Windows CE - Working with Custom SDKs

Making Qt Applications Start on a Custom Device

Sometimes, a Windows CE device has been created with a configuration different from the corresponding SDK's configuration. In this case, symbols that were available at linking stage will be missing from the run-time libraries.

Unfortunately, the operating system will not provide an error message that mentions which symbols are absent. Instead, a message box with the following message will appear:

app.exe is not a valid CE application!

To identify the missing symbols, you need to create a temporary application that attempts to dynamically load the Qt for Windows CE libraries using LoadLibrary. The following code can be used for this:

 wchar_t* libraries[] = {
     L"QtCore4.dll",
     L"QtGui4.dll",
     0
 };

 for (int i = 0; libraries[i] != 0; ++i) {
     HINSTANCE instance = LoadLibraryW(libraries[i]);
     OutputDebugStringW(libraries[i]);
     if (instance != NULL) {
         OutputDebugStringW(L" : Successfully instantiated\n");
         FreeLibrary(instance);
     } else {
         OutputDebugStringW(L" : Could not be loaded\n");
     }
 }

Once you have compiled and deployed the application as well as the Qt libraries, start a remote debugger. The debugger will then print the ordinal number of the unresolved symbol.

Search for parts of Qt that rely on these functions and disable them using the QFeatures functionality.

In our experience, when Qt applications do not start on Windows CE, it is usually the result of missing symbols for the following classes or features:

• Drag and Drop
• QClipboard
• QCursor

Please refer to the Microsoft documentation here for information on what ordinals are and how you can create them. Information on accessing the corresponding symbol name to a given ordinal value can also be found in the Microsoft documentation.