VisualStyleRenderer.GetBackgroundRegion(IDeviceContext, Rectangle) 方法

定義

命名空間:

System.Windows.Forms.VisualStyles

組件:

System.Windows.Forms.dll

來源:

VisualStyleRenderer.cs

回傳當前視覺風格元素背景的區域。

public:
 System::Drawing::Region ^ GetBackgroundRegion(System::Drawing::IDeviceContext ^ dc, System::Drawing::Rectangle bounds);

public System.Drawing.Region? GetBackgroundRegion(System.Drawing.IDeviceContext dc, System.Drawing.Rectangle bounds);

member this.GetBackgroundRegion : System.Drawing.IDeviceContext * System.Drawing.Rectangle -> System.Drawing.Region

Public Function GetBackgroundRegion (dc As IDeviceContext, bounds As Rectangle) As Region

參數

dc

IDeviceContext

IDeviceContext這次行動將使用。

bounds

Rectangle

Rectangle A 包含當前視覺風格元素的整個背景區域。

傳回

Region

那 Region 個包含當前視覺風格元素的背景。

例外狀況

ArgumentNullException

dc 為 null。

範例

以下程式碼範例示範如何在自訂控制中使用此 GetBackgroundRegion 方法。 此範例使用 GetBackgroundRegion 以取得 Region 由屬性回傳 VisualStyleElement.Window.Caption.Active 的視窗標題列元素。 此用 Region 來設定 Control.Region 控制項的屬性，使視窗標題列呈現出符合標準 Windows XP 視覺風格定義的圓角。 這個程式碼範例是為類別概述提供 VisualStyleRenderer 的完整範例的一部分。

    // Calculate and set the clipping region for the control
    // so that the corners of the title bar are rounded.
private:
    void SetClipRegion()
    {
        if (!Application::RenderWithVisualStyles)
        {
            return;
        }

        Graphics^ g = this->CreateGraphics();
        // Get the current region for the window caption.
        if (SetRenderer(windowElements["windowCaption"]))
        {
            System::Drawing::Region^ clipRegion =
                renderer->GetBackgroundRegion(g,
                elementRectangles["windowCaption"]);

            // Get the client rectangle, but exclude the region
            // of the window caption.
            int height = (int)clipRegion->GetBounds(g).Height;
            System::Drawing::Rectangle nonCaptionRect = Rectangle(
                ClientRectangle.X, ClientRectangle.Y + height,
                ClientRectangle.Width, ClientRectangle.Height - height);

            // Add the rectangle to the caption region, and
            // make this region the form's clipping region.
            clipRegion->Union(nonCaptionRect);
            this->Region = clipRegion;
        }

    }

// Calculate and set the clipping region for the control  
// so that the corners of the title bar are rounded.
private void SetClipRegion()
{
    if (!Application.RenderWithVisualStyles)
    {
        return;
    }

    using (Graphics g = this.CreateGraphics())
    {
        // Get the current region for the window caption.
        if (SetRenderer(windowElements["windowCaption"]))
        {
            Region clipRegion = renderer.GetBackgroundRegion(
                g, elementRectangles["windowCaption"]);

            // Get the client rectangle, but exclude the region 
            // of the window caption.
            int height = (int)clipRegion.GetBounds(g).Height;
            Rectangle nonCaptionRect = new Rectangle(
                ClientRectangle.X,
                ClientRectangle.Y + height,
                ClientRectangle.Width,
                ClientRectangle.Height - height);

            // Add the rectangle to the caption region, and  
            // make this region the form's clipping region.
            clipRegion.Union(nonCaptionRect);
            this.Region = clipRegion;
        }
    }
}

' Calculate and set the clipping region for the control  
' so that the corners of the title bar are rounded.
Private Sub SetClipRegion()
    If Not Application.RenderWithVisualStyles Then
        Return
    End If

    Using g As Graphics = Me.CreateGraphics()
        ' Get the current region for the window caption.
        If SetRenderer(windowElements("windowCaption")) Then
            Dim clipRegion As Region = _
                renderer.GetBackgroundRegion(g, _
                elementRectangles("windowCaption"))

            ' Get the client rectangle, but exclude the   
            ' region of the window caption.
            Dim height As Integer = _
                CInt(clipRegion.GetBounds(g).Height)
            Dim nonCaptionRect As _
                New Rectangle(ClientRectangle.X, _
                ClientRectangle.Y + height, _
                ClientRectangle.Width, _
                ClientRectangle.Height - height)

            ' Add the rectangle to the caption region, and  
            ' make this region the form's clipping region.
            clipRegion.Union(nonCaptionRect)
            Me.Region = clipRegion
        End If
    End Using
End Sub

備註

此方法可用於取得視覺風格元素背景中部分透明或 alpha 混合部分的 。Region