自定义控件中的绘制和无效机制
我正在创建的自定义控件需要在其客户端空间中绘制许多“项目”。对 Invalidate() 的调用将触发一个新的绘制周期，其中所有项目都将被重新绘制。
现在，当控件内有很多项目并且发生大量导航时，就需要进行优化；所以我需要触发一个绘制周期，其中只绘制一个或两个项目。我存储对这些项目的引用，以便绘制方法 (OnPaint) 知道它是“快速”的。
困难在于，当执行 OnPaint 时，很难知道是否同时进行了其他 Invalidate() 调用。在这种情况下，它应该进行“正常”的完整油漆。
我确实使用了剪辑矩形。当然，我可以检查 OnPaint 中的剪辑矩形是否已成为整个客户端矩形，这是调用 Invalidate() 的标志，但这并不是 100% 安全。我想到了其他类似的解决方案，但它们看起来很古怪。
这个问题通常或最好的解决方法是什么？
A custom control I am creating needs to draw many "items" in its client space. A call to Invalidate() would trigger a new paint cycle wherein all items would be redrawn.
Now when there are many items and a lot of navigation happens within the control, things need to be optimized; so I need to trigger a paint cycle where only one or two items are drawn. I store references to these items so that the paint method (OnPaint) knows it's a "quicky".
The difficulty is that when OnPaint is executed, it is hard to know if other Invalidate() calls have been made in the meantime. In that case it should do a "normal", complete paint.
I do make use of the clip rectangle. Of course I could check if the clip rectangle in OnPaint has become the whole of the client rectangle, a sign that Invalidate() was called, but this is not 100% safe. I thought of other similar solutions but they seem hacky.
What is the way this problem is usually, or best, solved?
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这里的解决方案是使用 BufferedGraphics 类的双缓冲方法。这样，您的 OnPaint 中就不会出现太多棘手的事情，并且您可以随时随地进行绘画。
MSDN：双缓冲图形（在“手动管理缓冲图形”下）
如下一个有用的例子：
C# 中的自定义绘图控件 – 手动双缓冲
The solution here would be to employ a double buffering approach with the BufferedGraphics class. This way you won't have so much tricky stuff going on in your OnPaint and you'll be able to paint whenever, whatever.
MSDN: Double Buffered Graphics (under "Manually Managing Buffered Graphics")
Here's a useful example:
Custom Drawing Controls in C# – Manual Double Buffering