c# - Panel DoubleBuffered property stopped the drawing, is invisible -

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i have component, inherited panel, overriding onpaint event draw graph 500 points. since need selection on graph, flickering. have found doublebuffered property when set true, in panel constructor, drawing disappears. debug , see drawing methods still execute there nothing on panel. know why happen?

this .net 3.5 - c#. winforms application

        try         {             graphics g = e.graphics;              //draw _grapharea:             g.drawrectangle(pens.black, _grapharea);              _drawingobjectlist.drawgraph(g, _mainlinepen, _difflinepen, _dotpen, _dotbrush, _notselectedbrush, _selectedbrush);              drawselectionrectangle(g);              g.dispose();         }         catch (exception ex)         {             messagebox.show(ex.message);         }

panel descendant constructor:

        this.backcolor = color.white;         this.setstyle(controlstyles.resizeredraw, true);         this.setstyle(controlstyles.userpaint, true);         this.setstyle(controlstyles.allpaintinginwmpaint, true);         this.setstyle(controlstyles.optimizeddoublebuffer, true);         this.updatestyles();

try using controlstyles.optimizeddoublebuffered instead. it's faster , works better. make sure controlstyles.allpaintinginwmpaint , controlstyles.userpaint enabled.

now, onpaint() should stuff draw window , method must called invalidation or using refresh(); must never call onpaint() yourself. not dispose graphics object. if fail of conditions, flickering , various other drawing bugs might occur.

class mycontrol : usercontrol {     public mycontrol()     {         setstyle(controlstyles.allpaintinginwmpaint, true);         setstyle(controlstyles.userpaint, true);         setstyle(controlstyles.optimizeddoublebuffer, true);     }      protected override void  onpaint(painteventargs e)     {         e.graphics.clear(color.red);     }      void randomeventthatrequiresrefresh(object sender, eventargs e)     {         refresh();     } }

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