapter);          coverFlow.setSpacing(-25);     coverFlow.setSelection(4, true);     coverFlow.setAnimationDuration(1000);               setContentView(coverFlow);    }     public class ImageAdapter extends BaseAdapter {     int mGalleryItemBackground;     private Context mContext;     private FileInputStream fis;             private Integer[] mImageIds = {       R.drawable.kasabian_kasabian,             R.drawable.starssailor_silence_is_easy,             R.drawable.killers_day_and_age,             R.drawable.garbage_bleed_like_me,             R.drawable.death_cub_for_cutie_the_photo_album,             R.drawable.kasabian_kasabian,             R.drawable.massive_attack_collected,             R.drawable.muse_the_resistance,             R.drawable.starssailor_silence_is_easy     };     private ImageView[] mImages;          public ImageAdapter(Context c) {      mContext = c;      mImages = new ImageView[mImageIds.length];     }  public boolean createReflectedImages() {          //The gap we want between the reflection and the original image          final int reflectionGap = 4;                              int index = 0;          for (int imageId : mImageIds) {        Bitmap originalImage = BitmapFactory.decodeResource(getResources(),           imageId);           int width = originalImage.getWidth();           int height = originalImage.getHeight();                           //This will not scale but will flip on the Y axis           Matrix matrix = new Matrix();           matrix.preScale(1, -1);                      //Create a Bitmap with the flip matrix applied to it.           //We only want the bottom half of the image           Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/2, width, height/2, matrix, false);                                     //Create a new bitmap with same width but taller to fit reflection           Bitmap bitmapWithReflection = Bitmap.createBitmap(width              , (height + height/2), Config.ARGB_8888);                   //Create a new Canvas with the bitmap that's big enough for          //the image plus gap plus reflection          Canvas canvas = new Canvas(bitmapWithReflection);          //Draw in the original image          canvas.drawBitmap(originalImage, 0, 0, null);          //Draw in the gap          Paint deafaultPaint = new Paint();          canvas.drawRect(0, height, width, height + reflectionGap, deafaultPaint);          //Draw in the reflection          canvas.drawBitmap(reflectionImage,0, height + reflectionGap, null);                    //Create a shader that is a linear gradient that covers the reflection          Paint paint = new Paint();           LinearGradient shader = new LinearGradient(0, originalImage.getHeight(), 0,             bitmapWithReflection.getHeight() + reflectionGap, 0x70ffffff, 0x00ffffff,             TileMode.CLAMP);           //Set the paint to use this shader (linear gradient)          paint.setShader(shader);           //Set the Transfer mode to be porter duff and destination in          paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));           //Draw a rectangle using the paint with our linear gradient          canvas.drawRect(0, height, width,             bitmapWithReflection.getHeight() + reflectionGap, paint);                     ImageView imageView = new ImageView(mContext);          imageView.setImageBitmap(bitmapWithReflection);          imageView.setLayoutParams(new CoverFlow.LayoutParams(120, 180));          imageView.setScaleType(ScaleType.MATRIX);          mImages[index++] = imageView;                    }       return true;  }     public int getCount() {         return mImageIds.length;     }     public Object getItem(int position) {         return position;     }     public long getItemId(int position) {         return position;     }     public View getView(int position, View convertView, ViewGroup parent) {      //Use this code if you want to load from resources         ImageView i = new ImageView(mContext);         i.setImageResource(mImageIds[position]);         i.setLayoutParams(new CoverFlow.LayoutParams(130, 130));         i.setScaleType(ImageView.ScaleType.CENTER_INSIDE);                   //Make sure we set anti-aliasing otherwise we get jaggies         BitmapDrawable drawable = (BitmapDrawable) i.getDrawable();         drawable.setAntiAlias(true);         return i;            //return mImages[position];     }   /** Returns the size (0.0f to 1.0f) of the views       * depending on the 'offset' to the center. */       public float getScale(boolean focused, int offset) {         /* Formula: 1 / (2 ^ offset) */           return Math.max(0, 1.0f / (float)Math.pow(2, Math.abs(offset)));       }  }}

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