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   1 /*
   2  * Copyright 2000-2018 Vaadin Ltd.
   3  *
   4  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
   5  * use this file except in compliance with the License. You may obtain a copy of
   6  * the License at
   7  *
   8  * http://www.apache.org/licenses/LICENSE-2.0
   9  *
  10  * Unless required by applicable law or agreed to in writing, software
  11  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  12  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  13  * License for the specific language governing permissions and limitations under
  14  * the License.
  15  */
  16 package com.vaadin.v7.client.widget.grid.selection;
  17
  18 import com.google.gwt.event.dom.client.KeyCodes;
  19 import com.google.gwt.event.shared.HandlerRegistration;
  20 import com.vaadin.v7.client.widget.grid.DataAvailableEvent;
  21 import com.vaadin.v7.client.widget.grid.DataAvailableHandler;
  22 import com.vaadin.v7.client.widget.grid.events.BodyKeyDownHandler;
  23 import com.vaadin.v7.client.widget.grid.events.BodyKeyUpHandler;
  24 import com.vaadin.v7.client.widget.grid.events.GridKeyDownEvent;
  25 import com.vaadin.v7.client.widget.grid.events.GridKeyUpEvent;
  26 import com.vaadin.v7.client.widgets.Grid;
  27 import com.vaadin.v7.shared.ui.grid.ScrollDestination;
  28
  29 /**
  30  * Generic class to perform selections when pressing space key.
  31  *
  32  * @author Vaadin Ltd
  33  * @param <T>
  34  *            row data type
  35  * @since 7.4
  36  */
  37 public class SpaceSelectHandler<T> {
  38
  39     /**
  40      * Handler for space key down events in Grid Body
  41      */
  42     private class SpaceKeyDownHandler implements BodyKeyDownHandler {
  43         private HandlerRegistration scrollHandler = null;
  44
  45         @Override
  46         public void onKeyDown(GridKeyDownEvent event) {
  47             if (!grid.isUserSelectionAllowed()) {
  48                 return;
  49             }
  50
  51             if (event.getNativeKeyCode() != KeyCodes.KEY_SPACE || spaceDown) {
  52                 return;
  53             }
  54
  55             // Prevent space page scrolling
  56             event.getNativeEvent().preventDefault();
  57
  58             spaceDown = true;
  59             final int rowIndex = event.getFocusedCell().getRowIndex();
  60
  61             if (scrollHandler != null) {
  62                 scrollHandler.removeHandler();
  63                 scrollHandler = null;
  64             }
  65
  66             scrollHandler = grid
  67                     .addDataAvailableHandler(new DataAvailableHandler() {
  68
  69                         @Override
  70                         public void onDataAvailable(
  71                                 DataAvailableEvent dataAvailableEvent) {
  72                             if (dataAvailableEvent.getAvailableRows()
  73                                     .contains(rowIndex)) {
  74                                 setSelected(grid, rowIndex);
  75                                 scrollHandler.removeHandler();
  76                                 scrollHandler = null;
  77                             }
  78                         }
  79                     });
  80             grid.scrollToRow(rowIndex, ScrollDestination.ANY);
  81         }
  82
  83         protected void setSelected(Grid<T> grid, int rowIndex) {
  84             T row = grid.getDataSource().getRow(rowIndex);
  85
  86             if (!grid.isSelected(row)) {
  87                 grid.select(row);
  88             } else if (deselectAllowed) {
  89                 grid.deselect(row);
  90             }
  91         }
  92     }
  93
  94     private boolean spaceDown = false;
  95     private Grid<T> grid;
  96     private HandlerRegistration spaceUpHandler;
  97     private HandlerRegistration spaceDownHandler;
  98     private boolean deselectAllowed = true;
  99
 100     /**
 101      * Constructor for SpaceSelectHandler. This constructor will add all
 102      * necessary handlers for selecting rows with space.
 103      *
 104      * @param grid
 105      *            grid to attach to
 106      */
 107     public SpaceSelectHandler(Grid<T> grid) {
 108         this.grid = grid;
 109         spaceDownHandler = grid
 110                 .addBodyKeyDownHandler(new SpaceKeyDownHandler());
 111         spaceUpHandler = grid.addBodyKeyUpHandler(new BodyKeyUpHandler() {
 112
 113             @Override
 114             public void onKeyUp(GridKeyUpEvent event) {
 115                 if (event.getNativeKeyCode() == KeyCodes.KEY_SPACE) {
 116                     spaceDown = false;
 117                 }
 118             }
 119         });
 120     }
 121
 122     /**
 123      * Clean up function for removing all now obsolete handlers.
 124      */
 125     public void removeHandler() {
 126         spaceDownHandler.removeHandler();
 127         spaceUpHandler.removeHandler();
 128     }
 129
 130     /**
 131      * Sets whether pressing space for the currently selected row should
 132      * deselect the row.
 133      *
 134      * @param deselectAllowed
 135      *            <code>true</code> to allow deselecting the selected row;
 136      *            otherwise <code>false</code>
 137      */
 138     public void setDeselectAllowed(boolean deselectAllowed) {
 139         this.deselectAllowed = deselectAllowed;
 140     }
 141 }