🚀 go-pugleaf

"Sky" <huangc913@msn.com> wrote in message
news:3eb47518@newsgroups.borland.com...
> hi all, i want transfer some memory by WM_COPYDATA,
> but i don't know how to get the actual size of a point,
> for example, i want transfer a TStrings *strs,
> but how can i get the size of strs?
> Any hint? TIA
>

TStrings, as far as C++ is concerned, is a class type with
virtual functions [in reality it is a Delphi type, but those details
shouldn't matter to you].   Basically, you should not try
to copy the object directly, but need to represent the
data *within it* as an array of char to send it with
WM_COPYDATA.

I suggest you read up on various properties of TStrings
(Count, Strings) first in the online help.   As the Strings
property allows acccess to AnsiStrings (which are also
a non-trivial class type) you will need to read up on that
type as well.

"Sky" <huangc913@msn.com> wrote in message
news:3eb47518@newsgroups.borland.com...
> hi all, i want transfer some memory by WM_COPYDATA,
> but i don't know how to get the actual size of a point,
> for example, i want transfer a TStrings *strs,
> but how can i get the size of strs?

You can't pass TStrings directly with WM_COPYDATA.  You'll have to first
extract the raw data from the TStrings into a separate buffer prior to then
sending that buffer using WM_COPYDATA, and then on the receiving end it will
have to read the data and translate it back into a TStrings.

Two possible implementation are as follows:

1) the easy way

    // sending side...
    TStrings *MyList = whatever;
    AnsiString buffer = MyList->CommaText;

    COPYDATASTRUCT cds = {0};
    cds.dwData = MyUniqueValue;
    cds.cbData = buffer.Length();
    cds.lpData = buffer.c_str();

    SendMessage(DestWindow, WM_COPYDATA, 0, (LPARAM)&cds);


    // receiving side...
    TStrings *MyList = whatever;

    COPYDATASTRUCT *cds = (COPYDATASTRUCT*)lParam;
    if( cds->dwData == MyUniqueValue )
        MyList->CommaText = AnsiString((char*)cds->lpData,
(int)cds->cbData);


2) the long way

    // sending side...
    TStrings *MyList = whatever;

    DWORD dwSize = sizeof(int);
    int iCount = MyList->Count;

    for(int i = 0; i < iCount; ++i)
        size += ( sizeof(int) + (MyList->Strings[i].Length() *
sizeof(char)) );

    char *buffer = new char[dwSize];
    char *ptr = buffer;

    memcpy(ptr, &iCount, sizeof(int));
    ptr += sizeof(int);

    for(int i = 0; i < iCount; ++i)
    {
        AnsiString str = MyList->Strings[i];
        int len = ( str.Length() * sizeof(char) );

        memcpy(ptr, &len, sizeof(int));
        ptr += sizeof(int);

        memcpy(ptr, str.c_str(), len);
        ptr += len;
    }

    COPYDATASTRUCT cds = {0};
    cds.dwData = MyUniqueValue;
    cds.cbData = size;
    cds.lpData = buffer;

    SendMessage(DestWindow, WM_COPYDATA, 0, (LPARAM)&cds);
    delete[] buffer;


    // receiving side...
    COPYDATASTRUCT *cds = (COPYDATASTRUCT*)lParam;
    if( cds->dwData == MyUniqueValue )
    {
        char *ptr = (char*)cds->lpData;

        TStrings *MyList = whatever;
        MyList->Clear();

        int iCount;
        memcpy(&iCount, ptr, sizeof(int));
        ptr += sizeof(int);

        for(int i = 0; x < iCount; x++)
        {
            int len;
            memcpy(&len, ptr, sizeof(int));
            ptr += sizeof(int);

            MyList->Add(AnsiString(ptr, len));
            ptr += ( len * sizeof(char) );
        }
    }


Gambit

Thanks! Remy and Rob.