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ListBox::IndexFromPoint Method (Point)

Returns the zero-based index of the item at the specified coordinates.

Namespace:  System.Windows.Forms
Assembly:  System.Windows.Forms (in System.Windows.Forms.dll)

public:
int IndexFromPoint(
	Point p
)

Parameters

p
Type: System.Drawing::Point

A Point object containing the coordinates used to obtain the item index.

Return Value

Type: System::Int32
The zero-based index of the item found at the specified coordinates; returns ListBox.NoMatches if no match is found.

This method enables you to determine which item is located at a specific location within the control. You can use this method to determine which item within the list is selected when a user right-clicks the ListBox. The location of the cursor can be determined and passed to the p parameter of the IndexFromPoint method to determine which item the user right-clicked the mouse over. You can then display a shortcut menu to the user to provide tasks and features based on the specific item.

The following code example demonstrates how to perform drag-and-drop operations using a ListBox control that contains items to drop into a RichTextBox control. The constructor of the form sets the AllowDrop property to true to enable drag-and-drop operations to occur in the RichTextBox. The example uses the MouseDown event of the ListBox to start the drag operation by calling the DoDragDrop method. The example uses the DragEnter event to determine if an item being dragged into the RichTextBox is a valid data type. The DragDrop event performs the actual dropping of a dragged item into the RichTextBox control at the current cursor location within the RichTextBox. This example requires that the DragDrop and DragEnter events have been connected to the event handlers defined in the example.

public:
   Form1()
   {
      InitializeComponent();

      // Sets the control to allow drops, and then adds the necessary event handlers. 
      this->richTextBox1->AllowDrop = true;
   }

private:
   void listBox1_MouseDown( Object^ sender, System::Windows::Forms::MouseEventArgs^ e )
   {
      // Determines which item was selected.
      ListBox^ lb = (dynamic_cast<ListBox^>(sender));
      Point pt = Point(e->X,e->Y);

      //Retrieve the item at the specified location within the ListBox. 
      int index = lb->IndexFromPoint( pt );

      // Starts a drag-and-drop operation. 
      if ( index >= 0 )
      {
         // Retrieve the selected item text to drag into the RichTextBox.
         lb->DoDragDrop( lb->Items[ index ]->ToString(), DragDropEffects::Copy );
      }
   }

   void richTextBox1_DragEnter( Object^ /*sender*/, DragEventArgs^ e )
   {
      // If the data is text, copy the data to the RichTextBox control. 
      if ( e->Data->GetDataPresent( "Text" ) )
            e->Effect = DragDropEffects::Copy;
   }

   void richTextBox1_DragDrop( Object^ /*sender*/, DragEventArgs^ e )
   {
      // Paste the text into the RichTextBox where at selection location.
      richTextBox1->SelectedText = e->Data->GetData( "System.String", true )->ToString();
   }

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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