Nicolas Besson - Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Windows Embedded CE Standard Shell is a required catalog item if you select the Enterprise Terminal design template when creating an OS design project in Visual Studio by using the OS Design Wizard. If you want to clone and customize this shell, you can find the source code in the %_WINCEROOT\Public\Shell\OAK\HPC folder. Chapter 1 explains how to clone catalog items and add them to an OS design.

The thin client shell, also called the Windows-based Terminal (WBT) shell in the product documentation, is a GUI shell for thin-client devices that do not run user applications locally. You can add Internet Explorer to a thin-client OS design, yet all other user applications must run on a Terminal server in the network. The thin client shell uses the Remote Desktop Protocol (RDP) to connect to the server and display the remote Windows desktop. By default, the thin client shell displays the remote desktop in full-screen mode.

You can also implement your own shell by cloning and customizing the Windows Task Manager (TaskMan) shell application. The source code in the %_WINCEROOT%\Public\Wceshellfe\Oak\Taskman folder is a good starting point.

The Control Panel is a special repository for central access to system and application configuration tools. The product documentation refers to these configuration tools as applets, to indicate the fact that they are embedded in the Control Panel. Each applet serves a specific and targeted purpose and does not depend on other applets. You can customize the content of the Control Panel by adding your own applets or by removing existing Control Panel applets included with Windows Embedded CE.

The Control Panel is a configuration system that relies on the following three key components:

■ Front-End (Control.exe)This application displays the user interface and facilitates starting Control Panel applets.

■ Host Application (Ctlpnl.exe)This application loads and runs the Control Panel applets.

■ AppletsThese are the individual configuration tools, implemented in form of .cpl files listed with icon and name in the Control Panel user interface.

For details regarding the implementation of the Windows Embedded CE Control Panel, check out the source code in the %_WINCEROOT%\Public\Wceshellfe\Oak\Ctlpnl folder. You can clone the Control Panel code and customize it to implement your own Control Panel version

As mentioned, a Control Panel applet is a configuration tool for a system component or user application implemented in form of a .cpl file and located in the Windows folder on the target device. Essentially, a .cpl file is a DLL that implements the CPlApplet API. A single .cpl file can contain multiple Control Panel applications, yet a single applet cannot span multiple .cpl files. Because all .cpl files implement the CPlApplet API, it is a straightforward process for Control.exe to obtain detailed info about the implemented applets at startup in order to display the set of available applets in the user interface. Control.exe only needs to enumerate all .cpl files in the Windows folder and to call the CPlApplet function in each file.

According to the DLL nature and CPlApplet API requirements, .cpl files must implement the following two public entry points:

■ BOOL APIENTRY DllMain(HANDLE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)Used to initialize the DLL. The system calls DllMain to load the DLL. The DLL returns true if initialization succeeded or false if initialization failed.

■ LONG CALLBACK CPlApplet(HWND hwndCPL, UINT message, LPARAM lParam1, LPARAM lParam2)A callback function that serves as the entry point for the Control Panel to perform actions on the applet.

You must export the DllMain and CPlApplet entry points so that the Control Panel application can access these functions. Non-exported functions are private to the DLL. Make sure the function definitions are in export "C" { }blocks to export the C interface.

The Control Panel calls the CPlApplet function to initialize the applet, obtain information, provide information about user actions, and to unload the applet. The applet must support several Control Panel messages, listed in Table 3-6, to implement a fully functional CPlApplet interface:

Table 3-6 Control Panel messages

Store the NEWCPLINFO information for each Control Panel application that you implement in a Control Panel applet in a resource embedded in the .cpl file. This facilitates the localization of icons, names, and applet descriptions returned in response to CPL_NEWINQUIRE messages.

To build a Control Panel applet and generate the corresponding .cpl file, find the source code folder of the applet subproject and add the following CPL build directive on a new line at the end of the Sources file:

CPL=1

You also must add the path to the Control Panel header file to the Include Directories entry on the C/C++ tab in the applet subproject settings in Visual Studio, as illustrated in Figure 3-3:

$(_PROJECTROOT)\CESysgen\Oak\Inc

Figure 3-3Include Directories entry for a Control Panel applet

Many Windows Embedded CE devices, such as medical monitoring devices, automated teller machines (ATM), or industrial control systems are dedicated to a single task. The standard graphical shell is not useful for these devices. Removing the standard shell restricts access to the Control Panel configuration settings and also protects users from starting additional applications. The result is a device in kiosk mode that opens an application according to the special purpose of the target device directly with no shell access.

Kiosk applications for Windows Embedded CE are developed in native code or managed code. The only requirement is to start this application in place of the standard shell (Explorer.exe). The system then starts a black shell, meaning no shell application is running on the device. You only need to configure the registry entries under the HKEY_LOCAL_MACHINE\Init key to implement this configuration. As mentioned earlier in this chapter, the LaunchXX entry for Explorer.exe is Launch50. Replace Explorer.exe with your custom kiosk application and consider the job completed, as shown in Table 3-7. Keep in mind that your custom kiosk application must implement the SignalStarted API for the kernel to manage the application dependencies correctly.