How to create a double list view

public DoubleListView(RecordIdentifier selectedId)
	: this()
{
	this.selectedId = selectedId;
}

public DoubleListView()
{
	InitializeComponent();

	Attributes = ViewAttributes.Audit |
		ViewAttributes.Close |
		ViewAttributes.ContextBar |
		ViewAttributes.Help;

	btnsTop.AddButtonEnabled = PluginEntry.DataModel.HasPermission(Permission.DoubleListViewPermission);

	lvTopObjects.ContextMenuStrip = new ContextMenuStrip();
	lvTopObjects.ContextMenuStrip.Opening += LvTopObjects_Opening;
	lvBottomObjects.ContextMenuStrip = new ContextMenuStrip();
	lvBottomObjects.ContextMenuStrip.Opening += LvBottomObjects_Opening;
}

The list view has two constructors. An empty one where no row in the top list view should have focus or one with an ID parameter that makes the row from the top list view with the selected ID have focus when the view opens.

Everything else here is the same as in chapter How to create a single list view so please take a look there to get details on the Attributes and AddButtonEnabled. The only thing different here is the fact that we are connecting functions to both the ContextMenuStrips of the list views (these are used when the user right-clicks on the list views).

protected override void LoadData(bool isRevert)
{
	LoadTopObjects();
}

private void LoadTopObjects()
{
	RecordIdentifier oldSelectedID = selectedID;
	lvTopObjects.ClearRows();

	List<TopDataObject> dataObjects = Providers.TopObjectData.GetTopList(PluginEntry.DataModel);

	foreach (TopDataObject obj in dataObjects)
	{
		Row row = new Row();
		row.AddText(obj.Text);
		row.AddText(obj.ExtraInfo);
		row.Tag = obj.ID;
		lvTopObjects.AddRow(row);
	
		if (oldSelectedID == obj.ID)
		{
			lvTopObjects.Selection.Set(lvTopObjects.RowCount - 1);
		}
	}
	
	lvTopObjects.AutoSizeColumns();
	lvTopObjects_SelectionChanged(this, EventArgs.Empty);
}

Here we are loading data into the top list view.

This function is the same as chapter How to create a single list view , so please take a look there to see details about the LoadObjects() function.

The only thing to note here is that the function lvTopObjects_SelectionChanged is responsible for showing the bottom list view. When the selection is changed in the top list, we need to populated the bottom list with the data corresponding to the selected object, or hide the bottom list if there is nothing selected in the top list.

private void LoadBottomObjects()
{
	if(lvTopObjects.Selection.Count == 0) return;
						
	lvBottomObjects.ClearRows();
	
	RecordIdentifier selectedTopObjectID = (RecordIdentifier)lvTopObjects.Selection[0].Tag;
	List<BottomDataObject> dataObjects = Providers.BottomObjectData.GetBottomList(PluginEntry.DataModel, selectedTopObjectID);

	foreach (BottomDataObject obj in dataObjects)
	{
		Row row = new Row();
		row.AddText(obj.Text);
		row.AddText(obj.SomeProperty);
		row.Tag = obj.ID;
		lvBottomObjects.AddRow(row);
	}
	
	lvBottomObjects.AutoSizeColumns();
	lvBottomObjects_SelectionChanged(this, EventArgs.Empty);
}

Here we are loading data into the bottom list view.

This function is almost identical to the LoadTopObjects() function previously covered with the exception that the data layer function requires the selection from the top list view so we get that selection in the variable selectedTopObjectID.

public override void OnDataChanged(DataEntityChangeType changeAction, 
				string objectName, 
				RecordIdentifier changeIdentifier, 
				object param)
{
	if (objectName == "dataObject")
	{
		LoadItems();
	}
}

Here we have the OnDataChanged(..) function that is used to respond to data changes in other views.

This function is the same as in chapter How to create a single list view where you can see details about the OnDataChanged(..) function.

private void lvTopObjects_SelectionChanged(object sender, EventArgs e)
{
	bool objectSelected = (lvTopObjects.Selection.Count != 0);

	RecordIdentifier selectedObjectId = objectSelected ? (RecordIdentifier)lvTopObjects.Selection[0].Tag : "";
	btnsTop.EditButtonEnabled = btnsTop.RemoveButtonEnabled = objectSelected;

	if (objectSelected)
	{
		if (!lblGroupHeader.Visible)
		{
			lblGroupHeader.Visible = true;
			lvBottomObjects.Visible = true;
			btnsBottom.Visible = true;
			lblNoSelection.Visible = false;
		}

		LoadBottomObjects();
	}
	else if (lblGroupHeader.Visible)
	{
		lblGroupHeader.Visible = false;
		lvBottomObjects.Visible = false;
		btnsBottom.Visible = false;
		lblNoSelection.Visible = true;
	}
}

private void lvBottomObjects_SelectionChanged(object sender, EventArgs e)
{
	bool objectSelected = (lvBottomObjects.Selection.Count != 0);
	btnsBottom.EditButtonEnabled = btnsBottom.RemoveButtonEnabled = objectSelected;
}

Here we have two selection-changed functions, one for each list view.

The function for the bottom list view (lvBottomObjects_SelectionChanged) is simple and just like the one for a single view. We are simply enabling or disabling the bottom Edit and Remove buttons based on if an item was selected in the list view.

The function for the top list view (LvTopObjects_SelectionChanged) is more complex. First we do the same thing as we do for the lower list view, enabling or disabling the edit and remove buttons. But then we need to manage the lower-list view. We show or hide the appropriate controls depending on if a data object was selected or not. If a data object was selected then we also load the lower list view with the function LoadBottomObjects()

private void lvTopObjects_RowDoubleClick(object sender, EventArgs e)
{
	if (btnsTop.EditButtonEnabled)
	{
		btnsTop_EditButtonClicked(this, EventArgs.Empty);
	}
}

private void lvBottomObjects_RowDoubleClick(object sender, EventArgs e)
{
	if (btnsBottom.EditButtonEnabled)
	{
		btnsBottom_EditButtonClicked(this, EventArgs.Empty);
	}
}

These two functions deal with double clicks on both the list views. In both functions we check if the edit button below the list view is enabled (if it is disabled then the user did not double click a data row) and if it is then we run the operation behind the edit button.

void LvTopObjects_Opening(object sender, CancelEventArgs e)
{
	ContextMenuStrip menu = lvTopObjects.ContextMenuStrip;
	menu.Items.Clear();
	
	var item = new ExtendedMenuItem(
		Properties.Resources.Edit,
		100,
		btnsTop_EditButtonClicked);
	item.Image = btnsTop.EditButtonImage;
	item.Enabled = btnsTop.EditButtonEnabled;
	item.Default = true; // The default item has a bold font
	menu.Items.Add(item);
	
	item = new ExtendedMenuItem(
		Properties.Resources.Add,
		200,
		new EventHandler(btnsTop_AddButtonClicked));
	item.Enabled = btnsTop.AddButtonEnabled;
	item.Image = btnsTop.AddButtonImage;
	menu.Items.Add(item);
	
	item = new ExtendedMenuItem(
		Properties.Resources.Delete,
		300,
		new EventHandler(btnsTop_RemoveButtonClicked));
	item.Image = btnsTop.RemoveButtonImage;
	item.Enabled = btnsTop.RemoveButtonEnabled;
	menu.Items.Add(item);
	
	e.Cancel = (menu.Items.Count == 0);
}

This function deals with right-clicking the list view. They are covered in more detail in chapter How to create a single list view , but the most important part is that these functions are rarely changed. For the bottom list view a similar function can be used with the appropriate buttons and event handlers. For each list, buttons can be added or removed from the drop down.

private void btnsTop_EditButtonClicked(object sender, EventArgs e)
{
	RecordIdentifier selectedId = (RecordIdentifier)lvTopObjects.Selection[0].Tag;
	PluginOperations.ShowTopObjectView(selectedId);
}

private void btnsTop_AddButtonClicked(object sender, EventArgs e)
{
	var dlg = new Dialogs.TopObjectDialog();
	if (dlg.ShowDialog() == DialogResult.OK)
	{
		LoadTopObjects();
	}          
}

private void btnsTop_RemoveButtonClicked(object sender, EventArgs e)
{
	if (QuestionDialog.Show(
	Properties.Resources.DeleteTopObjectQuestion,
	Properties.Resources.DeleteTopObject) == DialogResult.Yes)
	{
		RecordIdentifier selectedId = (RecordIdentifier)lvTopObjects.Selection[0].Tag;
		PluginProviders.TopObjectData.Delete(PluginEntry.DataModel, selectedId);
		LoadTopObjects();
	}
}

Here we have three functions for the three buttons below the top list view. These are the same buttons that we have in chapter How to create a single list view , where they are covered in more detail.

private void btnsBottom_EditButtonClicked(object sender, EventArgs e)
{
	RecordIdentifier selectedTopId = (RecordIdentifier)lvTopObjects.Selection[0].Tag;
	RecordIdentifier selectedBottomId = (RecordIdentifier)lvBottomObjects.Selection[0].Tag;
	var dlg = new Dialogs.BottomObjectDialog(selectedTopId, selectedBottomId);
	if (dlg.ShowDialog() == DialogResult.OK)
	{
		LoadBottomObjects();
	}   
}

private void btnsBottom_AddButtonClicked(object sender, EventArgs e)
{
	RecordIdentifier selectedTopId = (RecordIdentifier)lvTopObjects.Selection[0].Tag;
	var dlg = new Dialogs.BottomObjectDialog(selectedTopId);
	if (dlg.ShowDialog() == DialogResult.OK)
	{
		LoadBottomObjects();
	}          
}

private void btnsBottom_RemoveButtonClicked(object sender, EventArgs e)
{
	if (QuestionDialog.Show(
	Properties.Resources.DeleteBottomObjectQuestion,
	Properties.Resources.DeleteBottomObject) == DialogResult.Yes)
	{
		RecordIdentifier selectedId = (RecordIdentifier)lvBottomObjects.Selection[0].Tag;
		PluginProviders.BottomObjectData.Delete(PluginEntry.DataModel, selectedId);
		LoadBottomObjects();
	}
}

Here we have three functions for the three buttons below the bottom list view. These are very similar to the buttons for the top list view. The difference here is that we need to access the bottom list view to get the ID of the selected item. Another difference is that when editing an item we use the same dialog that we use when adding an item. We only use a different constructor for Add and Edit.