1 | /* Copyright (c) 2006-2010 by OpenLayers Contributors (see authors.txt for |
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2 | * full list of contributors). Published under the Clear BSD license. |
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3 | * See http://svn.openlayers.org/trunk/openlayers/license.txt for the |
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4 | * full text of the license. */ |
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5 | |
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6 | /** |
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7 | * @requires OpenLayers/Events.js |
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8 | */ |
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9 | |
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10 | /** |
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11 | * Class: OpenLayers.Handler |
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12 | * Base class to construct a higher-level handler for event sequences. All |
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13 | * handlers have activate and deactivate methods. In addition, they have |
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14 | * methods named like browser events. When a handler is activated, any |
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15 | * additional methods named like a browser event is registered as a |
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16 | * listener for the corresponding event. When a handler is deactivated, |
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17 | * those same methods are unregistered as event listeners. |
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18 | * |
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19 | * Handlers also typically have a callbacks object with keys named like |
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20 | * the abstracted events or event sequences that they are in charge of |
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21 | * handling. The controls that wrap handlers define the methods that |
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22 | * correspond to these abstract events - so instead of listening for |
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23 | * individual browser events, they only listen for the abstract events |
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24 | * defined by the handler. |
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25 | * |
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26 | * Handlers are created by controls, which ultimately have the responsibility |
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27 | * of making changes to the the state of the application. Handlers |
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28 | * themselves may make temporary changes, but in general are expected to |
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29 | * return the application in the same state that they found it. |
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30 | */ |
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31 | OpenLayers.Handler = OpenLayers.Class({ |
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32 | |
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33 | /** |
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34 | * Property: id |
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35 | * {String} |
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36 | */ |
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37 | id: null, |
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38 | |
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39 | /** |
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40 | * APIProperty: control |
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41 | * {<OpenLayers.Control>}. The control that initialized this handler. The |
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42 | * control is assumed to have a valid map property - that map is used |
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43 | * in the handler's own setMap method. |
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44 | */ |
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45 | control: null, |
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46 | |
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47 | /** |
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48 | * Property: map |
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49 | * {<OpenLayers.Map>} |
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50 | */ |
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51 | map: null, |
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52 | |
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53 | /** |
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54 | * APIProperty: keyMask |
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55 | * {Integer} Use bitwise operators and one or more of the OpenLayers.Handler |
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56 | * constants to construct a keyMask. The keyMask is used by |
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57 | * <checkModifiers>. If the keyMask matches the combination of keys |
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58 | * down on an event, checkModifiers returns true. |
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59 | * |
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60 | * Example: |
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61 | * (code) |
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62 | * // handler only responds if the Shift key is down |
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63 | * handler.keyMask = OpenLayers.Handler.MOD_SHIFT; |
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64 | * |
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65 | * // handler only responds if Ctrl-Shift is down |
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66 | * handler.keyMask = OpenLayers.Handler.MOD_SHIFT | |
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67 | * OpenLayers.Handler.MOD_CTRL; |
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68 | * (end) |
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69 | */ |
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70 | keyMask: null, |
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71 | |
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72 | /** |
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73 | * Property: active |
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74 | * {Boolean} |
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75 | */ |
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76 | active: false, |
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77 | |
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78 | /** |
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79 | * Property: evt |
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80 | * {Event} This property references the last event handled by the handler. |
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81 | * Note that this property is not part of the stable API. Use of the |
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82 | * evt property should be restricted to controls in the library |
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83 | * or other applications that are willing to update with changes to |
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84 | * the OpenLayers code. |
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85 | */ |
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86 | evt: null, |
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87 | |
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88 | /** |
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89 | * Constructor: OpenLayers.Handler |
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90 | * Construct a handler. |
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91 | * |
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92 | * Parameters: |
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93 | * control - {<OpenLayers.Control>} The control that initialized this |
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94 | * handler. The control is assumed to have a valid map property; that |
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95 | * map is used in the handler's own setMap method. If a map property |
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96 | * is present in the options argument it will be used instead. |
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97 | * callbacks - {Object} An object whose properties correspond to abstracted |
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98 | * events or sequences of browser events. The values for these |
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99 | * properties are functions defined by the control that get called by |
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100 | * the handler. |
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101 | * options - {Object} An optional object whose properties will be set on |
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102 | * the handler. |
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103 | */ |
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104 | initialize: function(control, callbacks, options) { |
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105 | OpenLayers.Util.extend(this, options); |
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106 | this.control = control; |
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107 | this.callbacks = callbacks; |
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108 | |
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109 | var map = this.map || control.map; |
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110 | if (map) { |
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111 | this.setMap(map); |
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112 | } |
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113 | |
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114 | this.id = OpenLayers.Util.createUniqueID(this.CLASS_NAME + "_"); |
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115 | }, |
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116 | |
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117 | /** |
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118 | * Method: setMap |
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119 | */ |
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120 | setMap: function (map) { |
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121 | this.map = map; |
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122 | }, |
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123 | |
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124 | /** |
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125 | * Method: checkModifiers |
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126 | * Check the keyMask on the handler. If no <keyMask> is set, this always |
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127 | * returns true. If a <keyMask> is set and it matches the combination |
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128 | * of keys down on an event, this returns true. |
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129 | * |
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130 | * Returns: |
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131 | * {Boolean} The keyMask matches the keys down on an event. |
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132 | */ |
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133 | checkModifiers: function (evt) { |
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134 | if(this.keyMask == null) { |
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135 | return true; |
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136 | } |
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137 | /* calculate the keyboard modifier mask for this event */ |
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138 | var keyModifiers = |
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139 | (evt.shiftKey ? OpenLayers.Handler.MOD_SHIFT : 0) | |
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140 | (evt.ctrlKey ? OpenLayers.Handler.MOD_CTRL : 0) | |
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141 | (evt.altKey ? OpenLayers.Handler.MOD_ALT : 0); |
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142 | |
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143 | /* if it differs from the handler object's key mask, |
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144 | bail out of the event handler */ |
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145 | return (keyModifiers == this.keyMask); |
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146 | }, |
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147 | |
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148 | /** |
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149 | * APIMethod: activate |
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150 | * Turn on the handler. Returns false if the handler was already active. |
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151 | * |
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152 | * Returns: |
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153 | * {Boolean} The handler was activated. |
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154 | */ |
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155 | activate: function() { |
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156 | if(this.active) { |
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157 | return false; |
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158 | } |
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159 | // register for event handlers defined on this class. |
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160 | var events = OpenLayers.Events.prototype.BROWSER_EVENTS; |
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161 | for (var i=0, len=events.length; i<len; i++) { |
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162 | if (this[events[i]]) { |
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163 | this.register(events[i], this[events[i]]); |
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164 | } |
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165 | } |
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166 | this.active = true; |
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167 | return true; |
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168 | }, |
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169 | |
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170 | /** |
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171 | * APIMethod: deactivate |
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172 | * Turn off the handler. Returns false if the handler was already inactive. |
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173 | * |
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174 | * Returns: |
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175 | * {Boolean} The handler was deactivated. |
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176 | */ |
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177 | deactivate: function() { |
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178 | if(!this.active) { |
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179 | return false; |
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180 | } |
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181 | // unregister event handlers defined on this class. |
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182 | var events = OpenLayers.Events.prototype.BROWSER_EVENTS; |
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183 | for (var i=0, len=events.length; i<len; i++) { |
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184 | if (this[events[i]]) { |
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185 | this.unregister(events[i], this[events[i]]); |
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186 | } |
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187 | } |
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188 | this.active = false; |
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189 | return true; |
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190 | }, |
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191 | |
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192 | /** |
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193 | * Method: callback |
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194 | * Trigger the control's named callback with the given arguments |
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195 | * |
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196 | * Parameters: |
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197 | * name - {String} The key for the callback that is one of the properties |
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198 | * of the handler's callbacks object. |
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199 | * args - {Array(*)} An array of arguments (any type) with which to call |
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200 | * the callback (defined by the control). |
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201 | */ |
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202 | callback: function (name, args) { |
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203 | if (name && this.callbacks[name]) { |
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204 | this.callbacks[name].apply(this.control, args); |
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205 | } |
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206 | }, |
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207 | |
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208 | /** |
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209 | * Method: register |
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210 | * register an event on the map |
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211 | */ |
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212 | register: function (name, method) { |
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213 | // TODO: deal with registerPriority in 3.0 |
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214 | this.map.events.registerPriority(name, this, method); |
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215 | this.map.events.registerPriority(name, this, this.setEvent); |
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216 | }, |
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217 | |
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218 | /** |
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219 | * Method: unregister |
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220 | * unregister an event from the map |
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221 | */ |
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222 | unregister: function (name, method) { |
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223 | this.map.events.unregister(name, this, method); |
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224 | this.map.events.unregister(name, this, this.setEvent); |
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225 | }, |
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226 | |
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227 | /** |
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228 | * Method: setEvent |
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229 | * With each registered browser event, the handler sets its own evt |
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230 | * property. This property can be accessed by controls if needed |
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231 | * to get more information about the event that the handler is |
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232 | * processing. |
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233 | * |
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234 | * This allows modifier keys on the event to be checked (alt, shift, |
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235 | * and ctrl cannot be checked with the keyboard handler). For a |
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236 | * control to determine which modifier keys are associated with the |
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237 | * event that a handler is currently processing, it should access |
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238 | * (code)handler.evt.altKey || handler.evt.shiftKey || |
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239 | * handler.evt.ctrlKey(end). |
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240 | * |
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241 | * Parameters: |
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242 | * evt - {Event} The browser event. |
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243 | */ |
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244 | setEvent: function(evt) { |
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245 | this.evt = evt; |
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246 | return true; |
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247 | }, |
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248 | |
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249 | /** |
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250 | * Method: destroy |
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251 | * Deconstruct the handler. |
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252 | */ |
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253 | destroy: function () { |
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254 | // unregister event listeners |
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255 | this.deactivate(); |
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256 | // eliminate circular references |
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257 | this.control = this.map = null; |
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258 | }, |
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259 | |
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260 | CLASS_NAME: "OpenLayers.Handler" |
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261 | }); |
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262 | |
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263 | /** |
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264 | * Constant: OpenLayers.Handler.MOD_NONE |
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265 | * If set as the <keyMask>, <checkModifiers> returns false if any key is down. |
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266 | */ |
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267 | OpenLayers.Handler.MOD_NONE = 0; |
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268 | |
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269 | /** |
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270 | * Constant: OpenLayers.Handler.MOD_SHIFT |
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271 | * If set as the <keyMask>, <checkModifiers> returns false if Shift is down. |
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272 | */ |
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273 | OpenLayers.Handler.MOD_SHIFT = 1; |
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274 | |
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275 | /** |
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276 | * Constant: OpenLayers.Handler.MOD_CTRL |
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277 | * If set as the <keyMask>, <checkModifiers> returns false if Ctrl is down. |
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278 | */ |
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279 | OpenLayers.Handler.MOD_CTRL = 2; |
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280 | |
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281 | /** |
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282 | * Constant: OpenLayers.Handler.MOD_ALT |
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283 | * If set as the <keyMask>, <checkModifiers> returns false if Alt is down. |
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284 | */ |
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285 | OpenLayers.Handler.MOD_ALT = 4; |
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286 | |
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287 | |
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