How to draw/get a text string in a Field

I am programing a simple database application for Palm using Palm Development Suite downloaded from
I got a problem when putting a text in a Field Control.
Some Field Function can do this but they all need FieldType Pointer such as:

void FldSetText (
   FieldType *fldP,
   MemHandle textHandle,
   UInt16 offset,
   UInt16 size

Char *FldGetTextPtr (
   const FieldType *fldP

And i don't know how to get this Pointer. All i have here is FieldID only. I also need to get a Pointer(FormType*) of a Form when having it's ID.
I want that when i click on a button, my Field has to show a given text string.
Help me, thanks.
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Ivan Rivera, MTI, SCPM, ITIL, Cobit, PMPProject ManagerCommented:

There is a FieldPtr type that is used to retrieve field's info from the Palm OS.

You can find further info for it in the docs.

Take a look at this Palm code (UPCASE comments are mine)

Hope it can give you a starting point.

static void NoteViewLoadRecord (void)
      UInt16 offset;
      FieldPtr fld;                             // THIS IS THE FIELD POINTER
      MemHandle recordH;
      Char * ptr;
      ApptDBRecordType      apptRec;

      // Get a pointer to the note field.
      fld = GetObjectPtr (NoteField);       // HERE YOU GET THE INFO

      // Set the font used in the note field.
      FldSetFont (fld, NoteFont);

      ApptGetRecord (ApptDB, CurrentRecord, &apptRec, &recordH);
      ErrFatalDisplayIf (! apptRec.note, "Invalid record");

      // Compute the offset within the appointment record of the note string.
      // The field object will edit the note in place, its is not copied
      // to the dynamic heap.
      ptr = MemHandleLock(recordH);
      offset = apptRec.note - ptr;
      FldSetText (fld, recordH, offset, StrLen(apptRec.note)+1);   //YOU HAVE TO PASS THIS POINTER TO THE FUNCTION

      MemHandleUnlock (recordH);
      MemHandleUnlock (recordH);            // was also locked by ApptGetRecord

BTW, i find using FldSetTextHandle more secure (In other posts I mention that memory handle is a little bit difficult in PalmOS).

      DateTimeType dateP;
      FormPtr frm;
      FieldPtr fld;
      UInt32 ref;
      float valor;

            frm      = FrmGetActiveForm();
            getObjectPtr (fIndex);

            // get the field's old text handle
            MemHandle      oldH      = FldGetTextHandle(fld);
            //Copy our string into a memhandle
            int      len      = StrToShow.Length();
            MemHandle      mH      = MemHandleNew(len+1);
            char      *mP      = (char *) MemHandleLock(mH);

            //The memhandle needs to be unlocked to work...

            //To establish the field's link to the handle

            //To draw the field
            // get rid of old handle
            if (oldH != NULL)
                  MemHandleFree (oldH);

Again, hope this can help you.

Ivan Rivera

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adchar43Author Commented:
Thanks for you help but i am having a little bug, i can not get the pointer of my Field although i have my field's ID.
I use this function:

static void *GetObjectPtr(UInt16 rsrcID)  //<== COPY FROM DOCS
      FormPtr formP;
      formP = FrmGetActiveForm();
      return FrmGetObjectPtr(formP, FrmGetObjectIndex(formP, rsrcID));

Fieldp = (FieldType *)GetObjectPtr(fieldFirstName);  <== Error cause by this function, i don't know why, i read in docs and they use this function like me.

In your post above, is the function getObjectPtr the same with my function?

I have the ID of the field resource, i want to set a text on this field, the text from Char * string(to test) not from my database.

On your code above:
FieldPtr fld;                             // THIS IS THE FIELD POINTER
fld = GetObjectPtr (NoteField);       // HERE YOU GET THE INFO
Is the function GetObjectPtr the same with my function and is NoteField = Your field ID?

Ivan Rivera, MTI, SCPM, ITIL, Cobit, PMPProject ManagerCommented:
Could you please post all the code and the error message to try to figure out whats happening?


Ivan Rivera
adchar43Author Commented:
I founded my error, that i can not get the pointer of the Main Form and that cause this error.
My new PROBLEM here :D


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