Question

I m drawing rectangle on mouse move in c#,

i wrote the code like this,

onmousemove:

Rectangle rect = new Rectangle(
    Math.Min(mouseMovePoint.X, mouseDownPoint.X), 
    Math.Min(mouseMovePoint.Y, mouseDownPoint.Y),
    Math.Abs(mouseMovePoint.X - mouseDownPoint.X), 
    Math.Abs(mouseMovePoint.Y - mouseDownPoint.Y)
);

    graphics.DrawRectangle(myPen, rect);

onmouseup:

this.Refresh();

Rectangle rect = new Rectangle(
    Math.Min(mouseMovePoint.X, mouseDownPoint.X), 
    Math.Min(mouseMovePoint.Y, mouseDownPoint.Y),
    Math.Abs(mouseMovePoint.X - mouseDownPoint.X), 
    Math.Abs(mouseMovePoint.Y - mouseDownPoint.Y)
);

graphics.DrawRectangle(myPen, rect);

But due to this refresh method when i draw the rectangle it appears like as if it s flickering how to avoid that?

Answer 1

Use ControlPaint.DrawReversibleFrame for drawing selection boxes, in conjunction with MouseDown, MouseMove and MouseUp events. Check this on MSDN.