How to load a picture from the Internet?
lazarus / 38-Networking and Web Programming

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Vlad1997 · 2010-01-07 18:36

How to load a picture from the Internet?
Formats: BMP, JPEG and GIF.
OS: Ubuntu

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skalogryz · 2010-01-07 19:30

Please, review examples and documentation of the following component:
http://wiki.freepascal.org/lNet

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Vlad1997 · 2010-01-08 11:25

And how to use it?

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skalogryz · 2010-01-08 13:53

have you tried any of lnet examples?
http://svn.freepascal.org/svn/fpcprojects/lnet/trunk/examples/visual/

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Vlad1997 · 2010-01-08 16:27

Thank you
And how to load just picture?
Code: [Select]function TMainForm.HTTPClientInput(ASocket:
TLHTTPClientSocket; ABuffer: pchar;
  ASize: dword): dword;
var
  oldLength: dword;
begin
  oldLength := Length(HTTPBuffer);
  setlength(HTTPBuffer,oldLength + ASize);
  move(ABuffer^,HTTPBuffer[oldLength + 1], ASize);
  MemoHTML.Text := HTTPBuffer;
  MemoHTML.SelStart := Length(HTTPBuffer);
  AppendToMemo(MemoStatus, IntToStr(ASize) + '...');
  Result := aSize; // tell the http buffer we read it all
end;

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theo · 2010-01-08 16:35

Probably easier with Synapse's HttpGetBinary

http://synapse.ararat.cz/doc/help/httpsend.html#HttpGetBinary

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skalogryz · 2010-01-08 19:22

Quote from: Vlad1997 on January 08, 2010, 05:27:18 pmThank you
And how to load just picture?
Provide Lnet component with URL of "just picture", let's say:
http://www.mysite.com/image.png

if you don't know the exact address, you'll need to load an .html file
and parse it... (that's how browsers work)

After you're sure that lnet is loading the picture (not .html), you
can decide what to do with the data.

The Lnet component writes the data from ABuffer to a stream... let's
say TMemoryStream or TFileStream (if you need to store the picture
into a file).

If you need to show the picture on the screen you can later load and
show it, using Graphics unit.

Code: [Select]uses
  ...lnet, graphics...

var
  pngstream: TStream;
  pngimage : TPortableNetworkGraphics;

function TMainForm.HTTPClientInput(ASocket: TLHTTPClientSocket;
ABuffer: pchar;
  ASize: dword): dword;
begin
  pngstream.Write(ABuffer^, ASize);
end;

procedure TMainForm.ShowPicture;
begin
  if not Assigned(png) then begin
    pngimage:=TPortableNetworkGraphics.Create;
    pngstream.Position:=0;
    pngimage.LoadFromStream(pngstream);
  end;
  Invalidate;
end;

procedure TMainForm.FormPaint;
begin
  if Assigned(pngimage) then
    Canvas.Draw(0,0,pngimage);
end;

It all depends on what you mean saying "how to load a picture". Lnet
will help you to get the picture data, but it's up to you how to use
it.

P.S. don't ask for the examples, write your own