c# - Dependency property of Custom Templated Control won't be set if it is set to binding in WinRT -

i wrote custom templated richtextblock in order represent emojis , links images , hyperlink buttons respectivly. has 1 "text" dependency property because conversion works process inside control when recieve plain text/string.

the problem if text property specific string text="asdasdsa", control represent "asdasdas" properly. if property set bind text="{binding something}", control won't work , setter text dependency property never fire.

the style of control this

<style targettype="local:myrichtextblock" >     <setter property="template">         <setter.value>             <controltemplate targettype="local:myrichtextblock">                 <border horizontalalignment="center" width="auto" height="auto">                     <stackpanel>                         <richtextblock x:name="childrichtextblock"/>                     </stackpanel>                 </border>              </controltemplate>         </setter.value>     </setter> </style> 

basically, converts plain text , replace emojis , hyperlinks in xaml, @ end add block of xaml code richtextblock paragraph.

the code of control

public sealed class myrichtextblock : control {     richtextblock _richtextblock;     stringbuilder builder = new stringbuilder();     regex urlrx = new regex(@"(?<url>(http:[/][/]|www.)([a-z]|[a-z]|[0-9]|[/.]|[~])*)", regexoptions.ignorecase);       public myrichtextblock()     {         this.defaultstylekey = typeof(myrichtextblock);          foreach (var key in emojidict.keys)         {             builder.append(key.replace("[", @"\[").replace("]", @"\]"));             builder.append("|");         }         builder.remove(builder.length - 1, 1);      }        private readonly dictionary<string, string> emojidict = new dictionary<string, string> {     //dictionary of emojis key };      protected override void onapplytemplate()     {         _richtextblock = gettemplatechild("childrichtextblock") richtextblock;         setrichtextblock(text);     }       public string text     {         { return (string)getvalue(textproperty); }         set { setvalue(textproperty, value); } //this setter won't fire     }      // using dependencyproperty backing store text.  enables animation, styling, binding, etc...     public static readonly dependencyproperty textproperty =         dependencyproperty.register("text", typeof(string), typeof(myrichtextblock), new propertymetadata(""));           //conversion work, not related property think     private void setrichtextblock(string value)     {         string abc = value;         matchcollection matches = urlrx.matches(value);         var r = new regex(builder.tostring());         var mc = r.matches(value);         foreach (match m in mc)         {             value = value.replace(m.value, string.format(@"<inlineuicontainer><border><image source=""ms-appx:///assets/emoji/{0}.png"" margin=""2,0,2,0"" width=""30"" height=""30""/></border></inlineuicontainer>", emojidict[m.value]));         }         foreach (match match in matches)         {             string url = match.groups["url"].value;             value = value.replace(url,                 string.format("<inlineuicontainer><border><hyperlinkbutton margin=\"0,0,0,-4\" padding=\"0,2,0,0\" navigateuri =\"{0}\"><stackpanel horizontalalignment=\"center\" height=\"25\" width=\"90\" background=\"#ffb8e9ff\" orientation = \"horizontal\"><image margin=\"5,0,0,0\" source = \"/assets/link.png\" width = \"15\" height = \"15\"/><textblock margin=\"4,2.5,0,0\" text=\"网页链接\" foreground=\"white\" fontfamily=\"microsoft yahei ui\" fontsize=\"14\" fontweight=\"bold\"/></stackpanel ></hyperlinkbutton></border></inlineuicontainer>", url));         }         value = value.replace("\r\n", "<linebreak/>");            var xaml = string.format(@"<paragraph                                      xmlns=""http://schemas.microsoft.com/winfx/2006/xaml/presentation""                                     xmlns:x=""http://schemas.microsoft.com/winfx/2006/xaml"">                                 <paragraph.inlines>                                 <run></run>                                   {0}                                 </paragraph.inlines>                             </paragraph>", value);         var p = (paragraph)xamlreader.load(xaml);         _richtextblock.blocks.add(p);     } } 

and way how use control

<datatemplate x:name="normaltemplate">         <grid grid.column="1"               grid.row="1"                d:layoutoverrides="leftmargin, rightmargin, topmargin, bottommargin"               margin="0,15,0,15"               name="normaltemplategrid">             //codes omit//                               <local:myrichtextblock x:name="weibotexttextblock"                        margin="20,35,0,0"                        text="{binding text}"                        grid.column="2"                        grid.row="1"                        d:layoutoverrides="horizontalalignment, topmargin, bottommargin, leftposition, rightposition, topposition, bottomposition"                        horizontalalignment="left"                         fontfamily="microsoft yahei"/>         </grid>     </datatemplate> 

any ideas problem , solution this?

the setter there sake of completing dependency property. need define property changed callback text property, -

public static readonly dependencyproperty textproperty =     dependencyproperty.register(nameof(text), typeof(string), typeof(myrichtextblock), new propertymetadata("", ontextchange));  private static void ontextchange(dependencyobject d, dependencypropertychangedeventargs e) {     var rtb = (myrichtextblock)d;     rtb.setrichtextblock(e.newvalue.tostring()); }