Lazarus

Free Pascal => Beginners => Topic started by: Weitentaaal on October 15, 2020, 02:32:12 pm

Title: Error handling and Pictures
Post by: Weitentaaal on October 15, 2020, 02:32:12 pm

Image := TPicture.Create;
         try
            DetHilfe.Image1.Picture := Image.LoadFromFile('C:\WGKBlck\Images\' +SQLQuery.FieldByName('PicName').AsString);
            DetHilfe.Label1.Caption:= SQLQuery.FieldByName(FeldD).AsString;
            //On Error go To 0
            DetHilfe.ShowModal;
            DetHilfe.Image1.Picture := DetHilfe.Image2.Picture;
            KvonZub := true;
         finally
            Image.Free;
         end;


Guys correct me pls. i Dont know How to handle errors and To Import an Image to Deploy on a Form

Title: Re: Error handling and Pictures
Post by: lucamar on October 15, 2020, 03:37:41 pm

It quite depends on what error you're expecting or wanting to trap and from where you're expecting it to come.

Nevertheless, maybe a better way to do what your code is trying would be something like:

Code: Pascal  [Select][+][-]

1. var
2.   AFilename: String;
3. begin
4.   AFilename := 'C:\WGKBlck\Images\' + SQLQuery.FieldByName('PicName').AsString;
5.   if FileExists(aFilename) then begin
6.     DetHilfe.Image1.Picture.LoadFromFile(AFilename);
7.     DetHilfe.Label1.Caption:= SQLQuery.FieldByName(FeldD).AsString;
8.     //On Error go To 0 ... what error do you expect?
9.     DetHilfe.ShowModal;
10.     DetHilfe.Image1.Picture := DetHilfe.Image2.Picture;
11.     KvonZub := true;
12.   end;
13. end;

Now, for example, if you're trying to guard against the image file being corrupt or not being a handled format, etc. that would be something like:

Code: Pascal  [Select][+][-]

1. var
2.   AFilename: String;
3. begin
4.   AFilename := 'C:\WGKBlck\Images\' + SQLQuery.FieldByName('PicName').AsString;
5.   if FileExists(aFilename) then
6.   try
7.     DetHilfe.Image1.Picture.LoadFromFile(AFilename);
8.     DetHilfe.Label1.Caption:= SQLQuery.FieldByName(FeldD).AsString;
9.     //On Error go To 0 ... what error do you expect?
10.     DetHilfe.ShowModal;
11.     DetHilfe.Image1.Picture := DetHilfe.Image2.Picture;
12.     KvonZub := true;
13.   except
14.     on e: EGraphicException do
15.       ShowMessage('Failed to load image:'
16.                   + LineEnding
17.                   + e.Message);
18.   end;
19. end;

If you still have doubts you should first read "chapter 17 - Exceptions (https://www.freepascal.org/docs-html/current/ref/refch17.html)" of the Reference Guide to get an overview of how errors (exceptions) are handled.

HTH!

Title: Re: Error handling and Pictures
Post by: Weitentaaal on October 23, 2020, 10:53:45 am

Thanks a Lot lucamar :)