c# - Button command(s) to select next / previous item in ListBox -
is there simple command can send standard wpf listbox using button select next / previous item in list?
currently i'm rolling solution:
<button width="30" height="30" x:name="previousbutton"> <i:interaction.triggers> <i:eventtrigger eventname="click"> <ei:changepropertyaction increment="true" propertyname="selectedindex" targetname="mylistbox" value="-1" /> </i:eventtrigger> </i:interaction.triggers> </button> <!-- listbox here. --> <button width="30" height="30" x:name="nextbutton"> <i:interaction.triggers> <i:eventtrigger eventname="click"> <ei:changepropertyaction increment="true" propertyname="selectedindex" targetname="mylistbox" value="1" /> </i:eventtrigger> </i:interaction.triggers> </button> which fine. cause exception if hit previous button when you're on first item on list (same last), current plan tell disable button if selectedindex first/last item in list.
i'm asking question see if i'm missing trick more anything. "no, that's not possible, have other way" acceptable answer if that's case.
using mvvm nice , simpler. how solve it.note sample code uses mvvmlight toolkit.
view
<window x:class="stackoverflow1.mainwindow" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:local="clr-namespace:stackoverflow1" xmlns:viewmodel="clr-namespace:stackoverflow1.viewmodel" mc:ignorable="d" title="mainwindow" height="350" width="525"> <window.resources> <viewmodel:mainviewmodel x:key="mainviewmodel"/> </window.resources> <grid datacontext="{staticresource mainviewmodel}"> <grid.rowdefinitions> <rowdefinition height="*"/> <rowdefinition height="auto"/> </grid.rowdefinitions> <listbox grid.row="0" horizontalalignment="stretch" verticalalignment="stretch" itemssource="{binding students}" x:name="listbox" selectedindex="{binding selectedindex}"/> <stackpanel orientation="horizontal" grid.row="1"> <button content="next" width="50" height="24" command="{binding nextcommand}" commandparameter="{binding elementname=listbox,path=selectedindex}"/> <button content="previous" width="50" height="24" command="{binding previouscommand}" commandparameter="{binding elementname=listbox,path=selectedindex}"/> </stackpanel> </grid> </window> viewmodel
using system.collections.generic; using system.collections.objectmodel; using system.windows.input; using galasoft.mvvmlight; using galasoft.mvvmlight.commandwpf; namespace stackoverflow1.viewmodel { public class mainviewmodel : viewmodelbase { public mainviewmodel() { nextcommand=new relaycommand<int>(onnext,cannext); previouscommand=new relaycommand<int>(onprevious,canprevious); selectedindex = 0; foreach (var student in getstudent()) { _students.add(student); } } public icommand nextcommand { get; set; } public icommand previouscommand { get; set; } private int _selectedindex; private list<student> getstudent() { return new list<student>() { new student {id = 0,name = "kwame0"}, new student {id = 0,name = "kwame1"}, new student {id = 0,name = "kwame2"}, new student {id = 0,name = "kwame3"}, new student {id = 0,name = "kwame4"}, new student {id = 0,name = "kwame5"}, new student {id = 0,name = "kwame6"}, new student {id = 0,name = "kwame7"}, new student {id = 0,name = "kwame8"}, new student {id = 0,name = "kwame9"}, new student {id = 0,name = "kwame10"}, new student {id = 0,name = "kwame11"}, new student {id = 0,name = "kwame12"}, new student {id = 0,name = "kwame13"}, new student {id = 0,name = "kwame14"}, new student {id = 0,name = "kwame15"}, }; } public int selectedindex { { return _selectedindex; } set { _selectedindex = value;raisepropertychanged(()=>selectedindex); } } private observablecollection<student> _students=new observablecollection<student>(); public observablecollection<student> students { { return _students; } set { _students = value; } } private void onnext(int index) { if (selectedindex != students.count) selectedindex += 1; else { selectedindex = 0; } } private bool cannext(int indext) { return selectedindex != students.count; } private void onprevious(int index) { if (selectedindex != 0) selectedindex -= 1; else { selectedindex = students.count; } } private bool canprevious(int index) { return selectedindex != 0; } } public class student { public int id { get; set; } public string name { get; set; } public override string tostring() { return $"{id}-{name}"; } } }
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