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Como desenhar uma forma contornada

  • Artigo

Este exemplo desenha elipses contornadas e retângulos em um formulário.

Exemplo

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

Compilando o código

Você não pode chamar esse método no manipulador de eventos Load. O conteúdo desenhado não será redesenhado se o formulário for redimensionado ou obscurecido por outra forma. Para reencontrar o conteúdo automaticamente, você deve substituir o método OnPaint.

Programação robusta

Você sempre deve chamar Dispose em todos os objetos criados que consomem recursos do sistema. No exemplo anterior, os objetos Pen e Graphics foram criados e descartados.

Consulte também