src/com/android/launcher3/folder/PreviewItemManager.java - LeafOS-Project/android_packages_apps_Launcher3 - Gitiles

 /*
  * Copyright (C) 2017 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.launcher3.folder;

 import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.ENTER_INDEX;
 import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.EXIT_INDEX;
 import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.MAX_NUM_ITEMS_IN_PREVIEW;
 import static com.android.launcher3.folder.FolderIcon.DROP_IN_ANIMATION_DURATION;
 import static com.android.launcher3.graphics.PreloadIconDrawable.newPendingIcon;
 import static com.android.launcher3.icons.BitmapInfo.FLAG_THEMED;

 import android.animation.Animator;
 import android.animation.AnimatorListenerAdapter;
 import android.animation.ObjectAnimator;
 import android.animation.ValueAnimator;
 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Path;
 import android.graphics.PointF;
 import android.graphics.Rect;
 import android.graphics.drawable.Drawable;
 import android.util.FloatProperty;
 import android.view.View;

 import androidx.annotation.NonNull;

 import com.android.launcher3.BubbleTextView;
 import com.android.launcher3.Utilities;
 import com.android.launcher3.graphics.PreloadIconDrawable;
 import com.android.launcher3.model.data.ItemInfoWithIcon;
 import com.android.launcher3.model.data.WorkspaceItemInfo;
 import com.android.launcher3.views.ActivityContext;

 import java.util.ArrayList;
 import java.util.List;
 import java.util.function.Predicate;

 /**
  * Manages the drawing and animations of {@link PreviewItemDrawingParams} for a {@link FolderIcon}.
  */
 public class PreviewItemManager {

     private static final FloatProperty<PreviewItemManager> CURRENT_PAGE_ITEMS_TRANS_X =
             new FloatProperty<PreviewItemManager>("currentPageItemsTransX") {
                 @Override
                 public void setValue(PreviewItemManager manager, float v) {
                     manager.mCurrentPageItemsTransX = v;
                     manager.onParamsChanged();
                 }

                 @Override
                 public Float get(PreviewItemManager manager) {
                     return manager.mCurrentPageItemsTransX;
                 }
             };

     private final Context mContext;
     private final FolderIcon mIcon;
     private final int mIconSize;

     // These variables are all associated with the drawing of the preview; they are stored
     // as member variables for shared usage and to avoid computation on each frame
     private float mIntrinsicIconSize = -1;
     private int mTotalWidth = -1;
     private int mPrevTopPadding = -1;
     private Drawable mReferenceDrawable = null;

     private int mNumOfPrevItems = 0;

     // These hold the first page preview items
     private ArrayList<PreviewItemDrawingParams> mFirstPageParams = new ArrayList<>();
     // These hold the current page preview items. It is empty if the current page is the first page.
     private ArrayList<PreviewItemDrawingParams> mCurrentPageParams = new ArrayList<>();

     // We clip the preview items during the middle of the animation, so that it does not go outside
     // of the visual shape. We stop clipping at this threshold, since the preview items ultimately
     // do not get cropped in their resting state.
     private final float mClipThreshold;
     private float mCurrentPageItemsTransX = 0;
     private boolean mShouldSlideInFirstPage;

     static final int INITIAL_ITEM_ANIMATION_DURATION = 350;
     private static final int FINAL_ITEM_ANIMATION_DURATION = 200;

     private static final int SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION_DELAY = 100;
     private static final int SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION = 300;
     private static final int ITEM_SLIDE_IN_OUT_DISTANCE_PX = 200;

     public PreviewItemManager(FolderIcon icon) {
         mContext = icon.getContext();
         mIcon = icon;
         mIconSize = ActivityContext.lookupContext(
                 mContext).getDeviceProfile().folderChildIconSizePx;
         mClipThreshold = Utilities.dpToPx(1f);
     }

     /**
      * @param reverse If true, animates the final item in the preview to be full size. If false,
      *                animates the first item to its position in the preview.
      */
     public FolderPreviewItemAnim createFirstItemAnimation(final boolean reverse,
             final Runnable onCompleteRunnable) {
         return reverse
                 ? new FolderPreviewItemAnim(this, mFirstPageParams.get(0), 0, 2, -1, -1,
                         FINAL_ITEM_ANIMATION_DURATION, onCompleteRunnable)
                 : new FolderPreviewItemAnim(this, mFirstPageParams.get(0), -1, -1, 0, 2,
                         INITIAL_ITEM_ANIMATION_DURATION, onCompleteRunnable);
     }

     Drawable prepareCreateAnimation(final View destView) {
         Drawable animateDrawable = ((BubbleTextView) destView).getIcon();
         computePreviewDrawingParams(animateDrawable.getIntrinsicWidth(),
                 destView.getMeasuredWidth());
         mReferenceDrawable = animateDrawable;
         return animateDrawable;
     }

     public void recomputePreviewDrawingParams() {
         if (mReferenceDrawable != null) {
             computePreviewDrawingParams(mReferenceDrawable.getIntrinsicWidth(),
                     mIcon.getMeasuredWidth());
         }
     }

     private void computePreviewDrawingParams(int drawableSize, int totalSize) {
         if (mIntrinsicIconSize != drawableSize || mTotalWidth != totalSize ||
                 mPrevTopPadding != mIcon.getPaddingTop()) {
             mIntrinsicIconSize = drawableSize;
             mTotalWidth = totalSize;
             mPrevTopPadding = mIcon.getPaddingTop();

             mIcon.mBackground.setup(mIcon.getContext(), mIcon.mActivity, mIcon, mTotalWidth,
                     mIcon.getPaddingTop());
             mIcon.mPreviewLayoutRule.init(mIcon.mBackground.previewSize, mIntrinsicIconSize,
                     Utilities.isRtl(mIcon.getResources()));

             updatePreviewItems(false);
         }
     }

     PreviewItemDrawingParams computePreviewItemDrawingParams(int index, int curNumItems,
             PreviewItemDrawingParams params) {
         // We use an index of -1 to represent an icon on the workspace for the destroy and
         // create animations
         if (index == -1) {
             return getFinalIconParams(params);
         }
         return mIcon.mPreviewLayoutRule.computePreviewItemDrawingParams(index, curNumItems, params);
     }

     private PreviewItemDrawingParams getFinalIconParams(PreviewItemDrawingParams params) {
         float iconSize = mIcon.mActivity.getDeviceProfile().iconSizePx;

         final float scale = iconSize / mReferenceDrawable.getIntrinsicWidth();
         final float trans = (mIcon.mBackground.previewSize - iconSize) / 2;

         params.update(trans, trans, scale);
         return params;
     }

     public void drawParams(Canvas canvas, ArrayList<PreviewItemDrawingParams> params,
             PointF offset, boolean shouldClipPath, Path clipPath) {
         // The first item should be drawn last (ie. on top of later items)
         for (int i = params.size() - 1; i >= 0; i--) {
             PreviewItemDrawingParams p = params.get(i);
             if (!p.hidden) {
                 // Exiting param should always be clipped.
                 boolean isExiting = p.index == EXIT_INDEX;
                 drawPreviewItem(canvas, p, offset, isExiting | shouldClipPath, clipPath);
             }
         }
     }

     /**
      * Draws the preview items on {@param canvas}.
      */
     public void draw(Canvas canvas) {
         int saveCount = canvas.getSaveCount();
         // The items are drawn in coordinates relative to the preview offset
         PreviewBackground bg = mIcon.getFolderBackground();
         Path clipPath = bg.getClipPath();
         float firstPageItemsTransX = 0;
         if (mShouldSlideInFirstPage) {
             PointF firstPageOffset = new PointF(bg.basePreviewOffsetX + mCurrentPageItemsTransX,
                     bg.basePreviewOffsetY);
             boolean shouldClip = mCurrentPageItemsTransX > mClipThreshold;
             drawParams(canvas, mCurrentPageParams, firstPageOffset, shouldClip, clipPath);
             firstPageItemsTransX = -ITEM_SLIDE_IN_OUT_DISTANCE_PX + mCurrentPageItemsTransX;
         }

         PointF firstPageOffset = new PointF(bg.basePreviewOffsetX + firstPageItemsTransX,
                 bg.basePreviewOffsetY);
         boolean shouldClipFirstPage = firstPageItemsTransX < -mClipThreshold;
         drawParams(canvas, mFirstPageParams, firstPageOffset, shouldClipFirstPage, clipPath);
         canvas.restoreToCount(saveCount);
     }

     public void onParamsChanged() {
         mIcon.invalidate();
     }

     /**
      * Draws each preview item.
      *
      * @param offset The offset needed to draw the preview items.
      * @param shouldClipPath Iff true, clip path using {@param clipPath}.
      * @param clipPath The clip path of the folder icon.
      */
     private void drawPreviewItem(Canvas canvas, PreviewItemDrawingParams params, PointF offset,
             boolean shouldClipPath, Path clipPath) {
         canvas.save();
         if (shouldClipPath) {
             canvas.clipPath(clipPath);
         }
         canvas.translate(offset.x + params.transX, offset.y + params.transY);
         canvas.scale(params.scale, params.scale);
         Drawable d = params.drawable;

         if (d != null) {
             Rect bounds = d.getBounds();
             canvas.save();
             canvas.translate(-bounds.left, -bounds.top);
             canvas.scale(mIntrinsicIconSize / bounds.width(), mIntrinsicIconSize / bounds.height());
             d.draw(canvas);
             canvas.restore();
         }
         canvas.restore();
     }

     public void hidePreviewItem(int index, boolean hidden) {
         // If there are more params than visible in the preview, they are used for enter/exit
         // animation purposes and they were added to the front of the list.
         // To index the params properly, we need to skip these params.
         index = index + Math.max(mFirstPageParams.size() - MAX_NUM_ITEMS_IN_PREVIEW, 0);

         PreviewItemDrawingParams params = index < mFirstPageParams.size() ?
                 mFirstPageParams.get(index) : null;
         if (params != null) {
             params.hidden = hidden;
         }
     }

     void buildParamsForPage(int page, ArrayList<PreviewItemDrawingParams> params, boolean animate) {
         List<WorkspaceItemInfo> items = mIcon.getPreviewItemsOnPage(page);

         // We adjust the size of the list to match the number of items in the preview.
         while (items.size() < params.size()) {
             params.remove(params.size() - 1);
         }
         while (items.size() > params.size()) {
             params.add(new PreviewItemDrawingParams(0, 0, 0));
         }

         int numItemsInFirstPagePreview = page == 0 ? items.size() : MAX_NUM_ITEMS_IN_PREVIEW;
         for (int i = 0; i < params.size(); i++) {
             PreviewItemDrawingParams p = params.get(i);
             setDrawable(p, items.get(i));

             if (!animate) {
                 if (p.anim != null) {
                     p.anim.cancel();
                 }
                 computePreviewItemDrawingParams(i, numItemsInFirstPagePreview, p);
                 if (mReferenceDrawable == null) {
                     mReferenceDrawable = p.drawable;
                 }
             } else {
                 FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, i,
                         mNumOfPrevItems, i, numItemsInFirstPagePreview, DROP_IN_ANIMATION_DURATION,
                         null);

                 if (p.anim != null) {
                     if (p.anim.hasEqualFinalState(anim)) {
                         // do nothing, let the current animation finish
                         continue;
                     }
                     p.anim.cancel();
                 }
                 p.anim = anim;
                 p.anim.start();
             }
         }
     }

     void onFolderClose(int currentPage) {
         // If we are not closing on the first page, we animate the current page preview items
         // out, and animate the first page preview items in.
         mShouldSlideInFirstPage = currentPage != 0;
         if (mShouldSlideInFirstPage) {
             mCurrentPageItemsTransX = 0;
             buildParamsForPage(currentPage, mCurrentPageParams, false);
             onParamsChanged();

             ValueAnimator slideAnimator = ObjectAnimator
                     .ofFloat(this, CURRENT_PAGE_ITEMS_TRANS_X, 0, ITEM_SLIDE_IN_OUT_DISTANCE_PX);
             slideAnimator.addListener(new AnimatorListenerAdapter() {
                 @Override
                 public void onAnimationEnd(Animator animation) {
                     mCurrentPageParams.clear();
                 }
             });
             slideAnimator.setStartDelay(SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION_DELAY);
             slideAnimator.setDuration(SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION);
             slideAnimator.start();
         }
     }

     void updatePreviewItems(boolean animate) {
         int numOfPrevItemsAux = mFirstPageParams.size();
         buildParamsForPage(0, mFirstPageParams, animate);
         mNumOfPrevItems = numOfPrevItemsAux;
     }

     void updatePreviewItems(Predicate<WorkspaceItemInfo> itemCheck) {
         boolean modified = false;
         for (PreviewItemDrawingParams param : mFirstPageParams) {
             if (itemCheck.test(param.item)) {
                 setDrawable(param, param.item);
                 modified = true;
             }
         }
         for (PreviewItemDrawingParams param : mCurrentPageParams) {
             if (itemCheck.test(param.item)) {
                 setDrawable(param, param.item);
                 modified = true;
             }
         }
         if (modified) {
             mIcon.invalidate();
         }
     }

     boolean verifyDrawable(@NonNull Drawable who) {
         for (int i = 0; i < mFirstPageParams.size(); i++) {
             if (mFirstPageParams.get(i).drawable == who) {
                 return true;
             }
         }
         return false;
     }

     float getIntrinsicIconSize() {
         return mIntrinsicIconSize;
     }

     /**
      * Handles the case where items in the preview are either:
      *  - Moving into the preview
      *  - Moving into a new position
      *  - Moving out of the preview
      *
      * @param oldItems The list of items in the old preview.
      * @param newItems The list of items in the new preview.
      * @param dropped The item that was dropped onto the FolderIcon.
      */
     public void onDrop(List<WorkspaceItemInfo> oldItems, List<WorkspaceItemInfo> newItems,
             WorkspaceItemInfo dropped) {
         int numItems = newItems.size();
         final ArrayList<PreviewItemDrawingParams> params = mFirstPageParams;
         buildParamsForPage(0, params, false);

         // New preview items for items that are moving in (except for the dropped item).
         List<WorkspaceItemInfo> moveIn = new ArrayList<>();
         for (WorkspaceItemInfo newItem : newItems) {
             if (!oldItems.contains(newItem) && !newItem.equals(dropped)) {
                 moveIn.add(newItem);
             }
         }
         for (int i = 0; i < moveIn.size(); ++i) {
             int prevIndex = newItems.indexOf(moveIn.get(i));
             PreviewItemDrawingParams p = params.get(prevIndex);
             computePreviewItemDrawingParams(prevIndex, numItems, p);
             updateTransitionParam(p, moveIn.get(i), ENTER_INDEX, newItems.indexOf(moveIn.get(i)),
                     numItems);
         }

         // Items that are moving into new positions within the preview.
         for (int newIndex = 0; newIndex < newItems.size(); ++newIndex) {
             int oldIndex = oldItems.indexOf(newItems.get(newIndex));
             if (oldIndex >= 0 && newIndex != oldIndex) {
                 PreviewItemDrawingParams p = params.get(newIndex);
                 updateTransitionParam(p, newItems.get(newIndex), oldIndex, newIndex, numItems);
             }
         }

         // Old preview items that need to be moved out.
         List<WorkspaceItemInfo> moveOut = new ArrayList<>(oldItems);
         moveOut.removeAll(newItems);
         for (int i = 0; i < moveOut.size(); ++i) {
             WorkspaceItemInfo item = moveOut.get(i);
             int oldIndex = oldItems.indexOf(item);
             PreviewItemDrawingParams p = computePreviewItemDrawingParams(oldIndex, numItems, null);
             updateTransitionParam(p, item, oldIndex, EXIT_INDEX, numItems);
             params.add(0, p); // We want these items first so that they are on drawn last.
         }

         for (int i = 0; i < params.size(); ++i) {
             if (params.get(i).anim != null) {
                 params.get(i).anim.start();
             }
         }
     }

     private void updateTransitionParam(final PreviewItemDrawingParams p, WorkspaceItemInfo item,
             int prevIndex, int newIndex, int numItems) {
         setDrawable(p, item);

         FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, prevIndex, numItems,
                 newIndex, numItems, DROP_IN_ANIMATION_DURATION, null);
         if (p.anim != null && !p.anim.hasEqualFinalState(anim)) {
             p.anim.cancel();
         }
         p.anim = anim;
     }

     private void setDrawable(PreviewItemDrawingParams p, WorkspaceItemInfo item) {
         if (item.hasPromiseIconUi() || (item.runtimeStatusFlags
                     & ItemInfoWithIcon.FLAG_SHOW_DOWNLOAD_PROGRESS_MASK) != 0) {
             PreloadIconDrawable drawable = newPendingIcon(mContext, item);
             drawable.setLevel(item.getProgressLevel());
             p.drawable = drawable;
         } else {
             p.drawable = item.newIcon(mContext, FLAG_THEMED);
         }
         p.drawable.setBounds(0, 0, mIconSize, mIconSize);
         p.item = item;

         // Set the callback to FolderIcon as it is responsible to drawing the icon. The
         // callback will be released when the folder is opened.
         p.drawable.setCallback(mIcon);
     }
 }
	/*
	* Copyright (C) 2017 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.launcher3.folder;

	import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.ENTER_INDEX;
	import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.EXIT_INDEX;
	import static com.android.launcher3.folder.ClippedFolderIconLayoutRule.MAX_NUM_ITEMS_IN_PREVIEW;
	import static com.android.launcher3.folder.FolderIcon.DROP_IN_ANIMATION_DURATION;
	import static com.android.launcher3.graphics.PreloadIconDrawable.newPendingIcon;
	import static com.android.launcher3.icons.BitmapInfo.FLAG_THEMED;

	import android.animation.Animator;
	import android.animation.AnimatorListenerAdapter;
	import android.animation.ObjectAnimator;
	import android.animation.ValueAnimator;
	import android.content.Context;
	import android.graphics.Canvas;
	import android.graphics.Path;
	import android.graphics.PointF;
	import android.graphics.Rect;
	import android.graphics.drawable.Drawable;
	import android.util.FloatProperty;
	import android.view.View;

	import androidx.annotation.NonNull;

	import com.android.launcher3.BubbleTextView;
	import com.android.launcher3.Utilities;
	import com.android.launcher3.graphics.PreloadIconDrawable;
	import com.android.launcher3.model.data.ItemInfoWithIcon;
	import com.android.launcher3.model.data.WorkspaceItemInfo;
	import com.android.launcher3.views.ActivityContext;

	import java.util.ArrayList;
	import java.util.List;
	import java.util.function.Predicate;

	/**
	* Manages the drawing and animations of {@link PreviewItemDrawingParams} for a {@link FolderIcon}.
	*/
	public class PreviewItemManager {

	private static final FloatProperty<PreviewItemManager> CURRENT_PAGE_ITEMS_TRANS_X =
	new FloatProperty<PreviewItemManager>("currentPageItemsTransX") {
	@Override
	public void setValue(PreviewItemManager manager, float v) {
	manager.mCurrentPageItemsTransX = v;
	manager.onParamsChanged();
	}

	@Override
	public Float get(PreviewItemManager manager) {
	return manager.mCurrentPageItemsTransX;
	}
	};

	private final Context mContext;
	private final FolderIcon mIcon;
	private final int mIconSize;

	// These variables are all associated with the drawing of the preview; they are stored
	// as member variables for shared usage and to avoid computation on each frame
	private float mIntrinsicIconSize = -1;
	private int mTotalWidth = -1;
	private int mPrevTopPadding = -1;
	private Drawable mReferenceDrawable = null;

	private int mNumOfPrevItems = 0;

	// These hold the first page preview items
	private ArrayList<PreviewItemDrawingParams> mFirstPageParams = new ArrayList<>();
	// These hold the current page preview items. It is empty if the current page is the first page.
	private ArrayList<PreviewItemDrawingParams> mCurrentPageParams = new ArrayList<>();

	// We clip the preview items during the middle of the animation, so that it does not go outside
	// of the visual shape. We stop clipping at this threshold, since the preview items ultimately
	// do not get cropped in their resting state.
	private final float mClipThreshold;
	private float mCurrentPageItemsTransX = 0;
	private boolean mShouldSlideInFirstPage;

	static final int INITIAL_ITEM_ANIMATION_DURATION = 350;
	private static final int FINAL_ITEM_ANIMATION_DURATION = 200;

	private static final int SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION_DELAY = 100;
	private static final int SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION = 300;
	private static final int ITEM_SLIDE_IN_OUT_DISTANCE_PX = 200;

	public PreviewItemManager(FolderIcon icon) {
	mContext = icon.getContext();
	mIcon = icon;
	mIconSize = ActivityContext.lookupContext(
	mContext).getDeviceProfile().folderChildIconSizePx;
	mClipThreshold = Utilities.dpToPx(1f);
	}

	/**
	* @param reverse If true, animates the final item in the preview to be full size. If false,
	* animates the first item to its position in the preview.
	*/
	public FolderPreviewItemAnim createFirstItemAnimation(final boolean reverse,
	final Runnable onCompleteRunnable) {
	return reverse
	? new FolderPreviewItemAnim(this, mFirstPageParams.get(0), 0, 2, -1, -1,
	FINAL_ITEM_ANIMATION_DURATION, onCompleteRunnable)
	: new FolderPreviewItemAnim(this, mFirstPageParams.get(0), -1, -1, 0, 2,
	INITIAL_ITEM_ANIMATION_DURATION, onCompleteRunnable);
	}

	Drawable prepareCreateAnimation(final View destView) {
	Drawable animateDrawable = ((BubbleTextView) destView).getIcon();
	computePreviewDrawingParams(animateDrawable.getIntrinsicWidth(),
	destView.getMeasuredWidth());
	mReferenceDrawable = animateDrawable;
	return animateDrawable;
	}

	public void recomputePreviewDrawingParams() {
	if (mReferenceDrawable != null) {
	computePreviewDrawingParams(mReferenceDrawable.getIntrinsicWidth(),
	mIcon.getMeasuredWidth());
	}
	}

	private void computePreviewDrawingParams(int drawableSize, int totalSize) {
	if (mIntrinsicIconSize != drawableSize \|\| mTotalWidth != totalSize \|\|
	mPrevTopPadding != mIcon.getPaddingTop()) {
	mIntrinsicIconSize = drawableSize;
	mTotalWidth = totalSize;
	mPrevTopPadding = mIcon.getPaddingTop();

	mIcon.mBackground.setup(mIcon.getContext(), mIcon.mActivity, mIcon, mTotalWidth,
	mIcon.getPaddingTop());
	mIcon.mPreviewLayoutRule.init(mIcon.mBackground.previewSize, mIntrinsicIconSize,
	Utilities.isRtl(mIcon.getResources()));

	updatePreviewItems(false);
	}
	}

	PreviewItemDrawingParams computePreviewItemDrawingParams(int index, int curNumItems,
	PreviewItemDrawingParams params) {
	// We use an index of -1 to represent an icon on the workspace for the destroy and
	// create animations
	if (index == -1) {
	return getFinalIconParams(params);
	}
	return mIcon.mPreviewLayoutRule.computePreviewItemDrawingParams(index, curNumItems, params);
	}

	private PreviewItemDrawingParams getFinalIconParams(PreviewItemDrawingParams params) {
	float iconSize = mIcon.mActivity.getDeviceProfile().iconSizePx;

	final float scale = iconSize / mReferenceDrawable.getIntrinsicWidth();
	final float trans = (mIcon.mBackground.previewSize - iconSize) / 2;

	params.update(trans, trans, scale);
	return params;
	}

	public void drawParams(Canvas canvas, ArrayList<PreviewItemDrawingParams> params,
	PointF offset, boolean shouldClipPath, Path clipPath) {
	// The first item should be drawn last (ie. on top of later items)
	for (int i = params.size() - 1; i >= 0; i--) {
	PreviewItemDrawingParams p = params.get(i);
	if (!p.hidden) {
	// Exiting param should always be clipped.
	boolean isExiting = p.index == EXIT_INDEX;
	drawPreviewItem(canvas, p, offset, isExiting \| shouldClipPath, clipPath);
	}
	}
	}

	/**
	* Draws the preview items on {@param canvas}.
	*/
	public void draw(Canvas canvas) {
	int saveCount = canvas.getSaveCount();
	// The items are drawn in coordinates relative to the preview offset
	PreviewBackground bg = mIcon.getFolderBackground();
	Path clipPath = bg.getClipPath();
	float firstPageItemsTransX = 0;
	if (mShouldSlideInFirstPage) {
	PointF firstPageOffset = new PointF(bg.basePreviewOffsetX + mCurrentPageItemsTransX,
	bg.basePreviewOffsetY);
	boolean shouldClip = mCurrentPageItemsTransX > mClipThreshold;
	drawParams(canvas, mCurrentPageParams, firstPageOffset, shouldClip, clipPath);
	firstPageItemsTransX = -ITEM_SLIDE_IN_OUT_DISTANCE_PX + mCurrentPageItemsTransX;
	}

	PointF firstPageOffset = new PointF(bg.basePreviewOffsetX + firstPageItemsTransX,
	bg.basePreviewOffsetY);
	boolean shouldClipFirstPage = firstPageItemsTransX < -mClipThreshold;
	drawParams(canvas, mFirstPageParams, firstPageOffset, shouldClipFirstPage, clipPath);
	canvas.restoreToCount(saveCount);
	}

	public void onParamsChanged() {
	mIcon.invalidate();
	}

	/**
	* Draws each preview item.
	*
	* @param offset The offset needed to draw the preview items.
	* @param shouldClipPath Iff true, clip path using {@param clipPath}.
	* @param clipPath The clip path of the folder icon.
	*/
	private void drawPreviewItem(Canvas canvas, PreviewItemDrawingParams params, PointF offset,
	boolean shouldClipPath, Path clipPath) {
	canvas.save();
	if (shouldClipPath) {
	canvas.clipPath(clipPath);
	}
	canvas.translate(offset.x + params.transX, offset.y + params.transY);
	canvas.scale(params.scale, params.scale);
	Drawable d = params.drawable;

	if (d != null) {
	Rect bounds = d.getBounds();
	canvas.save();
	canvas.translate(-bounds.left, -bounds.top);
	canvas.scale(mIntrinsicIconSize / bounds.width(), mIntrinsicIconSize / bounds.height());
	d.draw(canvas);
	canvas.restore();
	}
	canvas.restore();
	}

	public void hidePreviewItem(int index, boolean hidden) {
	// If there are more params than visible in the preview, they are used for enter/exit
	// animation purposes and they were added to the front of the list.
	// To index the params properly, we need to skip these params.
	index = index + Math.max(mFirstPageParams.size() - MAX_NUM_ITEMS_IN_PREVIEW, 0);

	PreviewItemDrawingParams params = index < mFirstPageParams.size() ?
	mFirstPageParams.get(index) : null;
	if (params != null) {
	params.hidden = hidden;
	}
	}

	void buildParamsForPage(int page, ArrayList<PreviewItemDrawingParams> params, boolean animate) {
	List<WorkspaceItemInfo> items = mIcon.getPreviewItemsOnPage(page);

	// We adjust the size of the list to match the number of items in the preview.
	while (items.size() < params.size()) {
	params.remove(params.size() - 1);
	}
	while (items.size() > params.size()) {
	params.add(new PreviewItemDrawingParams(0, 0, 0));
	}

	int numItemsInFirstPagePreview = page == 0 ? items.size() : MAX_NUM_ITEMS_IN_PREVIEW;
	for (int i = 0; i < params.size(); i++) {
	PreviewItemDrawingParams p = params.get(i);
	setDrawable(p, items.get(i));

	if (!animate) {
	if (p.anim != null) {
	p.anim.cancel();
	}
	computePreviewItemDrawingParams(i, numItemsInFirstPagePreview, p);
	if (mReferenceDrawable == null) {
	mReferenceDrawable = p.drawable;
	}
	} else {
	FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, i,
	mNumOfPrevItems, i, numItemsInFirstPagePreview, DROP_IN_ANIMATION_DURATION,
	null);

	if (p.anim != null) {
	if (p.anim.hasEqualFinalState(anim)) {
	// do nothing, let the current animation finish
	continue;
	}
	p.anim.cancel();
	}
	p.anim = anim;
	p.anim.start();
	}
	}
	}

	void onFolderClose(int currentPage) {
	// If we are not closing on the first page, we animate the current page preview items
	// out, and animate the first page preview items in.
	mShouldSlideInFirstPage = currentPage != 0;
	if (mShouldSlideInFirstPage) {
	mCurrentPageItemsTransX = 0;
	buildParamsForPage(currentPage, mCurrentPageParams, false);
	onParamsChanged();

	ValueAnimator slideAnimator = ObjectAnimator
	.ofFloat(this, CURRENT_PAGE_ITEMS_TRANS_X, 0, ITEM_SLIDE_IN_OUT_DISTANCE_PX);
	slideAnimator.addListener(new AnimatorListenerAdapter() {
	@Override
	public void onAnimationEnd(Animator animation) {
	mCurrentPageParams.clear();
	}
	});
	slideAnimator.setStartDelay(SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION_DELAY);
	slideAnimator.setDuration(SLIDE_IN_FIRST_PAGE_ANIMATION_DURATION);
	slideAnimator.start();
	}
	}

	void updatePreviewItems(boolean animate) {
	int numOfPrevItemsAux = mFirstPageParams.size();
	buildParamsForPage(0, mFirstPageParams, animate);
	mNumOfPrevItems = numOfPrevItemsAux;
	}

	void updatePreviewItems(Predicate<WorkspaceItemInfo> itemCheck) {
	boolean modified = false;
	for (PreviewItemDrawingParams param : mFirstPageParams) {
	if (itemCheck.test(param.item)) {
	setDrawable(param, param.item);
	modified = true;
	}
	}
	for (PreviewItemDrawingParams param : mCurrentPageParams) {
	if (itemCheck.test(param.item)) {
	setDrawable(param, param.item);
	modified = true;
	}
	}
	if (modified) {
	mIcon.invalidate();
	}
	}

	boolean verifyDrawable(@NonNull Drawable who) {
	for (int i = 0; i < mFirstPageParams.size(); i++) {
	if (mFirstPageParams.get(i).drawable == who) {
	return true;
	}
	}
	return false;
	}

	float getIntrinsicIconSize() {
	return mIntrinsicIconSize;
	}

	/**
	* Handles the case where items in the preview are either:
	* - Moving into the preview
	* - Moving into a new position
	* - Moving out of the preview
	*
	* @param oldItems The list of items in the old preview.
	* @param newItems The list of items in the new preview.
	* @param dropped The item that was dropped onto the FolderIcon.
	*/
	public void onDrop(List<WorkspaceItemInfo> oldItems, List<WorkspaceItemInfo> newItems,
	WorkspaceItemInfo dropped) {
	int numItems = newItems.size();
	final ArrayList<PreviewItemDrawingParams> params = mFirstPageParams;
	buildParamsForPage(0, params, false);

	// New preview items for items that are moving in (except for the dropped item).
	List<WorkspaceItemInfo> moveIn = new ArrayList<>();
	for (WorkspaceItemInfo newItem : newItems) {
	if (!oldItems.contains(newItem) && !newItem.equals(dropped)) {
	moveIn.add(newItem);
	}
	}
	for (int i = 0; i < moveIn.size(); ++i) {
	int prevIndex = newItems.indexOf(moveIn.get(i));
	PreviewItemDrawingParams p = params.get(prevIndex);
	computePreviewItemDrawingParams(prevIndex, numItems, p);
	updateTransitionParam(p, moveIn.get(i), ENTER_INDEX, newItems.indexOf(moveIn.get(i)),
	numItems);
	}

	// Items that are moving into new positions within the preview.
	for (int newIndex = 0; newIndex < newItems.size(); ++newIndex) {
	int oldIndex = oldItems.indexOf(newItems.get(newIndex));
	if (oldIndex >= 0 && newIndex != oldIndex) {
	PreviewItemDrawingParams p = params.get(newIndex);
	updateTransitionParam(p, newItems.get(newIndex), oldIndex, newIndex, numItems);
	}
	}

	// Old preview items that need to be moved out.
	List<WorkspaceItemInfo> moveOut = new ArrayList<>(oldItems);
	moveOut.removeAll(newItems);
	for (int i = 0; i < moveOut.size(); ++i) {
	WorkspaceItemInfo item = moveOut.get(i);
	int oldIndex = oldItems.indexOf(item);
	PreviewItemDrawingParams p = computePreviewItemDrawingParams(oldIndex, numItems, null);
	updateTransitionParam(p, item, oldIndex, EXIT_INDEX, numItems);
	params.add(0, p); // We want these items first so that they are on drawn last.
	}

	for (int i = 0; i < params.size(); ++i) {
	if (params.get(i).anim != null) {
	params.get(i).anim.start();
	}
	}
	}

	private void updateTransitionParam(final PreviewItemDrawingParams p, WorkspaceItemInfo item,
	int prevIndex, int newIndex, int numItems) {
	setDrawable(p, item);

	FolderPreviewItemAnim anim = new FolderPreviewItemAnim(this, p, prevIndex, numItems,
	newIndex, numItems, DROP_IN_ANIMATION_DURATION, null);
	if (p.anim != null && !p.anim.hasEqualFinalState(anim)) {
	p.anim.cancel();
	}
	p.anim = anim;
	}

	private void setDrawable(PreviewItemDrawingParams p, WorkspaceItemInfo item) {
	if (item.hasPromiseIconUi() \|\| (item.runtimeStatusFlags
	& ItemInfoWithIcon.FLAG_SHOW_DOWNLOAD_PROGRESS_MASK) != 0) {
	PreloadIconDrawable drawable = newPendingIcon(mContext, item);
	drawable.setLevel(item.getProgressLevel());
	p.drawable = drawable;
	} else {
	p.drawable = item.newIcon(mContext, FLAG_THEMED);
	}
	p.drawable.setBounds(0, 0, mIconSize, mIconSize);
	p.item = item;

	// Set the callback to FolderIcon as it is responsible to drawing the icon. The
	// callback will be released when the folder is opened.
	p.drawable.setCallback(mIcon);
	}
	}