source: Dev/trunk/src/client/dijit/_BidiMixin.js

define([], function(){

        // module:
        //              dijit/_BidiMixin

        // UCC - constants that will be used by bidi support.
        var bidi_const = {
                LRM : '\u200E',
                LRE : '\u202A',
                PDF : '\u202C',
                RLM : '\u200f',
                RLE : '\u202B'
        };

        return {
                // summary:
                //              When has("dojo-bidi") is true, _WidgetBase will mixin this class.   It enables support for the textdir
                //              property to control text direction independently from the GUI direction.
                // description:
                //              There's a special need for displaying BIDI text in rtl direction
                //              in ltr GUI, sometimes needed auto support.
                //              In creation of widget, if it's want to activate this class,
                //              the widget should define the "textDir".

                // textDir: String
                //              Bi-directional support, the main variable which is responsible for the direction of the text.
                //              The text direction can be different than the GUI direction by using this parameter in creation
                //              of a widget.
                //
                //              Allowed values:
                //
                //              1. "ltr"
                //              2. "rtl"
                //              3. "auto" - contextual the direction of a text defined by first strong letter.
                //
                //              By default is as the page direction.
                textDir: "",

                getTextDir: function(/*String*/ text){
                        // summary:
                        //              Gets the right direction of text.
                        // description:
                        //              If textDir is ltr or rtl returns the value.
                        //              If it's auto, calls to another function that responsible
                        //              for checking the value, and defining the direction.
                        // tags:
                        //              protected.
                        return this.textDir == "auto" ? this._checkContextual(text) : this.textDir;
                },

                _checkContextual: function(text){
                        // summary:
                        //              Finds the first strong (directional) character, return ltr if isLatin
                        //              or rtl if isBidiChar.
                        // tags:
                        //              private.

                        // look for strong (directional) characters
                        var fdc = /[A-Za-z\u05d0-\u065f\u066a-\u06ef\u06fa-\u07ff\ufb1d-\ufdff\ufe70-\ufefc]/.exec(text);
                        // if found return the direction that defined by the character, else return widgets dir as defult.
                        return fdc ? ( fdc[0] <= 'z' ? "ltr" : "rtl" ) : this.dir ? this.dir : this.isLeftToRight() ? "ltr" : "rtl";
                },

                applyTextDir: function(/*DOMNode*/ element, /*String?*/ text){
                        // summary:
                        //              Set element.dir according to this.textDir, assuming this.textDir has a value.
                        // element:
                        //              The text element to be set. Should have dir property.
                        // text:
                        //              If specified, and this.textDir is "auto", for calculating the right transformation
                        //              Otherwise text read from element.
                        // description:
                        //              If textDir is ltr or rtl returns the value.
                        //              If it's auto, calls to another function that responsible
                        //              for checking the value, and defining the direction.
                        // tags:
                        //              protected.

                        if(this.textDir){
                                var textDir = this.textDir;
                                if(textDir == "auto"){
                                        // convert "auto" to either "ltr" or "rtl"
                                        if(typeof text === "undefined"){
                                                // text not specified, get text from element
                                                var tagName = element.tagName.toLowerCase();
                                                text = (tagName == "input" || tagName == "textarea") ? element.value :
                                                        element.innerText || element.textContent || "";
                                        }
                                        textDir = this._checkContextual(text);
                                }

                                if(element.dir != textDir){
                                        // set element's dir to match textDir, but not when textDir is null and not when it already matches
                                        element.dir = textDir;
                                }
                        }
                },

                enforceTextDirWithUcc: function(option, text){
                        // summary:
                        //              Wraps by UCC (Unicode control characters) option's text according to this.textDir
                        // option:
                        //              The element (`<option>`) we wrapping the text for.
                        // text:
                        //              The text to be wrapped.
                        // description:
                        //              There's a dir problem with some HTML elements. For some elements (e.g. `<option>`, `<select>`)
                        //              defining the dir in different direction then the GUI orientation, won't display correctly.
                        //              FF 3.6 will change the alignment of the text in option - this doesn't follow the bidi standards (static text
                        //              should be aligned following GUI direction). IE8 and Opera11.10 completely ignore dir setting for `<option>`.
                        //              Therefore the only solution is to use UCC (Unicode  control characters) to display the text in correct orientation.
                        //              This function saves the original text value for later restoration if needed, for example if the textDir will change etc.
                        if(this.textDir){
                                if(option){
                                        option.originalText = text;
                                }
                                var dir = this.textDir == "auto" ? this._checkContextual(text) : this.textDir;
                                return (dir == "ltr" ? bidi_const.LRE : bidi_const.RLE ) + text + bidi_const.PDF;
                        }
                        return text;
                },

                restoreOriginalText: function(origObj){
                        // summary:
                        //              Restores the text of origObj, if needed, after enforceTextDirWithUcc, e.g. set("textDir", textDir).
                        // origObj:
                        //              The element (`<option>`) to restore.
                        // description:
                        //              Sets the text of origObj to origObj.originalText, which is the original text, without the UCCs.
                        //              The function than removes the originalText from origObj!
                        if(origObj.originalText){
                                origObj.text = origObj.originalText;
                                delete origObj.originalText;
                        }
                        return origObj;
                },

                _setTextDirAttr: function(/*String*/ textDir){
                        // summary:
                        //              Setter for textDir.
                        // description:
                        //              Users shouldn't call this function; they should be calling
                        //              set('textDir', value)
                        if(!this._created || this.textDir != textDir){
                                this._set("textDir", textDir);
                                var node = null;
                                if(this.displayNode){
                                        node = this.displayNode;
                                        this.displayNode.align = this.dir == "rtl" ? "right" : "left";
                                }else{
                                        node = this.textDirNode || this.focusNode || this.textbox;
                                }
                                if(node){
                                        this.applyTextDir(node);
                                }
                        }
                }
        };
});