delphi - VCL 表单应用程序和控制面板小程序有什么区别

Question

首先，维基百科将控制面板小程序定义为:

graphical user interface which allows users to view and manipulate basic system settings and controls via applets

它是否正确？

其次，就功能而言，VCL 应用程序和控制面板小程序有什么区别。与 VCL 应用程序相比，使用 CP Applet 更改基本系统设置是否更容易？

Answer 1

控制面板小程序是符合特定标准的 DLL，可在 Windows 控制面板中显示。 (有关详细信息，请参阅 MSDN 文档 CPlApplet()。)因此，第一个问题的答案是否定的，该定义不正确，第二个问题的答案是:VCL Forms 应用程序是基于 Delphi 的标准 Windows 应用程序VCL 和控制面板小程序是一个 DLL，旨在加载到 Windows 控制面板应用程序中(在 Win95 之后的大多数 Windows 版本中，您会发现它带有 Start->Control Panel)。
据此CodeProject article :

A control panel applet is a DLL that presents a standard interface to the Control Panel application. When Control Panel starts it locates all the .cpl files in the Windows System directory and tries to load them as DLLs. If this works then it tries to locate a function called CPlApplet() in the newly loaded DLL. If the DLL has the function entry point then it's a control panel applet! But there's more, a single DLL can contain multiple applets and they each appear as a separate icon in Control Panel.

CPlApplet() is a relatively simple function taking a window handle, a message and a couple of message specific parameters. Writing one is similar to writing a normal window proc and is reasonably well documented in MSDN and the VC++ online help.