Delphi, QR, WMF

Question

I got a "new job" to "archive" some data with QR Filter.

When the data structure modified and saved to database then we start a "silent printing" with WMF filter, I catch the files, and I store them all in log record, in a DataBase BLOB.

Everything was ok, but later they are needed to avoid repeating the same reports.

We disabled the "timestamp QR fields", but the record repeated.

I put some CRC in the database, and I calculated it from page data (WMF).

What was interesting was that when I exited the program, the newly generated WMF changed - so the CRC changed too.

I thought this was caused by QR, then I checked this with a simple Delphi program:

procedure TForm1.BitBtn1Click(Sender: TObject);
var
    WMF : TMetaFile;
    mfc : TMetaFileCanvas;
begin
    WMF := TMetaFile.Create;
    mfc := TMetaFileCanvas.Create(WMF, 0);
    try
        WMF.Width := 1000;
        WMF.Height := 1000;
        mfc.Brush.Color := clRed;
        mfc.FillRect(Rect(0, 0, 100, 100));
    finally
        mfc.Free;
        WMF.SaveToFile('test1.wmf');
        WMF.Free;
    end;
end;

When I restart the app, the new wmf file is different from the previous.

I thought that I solve the problem with stretch the wmf into the bmp.Canvas, but this has slowed down the logging, because every bmp was 4 MB, and with 10 pages I must CRC on 4 * 10 MB... (The WMF is only 85-100 KByte per page vs 4 MB bitmap)

So I am searching for some easy way I CAN calculate CRC on WMF, maybe if I can split the WMF header fully, then I get solve this problem... I don't know in this moment.

Do you have some idea? Please let me know!

Thanks.

By "QR," do you mean Quick Reports? Or something else? But since you seem to have determined that "QR" is not connected to your problem, why did you include it in your question at all? I'm not sure what you're asking. Please edit your question to remove irrelevant detail and get directly to the issue you're asking about. — Rob Kennedy, Jun 12 '12 at 16:09

score 0 · Accepted Answer · answered Jun 12 '12 at 21:45

0

Export the report as text, then compare its crc.

This is the easiest solution.

You can also enumerate the metafile elements, but it will be more difficult.

answered Jun 12 '12 at 21:45

Arnaud Bouchez

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Delphi, QR, WMF

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