src/com/android/dreams/phototable/PhotoCarousel.java - platform/packages/screensavers/PhotoTable - Git at Google

 /*
  * Copyright (C) 2012 The Android Open Source Project
  *
  * 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.
  */
 package com.android.dreams.phototable;

 import android.content.Context;
 import android.content.res.Resources;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.os.AsyncTask;
 import android.service.dreams.DreamService;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.GestureDetector;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewPropertyAnimator;
 import android.widget.FrameLayout;
 import android.widget.ImageView;

 import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.ListIterator;

 /**
  * A FrameLayout that holds two photos, back to back.
  */
 public class PhotoCarousel extends FrameLayout {
     private static final String TAG = "PhotoCarousel";
     private static final boolean DEBUG = false;

     private static final int LANDSCAPE = 1;
     private static final int PORTRAIT = 2;

     private final Flipper mFlipper;
     private final PhotoSourcePlexor mPhotoSource;
     private final GestureDetector mGestureDetector;
     private final View[] mPanel;
     private final int mFlipDuration;
     private final int mDropPeriod;
     private final int mBitmapQueueLimit;
     private final HashMap<View, Bitmap> mBitmapStore;
     private final LinkedList<Bitmap> mBitmapQueue;
     private final LinkedList<PhotoLoadTask> mBitmapLoaders;
     private View mSpinner;
     private int mOrientation;
     private int mWidth;
     private int mHeight;
     private int mLongSide;
     private int mShortSide;
     private long mLastFlipTime;

     class Flipper implements Runnable {
         @Override
         public void run() {
             maybeLoadMore();

             if (mBitmapQueue.isEmpty()) {
                 mSpinner.setVisibility(View.VISIBLE);
             } else {
                 mSpinner.setVisibility(View.GONE);
             }

             long now = System.currentTimeMillis();
             long elapsed = now - mLastFlipTime;

             if (elapsed < mDropPeriod) {
                 scheduleNext((int) mDropPeriod - elapsed);
             } else {
                 scheduleNext(mDropPeriod);
                 if (changePhoto() || canFlip()) {
                     flip(1f);
                     mLastFlipTime = now;
                 }
             }
         }

         private void scheduleNext(long delay) {
             removeCallbacks(mFlipper);
             postDelayed(mFlipper, delay);
         }
     }

     public PhotoCarousel(Context context, AttributeSet as) {
         super(context, as);
         final Resources resources = getResources();
         mDropPeriod = resources.getInteger(R.integer.carousel_drop_period);
         mBitmapQueueLimit = resources.getInteger(R.integer.num_images_to_preload);
         mFlipDuration = resources.getInteger(R.integer.flip_duration);
         mPhotoSource = new PhotoSourcePlexor(getContext(),
                 getContext().getSharedPreferences(FlipperDreamSettings.PREFS_NAME, 0));
         mBitmapStore = new HashMap<View, Bitmap>();
         mBitmapQueue = new LinkedList<Bitmap>();
         mBitmapLoaders = new LinkedList<PhotoLoadTask>();

         mPanel = new View[2];
         mFlipper = new Flipper();
         mGestureDetector = new GestureDetector(context,
                 new GestureDetector.SimpleOnGestureListener() {
                     @Override
                     public boolean onFling(MotionEvent e1, MotionEvent e2, float vX, float vY) {
                         log("fling with " + vX);
                         flip(Math.signum(vX));
                         return true;
                     }
                 });
     }

     private float lockTo180(float a) {
         return 180f * (float) Math.floor(a / 180f);
     }

     private float wrap360(float a) {
         return a - 360f * (float) Math.floor(a / 360f);
     }

     private class PhotoLoadTask extends AsyncTask<Void, Void, Bitmap> {
         private final BitmapFactory.Options mOptions;

         public PhotoLoadTask () {
             mOptions = new BitmapFactory.Options();
             mOptions.inTempStorage = new byte[32768];
         }

         @Override
         public Bitmap doInBackground(Void... unused) {
             Bitmap decodedPhoto;
             if (mLongSide == 0 || mShortSide == 0) {
                 return null;
             }
             decodedPhoto = mPhotoSource.next(mOptions, mLongSide, mShortSide);
             return decodedPhoto;
         }

         @Override
         public void onPostExecute(Bitmap photo) {
             if (photo != null) {
                 mBitmapQueue.offer(photo);
             }
             mFlipper.run();
         }
     };

     private void maybeLoadMore() {
         if (!mBitmapLoaders.isEmpty()) {
             for(ListIterator<PhotoLoadTask> i = mBitmapLoaders.listIterator(0);
                 i.hasNext();) {
                 PhotoLoadTask loader = i.next();
                 if (loader.getStatus() == AsyncTask.Status.FINISHED) {
                     i.remove();
                 }
             }
         }

         if ((mBitmapLoaders.size() + mBitmapQueue.size()) < mBitmapQueueLimit) {
             PhotoLoadTask task = new PhotoLoadTask();
             mBitmapLoaders.offer(task);
             task.execute();
         }
     }

     private ImageView getBackface() {
         return (ImageView) ((mPanel[0].getAlpha() < 0.5f) ? mPanel[0] : mPanel[1]);
     }

     private boolean canFlip() {
         return mBitmapStore.containsKey(getBackface());
     }

     private boolean changePhoto() {
         Bitmap photo = mBitmapQueue.poll();
         if (photo != null) {
             ImageView destination = getBackface();
             Bitmap old = mBitmapStore.get(destination);
             int width = photo.getWidth();
             int height = photo.getHeight();
             int orientation = (width > height ? LANDSCAPE : PORTRAIT);

             destination.setImageBitmap(photo);
             destination.setTag(R.id.photo_orientation, new Integer(orientation));
             destination.setTag(R.id.photo_width, new Integer(width));
             destination.setTag(R.id.photo_height, new Integer(height));
             setScaleType(destination);

             mBitmapStore.put(destination, photo);

             if (old != null) {
                 old.recycle();
             }

             return true;
         } else {
             return false;
         }
     }

     private void setScaleType(View photo) {
         if (photo.getTag(R.id.photo_orientation) != null) {
             int orientation = ((Integer) photo.getTag(R.id.photo_orientation)).intValue();
             int width = ((Integer) photo.getTag(R.id.photo_width)).intValue();
             int height = ((Integer) photo.getTag(R.id.photo_height)).intValue();

             if (width < mWidth && height < mHeight) {
                 log("too small: FIT_CENTER");
                 ((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_CROP);
             } else if (orientation == mOrientation) {
                 log("orientations match: CENTER_CROP");
                 ((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_CROP);
             } else {
                 log("orientations do not match: CENTER_INSIDE");
                 ((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_INSIDE);
             }
         } else {
             log("no tag!");
         }
     }

     public void flip(float sgn) {
         mPanel[0].animate().cancel();
         mPanel[1].animate().cancel();

         float frontY = mPanel[0].getRotationY();
         float backY = mPanel[1].getRotationY();
         float frontA = mPanel[0].getAlpha();
         float backA = mPanel[1].getAlpha();

         frontY = wrap360(frontY);
         backY = wrap360(backY);

         mPanel[0].setRotationY(frontY);
         mPanel[1].setRotationY(backY);

         frontY = lockTo180(frontY + sgn * 180f);
         backY = lockTo180(backY + sgn * 180f);
         frontA = 1f - frontA;
         backA = 1f - backA;

 	// Don't rotate
 	frontY = backY = 0f;

         ViewPropertyAnimator frontAnim = mPanel[0].animate()
                 .rotationY(frontY)
                 .alpha(frontA)
                 .setDuration(mFlipDuration);
         ViewPropertyAnimator backAnim = mPanel[1].animate()
                 .rotationY(backY)
                 .alpha(backA)
                 .setDuration(mFlipDuration)
                 .withEndAction(new Runnable() {
                     @Override
                     public void run() {
                         maybeLoadMore();
                     }
                 });

         frontAnim.start();
         backAnim.start();
     }

     @Override
     public void onAttachedToWindow() {
         mPanel[0]= findViewById(R.id.front);
         mPanel[1] = findViewById(R.id.back);
         mSpinner = findViewById(R.id.spinner);
         mFlipper.run();
     }

     @Override
     public void onLayout(boolean changed, int left, int top, int right, int bottom) {
         mHeight = bottom - top;
         mWidth = right - left;

         mOrientation = (mWidth > mHeight ? LANDSCAPE : PORTRAIT);

         boolean init = mLongSide == 0;
         mLongSide = (int) Math.max(mWidth, mHeight);
         mShortSide = (int) Math.min(mWidth, mHeight);

         // reset scale types for new aspect ratio
         setScaleType(mPanel[0]);
         setScaleType(mPanel[1]);

         super.onLayout(changed, left, top, right, bottom);
     }

     @Override
     public boolean onTouchEvent(MotionEvent event) {
         mGestureDetector.onTouchEvent(event);
         return true;
     }

     private void log(String message) {
         if (DEBUG) {
             Log.i(TAG, message);
         }
     }
 }
	/*
	* Copyright (C) 2012 The Android Open Source Project
	*
	* 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.
	*/
	package com.android.dreams.phototable;

	import android.content.Context;
	import android.content.res.Resources;
	import android.graphics.Bitmap;
	import android.graphics.BitmapFactory;
	import android.os.AsyncTask;
	import android.service.dreams.DreamService;
	import android.util.AttributeSet;
	import android.util.Log;
	import android.view.GestureDetector;
	import android.view.MotionEvent;
	import android.view.View;
	import android.view.ViewPropertyAnimator;
	import android.widget.FrameLayout;
	import android.widget.ImageView;

	import java.util.HashMap;
	import java.util.LinkedList;
	import java.util.ListIterator;

	/**
	* A FrameLayout that holds two photos, back to back.
	*/
	public class PhotoCarousel extends FrameLayout {
	private static final String TAG = "PhotoCarousel";
	private static final boolean DEBUG = false;

	private static final int LANDSCAPE = 1;
	private static final int PORTRAIT = 2;

	private final Flipper mFlipper;
	private final PhotoSourcePlexor mPhotoSource;
	private final GestureDetector mGestureDetector;
	private final View[] mPanel;
	private final int mFlipDuration;
	private final int mDropPeriod;
	private final int mBitmapQueueLimit;
	private final HashMap<View, Bitmap> mBitmapStore;
	private final LinkedList<Bitmap> mBitmapQueue;
	private final LinkedList<PhotoLoadTask> mBitmapLoaders;
	private View mSpinner;
	private int mOrientation;
	private int mWidth;
	private int mHeight;
	private int mLongSide;
	private int mShortSide;
	private long mLastFlipTime;

	class Flipper implements Runnable {
	@Override
	public void run() {
	maybeLoadMore();

	if (mBitmapQueue.isEmpty()) {
	mSpinner.setVisibility(View.VISIBLE);
	} else {
	mSpinner.setVisibility(View.GONE);
	}

	long now = System.currentTimeMillis();
	long elapsed = now - mLastFlipTime;

	if (elapsed < mDropPeriod) {
	scheduleNext((int) mDropPeriod - elapsed);
	} else {
	scheduleNext(mDropPeriod);
	if (changePhoto() \|\| canFlip()) {
	flip(1f);
	mLastFlipTime = now;
	}
	}
	}

	private void scheduleNext(long delay) {
	removeCallbacks(mFlipper);
	postDelayed(mFlipper, delay);
	}
	}

	public PhotoCarousel(Context context, AttributeSet as) {
	super(context, as);
	final Resources resources = getResources();
	mDropPeriod = resources.getInteger(R.integer.carousel_drop_period);
	mBitmapQueueLimit = resources.getInteger(R.integer.num_images_to_preload);
	mFlipDuration = resources.getInteger(R.integer.flip_duration);
	mPhotoSource = new PhotoSourcePlexor(getContext(),
	getContext().getSharedPreferences(FlipperDreamSettings.PREFS_NAME, 0));
	mBitmapStore = new HashMap<View, Bitmap>();
	mBitmapQueue = new LinkedList<Bitmap>();
	mBitmapLoaders = new LinkedList<PhotoLoadTask>();

	mPanel = new View[2];
	mFlipper = new Flipper();
	mGestureDetector = new GestureDetector(context,
	new GestureDetector.SimpleOnGestureListener() {
	@Override
	public boolean onFling(MotionEvent e1, MotionEvent e2, float vX, float vY) {
	log("fling with " + vX);
	flip(Math.signum(vX));
	return true;
	}
	});
	}

	private float lockTo180(float a) {
	return 180f * (float) Math.floor(a / 180f);
	}

	private float wrap360(float a) {
	return a - 360f * (float) Math.floor(a / 360f);
	}

	private class PhotoLoadTask extends AsyncTask<Void, Void, Bitmap> {
	private final BitmapFactory.Options mOptions;

	public PhotoLoadTask () {
	mOptions = new BitmapFactory.Options();
	mOptions.inTempStorage = new byte[32768];
	}

	@Override
	public Bitmap doInBackground(Void... unused) {
	Bitmap decodedPhoto;
	if (mLongSide == 0 \|\| mShortSide == 0) {
	return null;
	}
	decodedPhoto = mPhotoSource.next(mOptions, mLongSide, mShortSide);
	return decodedPhoto;
	}

	@Override
	public void onPostExecute(Bitmap photo) {
	if (photo != null) {
	mBitmapQueue.offer(photo);
	}
	mFlipper.run();
	}
	};

	private void maybeLoadMore() {
	if (!mBitmapLoaders.isEmpty()) {
	for(ListIterator<PhotoLoadTask> i = mBitmapLoaders.listIterator(0);
	i.hasNext();) {
	PhotoLoadTask loader = i.next();
	if (loader.getStatus() == AsyncTask.Status.FINISHED) {
	i.remove();
	}
	}
	}

	if ((mBitmapLoaders.size() + mBitmapQueue.size()) < mBitmapQueueLimit) {
	PhotoLoadTask task = new PhotoLoadTask();
	mBitmapLoaders.offer(task);
	task.execute();
	}
	}

	private ImageView getBackface() {
	return (ImageView) ((mPanel[0].getAlpha() < 0.5f) ? mPanel[0] : mPanel[1]);
	}

	private boolean canFlip() {
	return mBitmapStore.containsKey(getBackface());
	}

	private boolean changePhoto() {
	Bitmap photo = mBitmapQueue.poll();
	if (photo != null) {
	ImageView destination = getBackface();
	Bitmap old = mBitmapStore.get(destination);
	int width = photo.getWidth();
	int height = photo.getHeight();
	int orientation = (width > height ? LANDSCAPE : PORTRAIT);

	destination.setImageBitmap(photo);
	destination.setTag(R.id.photo_orientation, new Integer(orientation));
	destination.setTag(R.id.photo_width, new Integer(width));
	destination.setTag(R.id.photo_height, new Integer(height));
	setScaleType(destination);

	mBitmapStore.put(destination, photo);

	if (old != null) {
	old.recycle();
	}

	return true;
	} else {
	return false;
	}
	}

	private void setScaleType(View photo) {
	if (photo.getTag(R.id.photo_orientation) != null) {
	int orientation = ((Integer) photo.getTag(R.id.photo_orientation)).intValue();
	int width = ((Integer) photo.getTag(R.id.photo_width)).intValue();
	int height = ((Integer) photo.getTag(R.id.photo_height)).intValue();

	if (width < mWidth && height < mHeight) {
	log("too small: FIT_CENTER");
	((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_CROP);
	} else if (orientation == mOrientation) {
	log("orientations match: CENTER_CROP");
	((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_CROP);
	} else {
	log("orientations do not match: CENTER_INSIDE");
	((ImageView) photo).setScaleType(ImageView.ScaleType.CENTER_INSIDE);
	}
	} else {
	log("no tag!");
	}
	}

	public void flip(float sgn) {
	mPanel[0].animate().cancel();
	mPanel[1].animate().cancel();

	float frontY = mPanel[0].getRotationY();
	float backY = mPanel[1].getRotationY();
	float frontA = mPanel[0].getAlpha();
	float backA = mPanel[1].getAlpha();

	frontY = wrap360(frontY);
	backY = wrap360(backY);

	mPanel[0].setRotationY(frontY);
	mPanel[1].setRotationY(backY);

	frontY = lockTo180(frontY + sgn * 180f);
	backY = lockTo180(backY + sgn * 180f);
	frontA = 1f - frontA;
	backA = 1f - backA;

	// Don't rotate
	frontY = backY = 0f;

	ViewPropertyAnimator frontAnim = mPanel[0].animate()
	.rotationY(frontY)
	.alpha(frontA)
	.setDuration(mFlipDuration);
	ViewPropertyAnimator backAnim = mPanel[1].animate()
	.rotationY(backY)
	.alpha(backA)
	.setDuration(mFlipDuration)
	.withEndAction(new Runnable() {
	@Override
	public void run() {
	maybeLoadMore();
	}
	});

	frontAnim.start();
	backAnim.start();
	}

	@Override
	public void onAttachedToWindow() {
	mPanel[0]= findViewById(R.id.front);
	mPanel[1] = findViewById(R.id.back);
	mSpinner = findViewById(R.id.spinner);
	mFlipper.run();
	}

	@Override
	public void onLayout(boolean changed, int left, int top, int right, int bottom) {
	mHeight = bottom - top;
	mWidth = right - left;

	mOrientation = (mWidth > mHeight ? LANDSCAPE : PORTRAIT);

	boolean init = mLongSide == 0;
	mLongSide = (int) Math.max(mWidth, mHeight);
	mShortSide = (int) Math.min(mWidth, mHeight);

	// reset scale types for new aspect ratio
	setScaleType(mPanel[0]);
	setScaleType(mPanel[1]);

	super.onLayout(changed, left, top, right, bottom);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
	mGestureDetector.onTouchEvent(event);
	return true;
	}

	private void log(String message) {
	if (DEBUG) {
	Log.i(TAG, message);
	}
	}
	}