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

   1 package gr.grnet.pithos.web.client.components;
   2
   3 import com.google.gwt.event.dom.client.ClickEvent;
   4 import com.google.gwt.event.dom.client.ClickHandler;
   5 import com.google.gwt.event.logical.shared.ValueChangeEvent;
   6 import com.google.gwt.event.logical.shared.ValueChangeHandler;
   7 import com.google.gwt.event.shared.HandlerRegistration;
   8 import com.google.gwt.user.client.DOM;
   9 import com.google.gwt.user.client.Element;
  10 import com.google.gwt.user.client.ui.FocusWidget;
  11 import com.google.gwt.user.client.ui.HasValue;
  12
  13 /**
  14  * Checkbox with three states (checked, unchecked and undefined).
  15  *
  16  */
  17 public class TristateCheckBox extends FocusWidget implements HasValue<Boolean> {
  18
  19     private static final String UNCHECKED_IMG = "images/tristate_unchecked.gif";
  20
  21     private static final String UNKNOWN_IMG = "images/tristate_intermediate.gif";
  22
  23     private static final String CHECKED_IMG = "images/tristate_checked.gif";
  24
  25     private final Element buttonElement = DOM.createElement("input");
  26
  27     private boolean valueChangeHandlerInitialized;
  28
  29     private Boolean value;
  30
  31     private Boolean initialValue;
  32
  33     public TristateCheckBox(final Boolean state) {
  34         DOM.setElementProperty(buttonElement, "type", "image");
  35         setElement(buttonElement);
  36         setStyleName("tristateCheckbox");
  37         DOM.setElementAttribute(buttonElement, "src", UNCHECKED_IMG);
  38
  39         addClickHandler(new ClickHandler() {
  40
  41                         @Override
  42                         public void onClick(ClickEvent event) {
  43                 final String img = DOM.getElementAttribute(buttonElement, "src");
  44                 String newImg;
  45                 if (img.endsWith(UNCHECKED_IMG))
  46                                         newImg = CHECKED_IMG;
  47                                 else if (img.endsWith(UNKNOWN_IMG))
  48                                         newImg = UNCHECKED_IMG;
  49                                 else if (img.endsWith(CHECKED_IMG))
  50                                         if (initialValue==null) // Only show unknown choice if there is a reason for it
  51                                                 newImg = UNKNOWN_IMG;
  52                                         else
  53                                                 newImg = UNCHECKED_IMG;
  54                                 else
  55                                         throw new IllegalArgumentException("unknown checkbox state");
  56
  57                 DOM.setElementAttribute(buttonElement, "src", newImg);
  58             }
  59
  60         });
  61
  62         setState(state);
  63         initialValue = state;
  64     }
  65
  66     public void setState(final Boolean state) {
  67         DOM.setElementAttribute(buttonElement, "src", state == null ?
  68                         UNKNOWN_IMG : state.booleanValue() ? CHECKED_IMG : UNCHECKED_IMG);
  69     }
  70
  71     public Boolean getState() {
  72         final String img = DOM.getElementAttribute(buttonElement, "src");
  73         if (img.endsWith(UNCHECKED_IMG))
  74                         return Boolean.FALSE;
  75                 else if (img.endsWith(UNKNOWN_IMG))
  76                         return null;
  77                 else if (img.endsWith(CHECKED_IMG))
  78                         return Boolean.TRUE;
  79                 else
  80                         throw new IllegalArgumentException("unknown checkbox state");
  81     }
  82
  83     @Override
  84         public Boolean getValue() {
  85         return value;
  86     }
  87
  88     @Override
  89         public void setValue(final Boolean _value) {
  90         value = _value;
  91     }
  92
  93     @Override
  94         public HandlerRegistration addValueChangeHandler(
  95             ValueChangeHandler<Boolean> handler) {
  96             // Is this the first value change handler? If so, time to add handlers
  97             if (!valueChangeHandlerInitialized) {
  98                 ensureDomEventHandlers();
  99                 valueChangeHandlerInitialized = true;
 100             }
 101             return addHandler(handler, ValueChangeEvent.getType());
 102           }
 103
 104     protected void ensureDomEventHandlers() {
 105         addClickHandler(new ClickHandler() {
 106                 @Override
 107                         public void onClick(ClickEvent event) {
 108                         ValueChangeEvent.fire(TristateCheckBox.this, getValue());
 109                 }
 110         });
 111     }
 112
 113     @Override
 114         public void setValue(Boolean _value, boolean fireEvents) {
 115         Boolean oldValue = getValue();
 116         setValue(_value);
 117         if (_value.equals(oldValue))
 118                         return;
 119         if (fireEvents)
 120                         ValueChangeEvent.fire(this, _value);
 121     }
 122
 123 }