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assembler/ldt/lib/Keybinder.js

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+/* Keybinder.js
+ * written by Colin Kuebler 2012
+ * Part of LDT, dual licensed under GPLv3 and MIT
+ * Simplifies the creation of keybindings on any element
+ */
+
+var Keybinder = {
+	bind: function( element, keymap ){
+		element.keymap = keymap;
+		var keyNames = {
+			8: "Backspace",
+			9: "Tab",
+			13: "Enter",
+			16: "Shift",
+			17: "Ctrl",
+			18: "Alt",
+			19: "Pause",
+			20: "CapsLk",
+			27: "Esc",
+			33: "PgUp",
+			34: "PgDn",
+			35: "End",
+			36: "Home",
+			37: "Left",
+			38: "Up",
+			39: "Right",
+			40: "Down",
+			45: "Insert",
+			46: "Delete",
+			112: "F1",
+			113: "F2",
+			114: "F3",
+			115: "F4",
+			116: "F5",
+			117: "F6",
+			118: "F7",
+			119: "F8",
+			120: "F9",
+			121: "F10",
+			122: "F11",
+			123: "F12",
+			145: "ScrLk" };
+		var keyEventNormalizer = function(e){
+			// get the event object and start constructing a query
+			var e = e || window.event;
+			var query = "";
+			// add in prefixes for each key modifier
+			e.shiftKey && (query += "Shift-");
+			e.ctrlKey && (query += "Ctrl-");
+			e.altKey && (query += "Alt-");
+			e.metaKey && (query += "Meta-");
+			// determine the key code
+			var key = e.which || e.keyCode || e.charCode;
+			// if we have a name for it, use it
+			if( keyNames[key] )
+				query += keyNames[key];
+			// otherwise turn it into a string
+			else
+				query += String.fromCharCode(key).toUpperCase();
+			/* DEBUG */
+			//console.log("keyEvent: "+query);
+			// try to run the keybinding, cancel the event if it returns true
+			if( element.keymap[query] && element.keymap[query]() ){
+				e.preventDefault && e.preventDefault();
+				e.stopPropagation && e.stopPropagation();
+				return false;
+			}
+			return true;
+		};
+		// capture onkeydown and onkeypress events to capture repeating key events
+		// maintain a boolean so we only fire once per character
+		var fireOnKeyPress = true;
+		element.onkeydown = function(e){
+			fireOnKeyPress = false;
+			return keyEventNormalizer(e);
+		};
+		element.onkeypress = function(e){
+			if( fireOnKeyPress )
+				return keyEventNormalizer(e);
+			fireOnKeyPress = true;
+			return true;
+		};
+	}
+}
+