ListView.DrawSubItem 事件

定义

当绘制 ListView 的详细信息视图并且 OwnerDraw 属性设置为 true 时发生。

public:
 event System::Windows::Forms::DrawListViewSubItemEventHandler ^ DrawSubItem;
public event System.Windows.Forms.DrawListViewSubItemEventHandler DrawSubItem;
public event System.Windows.Forms.DrawListViewSubItemEventHandler? DrawSubItem;
member this.DrawSubItem : System.Windows.Forms.DrawListViewSubItemEventHandler 
Public Custom Event DrawSubItem As DrawListViewSubItemEventHandler 

事件类型

示例

下面的代码示例提供了 事件处理程序的 DrawSubItem 实现。 有关完整示例,请参阅 OwnerDraw 参考主题。

// Draws subitem text and applies content-based formatting.
private void listView1_DrawSubItem(object sender,
    DrawListViewSubItemEventArgs e)
{
    TextFormatFlags flags = TextFormatFlags.Left;

    using (StringFormat sf = new StringFormat())
    {
        // Store the column text alignment, letting it default
        // to Left if it has not been set to Center or Right.
        switch (e.Header.TextAlign)
        {
            case HorizontalAlignment.Center:
                sf.Alignment = StringAlignment.Center;
                flags = TextFormatFlags.HorizontalCenter;
                break;
            case HorizontalAlignment.Right:
                sf.Alignment = StringAlignment.Far;
                flags = TextFormatFlags.Right;
                break;
        }

        // Draw the text and background for a subitem with a 
        // negative value. 
        double subItemValue;
        if (e.ColumnIndex > 0 && Double.TryParse(
            e.SubItem.Text, NumberStyles.Currency,
            NumberFormatInfo.CurrentInfo, out subItemValue) &&
            subItemValue < 0)
        {
            // Unless the item is selected, draw the standard 
            // background to make it stand out from the gradient.
            if ((e.ItemState & ListViewItemStates.Selected) == 0)
            {
                e.DrawBackground();
            }

            // Draw the subitem text in red to highlight it. 
            e.Graphics.DrawString(e.SubItem.Text,
                listView1.Font, Brushes.Red, e.Bounds, sf);

            return;
        }

        // Draw normal text for a subitem with a nonnegative 
        // or nonnumerical value.
        e.DrawText(flags);
    }
}
' Draws subitem text and applies content-based formatting.
Private Sub listView1_DrawSubItem(ByVal sender As Object, _
    ByVal e As DrawListViewSubItemEventArgs) _
    Handles listView1.DrawSubItem

    Dim flags As TextFormatFlags = TextFormatFlags.Left

    Dim sf As New StringFormat()
    Try

        ' Store the column text alignment, letting it default
        ' to Left if it has not been set to Center or Right.
        Select Case e.Header.TextAlign
            Case HorizontalAlignment.Center
                sf.Alignment = StringAlignment.Center
                flags = TextFormatFlags.HorizontalCenter
            Case HorizontalAlignment.Right
                sf.Alignment = StringAlignment.Far
                flags = TextFormatFlags.Right
        End Select

        ' Draw the text and background for a subitem with a 
        ' negative value. 
        Dim subItemValue As Double
        If e.ColumnIndex > 0 AndAlso _
            Double.TryParse(e.SubItem.Text, NumberStyles.Currency, _
            NumberFormatInfo.CurrentInfo, subItemValue) AndAlso _
            subItemValue < 0 Then

            ' Unless the item is selected, draw the standard 
            ' background to make it stand out from the gradient.
            If (e.ItemState And ListViewItemStates.Selected) = 0 Then
                e.DrawBackground()
            End If

            ' Draw the subitem text in red to highlight it. 
            e.Graphics.DrawString(e.SubItem.Text, _
                Me.listView1.Font, Brushes.Red, e.Bounds, sf)

            Return

        End If

        ' Draw normal text for a subitem with a nonnegative 
        ' or nonnumerical value.
        e.DrawText(flags)

    Finally
        sf.Dispose()
    End Try

End Sub

注解

此事件允许你使用所有者绘图自定义控件的外观 ListView 。 仅当 属性设置为 且 属性设置为 View.DetailstrueOwnerDrawView才会引发该属性。 有关所有者绘图的详细信息,请参阅 OwnerDraw 属性参考主题。

注意

子项信息通常显示在磁贴视图和详细信息视图中,但在磁贴视图中,必须在事件的处理程序 DrawItem 中绘制子项信息。

每个DrawSubItemListView子项都可能发生 该事件。 可以处理 DrawItem 事件以绘制所有子项(如背景)共有的元素,并处理 DrawSubItem 事件以绘制单个子项(如文本值)的元素。 还可以仅使用两个事件中的一个来绘制控件中的所有 ListView 项,尽管这可能不太方便。 若要在详细信息视图中绘制列标题,必须处理 事件 DrawColumnHeader

注意

对于DrawSubItem未向集合中添加Columns任何ColumnHeader对象的子项,不会发生 该事件。 另请注意,每个 ListViewItem 对象的第一个子项表示父项本身,并显示在第一列中。

有关处理事件的详细信息,请参阅 处理和引发事件

适用于

另请参阅