Implementing a Custom Shell on a Microsoft Windows CE 2.1-based Device

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Microsoft Corporation
June 2000
Summary:This paper describes the new components in Microsoft Windows CE version 2.10 that support the development of custom shells, and provides an overview of the interface guidelines and development process involved in creating a customized shell. (6 printed pages)
Overview The Windows CE Desktop Developing and Installing Your Shell Adding Modules and Components Modifying Cesysgen.bat Building a Project For More Information
`Overview`


Microsoft Windows CE is a compact, scalable operating system
that is fast becoming the operating system of choice for many
embedded developers. Its modular design allows for full
customization-requiring you to select only the modules and
components you need to run your application.
In the Windows CE 2.10 release, Microsoft provides new
components to support the development of custom shells. You can
select from a set of components that support shell-related API
functionality, available in the Windows CE Embedded Development Kit
for Microsoft Visual C++.
These shell support components offer flexibility by enabling a
wide variety of shells. They are designed to make it as easy as
possible for embedded developers to create and use whatever shell
they desire. These components should be thought of as providing
underlying system support only. Sample code is provided to help you
to better understand system integration and to reduce your
development time. Note that Windows CE does not offer a full
implementation of a functioning shell for embedded systems
developers.
The new components include: 

taskman, the component that handles desktop painting, the
desktop bitmap, handling of battery warnings, and launching and
switching between applications 
components that support shell-related API functions: shexec
(ShellExecuteEx), shmisc (SHLoadDIBitmap, SHShowOutOfMemory),
shortcut (SHCreateShortcut, SHGetShortcutTarget), and shcore
(shared functions used by the other components) 
commdlg, Common dialogs 
commctrl, Common controls 
console, Console support, including the command processor
Cmd.exe 
control, the control panel and individual modules for each
control panel applet, including: system, screen, passwrd, sounds,
main, comm, intl, network, dialing, and power. 

The Windows CE Desktop
A shell is a set of user-interface components and underlying
support routines that translates user input into useful operating
system actions. A Windows CE platform can have its own unique shell
that is developed and customized for a device and its target
audience.
Platforms may also include the Windows CE desktop component.
This component provides the following functionality: 

Registration with the GWES module so that windows with hide
capability can be placed behind the desktop window. This desktop
also supports the use of a custom background bitmap. 
A task manager with a window that appears when you enter one of
the following key combinations: Alt-Tab, Ctrl-Esc, or
Ctrl-Alt-Backspace. The task manager provides access to all
top-level window applications. With it you can launch an
application, switch to a running application, or terminate a
running application. 
Handling of battery warnings and low memory situations
(WM_HIBERNATE). 
The desktop is one of several components the Windows CE
operating system provides to enable you to create a custom shell
for your target platform. Other system building blocks include: 

A Control Panel that accesses applets used to configure the
system. These applets include: Communications, Display, Keyboard,
Network, Dialing, Owner, Password, Power, Regional Settings, Remove
Programs; Pointing Device Settings (Stylus); Sounds, and Volume. 




Figure 1. Windows CE Control Panel (Details View)

Connectivity components to support remote application
programming calls between a development workstation and a Windows
CE target platform. 




Figure 2. Main View

Windows CE common controls and common dialogs. Windows CE
common dialogs include the Open, Save, Color, and Print dialog
boxes. Common controls include check boxes, combo boxes, command
bars, command buttons, list box, list views, menus, option buttons,
scroll bars, status bar, tabs, text fields, toolbars, trackbars,
treeviews, and others. 
API functions and related structures exposed by the Windows CE
SDK to make some shell services available for applications, such as
shortcut creation and resolution. For more information about these
services, see "Windows CE Shell Services" in the Windows CE SDK. 
A command line processor (console application) and console
device that supports a set of standard input/output API (STDIO)
calls. For more information about how you can write your own
console application using this API, see the software development
kit documentation. 
Notification APIs (offered as part of the GWES module) that
allow an application to register its name and an event with the
system. When the event occurs, the kernel automatically notifies
the application. 

Developing and Installing Your
Shell
The primary purpose of a shell is to make it easy for users to
access the features of a device. In that regard, developing a shell
is similar to developing an application. The same principles of
good design apply.
The first step in any development process is to determine the
unique configuration of the hardware platform for which you are
developing. Because Windows CE is a modular operating system, you
must decide which specific modules and components your target
audience will need to operate your device.
Once you have designed your target platform, you then must
decide what programming environment to use. You can choose
Microsoft Visual C++ or Microsoft Visual Basic. In addition to the
tools provided with the Windows CE Embedded Toolkit for Visual C++
5.0, each of these programming environments has its own unique
toolkit for you to use. They include: 

Windows CE Toolkit for Visual C++ 5.0 
Windows CE Toolkit for Visual Basic 5.0 
After choosing a programming environment and toolkit, you can
begin developing your shell. Use standard components and Win32
APIs. Keep usability in mind by designing a simple, easy-to-use
interface.
Here are some general UI design guidelines. 

A well-designed, responsive user interface contributes much
toward the user's perception of being in control of your shell and,
therefore, of your device. 
Use concepts familiar to users. A conceptual model enables
users to apply knowledge gained from experience toward
understanding the structure and use of the application. For
example, an Address application modeled after a typical paper-based
address book would allow users to apply their understanding of
address books to the new application. 
Be consistent in your UI. Don't ask "Do you want to save your
work before exiting?" in 9 out of 10 places and "Are you sure want
to discard your work?" in the other one! 
Give the user immediate and tangible feedback during
interaction with an application. Appropriate feedback includes
acknowledging a request, pointing out an error, or tracking the
progress of an operation. Although auditory feedback can be useful
for attracting a user's attention, it should be used sparingly. 
Keep your design simple. Simplicity is not only a
characteristic of good interface design, it hastens the user's
acceptance of the UI. 
Once completed, install your shell on your device and debug and
test your code just like any other application. To install a shell
onto a device, insert the name of your application in the following
Registry Key:
HKEY_LOCAL_MACHINE\Init
LaunchXX="MyShell.EXE"
DependsXX=hex:14,00,1e,00
When the system starts, it executes the LaunchXX keys in order,
launching Launch10, then Launch20, and so on. Make your shell the
last item numbered in the list.
Also, make sure you add a DependsXX key that lists dependencies
on previous launch components. The system will wait for dependent
components to run and initialize before launching the launch key
with the matching number. For example, if your shell is registered
as 'Launch60="MyShell.exe"', then you should have a 'Depends60' key
which lists components, such as GWES, that must be initialized
before your shell is launched. Before executing your Launch60 key,
the system will wait for all components listed in the Depends60 to
be executed and initialized.

Adding Modules and Components
Before you can select which components to add to your shell, you
must first decide which modules and components you want included in
your operating system. Then you must modify the file
Cesysgen.bat.
Out of the many modules and components available in Windows CE,
selecting the right combination of components to support your
target platform can be difficult. To assist you in this task,
Windows CE supplies several component configurations from which you
can choose. These configurations represent different sets of system
capabilities, ranging from a base system with minimal user input
and no display capabilities, to a system with keyboard and touch
pad input, a full color display, and fax/modem and networking
support. All configurations included with Windows CE have been
fully tested by Microsoft. Other combinations of modules and
components are possible, but Microsoft has not tested them and
therefore cannot guarantee their reliability. If you choose to
create your own configuration, contact Microsoft for
assistance.
Standard Windows CE configurations include:

Configuration 1—This configuration builds a minimal version
of Windows CE that kernel (Core.dll). You may also set the registry
so that Windows CE opens one executable application upon
startup.

Configuration 2—This configuration builds a minimal version
of Windows CE with the Windows CE Debug Shell Tool (CESH). CESH
provides you with a command-line interface to the Windows CE
operating system.

Configuration 3—This configuration builds a minimal version
of Windows CE with data communications and networking, but no user
interface.

Configuration 4—This configuration builds a minimal version
of Windows CE with user input support, but no communications or
window management.

Configuration 5—This configuration builds a minimal version
of Windows CE with graphics device interface (GDI) support, but no
window management.

Configuration 6—This configuration builds a nearly complete
version of Windows CE with a fully configured Graphics, Windowing,
and Event Subsystem (GWES).

Configuration 7—This configuration builds a fully configured
version of Windows CE, including support for a custom shell.

Modifying Cesysgen.bat
The file Cesysgen.bat specifies the environment variables used
to create your Windows CE project. Cesysgen.bat allows you to
choose the modules for your Windows CE operating system to install
on your hardware development platform. Some modules, such as the
operating system kernel module (Nk) are required.
To add components to your Cesysgen.bat, modify Cesysgen.bat in
the directory \Oak\Misc to specify the modules of the Windows CE
operating system to be included in your Windows CE project. See the
following example.
set CE_MODULES=%CE_MODULES%
gwes
set GWE1_COMPONENTS=wmbase gweshare
gwesmain immthunk msgque
if "%CONFIG5_NOCURSOR%"=="1" set
GWE3_COMPONENTS=icon cursor cursor8
On the basis of these modifications, Cesysgen.bat sets the value
of the component environment variables.

Building a Project
After Cesysgen.bat sets these environment variables, the Nmake
Tool (Nmake.exe) uses these specifications to build and copy the
modules for your Windows CE operating system.
The process of linking, building and copying the modules and
components you have selected is referred to as the sysgen phase. In
this phase, it creates a customized project directory based on the
common project directory. The sysgen phase filters the header file
and builds the components defined by your Cesysgen.bat file.

For More Information

For more information about user interface design, see The
Windows Interface Guidelines for Software Design, Microsoft Press. 
For more information on Windows CE development, see the Windows
CE Platform SDK documentation. 
For more information on customizing the Windows CE operating
system, see the Windows CE Embedded Toolkit for Visual C++ 5.0
documentation. 
For more information on the Microsoft Windows programming
environment, see The Microsoft Platform Software Development Kit
and Programming Windows by Charles Petzold. 








© 2004 Microsoft Corporation. All
rights reserved.
Implementing a Custom Shell on a Microsoft Windows CE 2.1–based Device

Contents

`Overview`

The Windows CE Desktop

Developing and Installing Your Shell

Adding Modules and Components

Modifying Cesysgen.bat

Building a Project

For More Information
