If you think about what happens when the field resizes the memory to allow
for more text, you will see why you cannot have two fields related to the
same handle. When the field resizes the handle, it must move data located
after the text storage such that the data is not overwritten, or similar
when the text gets smaller. So if you have another field accessing the data
that is being moved, it isn't going to work.
You must unpack your strings into the field's own handles, and pack them
back into the record after the user has tapped OK.
Matt
----- Original Message -----
From: "ritmanik" <[EMAIL PROTECTED]>
To: "Palm Developer Forum" <[EMAIL PROTECTED]>
Sent: Saturday, March 15, 2003 5:58 AM
Subject: Re: Editing db record in place with FldSetText
> Since your database is small 7 records with 6 characters each (42
> bytes total), why not keep the record size constant at 6 bytes?
> You're not going to save a lot of memory by resizing the records each
> time they are changed.
>
> The method that you are presently using works great for large
> variations in the amount of text in a record (for example an entry in
> the Memo app could be several paragraphs of text or a single
> character). Here you would definetly not want to have fixed size
> records. If you still would like to stick with the variable record
> size, you could checkout the code for the Memo application, but it'll
> be much easier to keep your records fixed.
>
> You could even keep all of the strings in a single record if you know
> that there will only be 7 strings. Easier yet, how about keeping
> these strings in the application prefrence database?
>
> --- In [EMAIL PROTECTED], Matthias Jordan <[EMAIL PROTECTED]>
> wrote:
> > Hi, folks.
> >
> > I'm experimenting with a setup that I suppose to work if I
> understand
> > the Palm API correctly.
> >
> > I have a database record that has some static fields at the
> beginning
> > (totaling 6 bytes). After this are 7 0-terminated strings. Initially
> > (i.e. after creation of the record), all strings are empty.
> >
> > I wrote a function that locks a handle on that record and stores the
> > offset to each string together with the handle in a struct. Later,
> I
> > assign the unlocked handle together with the different offsets to a
> > Field with FldSetText. For doing so, I wrote a small function that
> > determins the length of the string and puts everything in place:
> >
> > void FldSetHandleID(UInt16 id, MemHandle h, UInt16 offset)
> > {
> > FieldPtr fld;
> > UInt16 len;
> >
> > len = StrLenHandle(h, offset); // returns lenth of string at
> offset
> > fld = GetObjectPtr(id);
> > FldSetText(fld, h, offset, len+1);
> > FldSetMaxChars(fld, 20);
> > } /* FldSetHandleID */
> >
> >
> > Strangely, the whole thing does not work. To be more precise:
> contrary
> > to what's written in the API documentation, FldSetText does not
> resize
> > the record regardless of the parameters. It only resizes the record
> if I
> > only have /one/ string in the record assigned to a UI Field.
> > If I assign more strings to more UI Fields and set the number of
> > allocated bytes in FldSetText to 1 (because initially, the string
> only
> > consists of the terminator), I cannot enter any text at all. The
> Palm
> > says "The data storage of the handheld is full". If I set the
> number of
> > allocated strings to a higher value (say, n), n bytes are
> overwritten in
> > the record, scrambling the subsequent fields.
> >
> > I know that this whole thing works with text fields in table
> objects, so
> > what's going wrong here? Is there any sample code that shows how to
> get
> > this done?
> >
> > Matthias
> >
> >
> > --
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>
>
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