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Gary Mrenak
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 Posted: Tue Jul 29, 2003 9:13 pm Post subject: TImage and JPGs |
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D7, Win2k.
I'm trying to use a tImage component to display bitmaps or jpgs. The bitmaps
can be loaded using either timagename.picture or timagename.picture.graphic,
but jpgs produce an error (expects a bitmap) when I try to assign a
timagename.Picture.graphic to a tpersistent. If I want to be able to load
and display either a bmp or jpg into the same timage object, how is that
done?
Thanks.
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Peter Haas
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| Posted: Tue Jul 29, 2003 10:41 pm Post subject: Re: TImage and JPGs |
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Hi Gary,
Gary Mrenak wrote in <3f26e497$1 (AT) newsgroups (DOT) borland.com>:
| Quote: | D7, Win2k.
I'm trying to use a tImage component to display bitmaps or jpgs.
|
uses
..., JPEG, ...;
Bye Peter.
--
Why should we be interested is someone who considers us a waste basket?
Robert Marquardt (Team JEDI) in <b4mf4g$u0k$1 (AT) talkto (DOT) net> to me
regarding JEDI's disinterest on my contribution attempts.
Maybe JEDI users have more interest: http://jediplus.pjh2.de/index.php
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Gary Mrenak
Guest
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| Posted: Wed Jul 30, 2003 6:12 pm Post subject: Re: TImage and JPGs |
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Very helpful response! Thanks!
I'll get right on your suggestions.
Gary
"Peter Haas" <newsgroupfeedback (AT) pjh2 (DOT) de> wrote
| Quote: | Hi Gary,
Gary Mrenak wrote in <3f27c355$1 (AT) newsgroups (DOT) borland.com>:
If I can read in and display a jpg, how can I assign it to a tPersistent
object defined on a blob database field?
TPersistent is a abstract class, this do mean, that you can not use this
class, you need a class, which is derived from TPersistent.
To store a JPEG in a blob database field you must save it per stream,
e.g. (untested, written directly to the posting):
procedure SaveJpegToBlobField(Jpg: TJpegImage; BlobField: TBlobField);
var
Stream: TMemoryStream;
begin
Stream := TMemoryStream.Create;
try
Jpg.SaveToStream(Stream);
BlobField.LoadFromStream(Stream);
finally
Stream.Free;
end;
end;
The method TBlobField.Assign need to use a TJpegImage descendant, which
support Assign to a TBlobField:
type
TJpegImageBlob = class(TJpegImage)
protected
procedure AssignTo(Dest: TPersistent); override;
end;
procedure TJPEGImageBlob.AssignTo(Dest: TPersistent);
var
Stream: TMemoryStream;
begin
if Dest is TBlobField then
begin
Stream := TMemoryStream.Create;
try
SaveToStream(Stream);
TBlobField(Dest).LoadFromStream(Stream);
finally
Stream.Free;
end;
end
else
inherited AssignTo(Dest);
end;
Bye Peter.
p.s. Please optimize your quoting, read
http://info.borland.com/newsgroups/netiquette.html
--
Why should we be interested is someone who considers us a waste basket?
Robert Marquardt (Team JEDI) in <b4mf4g$u0k$1 (AT) talkto (DOT) net> to me
regarding JEDI's disinterest on my contribution attempts.
Maybe JEDI users have more interest: http://jediplus.pjh2.de/index.php
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