How to achieve smooth drawing with C# (like Paint .NET)?

Question

How Paint .NET can draw so fast using C#? Sample: The ellipse perimeter is drawn while the mouse is being dragged without any visible delay. At a simple windows form application in C# If you use the MouseMove event of a Picturebox and draw an ellipse based on the mouse position, there will be a lot of delay and flickering! So, how they do it so smoothly?

Great question - probably doesn't belong on S.O., but still a great question. — Nick Vaccaro, Feb 07 '12 at 17:38
http://blogs.msdn.com/b/directx/archive/2009/08/14/paint-net-uses-directwrite.aspx — ken2k, Feb 07 '12 at 17:40
Here is the link to an answer that has tips from the author of Paint.NET https://stackoverflow.com/a/11025428/11425141 — Phillip, Sep 23 '19 at 22:59

score 4 · Answer 1 · answered Feb 07 '12 at 17:34

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I have no special knowledge of the Paint.Net code, but most likely it's using Double Buffering, and probably implemented by hand on a custom drawing surface rather than the simplistic implementation in the pre-packaged controls.

answered Feb 07 '12 at 17:34

Joel Coehoorn

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Thanks. I will search for some DB sample to see if it really improves the drawing. – Pedro77 Feb 07 '12 at 18:56

score 4 · Answer 2 · answered Mar 22 '12 at 17:09

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Paint.NET calls Update() after calling Invalidate() which forces an immediate, synchronous WM_PAINT.

answered Mar 22 '12 at 17:09

Rick Brewster

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To elaborate on the lower-level details: `Invalidate()` in WinForms calls into the native `InvalidateRect()` function. `Update()` calls the native `UpdateWindow()`. `Refresh()` is the same as calling `Invalidate(true)` followed by `Update()`. – Rick Brewster Dec 15 '15 at 19:25

score 2 · Answer 3 · answered Feb 07 '12 at 17:38

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To get smooth drawing you should:

Use Double Buffering (http://msdn.microsoft.com/en-us/library/b367a457.aspx)
Use a dedicated toolkit for rendering (OpenGL/DirectDraw etc)

The best way to go in this case is with Double Buffering - it's supported 'out of the box' in the .NET framework, requires very little work, and will eliminate flickering.

answered Feb 07 '12 at 17:38

Dave Kerr

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I think double buffering wont fix the delay problem that is more cleary noted when the mouse is moved faster and a gap start to appear betwen its position and the ellipse being drawn. – Pedro77 Feb 07 '12 at 18:53

score 0 · Accepted Answer · answered Feb 15 '12 at 17:26

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They probably use WPF. It is much much faster than forms.

answered Feb 15 '12 at 17:26

Pedro77

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How to achieve smooth drawing with C# (like Paint .NET)?

4 Answers4