VisualStyleRenderer.GetBackgroundRegion(IDeviceContext, Rectangle) Método

Definição

Espaço de Nomes:

System.Windows.Forms.VisualStyles

Assemblagem:

System.Windows.Forms.dll

Devolve a região para o fundo do elemento visual atual.

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

Parâmetros

dc

IDeviceContext

Esta IDeviceContext operação irá usar.

bounds

Rectangle

A Rectangle que contém toda a área de fundo do elemento visual atual.

Devoluções

Region

O Region que contém o fundo do elemento visual atual.

Exceções

ArgumentNullException

dc é null.

Exemplos

O exemplo de código seguinte demonstra como usar o GetBackgroundRegion método num controlo personalizado. Este exemplo serve GetBackgroundRegion para obter Region o elemento da barra de título da janela devolvido pela VisualStyleElement.Window.Caption.Active propriedade. Este Region é usado para definir a propriedade Control.Region do controlo, de modo que a barra de título da janela apareça com os cantos arredondados definidos pelo estilo visual padrão Windows XP. Este exemplo de código faz parte de um exemplo maior fornecido para a VisualStyleRenderer visão geral da classe.

    // 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

Observações

Este método pode ser usado para obter o Region resultado de um elemento de estilo visual que tenha partes parcialmente transparentes ou com mistura alfa no fundo.