packages/DocumentsUI/src/com/android/documentsui/dirlist/FocusManager.java - platform/frameworks/base - Gitiles

 /*
  * Copyright (C) 2016 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.documentsui.dirlist;

 import android.support.v7.widget.GridLayoutManager;
 import android.support.v7.widget.RecyclerView;
 import android.util.Log;
 import android.view.KeyEvent;
 import android.view.View;

 import com.android.documentsui.Events;

 /**
  * A class that handles navigation and focus within the DirectoryFragment.
  */
 class FocusManager implements View.OnFocusChangeListener {
     private static final String TAG = "FocusManager";

     private RecyclerView mView;
     private RecyclerView.Adapter<?> mAdapter;
     private GridLayoutManager mLayout;

     private int mLastFocusPosition = RecyclerView.NO_POSITION;

     public FocusManager(RecyclerView view) {
         mView = view;
         mAdapter = view.getAdapter();
         mLayout = (GridLayoutManager) view.getLayoutManager();
     }

     /**
      * Handles navigation (setting focus, adjusting selection if needed) arising from incoming key
      * events.
      *
      * @param doc The DocumentHolder receiving the key event.
      * @param keyCode
      * @param event
      * @return Whether the event was handled.
      */
     public boolean handleKey(DocumentHolder doc, int keyCode, KeyEvent event) {
         boolean extendSelection = false;
         // Translate space/shift-space into PgDn/PgUp
         if (keyCode == KeyEvent.KEYCODE_SPACE) {
             if (event.isShiftPressed()) {
                 keyCode = KeyEvent.KEYCODE_PAGE_UP;
             } else {
                 keyCode = KeyEvent.KEYCODE_PAGE_DOWN;
             }
         } else {
             extendSelection = event.isShiftPressed();
         }

         if (Events.isNavigationKeyCode(keyCode)) {
             // Find the target item and focus it.
             int endPos = findTargetPosition(doc.itemView, keyCode, event);

             if (endPos != RecyclerView.NO_POSITION) {
                 focusItem(endPos);
             }
             // Swallow all navigation keystrokes. Otherwise they go to the app's global
             // key-handler, which will route them back to the DF and cause focus to be reset.
             return true;
         }
         return false;
     }

     @Override
     public void onFocusChange(View v, boolean hasFocus) {
         // Remember focus events on items.
         if (hasFocus && v.getParent() == mView) {
             mLastFocusPosition = mView.getChildAdapterPosition(v);
         }
     }

     /**
      * Requests focus on the item that last had focus. Scrolls to that item if necessary.
      */
     public void restoreLastFocus() {
         if (mLastFocusPosition != RecyclerView.NO_POSITION) {
             // The system takes care of situations when a view is no longer on screen, etc,
             focusItem(mLastFocusPosition);
         } else {
             // Focus the first visible item
             focusItem(mLayout.findFirstVisibleItemPosition());
         }
     }

     /**
      * @return The adapter position of the last focused item.
      */
     public int getFocusPosition() {
         return mLastFocusPosition;
     }

     /**
      * Finds the destination position where the focus should land for a given navigation event.
      *
      * @param view The view that received the event.
      * @param keyCode The key code for the event.
      * @param event
      * @return The adapter position of the destination item. Could be RecyclerView.NO_POSITION.
      */
     private int findTargetPosition(View view, int keyCode, KeyEvent event) {
         switch (keyCode) {
             case KeyEvent.KEYCODE_MOVE_HOME:
                 return 0;
             case KeyEvent.KEYCODE_MOVE_END:
                 return mAdapter.getItemCount() - 1;
             case KeyEvent.KEYCODE_PAGE_UP:
             case KeyEvent.KEYCODE_PAGE_DOWN:
                 return findPagedTargetPosition(view, keyCode, event);
         }

         // Find a navigation target based on the arrow key that the user pressed.
         int searchDir = -1;
         switch (keyCode) {
             case KeyEvent.KEYCODE_DPAD_UP:
                 searchDir = View.FOCUS_UP;
                 break;
             case KeyEvent.KEYCODE_DPAD_DOWN:
                 searchDir = View.FOCUS_DOWN;
                 break;
         }

         if (inGridMode()) {
             int currentPosition = mView.getChildAdapterPosition(view);
             // Left and right arrow keys only work in grid mode.
             switch (keyCode) {
                 case KeyEvent.KEYCODE_DPAD_LEFT:
                     if (currentPosition > 0) {
                         // Stop backward focus search at the first item, otherwise focus will wrap
                         // around to the last visible item.
                         searchDir = View.FOCUS_BACKWARD;
                     }
                     break;
                 case KeyEvent.KEYCODE_DPAD_RIGHT:
                     if (currentPosition < mAdapter.getItemCount() - 1) {
                         // Stop forward focus search at the last item, otherwise focus will wrap
                         // around to the first visible item.
                         searchDir = View.FOCUS_FORWARD;
                     }
                     break;
             }
         }

         if (searchDir != -1) {
             View targetView = view.focusSearch(searchDir);
             // TargetView can be null, for example, if the user pressed <down> at the bottom
             // of the list.
             if (targetView != null) {
                 // Ignore navigation targets that aren't items in the RecyclerView.
                 if (targetView.getParent() == mView) {
                     return mView.getChildAdapterPosition(targetView);
                 }
             }
         }

         return RecyclerView.NO_POSITION;
     }

     /**
      * Given a PgUp/PgDn event and the current view, find the position of the target view.
      * This returns:
      * <li>The position of the topmost (or bottom-most) visible item, if the current item is not
      *     the top- or bottom-most visible item.
      * <li>The position of an item that is one page's worth of items up (or down) if the current
      *      item is the top- or bottom-most visible item.
      * <li>The first (or last) item, if paging up (or down) would go past those limits.
      * @param view The view that received the key event.
      * @param keyCode Must be KEYCODE_PAGE_UP or KEYCODE_PAGE_DOWN.
      * @param event
      * @return The adapter position of the target item.
      */
     private int findPagedTargetPosition(View view, int keyCode, KeyEvent event) {
         int first = mLayout.findFirstVisibleItemPosition();
         int last = mLayout.findLastVisibleItemPosition();
         int current = mView.getChildAdapterPosition(view);
         int pageSize = last - first + 1;

         if (keyCode == KeyEvent.KEYCODE_PAGE_UP) {
             if (current > first) {
                 // If the current item isn't the first item, target the first item.
                 return first;
             } else {
                 // If the current item is the first item, target the item one page up.
                 int target = current - pageSize;
                 return target < 0 ? 0 : target;
             }
         }

         if (keyCode == KeyEvent.KEYCODE_PAGE_DOWN) {
             if (current < last) {
                 // If the current item isn't the last item, target the last item.
                 return last;
             } else {
                 // If the current item is the last item, target the item one page down.
                 int target = current + pageSize;
                 int max = mAdapter.getItemCount() - 1;
                 return target < max ? target : max;
             }
         }

         throw new IllegalArgumentException("Unsupported keyCode: " + keyCode);
     }

     /**
      * Requests focus for the item in the given adapter position, scrolling the RecyclerView if
      * necessary.
      *
      * @param pos
      */
     private void focusItem(final int pos) {
         // If the item is already in view, focus it; otherwise, scroll to it and focus it.
         RecyclerView.ViewHolder vh = mView.findViewHolderForAdapterPosition(pos);
         if (vh != null) {
             vh.itemView.requestFocus();
         } else {
             mView.smoothScrollToPosition(pos);
             // Set a one-time listener to request focus when the scroll has completed.
             mView.addOnScrollListener(
                     new RecyclerView.OnScrollListener() {
                         @Override
                         public void onScrollStateChanged(RecyclerView view, int newState) {
                             if (newState == RecyclerView.SCROLL_STATE_IDLE) {
                                 // When scrolling stops, find the item and focus it.
                                 RecyclerView.ViewHolder vh =
                                         view.findViewHolderForAdapterPosition(pos);
                                 if (vh != null) {
                                     vh.itemView.requestFocus();
                                 } else {
                                     // This might happen in weird corner cases, e.g. if the user is
                                     // scrolling while a delete operation is in progress. In that
                                     // case, just don't attempt to focus the missing item.
                                     Log.w(TAG, "Unable to focus position " + pos + " after scroll");
                                 }
                                 view.removeOnScrollListener(this);
                             }
                         }
                     });
         }
     }

     /**
      * @return Whether the layout manager is currently in a grid-configuration.
      */
     private boolean inGridMode() {
         return mLayout.getSpanCount() > 1;
     }
 }
	/*
	* Copyright (C) 2016 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.documentsui.dirlist;

	import android.support.v7.widget.GridLayoutManager;
	import android.support.v7.widget.RecyclerView;
	import android.util.Log;
	import android.view.KeyEvent;
	import android.view.View;

	import com.android.documentsui.Events;

	/**
	* A class that handles navigation and focus within the DirectoryFragment.
	*/
	class FocusManager implements View.OnFocusChangeListener {
	private static final String TAG = "FocusManager";

	private RecyclerView mView;
	private RecyclerView.Adapter<?> mAdapter;
	private GridLayoutManager mLayout;

	private int mLastFocusPosition = RecyclerView.NO_POSITION;

	public FocusManager(RecyclerView view) {
	mView = view;
	mAdapter = view.getAdapter();
	mLayout = (GridLayoutManager) view.getLayoutManager();
	}

	/**
	* Handles navigation (setting focus, adjusting selection if needed) arising from incoming key
	* events.
	*
	* @param doc The DocumentHolder receiving the key event.
	* @param keyCode
	* @param event
	* @return Whether the event was handled.
	*/
	public boolean handleKey(DocumentHolder doc, int keyCode, KeyEvent event) {
	boolean extendSelection = false;
	// Translate space/shift-space into PgDn/PgUp
	if (keyCode == KeyEvent.KEYCODE_SPACE) {
	if (event.isShiftPressed()) {
	keyCode = KeyEvent.KEYCODE_PAGE_UP;
	} else {
	keyCode = KeyEvent.KEYCODE_PAGE_DOWN;
	}
	} else {
	extendSelection = event.isShiftPressed();
	}

	if (Events.isNavigationKeyCode(keyCode)) {
	// Find the target item and focus it.
	int endPos = findTargetPosition(doc.itemView, keyCode, event);

	if (endPos != RecyclerView.NO_POSITION) {
	focusItem(endPos);
	}
	// Swallow all navigation keystrokes. Otherwise they go to the app's global
	// key-handler, which will route them back to the DF and cause focus to be reset.
	return true;
	}
	return false;
	}

	@Override
	public void onFocusChange(View v, boolean hasFocus) {
	// Remember focus events on items.
	if (hasFocus && v.getParent() == mView) {
	mLastFocusPosition = mView.getChildAdapterPosition(v);
	}
	}

	/**
	* Requests focus on the item that last had focus. Scrolls to that item if necessary.
	*/
	public void restoreLastFocus() {
	if (mLastFocusPosition != RecyclerView.NO_POSITION) {
	// The system takes care of situations when a view is no longer on screen, etc,
	focusItem(mLastFocusPosition);
	} else {
	// Focus the first visible item
	focusItem(mLayout.findFirstVisibleItemPosition());
	}
	}

	/**
	* @return The adapter position of the last focused item.
	*/
	public int getFocusPosition() {
	return mLastFocusPosition;
	}

	/**
	* Finds the destination position where the focus should land for a given navigation event.
	*
	* @param view The view that received the event.
	* @param keyCode The key code for the event.
	* @param event
	* @return The adapter position of the destination item. Could be RecyclerView.NO_POSITION.
	*/
	private int findTargetPosition(View view, int keyCode, KeyEvent event) {
	switch (keyCode) {
	case KeyEvent.KEYCODE_MOVE_HOME:
	return 0;
	case KeyEvent.KEYCODE_MOVE_END:
	return mAdapter.getItemCount() - 1;
	case KeyEvent.KEYCODE_PAGE_UP:
	case KeyEvent.KEYCODE_PAGE_DOWN:
	return findPagedTargetPosition(view, keyCode, event);
	}

	// Find a navigation target based on the arrow key that the user pressed.
	int searchDir = -1;
	switch (keyCode) {
	case KeyEvent.KEYCODE_DPAD_UP:
	searchDir = View.FOCUS_UP;
	break;
	case KeyEvent.KEYCODE_DPAD_DOWN:
	searchDir = View.FOCUS_DOWN;
	break;
	}

	if (inGridMode()) {
	int currentPosition = mView.getChildAdapterPosition(view);
	// Left and right arrow keys only work in grid mode.
	switch (keyCode) {
	case KeyEvent.KEYCODE_DPAD_LEFT:
	if (currentPosition > 0) {
	// Stop backward focus search at the first item, otherwise focus will wrap
	// around to the last visible item.
	searchDir = View.FOCUS_BACKWARD;
	}
	break;
	case KeyEvent.KEYCODE_DPAD_RIGHT:
	if (currentPosition < mAdapter.getItemCount() - 1) {
	// Stop forward focus search at the last item, otherwise focus will wrap
	// around to the first visible item.
	searchDir = View.FOCUS_FORWARD;
	}
	break;
	}
	}

	if (searchDir != -1) {
	View targetView = view.focusSearch(searchDir);
	// TargetView can be null, for example, if the user pressed <down> at the bottom
	// of the list.
	if (targetView != null) {
	// Ignore navigation targets that aren't items in the RecyclerView.
	if (targetView.getParent() == mView) {
	return mView.getChildAdapterPosition(targetView);
	}
	}
	}

	return RecyclerView.NO_POSITION;
	}

	/**
	* Given a PgUp/PgDn event and the current view, find the position of the target view.
	* This returns:
	* <li>The position of the topmost (or bottom-most) visible item, if the current item is not
	* the top- or bottom-most visible item.
	* <li>The position of an item that is one page's worth of items up (or down) if the current
	* item is the top- or bottom-most visible item.
	* <li>The first (or last) item, if paging up (or down) would go past those limits.
	* @param view The view that received the key event.
	* @param keyCode Must be KEYCODE_PAGE_UP or KEYCODE_PAGE_DOWN.
	* @param event
	* @return The adapter position of the target item.
	*/
	private int findPagedTargetPosition(View view, int keyCode, KeyEvent event) {
	int first = mLayout.findFirstVisibleItemPosition();
	int last = mLayout.findLastVisibleItemPosition();
	int current = mView.getChildAdapterPosition(view);
	int pageSize = last - first + 1;

	if (keyCode == KeyEvent.KEYCODE_PAGE_UP) {
	if (current > first) {
	// If the current item isn't the first item, target the first item.
	return first;
	} else {
	// If the current item is the first item, target the item one page up.
	int target = current - pageSize;
	return target < 0 ? 0 : target;
	}
	}

	if (keyCode == KeyEvent.KEYCODE_PAGE_DOWN) {
	if (current < last) {
	// If the current item isn't the last item, target the last item.
	return last;
	} else {
	// If the current item is the last item, target the item one page down.
	int target = current + pageSize;
	int max = mAdapter.getItemCount() - 1;
	return target < max ? target : max;
	}
	}

	throw new IllegalArgumentException("Unsupported keyCode: " + keyCode);
	}

	/**
	* Requests focus for the item in the given adapter position, scrolling the RecyclerView if
	* necessary.
	*
	* @param pos
	*/
	private void focusItem(final int pos) {
	// If the item is already in view, focus it; otherwise, scroll to it and focus it.
	RecyclerView.ViewHolder vh = mView.findViewHolderForAdapterPosition(pos);
	if (vh != null) {
	vh.itemView.requestFocus();
	} else {
	mView.smoothScrollToPosition(pos);
	// Set a one-time listener to request focus when the scroll has completed.
	mView.addOnScrollListener(
	new RecyclerView.OnScrollListener() {
	@Override
	public void onScrollStateChanged(RecyclerView view, int newState) {
	if (newState == RecyclerView.SCROLL_STATE_IDLE) {
	// When scrolling stops, find the item and focus it.
	RecyclerView.ViewHolder vh =
	view.findViewHolderForAdapterPosition(pos);
	if (vh != null) {
	vh.itemView.requestFocus();
	} else {
	// This might happen in weird corner cases, e.g. if the user is
	// scrolling while a delete operation is in progress. In that
	// case, just don't attempt to focus the missing item.
	Log.w(TAG, "Unable to focus position " + pos + " after scroll");
	}
	view.removeOnScrollListener(this);
	}
	}
	});
	}
	}

	/**
	* @return Whether the layout manager is currently in a grid-configuration.
	*/
	private boolean inGridMode() {
	return mLayout.getSpanCount() > 1;
	}
	}