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I'm using WinForms and C#.

The application I am developing draws rows of rectangles (using g.DrawRectangle()) inside of a panel. The panel can hold 6 rectangles in width (I don't want to have horizontal scrolling). I control this within the application by counting the rectangles in the row, and then adding to the y value after the sixth rectangle.

Vertically, I want to be able to add infinite rectangles and scroll down to see them. Right now, the rectangles are being added, but the Panel doesn't scroll (they are just added off screen).

Is there a way to add a vertical scrollbar? I have tried setting the AutoScroll property to true, but that doesn't do anything.

Logan Serman
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  • surprising. AutoScroll normally does that for me. I suspect it's because you are not adding controls.. – nawfal Jun 27 '12 at 23:31
  • Hmm. Maybe I can do something hacky, and add some invisible control to the panel every time I detect the rectangles overflowing the bottom of the panel? – Logan Serman Jun 27 '12 at 23:36
  • you could but very very bad way of doing it. Drawing a custom scrollbar will be difficult. Just see if the issue is with not having controls in panel and confirm. – nawfal Jun 27 '12 at 23:43
  • Hm. What I did was put the Panel inside of a TabControl and then set the TabPage AutoScroll property to true. This allowed me to scroll through the panel, but it seems like every time I scroll, the area of the panel outside of my current view gets erased. Is there a way to persist the drawn objects even when they are off-screen? Also, the objects that are originally off-screen (when the Panel is in it's starting position) are never drawn. – Logan Serman Jun 28 '12 at 00:03

1 Answers1

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The problem is that you are using graphics to draw on the panel. These are not controls, so they don't cause the panel to grow. you should create two panels - PanelA contains PanelB. PanelA has AutoScroll=true, but you draw on PanelB. As you draw, you also set the height of PanelB, so that when it gets bigger than PanelA, PanelA gets a scroll bar.

Michael
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