c# - How to draw line when mouse up? -

i trying set starting point when lmb down , draw line starting point current mouse position when lmb up, how mspaint it.

my problem can't seem line appear on picturebox when lmb up. can enlighten me please?

edit:sorry guys realised problem elsewhere, learned bunch of stuff in process, input.

public partial class formpaint : form {         point? startpoint = point.empty;     point? endpoint = point.empty;     bool ismousedown = new boolean();      private void picturebox1_mousedown(object sender, mouseeventargs e)     {         if (control.mousebuttons == mousebuttons.left)         {             startpoint = e.location;             ismousedown = true;         }     }      private void picturebox1_mouseup(object sender, mouseeventargs e)     {           brush = new solidbrush(color);          using (graphics g = graphics.fromimage(picturebox1.image))          {               g.drawline(new pen(brush), startpoint.value, endpoint.value);               picturebox1.invalidate();           }          ismousedown = false;      }     private void picturebox1_mousemove(object sender, mouseeventargs e)     {       endpoint = e.location;     }      private void picturebox1_paint(object sender, painteventargs e)     {          using (brush = new solidbrush(color))          {                e.graphics.drawline(new pen(brush, 5), startpoint.value, endpoint.value);          }     } } 

when call invalidate forces picture box repaint. problem though discards painted before. calls paint on picture box.

i suggest save drawing data list , perform painting inside paint event of picture box using saved data.

also read how draw circle , line in picturebox?