C #, WinForms. How to implement changing brush thickness on pictureBox?

Код отрисовки линии ниже

if (drawing) {
if (tool == 1) {
currentLayer->drawLine(Pens::Black, xPrev, yPrev, x, y);
pictureBox1->Invalidate();

xPrev = x;
yPrev = y;
}
}

Code

if (drawing) {

            if (tool == 1) {               

                currentLayer->drawLine(Pens::Black, xPrev, yPrev, x, y);

                pictureBox1->Invalidate();



                xPrev = x;

                yPrev = y;

            }

        }