# Yahoo! UI Library

### Logger Widget 2.3.1

Yahoo! UI Library > logger > LogReader.js (source view)

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    /**
     * The LogReader class provides UI to read messages logged to YAHOO.widget.Logger.
     *
     * @class LogReader
     * @constructor
     * @param elContainer {HTMLElement} (optional) DOM element reference of an existing DIV.
     * @param elContainer {String} (optional) String ID of an existing DIV.
     * @param oConfigs {Object} (optional) Object literal of configuration params.
     */
    YAHOO.widget.LogReader = function(elContainer, oConfigs) {
        this._sName = YAHOO.widget.LogReader._index;
        YAHOO.widget.LogReader._index++;

        // Internal vars
        this._buffer = []; // output buffer
        this._filterCheckboxes = {}; // pointers to checkboxes
        this._lastTime = YAHOO.widget.Logger.getStartTime(); // timestamp of last log message to console

        // Parse config vars here
        if (oConfigs && (oConfigs.constructor == Object)) {
            for(var param in oConfigs) {
                this[param] = oConfigs[param];
            }
        }

        this._initContainerEl(elContainer);
        if(!this._elContainer) {
            YAHOO.log("Could not instantiate LogReader due to an invalid container element " +
                    elContainer, "error", this.toString());
            return;
        }

        this._initHeaderEl();
        this._initConsoleEl();
        this._initFooterEl();

        this._initDragDrop();

        this._initCategories();
        this._initSources();

        // Subscribe to Logger custom events
        YAHOO.widget.Logger.newLogEvent.subscribe(this._onNewLog, this);
        YAHOO.widget.Logger.logResetEvent.subscribe(this._onReset, this);

        YAHOO.widget.Logger.categoryCreateEvent.subscribe(this._onCategoryCreate, this);
        YAHOO.widget.Logger.sourceCreateEvent.subscribe(this._onSourceCreate, this);

        this._filterLogs();
        YAHOO.log("LogReader initialized", null, this.toString());
    };

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public member variables
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Whether or not LogReader is enabled to output log messages.
     *
     * @property logReaderEnabled
     * @type Boolean
     * @default true
     */
    YAHOO.widget.LogReader.prototype.logReaderEnabled = true;

    /**
     * Public member to access CSS width of the LogReader container.
     *
     * @property width
     * @type String
     */
    YAHOO.widget.LogReader.prototype.width = null;

    /**
     * Public member to access CSS height of the LogReader container.
     *
     * @property height
     * @type String
     */
    YAHOO.widget.LogReader.prototype.height = null;

    /**
     * Public member to access CSS top position of the LogReader container.
     *
     * @property top
     * @type String
     */
    YAHOO.widget.LogReader.prototype.top = null;

    /**
     * Public member to access CSS left position of the LogReader container.
     *
     * @property left
     * @type String
     */
    YAHOO.widget.LogReader.prototype.left = null;

    /**
     * Public member to access CSS right position of the LogReader container.
     *
     * @property right
     * @type String
     */
    YAHOO.widget.LogReader.prototype.right = null;

    /**
     * Public member to access CSS bottom position of the LogReader container.
     *
     * @property bottom
     * @type String
     */
    YAHOO.widget.LogReader.prototype.bottom = null;

    /**
     * Public member to access CSS font size of the LogReader container.
     *
     * @property fontSize
     * @type String
     */
    YAHOO.widget.LogReader.prototype.fontSize = null;

    /**
     * Whether or not the footer UI is enabled for the LogReader.
     *
     * @property footerEnabled
     * @type Boolean
     * @default true
     */
    YAHOO.widget.LogReader.prototype.footerEnabled = true;

    /**
     * Whether or not output is verbose (more readable). Setting to true will make
     * output more compact (less readable).
     *
     * @property verboseOutput
     * @type Boolean
     * @default true
     */
    YAHOO.widget.LogReader.prototype.verboseOutput = true;

    /**
     * Whether or not newest message is printed on top.
     *
     * @property newestOnTop
     * @type Boolean
     */
    YAHOO.widget.LogReader.prototype.newestOnTop = true;

    /**
     * Output timeout buffer in milliseconds.
     *
     * @property outputBuffer
     * @type Number
     * @default 100
     */
    YAHOO.widget.LogReader.prototype.outputBuffer = 100;

    /**
     * Maximum number of messages a LogReader console will display.
     *
     * @property thresholdMax
     * @type Number
     * @default 500
     */
    YAHOO.widget.LogReader.prototype.thresholdMax = 500;

    /**
     * When a LogReader console reaches its thresholdMax, it will clear out messages
     * and print out the latest thresholdMin number of messages.
     *
     * @property thresholdMin
     * @type Number
     * @default 100
     */
    YAHOO.widget.LogReader.prototype.thresholdMin = 100;

    /**
     * True when LogReader is in a collapsed state, false otherwise.
     *
     * @property isCollapsed
     * @type Boolean
     * @default false
     */
    YAHOO.widget.LogReader.prototype.isCollapsed = false;

    /**
     * True when LogReader is in a paused state, false otherwise.
     *
     * @property isPaused
     * @type Boolean
     * @default false
     */
    YAHOO.widget.LogReader.prototype.isPaused = false;

    /**
     * Enables draggable LogReader if DragDrop Utility is present.
     *
     * @property draggable
     * @type Boolean
     * @default true
     */
    YAHOO.widget.LogReader.prototype.draggable = true;

    /////////////////////////////////////////////////////////////////////////////
    //
    // Public methods
    //
    /////////////////////////////////////////////////////////////////////////////

     /**
     * Public accessor to the unique name of the LogReader instance.
     *
     * @method toString
     * @return {String} Unique name of the LogReader instance.
     */
    YAHOO.widget.LogReader.prototype.toString = function() {
        return "LogReader instance" + this._sName;
    };
    /**
     * Pauses output of log messages. While paused, log messages are not lost, but
     * get saved to a buffer and then output upon resume of LogReader.
     *
     * @method pause
     */
    YAHOO.widget.LogReader.prototype.pause = function() {
        this.isPaused = true;
        this._btnPause.value = "Resume";
        this._timeout = null;
        this.logReaderEnabled = false;
    };

    /**
     * Resumes output of log messages, including outputting any log messages that
     * have been saved to buffer while paused.
     *
     * @method resume
     */
    YAHOO.widget.LogReader.prototype.resume = function() {
        this.isPaused = false;
        this._btnPause.value = "Pause";
        this.logReaderEnabled = true;
        this._printBuffer();
    };

    /**
     * Hides UI of LogReader. Logging functionality is not disrupted.
     *
     * @method hide
     */
    YAHOO.widget.LogReader.prototype.hide = function() {
        this._elContainer.style.display = "none";
    };

    /**
     * Shows UI of LogReader. Logging functionality is not disrupted.
     *
     * @method show
     */
    YAHOO.widget.LogReader.prototype.show = function() {
        this._elContainer.style.display = "block";
    };

    /**
     * Collapses UI of LogReader. Logging functionality is not disrupted.
     *
     * @method collapse
     */
    YAHOO.widget.LogReader.prototype.collapse = function() {
        this._elConsole.style.display = "none";
        if(this._elFt) {
            this._elFt.style.display = "none";
        }
        this._btnCollapse.value = "Expand";
        this.isCollapsed = true;
    };

    /**
     * Expands UI of LogReader. Logging functionality is not disrupted.
     *
     * @method expand
     */
    YAHOO.widget.LogReader.prototype.expand = function() {
        this._elConsole.style.display = "block";
        if(this._elFt) {
            this._elFt.style.display = "block";
        }
        this._btnCollapse.value = "Collapse";
        this.isCollapsed = false;
    };

    /**
     * Returns related checkbox element for given filter (i.e., category or source).
     *
     * @method getCheckbox
     * @param {String} Category or source name.
     * @return {Array} Array of all filter checkboxes.
     */
    YAHOO.widget.LogReader.prototype.getCheckbox = function(filter) {
        return this._filterCheckboxes[filter];
    };

    /**
     * Returns array of enabled categories.
     *
     * @method getCategories
     * @return {String[]} Array of enabled categories.
     */
    YAHOO.widget.LogReader.prototype.getCategories = function() {
        return this._categoryFilters;
    };

    /**
     * Shows log messages associated with given category.
     *
     * @method showCategory
     * @param {String} Category name.
     */
    YAHOO.widget.LogReader.prototype.showCategory = function(sCategory) {
        var filtersArray = this._categoryFilters;
        // Don't do anything if category is already enabled
        // Use Array.indexOf if available...
        if(filtersArray.indexOf) {
             if(filtersArray.indexOf(sCategory) >  -1) {
                return;
            }
        }
        // ...or do it the old-fashioned way
        else {
            for(var i=0; i<filtersArray.length; i++) {
               if(filtersArray[i] === sCategory){
                    return;
                }
            }
        }

        this._categoryFilters.push(sCategory);
        this._filterLogs();
        var elCheckbox = this.getCheckbox(sCategory);
        if(elCheckbox) {
            elCheckbox.checked = true;
        }
    };

    /**
     * Hides log messages associated with given category.
     *
     * @method hideCategory
     * @param {String} Category name.
     */
    YAHOO.widget.LogReader.prototype.hideCategory = function(sCategory) {
        var filtersArray = this._categoryFilters;
        for(var i=0; i<filtersArray.length; i++) {
            if(sCategory == filtersArray[i]) {
                filtersArray.splice(i, 1);
                break;
            }
        }
        this._filterLogs();
        var elCheckbox = this.getCheckbox(sCategory);
        if(elCheckbox) {
            elCheckbox.checked = false;
        }
    };

    /**
     * Returns array of enabled sources.
     *
     * @method getSources
     * @return {Array} Array of enabled sources.
     */
    YAHOO.widget.LogReader.prototype.getSources = function() {
        return this._sourceFilters;
    };

    /**
     * Shows log messages associated with given source.
     *
     * @method showSource
     * @param {String} Source name.
     */
    YAHOO.widget.LogReader.prototype.showSource = function(sSource) {
        var filtersArray = this._sourceFilters;
        // Don't do anything if category is already enabled
        // Use Array.indexOf if available...
        if(filtersArray.indexOf) {
             if(filtersArray.indexOf(sSource) >  -1) {
                return;
            }
        }
        // ...or do it the old-fashioned way
        else {
            for(var i=0; i<filtersArray.length; i++) {
               if(sSource == filtersArray[i]){
                    return;
                }
            }
        }
        filtersArray.push(sSource);
        this._filterLogs();
        var elCheckbox = this.getCheckbox(sSource);
        if(elCheckbox) {
            elCheckbox.checked = true;
        }
    };

    /**
     * Hides log messages associated with given source.
     *
     * @method hideSource
     * @param {String} Source name.
     */
    YAHOO.widget.LogReader.prototype.hideSource = function(sSource) {
        var filtersArray = this._sourceFilters;
        for(var i=0; i<filtersArray.length; i++) {
            if(sSource == filtersArray[i]) {
                filtersArray.splice(i, 1);
                break;
            }
        }
        this._filterLogs();
        var elCheckbox = this.getCheckbox(sSource);
        if(elCheckbox) {
            elCheckbox.checked = false;
        }
    };

    /**
     * Does not delete any log messages, but clears all printed log messages from
     * the console. Log messages will be printed out again if user re-filters. The
     * static method YAHOO.widget.Logger.reset() should be called in order to
     * actually delete log messages.
     *
     * @method clearConsole
     */
    YAHOO.widget.LogReader.prototype.clearConsole = function() {
        // Clear the buffer of any pending messages
        this._timeout = null;
        this._buffer = [];
        this._consoleMsgCount = 0;

        var elConsole = this._elConsole;
        while(elConsole.hasChildNodes()) {
            elConsole.removeChild(elConsole.firstChild);
        }
    };

    /**
     * Updates title to given string.
     *
     * @method setTitle
     * @param sTitle {String} New title.
     */
    YAHOO.widget.LogReader.prototype.setTitle = function(sTitle) {
        this._title.innerHTML = this.html2Text(sTitle);
    };

    /**
     * Gets timestamp of the last log.
     *
     * @method getLastTime
     * @return {Date} Timestamp of the last log.
     */
    YAHOO.widget.LogReader.prototype.getLastTime = function() {
        return this._lastTime;
    };

    /**
     * Formats message string to HTML for output to console.
     *
     * @method formatMsg
     * @param oLogMsg {Object} Log message object.
     * @return {String} HTML-formatted message for output to console.
     */
    YAHOO.widget.LogReader.prototype.formatMsg = function(oLogMsg) {
        var category = oLogMsg.category;

        // Label for color-coded display
        var label = category.substring(0,4).toUpperCase();

        // Calculate the elapsed time to be from the last item that passed through the filter,
        // not the absolute previous item in the stack

        var time = oLogMsg.time;
        if (time.toLocaleTimeString) {
            var localTime  = time.toLocaleTimeString();
        }
        else {
            localTime = time.toString();
        }

        var msecs = time.getTime();
        var startTime = YAHOO.widget.Logger.getStartTime();
        var totalTime = msecs - startTime;
        var elapsedTime = msecs - this.getLastTime();

        var source = oLogMsg.source;
        var sourceDetail = oLogMsg.sourceDetail;
        var sourceAndDetail = (sourceDetail) ?
            source + " " + sourceDetail : source;

        // Escape HTML entities in the log message itself for output to console
        //var msg = this.html2Text(oLogMsg.msg); //TODO: delete
        var msg = this.html2Text(YAHOO.lang.dump(oLogMsg.msg));

        // Verbose output includes extra line breaks
        var output =  (this.verboseOutput) ?
            ["<pre class=\"yui-log-verbose\"><p><span class='", category, "'>", label, "</span> ",
            totalTime, "ms (+", elapsedTime, ") ",
            localTime, ": ",
            "</p><p>",
            sourceAndDetail,
            ": </p><p>",
            msg,
            "</p></pre>"] :

            ["<pre><p><span class='", category, "'>", label, "</span> ",
            totalTime, "ms (+", elapsedTime, ") ",
            localTime, ": ",
            sourceAndDetail, ": ",
            msg, "</p></pre>"];

        return output.join("");
    };

    /**
     * Converts input chars "<", ">", and "&" to HTML entities.
     *
     * @method html2Text
     * @param sHtml {String} String to convert.
     * @private
     */
    YAHOO.widget.LogReader.prototype.html2Text = function(sHtml) {
        if(sHtml) {
            sHtml += "";
            return sHtml.replace(/&/g, "&#38;").replace(/</g, "&#60;").replace(/>/g, "&#62;");
        }
        return "";
    };

    /////////////////////////////////////////////////////////////////////////////
    //
    // Private member variables
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Internal class member to index multiple LogReader instances.
     *
     * @property _memberName
     * @static
     * @type Number
     * @default 0
     * @private
     */
    YAHOO.widget.LogReader._index = 0;

    /**
     * Name of LogReader instance.
     *
     * @property _sName
     * @type String
     * @private
     */
    YAHOO.widget.LogReader.prototype._sName = null;

    //TODO: remove
    /**
     * A class member shared by all LogReaders if a container needs to be
     * created during instantiation. Will be null if a container element never needs to
     * be created on the fly, such as when the implementer passes in their own element.
     *
     * @property _elDefaultContainer
     * @type HTMLElement
     * @private
     */
    //YAHOO.widget.LogReader._elDefaultContainer = null;

    /**
     * Buffer of log message objects for batch output.
     *
     * @property _buffer
     * @type Object[]
     * @private
     */
    YAHOO.widget.LogReader.prototype._buffer = null;

    /**
     * Number of log messages output to console.
     *
     * @property _consoleMsgCount
     * @type Number
     * @default 0
     * @private
     */
    YAHOO.widget.LogReader.prototype._consoleMsgCount = 0;

    /**
     * Date of last output log message.
     *
     * @property _lastTime
     * @type Date
     * @private
     */
    YAHOO.widget.LogReader.prototype._lastTime = null;

    /**
     * Batched output timeout ID.
     *
     * @property _timeout
     * @type Number
     * @private
     */
    YAHOO.widget.LogReader.prototype._timeout = null;

    /**
     * Hash of filters and their related checkbox elements.
     *
     * @property _filterCheckboxes
     * @type Object
     * @private
     */
    YAHOO.widget.LogReader.prototype._filterCheckboxes = null;

    /**
     * Array of filters for log message categories.
     *
     * @property _categoryFilters
     * @type String[]
     * @private
     */
    YAHOO.widget.LogReader.prototype._categoryFilters = null;

    /**
     * Array of filters for log message sources.
     *
     * @property _sourceFilters
     * @type String[]
     * @private
     */
    YAHOO.widget.LogReader.prototype._sourceFilters = null;

    /**
     * LogReader container element.
     *
     * @property _elContainer
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elContainer = null;

    /**
     * LogReader header element.
     *
     * @property _elHd
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elHd = null;

    /**
     * LogReader collapse element.
     *
     * @property _elCollapse
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elCollapse = null;

    /**
     * LogReader collapse button element.
     *
     * @property _btnCollapse
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._btnCollapse = null;

    /**
     * LogReader title header element.
     *
     * @property _title
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._title = null;

    /**
     * LogReader console element.
     *
     * @property _elConsole
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elConsole = null;

    /**
     * LogReader footer element.
     *
     * @property _elFt
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elFt = null;

    /**
     * LogReader buttons container element.
     *
     * @property _elBtns
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elBtns = null;

    /**
     * Container element for LogReader category filter checkboxes.
     *
     * @property _elCategoryFilters
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elCategoryFilters = null;

    /**
     * Container element for LogReader source filter checkboxes.
     *
     * @property _elSourceFilters
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._elSourceFilters = null;

    /**
     * LogReader pause button element.
     *
     * @property _btnPause
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._btnPause = null;

    /**
     * Clear button element.
     *
     * @property _btnClear
     * @type HTMLElement
     * @private
     */
    YAHOO.widget.LogReader.prototype._btnClear = null;

    /////////////////////////////////////////////////////////////////////////////
    //
    // Private methods
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Initializes the primary container element.
     *
     * @method _initContainerEl
     * @param elContainer {HTMLElement} Container element by reference or string ID.
     * @private
     */
    YAHOO.widget.LogReader.prototype._initContainerEl = function(elContainer) {
        // Validate container
        elContainer = YAHOO.util.Dom.get(elContainer);
        // Attach to existing container...
        if(elContainer && elContainer.tagName && (elContainer.tagName.toLowerCase() == "div")) {
            this._elContainer = elContainer;
            YAHOO.util.Dom.addClass(this._elContainer,"yui-log");
        }
        // ...or create container from scratch
        else {
            this._elContainer = document.body.appendChild(document.createElement("div"));
            //this._elContainer.id = "yui-log" + this._sName;
            YAHOO.util.Dom.addClass(this._elContainer,"yui-log");
            YAHOO.util.Dom.addClass(this._elContainer,"yui-log-container");

            //YAHOO.widget.LogReader._elDefaultContainer = this._elContainer;

            // If implementer has provided container values, trust and set those
            var containerStyle = this._elContainer.style;
            if(this.width) {
                containerStyle.width = this.width;
            }
            if(this.right) {
                containerStyle.right = this.right;
            }
            if(this.top) {
                containerStyle.top = this.top;
            }
             if(this.left) {
                containerStyle.left = this.left;
                containerStyle.right = "auto";
            }
            if(this.bottom) {
                containerStyle.bottom = this.bottom;
                containerStyle.top = "auto";
            }
           if(this.fontSize) {
                containerStyle.fontSize = this.fontSize;
            }
            // For Opera
            if(navigator.userAgent.toLowerCase().indexOf("opera") != -1) {
                document.body.style += '';
            }
        }
    };

    /**
     * Initializes the header element.
     *
     * @method _initHeaderEl
     * @private
     */
    YAHOO.widget.LogReader.prototype._initHeaderEl = function() {
        var oSelf = this;

        // Destroy header
        if(this._elHd) {
            // Unhook DOM events
            YAHOO.util.Event.purgeElement(this._elHd, true);

            // Remove DOM elements
            this._elHd.innerHTML = "";
        }

        // Create header
        this._elHd = this._elContainer.appendChild(document.createElement("div"));
        this._elHd.id = "yui-log-hd" + this._sName;
        this._elHd.className = "yui-log-hd";

        this._elCollapse = this._elHd.appendChild(document.createElement("div"));
        this._elCollapse.className = "yui-log-btns";

        this._btnCollapse = document.createElement("input");
        this._btnCollapse.type = "button";
        //this._btnCollapse.style.fontSize =
        //    YAHOO.util.Dom.getStyle(this._elContainer,"fontSize");
        this._btnCollapse.className = "yui-log-button";
        this._btnCollapse.value = "Collapse";
        this._btnCollapse = this._elCollapse.appendChild(this._btnCollapse);
        YAHOO.util.Event.addListener(
            oSelf._btnCollapse,'click',oSelf._onClickCollapseBtn,oSelf);

        this._title = this._elHd.appendChild(document.createElement("h4"));
        this._title.innerHTML = "Logger Console";
    };

    /**
     * Initializes the console element.
     *
     * @method _initConsoleEl
     * @private
     */
    YAHOO.widget.LogReader.prototype._initConsoleEl = function() {
        // Destroy console
        if(this._elConsole) {
            // Unhook DOM events
            YAHOO.util.Event.purgeElement(this._elConsole, true);

            // Remove DOM elements
            this._elConsole.innerHTML = "";
        }

        // Ceate console
        this._elConsole = this._elContainer.appendChild(document.createElement("div"));
        this._elConsole.className = "yui-log-bd";

        // If implementer has provided console, trust and set those
        if(this.height) {
            this._elConsole.style.height = this.height;
        }
    };

    /**
     * Initializes the footer element.
     *
     * @method _initFooterEl
     * @private
     */
    YAHOO.widget.LogReader.prototype._initFooterEl = function() {
        var oSelf = this;

        // Don't create footer elements if footer is disabled
        if(this.footerEnabled) {
            // Destroy console
            if(this._elFt) {
                // Unhook DOM events
                YAHOO.util.Event.purgeElement(this._elFt, true);

                // Remove DOM elements
                this._elFt.innerHTML = "";
            }

            this._elFt = this._elContainer.appendChild(document.createElement("div"));
            this._elFt.className = "yui-log-ft";

            this._elBtns = this._elFt.appendChild(document.createElement("div"));
            this._elBtns.className = "yui-log-btns";

            this._btnPause = document.createElement("input");
            this._btnPause.type = "button";
            //this._btnPause.style.fontSize =
            //    YAHOO.util.Dom.getStyle(this._elContainer,"fontSize");
            this._btnPause.className = "yui-log-button";
            this._btnPause.value = "Pause";
            this._btnPause = this._elBtns.appendChild(this._btnPause);
            YAHOO.util.Event.addListener(
                oSelf._btnPause,'click',oSelf._onClickPauseBtn,oSelf);

            this._btnClear = document.createElement("input");
            this._btnClear.type = "button";
            //this._btnClear.style.fontSize =
            //    YAHOO.util.Dom.getStyle(this._elContainer,"fontSize");
            this._btnClear.className = "yui-log-button";
            this._btnClear.value = "Clear";
            this._btnClear = this._elBtns.appendChild(this._btnClear);
            YAHOO.util.Event.addListener(
                oSelf._btnClear,'click',oSelf._onClickClearBtn,oSelf);

            this._elCategoryFilters = this._elFt.appendChild(document.createElement("div"));
            this._elCategoryFilters.className = "yui-log-categoryfilters";
            this._elSourceFilters = this._elFt.appendChild(document.createElement("div"));
            this._elSourceFilters.className = "yui-log-sourcefilters";
        }
    };

    /**
     * Initializes Drag and Drop on the header element.
     *
     * @method _initDragDrop
     * @private
     */
    YAHOO.widget.LogReader.prototype._initDragDrop = function() {
        // If Drag and Drop utility is available...
        // ...and draggable is true...
        // ...then make the header draggable
        if(YAHOO.util.DD && this.draggable && this._elHd) {
            var ylog_dd = new YAHOO.util.DD(this._elContainer);
            ylog_dd.setHandleElId(this._elHd.id);
            //TODO: use class name
            this._elHd.style.cursor = "move";
        }
    };

    /**
     * Initializes category filters.
     *
     * @method _initCategories
     * @private
     */
    YAHOO.widget.LogReader.prototype._initCategories = function() {
        // Initialize category filters
        this._categoryFilters = [];
        var aInitialCategories = YAHOO.widget.Logger.categories;

        for(var j=0; j < aInitialCategories.length; j++) {
            var sCategory = aInitialCategories[j];

            // Add category to the internal array of filters
            this._categoryFilters.push(sCategory);

            // Add checkbox element if UI is enabled
            if(this._elCategoryFilters) {
                this._createCategoryCheckbox(sCategory);
            }
        }
    };

    /**
     * Initializes source filters.
     *
     * @method _initSources
     * @private
     */
    YAHOO.widget.LogReader.prototype._initSources = function() {
        // Initialize source filters
        this._sourceFilters = [];
        var aInitialSources = YAHOO.widget.Logger.sources;

        for(var j=0; j < aInitialSources.length; j++) {
            var sSource = aInitialSources[j];

            // Add source to the internal array of filters
            this._sourceFilters.push(sSource);

            // Add checkbox element if UI is enabled
            if(this._elSourceFilters) {
                this._createSourceCheckbox(sSource);
            }
        }}
    ;

    /**
     * Creates the UI for a category filter in the LogReader footer element.
     *
     * @method _createCategoryCheckbox
     * @param sCategory {String} Category name.
     * @private
     */
    YAHOO.widget.LogReader.prototype._createCategoryCheckbox = function(sCategory) {
        var oSelf = this;

        if(this._elFt) {
            var elParent = this._elCategoryFilters;
            var elFilter = elParent.appendChild(document.createElement("span"));
            elFilter.className = "yui-log-filtergrp";

            // Append el at the end so IE 5.5 can set "type" attribute
            // and THEN set checked property
            var chkCategory = document.createElement("input");
            chkCategory.id = "yui-log-filter-" + sCategory + this._sName;
            chkCategory.className = "yui-log-filter-" + sCategory;
            chkCategory.type = "checkbox";
            chkCategory.category = sCategory;
            chkCategory = elFilter.appendChild(chkCategory);
            chkCategory.checked = true;

            // Subscribe to the click event
            YAHOO.util.Event.addListener(chkCategory,'click',oSelf._onCheckCategory,oSelf);

            // Create and class the text label
            var lblCategory = elFilter.appendChild(document.createElement("label"));
            lblCategory.htmlFor = chkCategory.id;
            lblCategory.className = sCategory;
            lblCategory.innerHTML = sCategory;

            this._filterCheckboxes[sCategory] = chkCategory;
        }
    };

    /**
     * Creates a checkbox in the LogReader footer element to filter by source.
     *
     * @method _createSourceCheckbox
     * @param sSource {String} Source name.
     * @private
     */
    YAHOO.widget.LogReader.prototype._createSourceCheckbox = function(sSource) {
        var oSelf = this;

        if(this._elFt) {
            var elParent = this._elSourceFilters;
            var elFilter = elParent.appendChild(document.createElement("span"));
            elFilter.className = "yui-log-filtergrp";

            // Append el at the end so IE 5.5 can set "type" attribute
            // and THEN set checked property
            var chkSource = document.createElement("input");
            chkSource.id = "yui-log-filter" + sSource + this._sName;
            chkSource.className = "yui-log-filter" + sSource;
            chkSource.type = "checkbox";
            chkSource.source = sSource;
            chkSource = elFilter.appendChild(chkSource);
            chkSource.checked = true;

            // Subscribe to the click event
            YAHOO.util.Event.addListener(chkSource,'click',oSelf._onCheckSource,oSelf);

            // Create and class the text label
            var lblSource = elFilter.appendChild(document.createElement("label"));
            lblSource.htmlFor = chkSource.id;
            lblSource.className = sSource;
            lblSource.innerHTML = sSource;

            this._filterCheckboxes[sSource] = chkSource;
        }
    };

    /**
     * Reprints all log messages in the stack through filters.
     *
     * @method _filterLogs
     * @private
     */
    YAHOO.widget.LogReader.prototype._filterLogs = function() {
        // Reprint stack with new filters
        if (this._elConsole !== null) {
            this.clearConsole();
            this._printToConsole(YAHOO.widget.Logger.getStack());
        }
    };

    /**
     * Sends buffer of log messages to output and clears buffer.
     *
     * @method _printBuffer
     * @private
     */
    YAHOO.widget.LogReader.prototype._printBuffer = function() {
        this._timeout = null;

        if(this._elConsole !== null) {
            var thresholdMax = this.thresholdMax;
            thresholdMax = (thresholdMax && !isNaN(thresholdMax)) ? thresholdMax : 500;
            if(this._consoleMsgCount < thresholdMax) {
                var entries = [];
                for (var i=0; i<this._buffer.length; i++) {
                    entries[i] = this._buffer[i];
                }
                this._buffer = [];
                this._printToConsole(entries);
            }
            else {
                this._filterLogs();
            }

            if(!this.newestOnTop) {
                this._elConsole.scrollTop = this._elConsole.scrollHeight;
            }
        }
    };

    /**
     * Cycles through an array of log messages, and outputs each one to the console
     * if its category has not been filtered out.
     *
     * @method _printToConsole
     * @param aEntries {Object[]} Array of LogMsg objects to output to console.
     * @private
     */
    YAHOO.widget.LogReader.prototype._printToConsole = function(aEntries) {
        // Manage the number of messages displayed in the console
        var entriesLen = aEntries.length;
        var thresholdMin = this.thresholdMin;
        if(isNaN(thresholdMin) || (thresholdMin > this.thresholdMax)) {
            thresholdMin = 0;
        }
        var entriesStartIndex = (entriesLen > thresholdMin) ? (entriesLen - thresholdMin) : 0;

        // Iterate through all log entries
        var sourceFiltersLen = this._sourceFilters.length;
        var categoryFiltersLen = this._categoryFilters.length;
        for(var i=entriesStartIndex; i<entriesLen; i++) {
            // Print only the ones that filter through
            var okToPrint = false;
            var okToFilterCats = false;

            // Get log message details
            var entry = aEntries[i];
            var source = entry.source;
            var category = entry.category;

            for(var j=0; j<sourceFiltersLen; j++) {
                if(source == this._sourceFilters[j]) {
                    okToFilterCats = true;
                    break;
                }
            }
            if(okToFilterCats) {
                for(var k=0; k<categoryFiltersLen; k++) {
                    if(category == this._categoryFilters[k]) {
                        okToPrint = true;
                        break;
                    }
                }
            }
            if(okToPrint) {
                var output = this.formatMsg(entry);
                if(this.newestOnTop) {
                    this._elConsole.innerHTML = output + this._elConsole.innerHTML;
                }
                else {
                    this._elConsole.innerHTML += output;
                }
                this._consoleMsgCount++;
                this._lastTime = entry.time.getTime();
            }
        }
    };

    /////////////////////////////////////////////////////////////////////////////
    //
    // Private event handlers
    //
    /////////////////////////////////////////////////////////////////////////////

    /**
     * Handles Logger's categoryCreateEvent.
     *
     * @method _onCategoryCreate
     * @param sType {String} The event.
     * @param aArgs {Object[]} Data passed from event firer.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onCategoryCreate = function(sType, aArgs, oSelf) {
        var category = aArgs[0];

        // Add category to the internal array of filters
        oSelf._categoryFilters.push(category);

        if(oSelf._elFt) {
            oSelf._createCategoryCheckbox(category);
        }
    };

    /**
     * Handles Logger's sourceCreateEvent.
     *
     * @method _onSourceCreate
     * @param sType {String} The event.
     * @param aArgs {Object[]} Data passed from event firer.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onSourceCreate = function(sType, aArgs, oSelf) {
        var source = aArgs[0];

        // Add source to the internal array of filters
        oSelf._sourceFilters.push(source);

        if(oSelf._elFt) {
            oSelf._createSourceCheckbox(source);
        }
    };

    /**
     * Handles check events on the category filter checkboxes.
     *
     * @method _onCheckCategory
     * @param v {HTMLEvent} The click event.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onCheckCategory = function(v, oSelf) {
        var category = this.category;
        if(!this.checked) {
            oSelf.hideCategory(category);
        }
        else {
            oSelf.showCategory(category);
        }
    };

    /**
     * Handles check events on the category filter checkboxes.
     *
     * @method _onCheckSource
     * @param v {HTMLEvent} The click event.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onCheckSource = function(v, oSelf) {
        var source = this.source;
        if(!this.checked) {
            oSelf.hideSource(source);
        }
        else {
            oSelf.showSource(source);
        }
    };

    /**
     * Handles click events on the collapse button.
     *
     * @method _onClickCollapseBtn
     * @param v {HTMLEvent} The click event.
     * @param oSelf {Object} The LogReader instance
     * @private
     */
    YAHOO.widget.LogReader.prototype._onClickCollapseBtn = function(v, oSelf) {
        if(!oSelf.isCollapsed) {
            oSelf.collapse();
        }
        else {
            oSelf.expand();
        }
    };

    /**
     * Handles click events on the pause button.
     *
     * @method _onClickPauseBtn
     * @param v {HTMLEvent} The click event.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onClickPauseBtn = function(v, oSelf) {
        if(!oSelf.isPaused) {
            oSelf.pause();
        }
        else {
            oSelf.resume();
        }
    };

    /**
     * Handles click events on the clear button.
     *
     * @method _onClickClearBtn
     * @param v {HTMLEvent} The click event.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onClickClearBtn = function(v, oSelf) {
        oSelf.clearConsole();
    };

    /**
     * Handles Logger's newLogEvent.
     *
     * @method _onNewLog
     * @param sType {String} The event.
     * @param aArgs {Object[]} Data passed from event firer.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onNewLog = function(sType, aArgs, oSelf) {
        var logEntry = aArgs[0];
        oSelf._buffer.push(logEntry);

        if (oSelf.logReaderEnabled === true && oSelf._timeout === null) {
            oSelf._timeout = setTimeout(function(){oSelf._printBuffer();}, oSelf.outputBuffer);
        }
    };

    /**
     * Handles Logger's resetEvent.
     *
     * @method _onReset
     * @param sType {String} The event.
     * @param aArgs {Object[]} Data passed from event firer.
     * @param oSelf {Object} The LogReader instance.
     * @private
     */
    YAHOO.widget.LogReader.prototype._onReset = function(sType, aArgs, oSelf) {
        oSelf._filterLogs();
    };

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