c# - Count DataGridCells according to a boolean AttachedProperty -

i have e highlighting mechanism changes background of datagridcell according searched pattern.

<setter property="converters:datagridtextsearch.istextmatch">                 <setter.value>                     <multibinding converter="{staticresource searchvalueconverter}">                         <binding relativesource="{relativesource self}" path="content.text"/>                         <binding relativesource="{relativesource self}" path="(converters:datagridtextsearch.searchvalue)" />                         <binding relativesource="{relativesource self}" path="column.header" />                     </multibinding>                 </setter.value> </setter> 

and trigger defined :

<style.triggers>                 <trigger property="converters:datagridtextsearch.istextmatch" value="true">                     <setter property="background" value="lightgray" />                 </trigger> </style.triggers> 

code attachedproperty:

    // using dependencyproperty backing store istextmatch.  enables animation, styling, binding, etc...     public static readonly dependencyproperty istextmatchproperty =         dependencyproperty.registerattached("istextmatch", typeof(bool), typeof(datagridtextsearch), new uipropertymetadata(false));      public static bool getistextmatch(dependencyobject obj)     {         return (bool)obj.getvalue(istextmatchproperty);     }      public static void setistextmatch(dependencyobject obj, bool value)     {         obj.setvalue(istextmatchproperty, value);     } 

i count cells have istextmatch true. further more need count rows, there might many cells on 1 row have detect trying go step step.

i tried add attached property in static class count how many "true" set. updated value propertychangedcallback of istextmatchproperty didn't work.

this xaml access property :

  converters:datagridtextsearch.cellscount="{binding relativesource={relativesource self}, path=tag, mode=twoway, updatesourcetrigger=propertychanged}" 

where datagridtextsearch static class in properties resides.

is there other approach? if not, doing wrong here?

basic approach create supervising object, counter, responsible counting of highlighted cells.

public class counter : inotifypropertychanged {     hashset<dependencyobject> _hash = new hashset<dependencyobject>();      public void add(dependencyobject obj)     {         this._hash.add(obj);         this.raisepropertychanged("count");     }      public void remove(dependencyobject obj)     {         this._hash.remove(obj);         this.raisepropertychanged("count");     }      public int count     {                 {             return this._hash.count;         }     }      // inotifypropertychanged implementation omitted... } 

add attached dependency property cellcounter behavior:

// get/set methods omitted  public static readonly dependencyproperty counterproperty = dependencyproperty.registerattached(     "cellscounter",      typeof(counter),      typeof(gridbehavior),      new frameworkpropertymetadata(gridbehavior.oncellscounterpropertychanged));  private static void oncellscounterpropertychanged(dependencyobject d, dependencypropertychangedeventargs e) {     var oldcounter = e.oldvalue counter;     if (oldcounter != null)     {         oldcounter.remove(d);     }      var newcounter = e.newvalue counter;     if (newcounter != null)     {         var isselected = gridbehavior.getisselected(d);         if (isselected)         {             newcounter.add(d);         }     } } 

add logic of incrementing/decrementing of counter istextmatch property:

// get/set methods omitted    public static readonly dependencyproperty istextmatchproperty =         dependencyproperty.registerattached(             "istextmatch",              typeof(bool),              typeof(gridbehavior),              new frameworkpropertymetadata(gridbehavior.onistextmatchpropertychanged));      private static void onistextmatchpropertychanged(dependencyobject d, dependencypropertychangedeventargs e)     {         var counter = d.getvalue(gridbehavior.cellscounterproperty) counter;         if (counter == null)         {             return;         }          if ((bool)e.newvalue)         {             counter.add(d);         }         else         {             counter.remove(d);         }     } 

then define single counter in resources section of window/control , poll count property wherever want. due inotifypropertychanged nature of counter changes automatically dispatched counter's consumer. (i used listbox instead of datagrid , didn't use view model simplicity doesn't matter):

<window x:class="wpfapplication3.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"                 xmlns:view="clr-namespace:wpfapplication3">     <window.resources>         <view:counter x:key="counterkey"/>     </window.resources>     <stackpanel>         <listbox>             <listboxitem view:gridbehavior.istextmatch="true"                          view:gridbehavior.cellscounter="{staticresource counterkey}"                          content="a"/>             <listboxitem view:gridbehavior.istextmatch="false"                          view:gridbehavior.cellscounter="{staticresource counterkey}"                          content="b"/>             <listboxitem view:gridbehavior.istextmatch="false"                          view:gridbehavior.cellscounter="{staticresource counterkey}"                          content="c"/>             <listboxitem view:gridbehavior.istextmatch="true"                          view:gridbehavior.cellscounter="{staticresource counterkey}"                          content="d"/>         </listbox>          <textblock text="{binding path=count,source={staticresource counterkey}}"/>     </stackpanel> </window> 

n.b. need go further , enhance remove logic. example, if remove item istextmatch=true list, doesn't affect counter. believe, skilled enough yourself.