Hit Information

Apr 01, 2021
2 minutes to read

Hit testing allows you to recognize which element is located at the specified screen coordinates. For instance, you may have to determine which part of a View a user has clicked or double-clicked. To obtain this information, use the TableView.CalcHitInfo method (CardView.CalcHitInfo in a card view, TreeListView.CalcHitInfo in a treelist view). This method accepts a test dependency object and returns the hit info object, containing information about the test object’s position within a view.

Each type of View provides its own hit info object (see the table below):

Hit Info Object	Description
GridViewHitInfoBase	Serves as the base for classes providing information about a specific object within a View.
TableViewHitInfo	Contains the information about a specific object within a table view.
CardViewHitInfo	Contains the information about a specific object within a card view.
TreeListViewHitInfo	Contains the information about a specific object within a treelist view.

Properties provided by hit info objects allow you to obtain:

A view element located under the test object (column header, expand button, scrollbar, filter panel, etc.). Use the TableViewHitInfo.HitTest property (CardViewHitInfo.HitTest in a card view).
A view element to which the test object belongs (e.g. a row, column, group panel). Some visual elements can contain other visual elements. For example, the Filter Panel displays the filter expression, filter and close buttons. Use the following properties: GridViewHitInfoBase.InRow, TableViewHitInfo.InRowCell, GridViewHitInfoBase.InGroupPanel, GridViewHitInfoBase.InFilterPanel, GridViewHitInfoBase.InColumnHeader, etc.
A row and column located under the test object. Use the GridViewHitInfoBase.RowHandle and GridViewHitInfoBase.Column properties.

To get Hit-Test information of a detail grid, call master grid methods.

Example

This example shows how to determine which element in a table view is located under the mouse pointer.

C#
VB.NET

csharp

private void grid_MouseMove(object sender, MouseEventArgs e) {
    TableViewHitInfo hi =
        ((TableView)grid.View).CalcHitInfo(e.OriginalSource as DependencyObject);
    textBlock.Text = hi.HitTest.ToString();
}

Private Sub gridControl1_MouseMove(ByVal sender As Object, ByVal e As MouseEventArgs)
    Dim hi As TableViewHitInfo = CType(gridControl1.View, TableView).CalcHitInfo(TryCast(e.OriginalSource, DependencyObject))
    textBlock.Text = hi.HitTest.ToString()
End Sub