Power++ Tips

August 30^th, 1997:
This week's tip comes from Dennis Woo who gives us some advice for making functions that you want to be available to your whole application. Of course you could just make a global function, but some might call that sacrilegious. Another option is to make one class in your application that has a bunch of static functions in it. But why make a new class when there is already one that is made for you and that all forms in your program can see - namely, the Application class. Just open up this class and create a public user function as always for it. The problem is that if you then try to access the function by doing something like:
    WAppObject.MyCoolFunc();
You will find that you can't; because WAppObject is of type WApplication, and your functions are only defined in your subclass of WApplication. The trick is to use the Application pointer, which points to the instance of your class and is of the correct type, as in:
    Application->MyCoolFunc();
In an update to this tip, Darrell Black writes in to remind us that in order to get this to work, we need to:
    #include "applic.hpp"
    #include "main.hpp"
In either the CPP or HPP prefix.
August 24^th, 1997:
This week Paul Ackley brings us a quick warning about using the full debug version of WCMDDA20.DLL (available on the Power++ Code page). Although it is extremely useful in many situations, it will unfortunately cause problems if you try to use the DataWindow in conjunction with it. You have been warned!
August 17^th, 1997:
Bruce Schubert writes in this week with the solution to a frequently asked question: How does one go about using their program's Version Resources from within the program itself? Here is the guts of a class that Bruce wrote in order to do exactly that. Note, the code uses the Windows API and exception handling -- you'll need to edit your target's pre-compiled header to use the API, and either turn on exception handling or edit out the try/catch blocks:
/////////////////////////////////////////////////////////////////
class VFileVersion : public WObject
{
    private:
        //
        // Version information strings
        //
        WString companyName;
        WString fileDescription;
        WString fileVersion;
        WString internalName;
        WString legalCopyright;
        WString originalFilename;
        WString productName;
        WString productVersion;
    protected:
        //
        // Version information structures
        //
        void    *versionData;
        WByte   *translationTable;

    public:
        WString GetCompanyName() const;
        WString GetFileDescription() const;
        WString GetFileVersion() const;
        WString GetInternalName() const;
        WString GetLegalCopyright() const;
        WString GetOriginalFilename() const;
        WString GetProductName() const;
        WString GetProductVersion() const;
        VFileVersion();
        ~VFileVersion();
};

// Code added here will be included at the top of the .CPP file
//  Include definitions for resources.
#include "WRes.h"

//
// CompanyName Property
//
WString VFileVersion::GetCompanyName() const
{
  return companyName;
}

.
.   Add the rest of your Get... property methods
.

//
// Constructor
//
VFileVersion::VFileVersion()
:   versionData( 0 ), translationTable( 0 )
{
    try {

        // We'll use application's filename to identify the module
        // to get the version resource from.
        //
        char filename[255];
        strcpy(filename, WAppObject.GetExecutableModule().GetName().GetText());

        // We need the size of the version information to allocate memory
        // for the version resource data
        //
        DWORD versionHandle;    // this var is ignored by GetFileVersionInfo
        DWORD versionSize = ::GetFileVersionInfoSize(filename, &versionHandle);
        WASSERT (versionSize);
        if (!versionSize)
            throw;

        versionData = (void *) new char[(UINT)versionSize];
        if (!::GetFileVersionInfo( filename, versionHandle,
          versionSize, versionData) )
            throw;

        // Initialize the class members with the values retreived
        // from the version data.
        // The Win32 API contains the following predefined version
        // information strings:
        //   CompanyName FileDescription FileVersion InternalName
        //   LegalCopyright OriginalFilename ProductName ProductVersion
        //
        char subBlockName[ 255 ];
        UINT querySize;

        // Get a pointer to the language and character-set identifiers.
        if (!::VerQueryValue(versionData, "\\VarFileInfo\\Translation",
          (void **)&translationTable, &querySize))
            throw;

        // Swap the words so wsprintf will print the lang-charset
        // in the correct format.
        *(DWORD *)translationTable = MAKELONG(
            HIWORD( *(DWORD*)translationTable ),
            LOWORD( *(DWORD*)translationTable ));

        // Pointer to a buffer that receives a pointer
        // to the version-information value.
        void *queryData;

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"CompanyName");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            companyName.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"FileDescription");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            fileDescription.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"FileVersion");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            fileVersion.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"InternalName");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            internalName.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"LegalCopyright");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            legalCopyright.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"OriginalFilename");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            originalFilename.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"ProductName");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            productName.SetText( (char *)queryData );

        wsprintf(subBlockName, "\\StringFileInfo\\%08lx\\%s",
                 *(DWORD *)translationTable, (LPSTR)"ProductVersion");
        if (::VerQueryValue(versionData, subBlockName, &queryData, &querySize))
            productVersion.SetText( (char *)queryData );

    }
    catch (...) {
        if (versionData) {
            delete[] versionData;
            versionData = 0;
        }
    }

}

VFileVersion::~VFileVersion()
{
    if (versionData) {
        delete[] versionData;
        versionData = 0;
    }
}
August 10^th, 1997:
This week Glenn Pope brings us a very simple tip that can make a big difference: "Develop as close to the user environment as possible. For SQL Anywhere applications, there are differences between the db engine (dbeng50.exe) and the runtime desktop engine (rtdsk50.exe) that aren't documented. To avoid breaking any code, try to use the runtime engine through ODBC instead of the main engine when you develop stand alone applications."
August 3^rd, 1997:
This week's tip is brought to you by Bruce D. Schubert. Bruce writes in explaining how to set up an accelerator table for a tab control so that you can have a keyboard shortcut for each tab on the control. (Note that I am informed that this will not work for Win32s since Win32s does not support accelerators.) In this example we'll have a tab control set up with three tab pages named: &Testing, &Wow, and &Zowie; where the ampersand means that the next letter is underlined (for example, you'd expect the Alt-W key combination to bring you to the Wow page). Note that the example uses the LOWORD and HIWORD macros which are defined in the Win32 SDK. If you don't have the SDK, or don't want to include it in your project, add the following lines to the .CPP prefix section of your form which contains the tab control:
typedef unsigned long  DWORD;
typedef unsigned short WORD;
#define LOWORD(l)      ((WORD)(l))
#define HIWORD(l)      ((WORD)(((DWORD)(l) >> 16) & 0xFFFF))
And in the form's Create event handler, you would add code such as the following:
// The tab control doesn't support access keys for the individual
// tabs, so we'll setup an accelerator table to simulate the behavior.
// The tab's ordinal page number is stored in the command id param
// and will be used to select the page in Command event handler.
// We use the ordinal number instead of the page's array index
// because we can't store a '0' in the accel table.
WAcceleratorTable accelTable = GetAcceleratorTable();
accelTable.Add( WKAltPressed, WKeyT, 1 );   // &Testing
accelTable.Add( WKAltPressed, WKeyW, 2 );   // &Wow
accelTable.Add( WKAltPressed, WKeyZ, 3 );   // &Zowie
SetAcceleratorTable( accelTable );
Finally, in the form's Command event handler, you would add the folliwing code:
// Activate the tab page associated with the accelerator.
// The event->wParam member has ordinal page# stored in it.
if( HIWORD(event->wParam) == 1 ) {  // 1 == accelerator
    WInt currentPage    = tabctrl_1->GetSelected();
    WInt selectedPage   = LOWORD( event->wParam ) - 1;
    if( currentPage != selectedPage )
        tabctrl_1->SetSelected( selectedPage );
}

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