Windows 7 发送不必要的 WM_PAINT 消息
我有一个关于发送到我的窗口的奇怪来源的 WM_PAINT 消息的问题。它发生在Windows 7上，但不会发生在Windows XP上。
详细信息
在我的程序中，我有一个触发 GUI 更新的计时器，该计时器基于此 API 调用：
CreateTimerQueueTimer
在系统提供的线程中处理计时器到期，我做了一些 GUI 更新，即，在窗口中画一条线 (0,0)->(57,50)：
HDC hdc = GetDC (hwnd);
MoveToEx (hdc, 0, 0, NULL);
LineTo (hdc, 57, 50);
ReleaseDC(hwnd,hdc);
在 Windows XP 上按我的预期工作，但在 Windows7 上 这使得系统向该窗口发送 WM_PAINT 消息，更新区域为：(0,0,58,51)。请注意，矩形比受线影响的正方形区域宽 1 个像素。
由于这张图而到达的 WM_PAINT 是我不明白的。窗口没有被触摸/重叠/调整大小或其他什么。显然，这条线被系统识别为矩形的无效。
这种情况仅发生在 Windows 7 中（而不是 Windows XP）。
问题
W7 中的 WDM 或窗口处理有什么新内容吗？有什么办法可以避免这种情况吗？
这可能是我的程序或我正在使用的图形工具包（或两者）中的错误。但为什么它只出现在 Windows 7 上呢？
感谢您提供任何线索！
丹尼
I have a question about strangely originating WM_PAINT messages sent to my window. It happens on Windows 7 and doesn’t happen on Windows XP.
Details
In my program, I have a timer that triggers GUI updates, the timer is based on this API call:
CreateTimerQueueTimer
In the thread provided my the system to process timer expiration, I do some GUI updates, namely, drawing a line in the window (0,0)->(57,50):
HDC hdc = GetDC (hwnd);
MoveToEx (hdc, 0, 0, NULL);
LineTo (hdc, 57, 50);
ReleaseDC(hwnd,hdc);
In works as I would expect on Windows XP, but on Windows7 this makes a system to send WM_PAINT message to this window with update region: (0,0,58,51). Notice that rectangle is by one pixel wider than the square area affected by the line.
This WM_PAINT arriving because of this drawing is something that I don’t understand. The window is not touched/overlapped/resized or whatever. Apparently, this line is recognized by the system as invalidation of the rectangle.
And this only happens when in Windows 7 (as opposed to Windows XP).
Question
Is it something new about WDM or windows handling in W7? Any way to avoid this?
It maybe a bug in my program or the graphic toolkit I’m using (or both). But why it only manifests on Windows 7 then?
Thanks for any clue!
Denny
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
心理调试时间（换句话说，我完全是猜测）...
请记住，您只能从创建窗口的线程更新窗口的内容。如果您从创建窗口的线程以外的线程调用 GetDC()..ReleaseDC() ，我并不奇怪它会导致问题。
Vista/Win7 的计时器 API 与 XP 中的计时器 API 的实现完全不同，您的计时器完全有可能运行在不同的线程上。
为什么不向窗口发布一条消息来指示计时器已触发，而不是在计时器中绘制呢？然后在消息处理程序中，使窗口区域无效。然后在 WM_PAINT 处理程序中处理线条的绘制。
一般来说，如果您在 WM_PAINT 处理程序中的窗口上绘画而不是在其他窗口消息期间绘画，Windows 会更高兴。
Psychic debugging time (in other words, I'm totally guessing)...
Remember that you can only update the content of a window from the thread which created the window. If you're calling GetDC()..ReleaseDC() from a thread other than the thread which created the window, I'm not suprised it's causing problems.
The timer APIs for Vista/Win7 have a totally different implementation from the timer APIs in XP, it's entirely possible that your timer might be running on a different thread.
Instead of drawing in the timer, why not post a message to the window indicating that the timer fired. Then in the message handler, invalidate the region for the window. Then handle drawing the line in the WM_PAINT handler.
In general Windows is much happier if you paint on a window in the WM_PAINT handler instead of painting during other window messages.