use null char to start text cell placeholders

IPython/frontend/html/notebook/static/js/textcell.js

@@ -1,270 +1,270 b''
 //----------------------------------------------------------------------------
 //  Copyright (C) 2008-2011  The IPython Development Team
 //
 //  Distributed under the terms of the BSD License.  The full license is in
 //  the file COPYING, distributed as part of this software.
 //----------------------------------------------------------------------------
 
 //============================================================================
 // TextCell
 //============================================================================
 
 var IPython = (function (IPython) {
 
     // TextCell base class
 
     var TextCell = function (notebook) {
         this.code_mirror_mode = this.code_mirror_mode || 'htmlmixed';
-        this.placeholder = this.placeholder || '𝄆';
+        this.placeholder = this.placeholder || '\u0000';
         IPython.Cell.apply(this, arguments);
         this.rendered = false;
         this.cell_type = this.cell_type || 'text';
     };
 
 
     TextCell.prototype = new IPython.Cell();
 
 
     TextCell.prototype.create_element = function () {
         var cell = $("<div>").addClass('cell text_cell border-box-sizing');
         cell.attr('tabindex','2');
         var input_area = $('<div/>').addClass('text_cell_input');
         this.code_mirror = CodeMirror(input_area.get(0), {
             indentUnit : 4,
             mode: this.code_mirror_mode,
             theme: 'default',
             value: this.placeholder
         });
         // The tabindex=-1 makes this div focusable.
         var render_area = $('<div/>').addClass('text_cell_render').
             addClass('rendered_html').attr('tabindex','-1');
         cell.append(input_area).append(render_area);
         this.element = cell;
     };
 
 
     TextCell.prototype.bind_events = function () {
         IPython.Cell.prototype.bind_events.apply(this);
         var that = this;
         this.element.keydown(function (event) {
             if (event.which === 13) {
                 if (that.rendered) {
                     that.edit();
                     event.preventDefault();
                 };
             };
         });
     };
 
 
     TextCell.prototype.select = function () {
         IPython.Cell.prototype.select.apply(this);
         var output = this.element.find("div.text_cell_render");
         output.trigger('focus');
     };
 
 
     TextCell.prototype.edit = function () {
         if (this.rendered === true) {
             var text_cell = this.element;
             var output = text_cell.find("div.text_cell_render");  
             output.hide();
             text_cell.find('div.text_cell_input').show();
             this.code_mirror.focus();
             this.code_mirror.refresh();
             this.rendered = false;
             if (this.get_source() === this.placeholder) {
                 this.set_source('');
             };
         };
     };
 
 
     // Subclasses must define render.
     TextCell.prototype.render = function () {};
 
 
     TextCell.prototype.config_mathjax = function () {
         var text_cell = this.element;
         var that = this;
         text_cell.click(function () {
             that.edit();
         }).focusout(function () {
             that.render();
         });
         
         text_cell.trigger("focusout");
     };
 
 
     TextCell.prototype.get_source = function() {
         return this.code_mirror.getValue();
     };
 
 
     TextCell.prototype.set_source = function(text) {
         this.code_mirror.setValue(text);
         this.code_mirror.refresh();
     };
 
 
     TextCell.prototype.get_rendered = function() {
         return this.element.find('div.text_cell_render').html();
     };
 
 
     TextCell.prototype.set_rendered = function(text) {
         this.element.find('div.text_cell_render').html(text);
     };
 
 
     TextCell.prototype.at_top = function () {
         if (this.rendered) {
             return true;
         } else {
             return false;
         }
     };
 
 
     TextCell.prototype.at_bottom = function () {
         if (this.rendered) {
             return true;
         } else {
             return false;
         }
     };
 
 
     TextCell.prototype.fromJSON = function (data) {
         if (data.cell_type === this.cell_type) {
             if (data.source !== undefined) {
                 this.set_source(data.source);
                 this.set_rendered(data.rendered || '');
                 this.rendered = false;
                 this.render();
             };
         };
     };
 
 
     TextCell.prototype.toJSON = function () {
         var data = {}
         data.cell_type = this.cell_type;
         data.source = this.get_source();
         return data;
     };
 
 
     // HTMLCell
 
     var HTMLCell = function (notebook) {
-        this.placeholder = "&#x1D106; Type <strong>HTML</strong> and LaTeX: $\\alpha^2$";
+        this.placeholder = "\u0000Type <strong>HTML</strong> and LaTeX: $\\alpha^2$";
         IPython.TextCell.apply(this, arguments);
         this.cell_type = 'html';
     };
 
 
     HTMLCell.prototype = new TextCell();
 
 
     HTMLCell.prototype.render = function () {
         if (this.rendered === false) {
             var text = this.get_source();
             if (text === "") {text = this.placeholder;};
             this.set_rendered(text);
             MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
             this.element.find('div.text_cell_input').hide();
             this.element.find("div.text_cell_render").show();
             this.rendered = true;
         };
     };
 
 
     // MarkdownCell
 
     var MarkdownCell = function (notebook) {
-        this.placeholder = "&#x1D106; Type *Markdown* and LaTeX: $\\alpha^2$";
+        this.placeholder = "\u0000Type *Markdown* and LaTeX: $\\alpha^2$";
         IPython.TextCell.apply(this, arguments);
         this.cell_type = 'markdown';
     };
 
 
     MarkdownCell.prototype = new TextCell();
 
 
     MarkdownCell.prototype.render = function () {
         if (this.rendered === false) {
             var text = this.get_source();
             if (text === "") {text = this.placeholder;};
             var html = IPython.markdown_converter.makeHtml(text);
             this.set_rendered(html);
             MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
             this.element.find('div.text_cell_input').hide();
             this.element.find("div.text_cell_render").show();
             var code_snippets = this.element.find("pre > code");
             code_snippets.replaceWith(function () {
                 var code = $(this).html();
                 /* Substitute br for newlines and &nbsp; for spaces
                    before highlighting, since prettify doesn't
                    preserve those on all browsers */
                 code = code.replace(/(\r\n|\n|\r)/gm, "<br/>");
                 code = code.replace(/ /gm, '&nbsp;');
                 code = prettyPrintOne(code);
 
                 return '<code class="prettyprint">' + code + '</code>';
             });
             this.rendered = true;
         };
     };
 
 
     // RSTCell
 
     var RSTCell = function (notebook) {
-        this.placeholder = "&#x1D106; Type *ReStructured Text* and LaTeX: $\\alpha^2$";
+        this.placeholder = "\u0000Type *ReStructured Text* and LaTeX: $\\alpha^2$";
         IPython.TextCell.apply(this, arguments);
         this.cell_type = 'rst';
     };
 
 
     RSTCell.prototype = new TextCell();
 
 
     RSTCell.prototype.render = function () {
         if (this.rendered === false) {  
             var text = this.get_source();
             if (text === "") {text = this.placeholder;};
             var settings = {
                 processData : false,
                 cache : false,
                 type : "POST",
                 data : text,
                 headers : {'Content-Type': 'application/x-rst'},
                 success : $.proxy(this.handle_render,this)
             };
             $.ajax("/rstservice/render", settings);
             this.element.find('div.text_cell_input').hide();
             this.element.find("div.text_cell_render").show();
             this.set_rendered("Rendering...");
         };
     };
 
 
     RSTCell.prototype.handle_render = function (data, status, xhr) {
         this.set_rendered(data);
         MathJax.Hub.Queue(["Typeset",MathJax.Hub]);
         this.rendered = true;
     };
 
 
     IPython.TextCell = TextCell;
     IPython.HTMLCell = HTMLCell;
     IPython.MarkdownCell = MarkdownCell;
     IPython.RSTCell = RSTCell;
 
 
     return IPython;
 
 }(IPython));