什么是MouseEventArgs.X的类型？ [英] What is the type of MouseEventArgs.X?

问题描述

用C＃工作在Visual Studio 2008（.NET 3.5）。展望 System.Windows.Forms.MouseEventArgs 。

Working with C# in Visual Studio 2008 (.NET 3.5). Looking into System.Windows.Forms.MouseEventArgs.

我看到奇怪的现象，长板，当我拦截处理的MouseMove 事件。看来， MouseEventArgs.X 从0到32767，然后回绕到-32768。

I'm seeing strange behavior with long Panel when I intercept handle the MouseMove event. It appears that MouseEventArgs.X goes from 0 to 32767, and wraps around to -32768.

当我看到在Visual Studio中的变量，它声称它的类型 INT 。

When I watch the variable in Visual Studio, it claims that it's of type int.

显然，这是一个16位有符号整数，这样它的行为。这是真的？这是一个硬性限制？

Apparently it's a 16-bit signed integer the way it's behaving. Is this true? Is this a hard limit?

谢谢！

推荐答案

这可能来自一个事实，即Windows窗体基本上以C Windows API的一个.NET包装。对于 WM_MOUSEMOVE 以及相关的消息（WM_LBUTTONDOWN，等），鼠标坐标发送在LPARAM参数。 LPARAM是一种类型定义LONG_PTR，它在32位Windows（只）是又一个typedef长。由于文档的WM_MOUSEMOVE说，你可以通过使用GET_X_LPARAM和GET_Y_LPARAM宏，返回低位int和高阶INT分别获得光标的位置。

This probably comes from the fact that Windows Forms is basically a .NET wrapper around the C Windows API. For the WM_MOUSEMOVE and related messages (WM_LBUTTONDOWN, etc.), the mouse coordinates are sent in the LPARAM parameter. LPARAM is a typedef for LONG_PTR, which on 32-bit Windows (only) is in turn a typedef for long. As the docs for WM_MOUSEMOVE say, you can get the cursor position by using the GET_X_LPARAM and GET_Y_LPARAM macros, which return the low-order int and the high-order int, respectively.

由于值是32位开始与（在32位的Windows），这是有意义的唯一方法是用于x和y坐标实际上是16位的值。基于对windowsx.h的GET_X_LPARAM的定义，我也猜（但没有，说来的官方消息），即使在64只低32位的LPARAM被用于鼠标坐标。

Since the value is 32 bits to start with (on 32-bit Windows), the only way this makes sense is for the x and y coordinates to actually be 16-bit values. Based on the definition of GET_X_LPARAM in windowsx.h, I would also guess (but do not have an official source that says) that even on x64 only the lower 32 bits of the LPARAM are used for the mouse coordinates.

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