VisualStyleRenderer.GetBackgroundRegion(IDeviceContext, Rectangle) Metode

Definisi

Ruang nama:

System.Windows.Forms.VisualStyles

Rakitan:

System.Windows.Forms.dll

Sumber:

VisualStyleRenderer.cs

Mengembalikan wilayah untuk latar belakang elemen gaya visual saat ini.

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

Parameter

dc

IDeviceContext

Operasi IDeviceContext ini akan menggunakan.

bounds

Rectangle

Rectangle yang berisi seluruh area latar belakang elemen gaya visual saat ini.

Mengembalikan

Region

Region yang berisi latar belakang elemen gaya visual saat ini.

Pengecualian

ArgumentNullException

dc adalah null.

Contoh

Contoh kode berikut menunjukkan cara menggunakan GetBackgroundRegion metode dalam kontrol kustom. Contoh ini menggunakan GetBackgroundRegion untuk mendapatkan Region elemen bilah judul jendela yang dikembalikan oleh VisualStyleElement.Window.Caption.Active properti . Ini Region digunakan untuk mengatur Control.Region properti kontrol, sehingga bilah judul jendela akan muncul dengan sudut bulat yang ditentukan oleh gaya visual Windows XP standar. Contoh kode ini adalah bagian dari contoh yang lebih besar yang disediakan untuk VisualStyleRenderer gambaran umum kelas.

    // 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

Keterangan

Metode ini dapat digunakan untuk mendapatkan Region elemen gaya visual yang memiliki bagian transparan sebagian atau alpha-blended di latar belakangnya.