c# Winforms - Graphics/GDI pen color stuck as black -

update: code has been updated , seems working pretty well. feel free comment.

so have program takes screenshot , lets user draw on screen. similar snipping tool has different purpose irrelevant this.

i @ page: link here , interested in how works. able adapt program color work right. reason, draws in black!!!

here have:

public partial class drawtool : form {     private bool is_mouse_down { get; set; } // check if mouse down or not.      list<list<point>> list_points = new list<list<point>>();     private int count { get; set; }     private bool start { get; set; }      public drawtool()     {         initializecomponent();          picturebox1.dock = dockstyle.fill;          picturebox1.mousedown += picturebox1_mousedown;         picturebox1.mouseup += picturebox1_mouseup;         picturebox1.mousemove += picturebox1_mousemove;         picturebox1.paint += picturebox1_onpaint;     }      [dllimport("gdi32.dll")]     static extern int setrop2(intptr hdc, int fndrawmode);      [dllimport("gdi32.dll")]     static extern intptr createpen(int fnpenstyle, int nwidth, uint crcolor);      [dllimport("gdi32.dll")]     static extern intptr selectobject(intptr hdc, intptr hgdiobj);      [dllimport("gdi32.dll")]     static extern bool deleteobject(intptr hobject);      [dllimport("gdi32.dll")]     static extern bool movetoex(intptr hdc, int x, int y, intptr lppoint);      [dllimport("gdi32.dll")]     static extern bool lineto(intptr hdc, int nxend, int nyend);      private const int ps_solid = 0;     private const int r2_maskpen = 9;     private const int r2_copypen = 13;      list<point> points = new list<point>();      private void drawhighlight(graphics g, point[] usepoints, int brushsize, color brushcolor)     {         int usecolor = system.drawing.colortranslator.towin32(brushcolor);         intptr pen = createpen(ps_solid, brushsize, (uint)usecolor);         intptr hdc = g.gethdc();         intptr xdc = selectobject(hdc, pen);         setrop2(hdc, r2_maskpen);         (int = 1; <= usepoints.length - 1; i++)         {             point p1 = usepoints[i - 1];             point p2 = usepoints[i];             movetoex(hdc, p1.x, p1.y, intptr.zero);             lineto(hdc, p2.x, p2.y);         }         setrop2(hdc, r2_copypen);         selectobject(hdc, xdc);         deleteobject(pen);         g.releasehdc(hdc);     }      private void picturebox1_onpaint(object sender, painteventargs e)     {         if (start)         {             base.onpaint(e);              (int = 0; < list_points.count; i++)             {                 drawhighlight(e.graphics, list_points[i].toarray(), 16, color.red);             }         }     }      private void picturebox1_mousedown(object sender, mouseeventargs e)     {         list_points.add(new list<point>());          start = true;          is_mouse_down = true;     }      private void picturebox1_mouseup(object sender, mouseeventargs e)     {         count = count + 1;          is_mouse_down = false;     }      private void picturebox1_mousemove(object sender, mouseeventargs e)     {         if (is_mouse_down == true) // check see if mouse button down while moving on form.         {             list_points[count].add(new point(e.x, e.y));             picturebox1.invalidate();         }     } 

to answer question why not using graphics.drawline() , have add photo:

as can see...it weird jagged lines.