ListView.DrawSubItem 事件

  • 參考

定義

命名空間:
System.Windows.Forms
組件:
System.Windows.Forms.dll

當已繪製 ListView 的詳細資料檢視而且 OwnerDraw 屬性設定為 true 時發生。

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

事件類型

DrawListViewSubItemEventHandler

範例

下列程式碼範例提供事件處理常式的實作 DrawSubItem 。 如需完整的範例，請參閱 OwnerDraw 參考主題。

// 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

備註

此事件可讓您使用擁有者繪圖自訂控制項的外觀 ListView 。 只有當 屬性設定為 true 且 View 屬性設定為 View.Details 時 OwnerDraw ，才會引發這個屬性。 如需擁有者繪圖的詳細資訊，請參閱 OwnerDraw 屬性參考主題。

注意

子專案資訊通常會出現在磚檢視和詳細資料檢視中，但在磚檢視中，它必須繪製在 事件的處理常式中 DrawItem 。

每個 ListView 子專案都可以發生此 DrawSubItem 事件。 您可以處理 DrawItem 事件來繪製所有子專案通用的專案，例如背景，並處理 DrawSubItem 事件來繪製個別子專案的元素，例如文字值。 您也可以只使用兩個事件之一來繪製 控制項中的所有 ListView 專案，但這可能較不方便。 若要在詳細資料檢視中繪製資料行標頭，您必須處理 DrawColumnHeader 事件。

注意

未將物件新增至 Columns 集合的任何子專案 ColumnHeader 都不會發生此 DrawSubItem 事件。 另請注意，每個 ListViewItem 物件的第一個子專案代表父專案本身，並顯示在第一個資料行中。

如需處理事件的詳細資訊，請參閱 處理和引發事件。

適用於

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