c# - ListBox SelectionChanged only once? -
i have listbox add items to. each time select item object of person person properties should showed in textboxes. person have person properties age, name, sex , on.
my listbox selection changed event triggers 1 time or on new added items. doesn't trigger when click , not added.
mainwindow.xaml.cs
namespace gui_wpf_eksamen { /// <summary> /// interaction logic mainwindow.xaml /// </summary> public partial class mainwindow : window { backlog bl = new backlog(); public mainwindow() { initializecomponent(); datacontext = bl; this.prioritycombobox.items.add("high"); this.prioritycombobox.items.add("medium"); this.prioritycombobox.items.add("low"); } private void addtoproductbacklogbtn_click(object sender, routedeventargs e) { this.productbackloglist.items.add(bl); this.nametextbox.text = string.empty; } private void productbackloglist_selectionchanged(object sender, selectionchangedeventargs e) { var item = this.productbackloglist.selecteditem backlog; this.namelabel.content = item.name; this.descriptiontextblock.text = item.description; this.prioritylabel.content = item.priority; this.timelabel.content = item.time; } private void addtosprint_click(object sender, routedeventargs e) { var currentitem = this.productbackloglist.selecteditem backlog; this.sprintbackloglist.items.add(currentitem); } } } mainwindow.xaml
<window x:class="gui_wpf_eksamen.mainwindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:local="clr-namespace:gui_wpf_eksamen" title="gui wpf application" height="800" width="1200"> <window.background> <imagebrush imagesource="images/chalkboard.jpg"/> </window.background> <grid> <grid.rowdefinitions> <rowdefinition height="69*"/> <rowdefinition height="700*"/> </grid.rowdefinitions> <label x:name="title" content="scrum-board xxl" horizontalalignment="center" horizontalcontentalignment="center" margin="15,10,5,0" verticalalignment="top" width="1172" height="56" fontsize="36" fontstyle="italic" fontweight="bold" foreground="white"/> <grid horizontalalignment="left" height="680" margin="15,10,0,0" grid.row="1" verticalalignment="top" width="354"> <grid.rowdefinitions> <rowdefinition height="94*"/> <rowdefinition height="44*"/> <rowdefinition height="131*"/> <rowdefinition height="53*"/> <rowdefinition height="40*"/> <rowdefinition height="46*"/> <rowdefinition height="272*"/> </grid.rowdefinitions> <label content="navn" horizontalalignment="left" margin="0,44,0,0" verticalalignment="top" width="77" fontsize="16" foreground="white"/> <label content="beskrivelse
" horizontalalignment="left" margin="0,10,0,0" verticalalignment="top" foreground="white" fontsize="16" height="31" grid.row="1"/> <label content="prioritet" horizontalalignment="left" margin="0,7,0,0" verticalalignment="top" width="67" fontsize="16" foreground="white" grid.row="3"/> <label content="estimeret tidsforbrug" horizontalalignment="left" margin="0,10,0,0" verticalalignment="top" foreground="white" fontsize="16" grid.row="4" grid.rowspan="2"/> <textbox x:name="nametextbox" horizontalalignment="left" height="23" margin="51,52,0,0" textwrapping="wrap" verticalalignment="top" width="303" opacity="0.5" text="{binding path=name}"/> <combobox x:name="prioritycombobox" horizontalalignment="left" margin="73,12,0,0" verticalalignment="top" width="152" rendertransformorigin="0.5,0.5" opacity="0.5" grid.row="3" selecteditem="{binding path=priority}"> <combobox.rendertransform> <transformgroup> <scaletransform/> <skewtransform/> <rotatetransform angle="0.036"/> <translatetransform/> </transformgroup> </combobox.rendertransform> </combobox> <textbox x:name="timetextbox" horizontalalignment="left" height="23" margin="0,6,0,0" textwrapping="wrap" verticalalignment="top" width="204" opacity="0.5" grid.row="5" text="{binding path=time}"/> <label content="time(r)" horizontalalignment="left" margin="209,38,0,0" verticalalignment="top" foreground="white" fontsize="16" width="57" grid.row="4" grid.rowspan="2"/> <textbox x:name="descriptiontextbox" horizontalalignment="left" height="111" margin="0,10,0,0" grid.row="2" textwrapping="wrap" verticalalignment="top" width="354" opacity="0.5" text="{binding path=description}"/> <button x:name="addtoproductbacklogbtn" content="add backlog item" horizontalalignment="left" grid.row="6" verticalalignment="top" width="200" height="27" margin="66,0,0,0" background="white" opacity="0.7" click="addtoproductbacklogbtn_click"/> </grid> <grid horizontalalignment="left" height="680" margin="374,10,0,0" grid.row="1" verticalalignment="top" width="808" rendertransformorigin="0.459,0.431"> <grid.columndefinitions> <columndefinition width="79*"/> <columndefinition width="47*"/> <columndefinition width="76*"/> </grid.columndefinitions> <grid.rowdefinitions> <rowdefinition height="209*"/> <rowdefinition height="131*"/> </grid.rowdefinitions> <label content="navn" horizontalalignment="left" margin="10,10,0,0" grid.row="1" verticalalignment="top" fontsize="16" foreground="white" height="31" width="47"/> <label content="beskrivelse" horizontalalignment="left" margin="10,55,0,0" grid.row="1" verticalalignment="top" foreground="white" fontsize="16" height="31" width="87"/> <label content="prioritet
" horizontalalignment="left" margin="10,10,0,0" grid.row="1" verticalalignment="top" foreground="white" fontsize="16" height="32" grid.column="1" width="66"/> <label content="estimeret tidsforbrug" grid.column="1" horizontalalignment="left" margin="10,55,0,0" grid.row="1" verticalalignment="top" foreground="white" fontsize="16" height="31" width="159"/> <label x:name="prioritylabel" content="" grid.column="1" horizontalalignment="left" margin="90,10,0,0" grid.row="1" verticalalignment="top" fontsize="16" foreground="white" width="79" height="31"/> <label x:name="timelabel" grid.column="2" horizontalalignment="left" margin="10,55,0,0" grid.row="1" verticalalignment="top" foreground="white" fontsize="16" width="208" height="31"/> <listbox x:name="productbackloglist" horizontalalignment="left" height="353" margin="10,55,0,0" verticalalignment="top" width="292" displaymemberpath="name" opacity="0.505" selectionchanged="productbackloglist_selectionchanged" rendertransformorigin="0.5,0.5"> <listbox.rendertransform> <transformgroup> <scaletransform/> <skewtransform angley="-0.195"/> <rotatetransform/> <translatetransform y="-0.497"/> </transformgroup> </listbox.rendertransform> </listbox> <listbox x:name="sprintbackloglist" horizontalalignment="left" height="353" margin="10,55,0,0" verticalalignment="top" width="284" displaymemberpath="name" grid.column="2" opacity="0.5"/> <label x:name="namelabel" horizontalalignment="left" margin="62,14,0,0" grid.row="1" verticalalignment="top" width="244" height="27" content="{binding path=name}" foreground="white"/> <button x:name="addtosprint" content="add >>" grid.column="1" horizontalalignment="left" margin="54,201,0,0" verticalalignment="top" width="75" height="20" opacity="0.7" click="addtosprint_click"/> <textblock x:name="descriptiontextblock" horizontalalignment="left" margin="10,86,0,0" grid.row="1" textwrapping="wrap" verticalalignment="top" height="166" width="296" foreground="white"/> </grid> </grid>
that way of selection changed can accomplished easily:
have here:
<window x:class="listboxselection.mainwindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" title="mainwindow" height="350" width="525"> <dockpanel> <listbox itemssource="{binding persons}" issynchronizedwithcurrentitem="true" dockpanel.dock="top"> <listbox.itemtemplate> <datatemplate> <stackpanel orientation="horizontal"> <textblock text="{binding name}" margin="5,0"/> <textblock text="{binding age, stringformat=is {0} years old}" margin="5,0"/> </stackpanel> </datatemplate> </listbox.itemtemplate> </listbox> <stackpanel orientation="horizontal" datacontext="{binding persons}" dockpanel.dock="top"> <textblock text="you have selected: " fontweight="semibold"/> <textbox text="{binding name, updatesourcetrigger=propertychanged}" margin="5,0" fontweight="semibold" verticalalignment="top" horizontalalignment="center"/> <textbox text="{binding age, updatesourcetrigger=propertychanged}" margin="5,0" fontweight="semibold" verticalalignment="top" horizontalalignment="left"/> </stackpanel> <button content="add item" dockpanel.dock="top" width="60" verticalalignment="top" margin="20" click="btnadditem_click"/> </dockpanel> note down: issynchronizedwithcurrentitem="true"
from msdn:
gets or sets value indicates whether selector should keep selecteditem synchronized current item in items property.
what's next step? display selected item:
<stackpanel datacontext="{binding persons}"/> stackpanel not itemscontrol, not try display items in persons instead selected one.
the icollectionview interface contains member called currentitem. issynchronizedwithcurrentitem is: whenever item clicked on itemscontrol, sets currentitem collection view. icollectionview has 2 events: currentitemchanging , currentitemchanged. when issynchronizedwithcurrentitem property set, itemscontrol update selecteditem based on icollectionview's currentitem is.
further more, using updatesourcetrigger=propertychanged able update selected item , displayed in listbox.
ok, that's about, here rest of code:
public class person : inotifypropertychanged { private string _name; public string name { { return _name; } set { _name = value; propertychanged(this, new propertychangedeventargs("name")); } } private int _age; public int age { { return _age; } set { _age = value; propertychanged(this, new propertychangedeventargs("age")); } } public event propertychangedeventhandler propertychanged = delegate { }; } and codebehind:
public partial class mainwindow : window { public observablecollection<person> persons { get; set; } public person selectedperson { { return (person)getvalue(selectedpersonproperty); } set { setvalue(selectedpersonproperty, value); } } // using dependencyproperty backing store selectedperson. enables animation, styling, binding, etc... public static readonly dependencyproperty selectedpersonproperty = dependencyproperty.register("selectedperson", typeof(person), typeof(mainwindow), new propertymetadata(null)); public mainwindow() { initializecomponent(); persons = new observablecollection<person>(); persons.add(new person() { name = "name1", age = 20 }); persons.add(new person() { name = "name2", age = 25 }); persons.add(new person() { name = "name3", age = 30 }); this.datacontext = this; } private void btnadditem_click(object sender, routedeventargs e) { persons.add(new person() { name = "nameadded", age = 50 }); } } as see, selectionchanged handler not needed anymore.
you may asking, selectedperson in code behind:
add binding on listbox:
selecteditem="{binding selectedperson}" and in addtosprint_click use selectedperson person instead of directly accessing listbox.
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