code.grnet.gr Git - pithos/blob - web_client/src/gr/grnet/pithos/web/client/components/TristateCheckBox.java

   1 /*
   2  * Copyright 2011 GRNET S.A. All rights reserved.
   3  *
   4  * Redistribution and use in source and binary forms, with or
   5  * without modification, are permitted provided that the following
   6  * conditions are met:
   7  *
   8  *   1. Redistributions of source code must retain the above
   9  *      copyright notice, this list of conditions and the following
  10  *      disclaimer.
  11  *
  12  *   2. Redistributions in binary form must reproduce the above
  13  *      copyright notice, this list of conditions and the following
  14  *      disclaimer in the documentation and/or other materials
  15  *      provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY GRNET S.A. ``AS IS'' AND ANY EXPRESS
  18  * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  19  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  20  * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL GRNET S.A OR
  21  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  22  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  23  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
  24  * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  27  * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  28  * POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  * The views and conclusions contained in the software and
  31  * documentation are those of the authors and should not be
  32  * interpreted as representing official policies, either expressed
  33  * or implied, of GRNET S.A.
  34  */
  35 package gr.grnet.pithos.web.client.components;
  36
  37 import com.google.gwt.event.dom.client.ClickEvent;
  38 import com.google.gwt.event.dom.client.ClickHandler;
  39 import com.google.gwt.event.logical.shared.ValueChangeEvent;
  40 import com.google.gwt.event.logical.shared.ValueChangeHandler;
  41 import com.google.gwt.event.shared.HandlerRegistration;
  42 import com.google.gwt.user.client.DOM;
  43 import com.google.gwt.user.client.Element;
  44 import com.google.gwt.user.client.ui.FocusWidget;
  45 import com.google.gwt.user.client.ui.HasValue;
  46
  47 /**
  48  * Checkbox with three states (checked, unchecked and undefined).
  49  *
  50  */
  51 public class TristateCheckBox extends FocusWidget implements HasValue<Boolean> {
  52
  53     private static final String UNCHECKED_IMG = "images/tristate_unchecked.gif";
  54
  55     private static final String UNKNOWN_IMG = "images/tristate_intermediate.gif";
  56
  57     private static final String CHECKED_IMG = "images/tristate_checked.gif";
  58
  59     protected final Element buttonElement = DOM.createElement("input");
  60
  61     private boolean valueChangeHandlerInitialized;
  62
  63     private Boolean value;
  64
  65     protected Boolean initialValue;
  66
  67     public TristateCheckBox(final Boolean state) {
  68         DOM.setElementProperty(buttonElement, "type", "image");
  69         setElement(buttonElement);
  70         setStyleName("tristateCheckbox");
  71         DOM.setElementAttribute(buttonElement, "src", UNCHECKED_IMG);
  72
  73         addClickHandler(new ClickHandler() {
  74
  75                         @Override
  76                         public void onClick(@SuppressWarnings("unused") ClickEvent event) {
  77                 final String img = DOM.getElementAttribute(buttonElement, "src");
  78                 String newImg;
  79                 if (img.endsWith(UNCHECKED_IMG))
  80                                         newImg = CHECKED_IMG;
  81                                 else if (img.endsWith(UNKNOWN_IMG))
  82                                         newImg = UNCHECKED_IMG;
  83                                 else if (img.endsWith(CHECKED_IMG))
  84                                         if (initialValue==null) // Only show unknown choice if there is a reason for it
  85                                                 newImg = UNKNOWN_IMG;
  86                                         else
  87                                                 newImg = UNCHECKED_IMG;
  88                                 else
  89                                         throw new IllegalArgumentException("unknown checkbox state");
  90
  91                 DOM.setElementAttribute(buttonElement, "src", newImg);
  92             }
  93
  94         });
  95
  96         setState(state);
  97         initialValue = state;
  98     }
  99
 100     public void setState(final Boolean state) {
 101         DOM.setElementAttribute(buttonElement, "src", state == null ?
 102                         UNKNOWN_IMG : state.booleanValue() ? CHECKED_IMG : UNCHECKED_IMG);
 103     }
 104
 105     public Boolean getState() {
 106         final String img = DOM.getElementAttribute(buttonElement, "src");
 107         if (img.endsWith(UNCHECKED_IMG))
 108                         return Boolean.FALSE;
 109                 else if (img.endsWith(UNKNOWN_IMG))
 110                         return null;
 111                 else if (img.endsWith(CHECKED_IMG))
 112                         return Boolean.TRUE;
 113                 else
 114                         throw new IllegalArgumentException("unknown checkbox state");
 115     }
 116
 117     @Override
 118         public Boolean getValue() {
 119         return value;
 120     }
 121
 122     @Override
 123         public void setValue(final Boolean _value) {
 124         value = _value;
 125     }
 126
 127     @Override
 128         public HandlerRegistration addValueChangeHandler(
 129             ValueChangeHandler<Boolean> handler) {
 130             // Is this the first value change handler? If so, time to add handlers
 131             if (!valueChangeHandlerInitialized) {
 132                 ensureDomEventHandlers();
 133                 valueChangeHandlerInitialized = true;
 134             }
 135             return addHandler(handler, ValueChangeEvent.getType());
 136           }
 137
 138     protected void ensureDomEventHandlers() {
 139         addClickHandler(new ClickHandler() {
 140                 @Override
 141                         public void onClick(@SuppressWarnings("unused") ClickEvent event) {
 142                         ValueChangeEvent.fire(TristateCheckBox.this, getValue());
 143                 }
 144         });
 145     }
 146
 147     @Override
 148         public void setValue(Boolean _value, boolean fireEvents) {
 149         Boolean oldValue = getValue();
 150         setValue(_value);
 151         if (_value.equals(oldValue))
 152                         return;
 153         if (fireEvents)
 154                         ValueChangeEvent.fire(this, _value);
 155     }
 156
 157 }