Please refer to the attached sample project. After running it, the following error is observed:

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.RadPictureBoxElement.UpdateParentControl()
   at Telerik.WinControls.UI.RadPictureBoxElement.OnParentChanged(RadElement previousParent)
   at Telerik.WinControls.RadElement.SetParent(RadElement parent)
   at Telerik.WinControls.RadElement.ChangeCollection(RadElement child, ItemsChangeOperation changeOperation)
   at Telerik.WinControls.RadElementCollection.OnInsertComplete(Int32 index, Object value)
   at System.Collections.CollectionBase.System.Collections.IList.Add(Object value)
   at Telerik.WinControls.RadElementCollection.Add(RadElement value)
   at _1574930GanttCustomDataItem.RadForm1.customGanttViewTextViewCellElement.CreateChildElements() in C:\Projects\1574930GanttCustomDataItem\1574930GanttCustomDataItem\RadForm1.vb:line 75
   at Telerik.WinControls.RadElement.CallCreateChildElements()
   at Telerik.WinControls.RadElement.Construct()
   at Telerik.WinControls.RadElement..ctor()
   at Telerik.WinControls.RadItem..ctor()
   at Telerik.WinControls.UI.GanttViewTextViewCellElement..ctor(GanttViewTextItemElement owner, GanttViewTextViewColumn column)
   at _1574930GanttCustomDataItem.RadForm1.customGanttViewTextViewCellElement..ctor(GanttViewTextItemElement owner, GanttViewTextViewColumn column) in C:\Projects\1574930GanttCustomDataItem\1574930GanttCustomDataItem\RadForm1.vb:line 59
   at _1574930GanttCustomDataItem.RadForm1.radGanttView1_DataCellElementCreating(Object sender, GanttViewDataCellElementCreatingEventArgs e) in C:\Projects\1574930GanttCustomDataItem\1574930GanttCustomDataItem\RadForm1.vb:line 51
   at Telerik.WinControls.UI.RadGanttViewElement.OnDataCellCreating(GanttViewDataCellElementCreatingEventArgs e)
   at Telerik.WinControls.UI.GanttViewTextViewCellElementProvider.CreateElement(GanttViewTextViewColumn data, Object context)
   at Telerik.WinControls.UI.BaseVirtualizedElementProvider`1.GetElement(T data, Object context)
   at Telerik.WinControls.UI.BaseVirtualizedContainer`1.UpdateElement(Int32 position, T data)
   at Telerik.WinControls.UI.BaseVirtualizedContainer`1.MeasureElements()
   at Telerik.WinControls.UI.BaseVirtualizedContainer`1.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.UI.LightVisualElement.MeasureElements(SizeF availableSize, SizeF clientSize, Padding borderThickness)
   at Telerik.WinControls.UI.LightVisualElement.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.UI.VirtualizedStackContainer`1.MeasureElementCore(RadElement element, SizeF availableSize)
   at Telerik.WinControls.UI.VirtualizedStackContainer`1.MeasureElement(IVirtualizedElement`1 element)
   at Telerik.WinControls.UI.BaseVirtualizedContainer`1.MeasureElements()
   at Telerik.WinControls.UI.BaseVirtualizedContainer`1.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.UI.GanttViewTextViewElement.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.UI.RadGanttViewElement.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.RootRadElement.MeasureOverride(SizeF availableSize)
   at Telerik.WinControls.RootRadElement.MeasureCore(SizeF availableSize)
   at Telerik.WinControls.RadElement.Measure(SizeF availableSize)
   at Telerik.WinControls.RadElementTree.PerformInnerLayout(Boolean performMeasure, Int32 x, Int32 y, Int32 width, Int32 height)
   at Telerik.WinControls.RadControl.OnLoad(Size desiredSize)
   at Telerik.WinControls.RadControl.LoadElementTree(Size desiredSize)
   at Telerik.WinControls.RadControl.OnCreateControl()
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl(Boolean fIgnoreVisible)
   at System.Windows.Forms.Control.CreateControl()
   at System.Windows.Forms.Control.WmShowWindow(Message& m)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
   at System.Windows.Forms.Form.WmShowWindow(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at Telerik.WinControls.UI.RadFormControlBase.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)


************** Loaded Assemblies **************

Workaround: set the RadOictureBoxElement.PanelDisplayMode property to PictureBoxPanelDisplayMode.None.

I have integration radscheduler and radganttview.

Load data

Dim ds as new DataSource

Dim dvAppointments As New DataView

Dim appointmentMappingInfo As New AppointmentMappingInfo()
        Dim SchedSource As New SchedulerBindingDataSource()
        appointmentMappingInfo.Mappings.Add(New SchedulerMapping("Kontrahent", "pln_kntakronim"))
        appointmentMappingInfo.Start = "pln_start"
        appointmentMappingInfo.End = "pln_stop"
        appointmentMappingInfo.Location = "pln_nr"
        appointmentMappingInfo.ResourceId = "pln_zamgidnumer"
        appointmentMappingInfo.Description = "pln_opis"
        appointmentMappingInfo.Resources = ""
        appointmentMappingInfo.Location = "pln_nrzam"
        appointmentMappingInfo.Summary = "pln_twrkod"
        appointmentMappingInfo.StatusId = "pln_status"

        dvAppointments.Table = ds.Tables("PlanowanieTamborow")
        SchedSource.EventProvider.Mapping = appointmentMappingInfo

        bsPlanowanie.DataSource = dvAppointments  'BindingSource
        SchedSource.EventProvider.DataSource = bsPlanowanie
    
        RadScheduler1.DataSource = SchedSource

        RadGanttView1.DataProvider = New GanttViewIntegrationProvider(RadScheduler1)

refresh data

Dim reader As System.Data.SqlClient.SqlDataReader = comm.ExecuteReader

 ds.Tables("PlanowanieTamborow").Clear()
 ds.Tables("PlanowanieTamborow").Load(reader)
 ds.Tables("PlanowanieTamborow").AcceptChanges()

 ds.Tables("PlanowanieTamborow")

If I refresh the Radscheduler then RadGanttView doesn't refresh

Radscheduleris working properly

Run the attached sample project and select the second page. You will notice that the tasks are missing. This used to work in R2 2019 (version 2019.2.508).

Workaround: Initialize the RadGanttView.BindingContext before adding it to the page:

Please use the following code snippet to setup the Gantt view:

Sub New()

        InitializeComponent()

        Dim dt As New DataTable
        dt.Columns.Add("ID", GetType(Integer))
        dt.Columns.Add("Group_ID", GetType(Integer))
        dt.Columns.Add("Title", GetType(String))
        dt.Columns.Add("Start", GetType(DateTime))
        dt.Columns.Add("End", GetType(DateTime))

        dt.Rows.Add(-999, 0, "Root", New DateTime(2019, 8, 21), New DateTime(2019, 8, 30))
        dt.Rows.Add(6, -999, "Item 1", New DateTime(2019, 8, 21), New DateTime(2019, 8, 23))
        dt.Rows.Add(7, -999, "Item 2", New DateTime(2019, 8, 26), New DateTime(2019, 8, 30))
        dt.Rows.Add(1000, 6, "Sub1.1", New DateTime(2019, 8, 21), New DateTime(2019, 8, 22))
        dt.Rows.Add(1001, 6, "Sub1.2", New DateTime(2019, 8, 22), New DateTime(2019, 8, 23))
        dt.Rows.Add(1002, 6, "Sub1.3", New DateTime(2019, 8, 23), New DateTime(2019, 8, 23))
        dt.Rows.Add(1003, 7, "Sub2.1", New DateTime(2019, 8, 26), New DateTime(2019, 8, 29))



        Me.RadGanttView1.DataSource = dt
        Me.RadGanttView1.ChildMember = "ID"
        Me.RadGanttView1.ParentMember = "Group_ID"
        Me.RadGanttView1.TitleMember = "Title"
        Me.RadGanttView1.StartMember = "Start"
        Me.RadGanttView1.EndMember = "End"

        Me.RadGanttView1.Columns.Add("ID")
        Me.RadGanttView1.Columns.Add("Title")
        Me.RadGanttView1.GanttViewElement.GraphicalViewElement.TimelineStart = New DateTime(2019, 8, 20)
    End Sub 

However, if you switch the order of adding the rows, not all items will be visible in RadGanttView:

dt.Rows.Add(1000, 6, "Sub1.1", New DateTime(2019, 8, 21), New DateTime(2019, 8, 22))
        dt.Rows.Add(1001, 6, "Sub1.2", New DateTime(2019, 8, 22), New DateTime(2019, 8, 23))
        dt.Rows.Add(1002, 6, "Sub1.3", New DateTime(2019, 8, 23), New DateTime(2019, 8, 23))
        dt.Rows.Add(1003, 7, "Sub2.1", New DateTime(2019, 8, 26), New DateTime(2019, 8, 29))

Please refer to the attached sample project and run it. Select a random item and press the button. You will obtain the error. If no selection is available, the item is removed as expected. 

Workaround: use Begin/EndUpdate block while deleting a record from the DataTable:

Please run the attached sample project. Select one of the child tasks and click the button. The new task is expected to be inserted at the selected item's position. However, it is appended at the bottom as it is demonstrated in the gif file.

Workaround: rebind RadGanttView after inserting a new row to the DataTable: 

The latest release of WinForms causes a fatal exception when adding an item to a BindingList that is used in a RadGridView and a RadGanttView.

The first time an item is added there is not issue.

The second time an item is added, the following exception occurs.

System.NullReferenceException: Object reference not set to an instance of an object.
   at Telerik.WinControls.UI.GanttViewBindingProvider.GanttTaskList.IndexOf(Object key)
   at Telerik.WinControls.UI.GanttViewBindingProvider.GanttTaskList.get_Item(Object key)
   at Telerik.WinControls.UI.GanttViewBindingProvider.AddTaskByCM(CurrencyManager cm, Int32 index)
   at System.ComponentModel.ListChangedEventHandler.Invoke(Object sender, ListChangedEventArgs e)
   at System.Windows.Forms.CurrencyManager.OnListChanged(ListChangedEventArgs e)
   at System.Windows.Forms.CurrencyManager.List_ListChanged(Object sender, ListChangedEventArgs e)
   at System.ComponentModel.BindingList`1.OnListChanged(ListChangedEventArgs e)
   at System.ComponentModel.BindingList`1.FireListChanged(ListChangedType type, Int32 index)
   at MissileWarningThreatPlanner.EventWindow.EventList.GenMissileEventWorker_RunWorkerCompleted(Object sender, RunWorkerCompletedEventArgs e) in C:\Shape Source\VS\MissileWarningThreatPlanner - VS2010\MissileWarningThreatPlanner\EventWindow\EventList.cs:line 5329
   at System.ComponentModel.BackgroundWorker.OnRunWorkerCompleted(RunWorkerCompletedEventArgs e)

This is code that has not been modified for quite some time.  There has been no issue until the latest release.

I do not have time to try to create a simple example to try to reproduce the error at this time.  I will if possible.

For now, we are forced to revert to a previous version.

Ken...

Hi,

why is the datatype of the ChildMember/ParentMember item limited to Int32? This is a problem when displaying tasks or events from tables with string or UUID idents. It would be a more flexible control if the type could be any type. Should not be a big deal to change this or is it?

Thank you und kind regards

Karsten

Hey,

We have a problem with the GanttViewTimeLineContainer as you see in the screeshot  : gantt_print2.png

When we are in TimeLineRange = TimeRange.Year and we print the gantt, we have a problem with the appearence of GanttViewTimeLineContainer, we can see the first line with the year (it's ok) but after, the second line we can see a reperition of all month : jfmamjjasond jfmamjjasond jfmamjjasond jfmamjjasond etc etc etc

Can we change the appearence ? Do you have an explanation for this visualization ? 

Thank you,

Regards,

Valériane E.

When you edit a link, e.g. change its end item, there is no appropriate event to handle this situation. The Links.CollectionChanged event is not fired. It would be nice to have a LinkChanged event which will be fired when a link is modified similar to the ItemChanged event for the tasks.

Workaround:
            foreach (GanttViewLinkDataItem link in this.radGanttView1.Links)
            {
                link.PropertyChanged += link_PropertyChanged;
            }

        private void link_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            if (e.PropertyName == "EndItem")
            {
            }
            
        }

To reproduce: please run the sample project and follow the steps illustrated in the attached gif file. This shows how I’m attempting to add children to a root task. Upon adding a child task I am unable to scroll down to see the rest of the pre-existent root tasks until I first collapse and expand any visible root or child task.

Workaround:

        public RadForm2()
        {
            InitializeComponent();

            this.radGanttView1.ItemAdded += radGanttView1_ItemAdded;  
        }
       
        private void radGanttView1_ItemAdded(object sender, Telerik.WinControls.UI.GanttViewItemAddedEventArgs e)
        {
            item = e.Item;
        }

        GanttViewDataItem item;
        
        private void radButton1_Click(object sender, EventArgs e)
        {
            this.radGanttView1.GanttViewElement.InvalidateMeasure(true);
            this.radGanttView1.GanttViewElement.UpdateLayout();

            this.radGanttView1.GanttViewElement.GraphicalViewElement.Scroller.ScrollToItem(item);
        }

To reproduce: run the sample project and try to move a task.

Workaround:

 Timer timer = new Timer();

        private void DragDropService_Stopped(object sender, EventArgs e)
        {
            timer = new Timer();
            timer.Interval = 300;
            timer.Tick += timer_Tick;
            
        }

        private void timer_Tick(object sender, EventArgs e)
        {
            timer.Stop();
            data.Tables["Tasks"].Clear();
        }

Workaround 2:

        private void radGanttView1_ItemElementCreating(object sender, Telerik.WinControls.UI.GanttViewItemElementCreatingEventArgs e)
        {
            if (e.Item.Items.Count == 0 && e.ViewElement is GanttViewGraphicalViewElement)
            {
                e.ItemElement = new MyGanttViewTaskItemElement(e.ViewElement as GanttViewGraphicalViewElement); 
            }
        }

        public class MyGanttViewTaskItemElement : GanttViewTaskItemElement
        {
            public MyGanttViewTaskItemElement(GanttViewGraphicalViewElement ganttViewBaseViewElement) : base(ganttViewBaseViewElement)
            {
            }
            
            protected override Type ThemeEffectiveType
            {
                get
                {
                    return typeof(GanttViewTaskItemElement);
                }
            }

            public override void Detach()
            {
                var obj = this.Data;
                this.Data.SuspendPropertyNotifications();
                base.Detach();
                obj.ResumePropertyNotifications(); 
            }

            public override void Synchronize()
            {
                DataSet ds = this.Data.GanttViewElement.DataSource as DataSet;
                if (ds != null && this.Data != null)
                {
                    DataRowView rowView = this.Data.DataBoundItem as DataRowView;
                    if (rowView != null && !RowExists(rowView.Row))//!ds.Tables[0].Rows.Contains(rowView.Row))
                    {
                        return;
                    }
                }
                base.Synchronize();
            }

            private bool RowExists(DataRow dataRow)
            {
                DataSet ds = this.Data.GanttViewElement.DataSource as DataSet;
                bool res = false;
                foreach (DataRow r in ds.Tables[0].Rows)
                {
                    if (r.Equals(dataRow))
                    {
                        return true;
                    }
                }
                return res;
            }
        }

To reproduce:
1) Open the Demo application >> Settings example.
2) Select a task and activate the editor for it.
3) Delete the task by clicking the button above.

It may be necessary to repeat the steps several times. The error is not reproduced immediately. 

To reproduce:
- Set the range to lest than one day.
- Set the TimelineRange to DayHalfHours

Workaround: 
Make sure that the range is at least one day. 

Even though you can't  modify the tasks you can see the link handles which are usually used for linking different tasks. They shouldn't be displayed when the RadGanttView is in read-only mode.

Workaround: handle the GraphicalViewItemFormatting event and manually hide the link handles: 

        private void radGanttView1_GraphicalViewItemFormatting(object sender, GanttViewGraphicalViewItemFormattingEventArgs e)
        {
            GanttGraphicalViewBaseItemElement itemElement = e.ItemElement as GanttGraphicalViewBaseItemElement;
            if (itemElement != null)
            {
                Console.WriteLine(itemElement.LeftLinkHandleElement.Visibility);
                itemElement.LeftLinkHandleElement.Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
                itemElement.LeftLinkHandleElement.PropertyChanged -= LeftLinkHandleElement_PropertyChanged;
                itemElement.LeftLinkHandleElement.PropertyChanged += LeftLinkHandleElement_PropertyChanged;
                itemElement.RightLinkHandleElement.Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
                itemElement.RightLinkHandleElement.PropertyChanged -= LeftLinkHandleElement_PropertyChanged;
                itemElement.RightLinkHandleElement.PropertyChanged += LeftLinkHandleElement_PropertyChanged;
            }
        }

        private void LeftLinkHandleElement_PropertyChanged(object sender, PropertyChangedEventArgs e)
        {
            GanttViewTaskLinkHandleElement linkHanle = sender as GanttViewTaskLinkHandleElement;
            if (e.PropertyName == "Visibility" && linkHanle.Visibility == Telerik.WinControls.ElementVisibility.Visible)
            {
                linkHanle.Visibility = Telerik.WinControls.ElementVisibility.Collapsed;
            }
        }

The spin editor has a default minimum and maximum (0,100)

Workaround:
private void GanttViewElement_EditorInitialized(object sender, GanttViewItemEditorInitializedEventArgs e)
{
    var editor = e.Editor as BaseSpinEditor;
    if (editor != null)
    {
        editor.MaxValue = int.MaxValue;
        var value = e.Item[radGanttView1.CurrentColumn];
        editor.Value = value;
    }
}

To reproduce: have a look at the attached gif file and sample project.

Workaround:

            this.radGanttView1.CursorChanged += radGanttView1_CursorChanged;
            this.radGanttView1.MouseMove += radGanttView1_MouseMove;

        private void radGanttView1_MouseMove(object sender, MouseEventArgs e)
        {
            GanttViewGraphicalViewElement view = this.radGanttView1.ElementTree.GetElementAtPoint(e.Location).FindAncestor<GanttViewGraphicalViewElement>();
            Console.WriteLine(this.radGanttView1.ElementTree.GetElementAtPoint(e.Location));
            if (view != null)
                isOverGraphicalView = true;
            else
                isOverGraphicalView = false;
        }

        bool isOverGraphicalView = false;

        private void radGanttView1_CursorChanged(object sender, EventArgs e)
        {
            if (isOverGraphicalView)
            {
                this.radGanttView1.CursorChanged -= radGanttView1_CursorChanged;
                this.radGanttView1.Cursor = Cursors.Default;
                this.radGanttView1.CursorChanged += radGanttView1_CursorChanged;
            }
        }