How to Add a Week Selection in RadCalendar Control

Environment

Product Version	Product	Author
2021.3.914	RadCalendar for WinForms	Dinko Krastev

Description

In order to achieve week selection, you can clear all dates that don't belong to the week from the SelectedDates collection and select each date of the week. The following code snippet demonstrate how you can achieve this.

 public partial class RadForm1 : Telerik.WinControls.UI.RadForm
    {
        public RadForm1()
        {
            InitializeComponent();
            this.radCalendar1.AllowMultipleSelect = true;
            this.radCalendar1.SelectionChanged += RadCalendar1_SelectionChanged;
        }

        private void RadCalendar1_SelectionChanged(object sender, EventArgs e)
        {
            this.radCalendar1.SelectionChanged -= RadCalendar1_SelectionChanged;
            if (this.radCalendar1.SelectedDates.Count != 1)
            {
                this.radCalendar1.SelectedDates.Clear();
            }
            DateTime startDate = radCalendar1.FocusedDate.StartOfWeek(DayOfWeek.Monday).AddDays(-1);
            DateTime endDate = startDate.AddDays(6);
            while (startDate <= endDate)
            {
                this.radCalendar1.SelectedDates.Add(startDate);
                startDate = startDate.AddDays(1);
            }

            this.radCalendar1.SelectionChanged += RadCalendar1_SelectionChanged;
        }
    }
    public static class DateTimeExtensions
    {
        public static DateTime StartOfWeek(this DateTime dt, DayOfWeek startOfWeek)
        {
            int diff = dt.DayOfWeek - startOfWeek;
            if (diff < 0)
            {
                diff += 7;
            }
            return dt.AddDays(-1 * diff).Date;
        }
    }

Imports System.Runtime.CompilerServices
Partial Public Class Form1
    Inherits Form

    Public Sub New()
        InitializeComponent()
        Me.RadCalendar1.AllowMultipleSelect = True
        AddHandler Me.RadCalendar1.SelectionChanged, AddressOf RadCalendar1_SelectionChanged
    End Sub

    Private Sub RadCalendar1_SelectionChanged(ByVal sender As Object, ByVal e As EventArgs)
        RemoveHandler Me.RadCalendar1.SelectionChanged, AddressOf RadCalendar1_SelectionChanged
        If Me.RadCalendar1.SelectedDates.Count <> 1 Then
            Me.RadCalendar1.SelectedDates.Clear()
        End If

        Dim startDate As DateTime = Me.RadCalendar1.FocusedDate.StartOfWeek(DayOfWeek.Monday).AddDays(-1)
        Dim endDate As DateTime = startDate.AddDays(6)

        While startDate <= endDate
            Me.RadCalendar1.SelectedDates.Add(startDate)
            startDate = startDate.AddDays(1)
        End While

        AddHandler Me.RadCalendar1.SelectionChanged, AddressOf RadCalendar1_SelectionChanged

    End Sub
End Class

Module DateTimeExtensions
    <Extension()>
    Function StartOfWeek(ByVal dt As DateTime, startOfWeekPam As DayOfWeek) As DateTime
        Dim diff As Integer = dt.DayOfWeek - startOfWeekPam

        If diff < 0 Then
            diff += 7
        End If

        Return dt.AddDays(-1 * diff).Date
    End Function
End Module