C #: ¿Es necesario disponer de un elemento gráfico dentro de un control personalizado?

Question

Nov 30, 2010, 05:41 PM

C #: ¿Es necesario disponer de un elemento gráfico dentro de un control personalizado?

He creado un control personalizado, anulado su evento de pintura. Cuando intento deshacerme de los gráficos que creo, simplemente desaparecen de la pantalla. ¿No necesito usar dispose en controles personalizados?

EDITAR: he incluido un fragmento de código. ¿Por qué no puedo deshacerme del objeto de gráficos de CC, creado a partir de PaintEventArgs? ¿Necesito deshacerme de él?

class canvas : Control
    {

        PointF mouseDown;

        float newX;
        float newY;
        float zoomFactor = 1F;

        Graphics _dc;

        public canvas()
        {
            this.DoubleBuffered = true;
            mouseDown = new PointF(0F, 0F);
            this.Paint += new PaintEventHandler(ctrl_Paint);
        }

        private void ctrl_Paint(object sender, PaintEventArgs e)
        {


            Graphics dc = e.Graphics;
            _dc = dc;

            dc.SmoothingMode = SmoothingMode.AntiAlias;

            Color gridColor = Color.FromArgb(230, 230, 230);
            Pen gridPen = new Pen(gridColor, 1);

            float offX = (float)((Math.Sqrt(Math.Pow(newX, 2)) % (30 * zoomFactor)));
            float offY = (float)((Math.Sqrt(Math.Pow(newY, 2)) % (30 * zoomFactor)));

            for (float y = offY; y < this.Height; y = y + 30 * zoomFactor)
            {
                dc.DrawLine(gridPen, 0, y, this.Width, y);
            }
            for (float x = offX; x < this.Width; x = x + 30 * zoomFactor)
            {
                dc.DrawLine(gridPen, x, 0, x, this.Height);
            }

            dc.TranslateTransform(newX, newY);
            dc.ScaleTransform(zoomFactor, zoomFactor, MatrixOrder.Prepend);

            float XPosition = 10;
            float YPosition = 10;
            float CornerRadius = 5;
            float Width = 50;
            float Height = 50;

            Color BoxColor = Color.FromArgb(0, 0, 0);
            Pen BoxPen = new Pen(BoxColor, 2);

            GraphicsPath Path = new GraphicsPath();

            Path.AddLine(XPosition + CornerRadius, YPosition, XPosition + Width - (CornerRadius * 2), YPosition);
            Path.AddArc(XPosition + Width - (CornerRadius * 2), YPosition, CornerRadius * 2, CornerRadius * 2, 270, 90);
            Path.AddLine(XPosition + Width, YPosition + CornerRadius, XPosition + Width, YPosition + Height - (CornerRadius * 2));
            Path.AddArc(XPosition + Width - (CornerRadius * 2), YPosition + Height - (CornerRadius * 2), CornerRadius * 2, CornerRadius * 2, 0, 90);
            Path.AddLine(XPosition + Width - (CornerRadius * 2), YPosition + Height, XPosition + CornerRadius, YPosition + Height);
            Path.AddArc(XPosition, YPosition + Height - (CornerRadius * 2), CornerRadius * 2, CornerRadius * 2, 90, 90);
            Path.AddLine(XPosition, YPosition + Height - (CornerRadius * 2), XPosition, YPosition + CornerRadius);
            Path.AddArc(XPosition, YPosition, CornerRadius * 2, CornerRadius * 2, 180, 90);

            Path.CloseFigure();

            dc.DrawPath(BoxPen, Path);

            LinearGradientBrush lgb = new LinearGradientBrush(new PointF(XPosition + (Width / 2), YPosition), new PointF(XPosition + (Width / 2), YPosition + Height), Color.RosyBrown, Color.Red);

            dc.FillPath(lgb, Path);

        }
}