Procedura: Disegnare una forma con contornoHow to: Draw an Outlined Shape

In questo esempio disegna ellissi e rettangoli in un form.This example draws outlined ellipses and rectangles on a form.

EsempioExample

private:
    void DrawEllipse()
    {
        System::Drawing::Pen^ myPen =
            gcnew System::Drawing::Pen(System::Drawing::Color::Red);
        System::Drawing::Graphics^ formGraphics;
        formGraphics = this->CreateGraphics();
        formGraphics->DrawEllipse(myPen, Rectangle(0, 0, 200, 300));
        delete myPen;
        delete formGraphics;
    }

private:
    void DrawRectangle()
    {
        System::Drawing::Pen^ myPen =
            gcnew System::Drawing::Pen(System::Drawing::Color::Red);
        System::Drawing::Graphics^ formGraphics;
        formGraphics = this->CreateGraphics();
        formGraphics->DrawRectangle(myPen, Rectangle(0, 0, 200, 300));
        delete myPen;
        delete formGraphics;
    }

private void DrawEllipse()
{
    System.Drawing.Pen myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
    System.Drawing.Graphics formGraphics;
    formGraphics = this.CreateGraphics();
    formGraphics.DrawEllipse(myPen, new Rectangle(0, 0, 200, 300));
    myPen.Dispose();
    formGraphics.Dispose();
}

private void DrawRectangle()
{
    System.Drawing.Pen myPen = new System.Drawing.Pen(System.Drawing.Color.Red);
    System.Drawing.Graphics formGraphics;
    formGraphics = this.CreateGraphics();
    formGraphics.DrawRectangle(myPen, new Rectangle(0, 0, 200, 300));
    myPen.Dispose();
    formGraphics.Dispose();
}

Private Sub DrawEllipse()
    Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
    Dim formGraphics As System.Drawing.Graphics
    formGraphics = Me.CreateGraphics()
    formGraphics.DrawEllipse(myPen, New Rectangle(0, 0, 200, 300))
    myPen.Dispose()
    formGraphics.Dispose()
End Sub

Private Sub DrawRectangle()
    Dim myPen As New System.Drawing.Pen(System.Drawing.Color.Red)
    Dim formGraphics As System.Drawing.Graphics
    formGraphics = Me.CreateGraphics()
    formGraphics.DrawRectangle(myPen, New Rectangle(0, 0, 200, 300))
    myPen.Dispose()
    formGraphics.Dispose()
End Sub

Compilazione del codiceCompiling the Code

È possibile chiamare questo metodo nel Load gestore dell'evento.You cannot call this method in the Load event handler. Il contenuto creato non verrà ridisegnato se il form viene ridimensionato o nascosto da un altro form.The drawn content will not be redrawn if the form is resized or obscured by another form. Per rendere il contenuto viene ridisegnata automaticamente, è necessario eseguire l'override di OnPaint (metodo).To make your content automatically repaint, you should override the OnPaint method.

Programmazione efficienteRobust Programming

È sempre necessario chiamare Dispose tutti gli oggetti che utilizzano le risorse di sistema, ad esempio Pen e Graphics oggetti.You should always call Dispose on any objects that consume system resources, such as Pen and Graphics objects.

Vedere ancheSee also