Author: Tomas Rutkauskas

Does anybody know whether it is possible to write some small TBitmaps with 
different widths and heights into one file?

Answer:

Saving the TBitmap to a Stream, and appending other TBitmaps to that stream, then 
saving the stream to disk would be the method.
1   
2   procedure SaveBitmapToStream(aBitmap: TBitmap; aStream: TStream);
3   var
4     ms: TMemoryStream;
5     size: Integer;
6   begin
7     Assert(Assigned(aBitmap));
8     Assert(Assigned(aStream));
9     ms := TMemoryStream.Create;
10    try
11      aBitmap.SaveToStream(ms);
12      ms.position := 0;
13      size := ms.Size;
14      aStream.WriteBuffer(size, Sizeof(size));
15      aStream.CopyFrom(ms, size);
16    finally
17      ms.free
18    end;
19  end;
20  
21  //then
22  
23  aStream.SaveToFile('FileName');
24  
25  //to read then first off do:
26  
27  aStream.LoadFromFile('FileName');
28  
29  //then
30  
31  procedure LoadBitmapFromStream(aBitmap: TBitmap; aStream: TStream);
32  var
33    ms: TMemoryStream;
34    size: Integer;
35  begin
36    Assert(Assigned(aBitmap));
37    Assert(Assigned(aStream));
38    ms := TMemoryStream.Create;
39    try
40      aStream.ReadBuffer(size, Sizeof(size));
41      ms.CopyFrom(aStream, size);
42      ms.position := 0;
43      aBitmap.LoadfromStream(ms);
44    finally
45      ms.free
46    end;
47  end;