BorlandTalk.com Borland discussion newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Bitmap from OLEVariant?          BorlandTalk.com Forum Index -> Delphi Graphics View previous topic :: View next topic   Author Message Peter C Guest Posted: Sun Oct 08, 2006 5:48 am    Post subject: Bitmap from OLEVariant? I have a function that returns a Device Independant Bitmap in an OLEVariant variable, but I do not know how to use this. How can I transfer the DIB from the OLEVariant to a TBitmap object or other graphics object? I ultimately want to store the graphic in a BLOB field in a JPG format. Would appreciate any suggestions. Peter Back to top Peter Below (TeamB) Guest Posted: Sun Oct 08, 2006 2:21 pm    Post subject: Re: Bitmap from OLEVariant? Peter C wrote: Quote: I have a function that returns a Device Independant Bitmap in an OLEVariant variable, but I do not know how to use this. How can I transfer the DIB from the OLEVariant to a TBitmap object or other graphics object? That depends completely on what the variant you get actually contains. If it if a variant array of bytes ((VarType(theVariant) AND varTypeMask) = varByte) and VarIsArray(theVariant)) it may just contain the same data you could find in a BMP file. In this case the following should work (V is the variant): Var ms: TMemoryStream; len, i: Integer; p: POinter; Begin ms: TMemoryStream.Create; try len:= VarArrayHighBound( V, 1 ) - VarArrayLowBound(V, 1) + 1; p:= varArrayLock( V ); try ms.Writebuffer( p^, len ); finally varArrayUnlock( V ); end; ms.Position := 0; aBitmap.LoadFromStream(ms); finally ms.free end; If this does not work start by figuring out the actual type of the variant data, by examining the result of VarType. -- Peter Below (TeamB) Don't be a vampire (http://slash7.com/pages/vampires), use the newsgroup archives : http://www.tamaracka.com/search.htm http://groups.google.com http://www.prolix.be Back to top Peter C Guest Posted: Mon Oct 09, 2006 8:11 am    Post subject: Re: Bitmap from OLEVariant? Thanks Peter, This helped a lot. I had been doing something similiar, but I did not know I had to lock the array, which made all the difference. I also had to generate a 14 byte Bitmap File Header and write it too the stream before I wrote the DIB content. Everything now seems to be working fine. Thanks Again, Peter Collas "Peter Below (TeamB)" <none> wrote in message news:xn0es82tl2obzs001 (AT) newsgroups (DOT) borland.com... Quote: Peter C wrote: I have a function that returns a Device Independant Bitmap in an OLEVariant variable, but I do not know how to use this. How can I transfer the DIB from the OLEVariant to a TBitmap object or other graphics object? That depends completely on what the variant you get actually contains. If it if a variant array of bytes ((VarType(theVariant) AND varTypeMask) = varByte) and VarIsArray(theVariant)) it may just contain the same data you could find in a BMP file. In this case the following should work (V is the variant): Var ms: TMemoryStream; len, i: Integer; p: POinter; Begin ms: TMemoryStream.Create; try len:= VarArrayHighBound( V, 1 ) - VarArrayLowBound(V, 1) + 1; p:= varArrayLock( V ); try ms.Writebuffer( p^, len ); finally varArrayUnlock( V ); end; ms.Position := 0; aBitmap.LoadFromStream(ms); finally ms.free end; If this does not work start by figuring out the actual type of the variant data, by examining the result of VarType. -- Peter Below (TeamB) Don't be a vampire (http://slash7.com/pages/vampires), use the newsgroup archives : http://www.tamaracka.com/search.htm http://groups.google.com http://www.prolix.be Back to top Warrick Wilson Guest Posted: Wed Oct 11, 2006 9:06 pm    Post subject: Re: Bitmap from OLEVariant? "Peter C" <ozcelt (AT) hotmail (DOT) com> wrote in message news:4529da11 (AT) newsgroups (DOT) borland.com... Quote: Thanks Peter, This helped a lot. I had been doing something similiar, but I did not know I had to lock the array, which made all the difference. I also had to generate a 14 byte Bitmap File Header and write it too the stream before I wrote the DIB content. Everything now seems to be working fine. Thanks Again, Peter Collas Peter C, Any chance you could post your updated routine that solves the problem so that this thread becomes a complete solution? Having that will help the next guy who comes along with your question. Thanks...Warrick Back to top Peter C Guest Posted: Sun Oct 15, 2006 8:11 am    Post subject: Re: Bitmap from OLEVariant? Here's the basics of my solution. I'm using an OLEControl which returns a DIB. For anyone interested, the control is called Facesnap which has come from the C-VIS company in Germany. It's a brilliant little control which reads graphics from a file or Twain device, identifies faces, and automatically crops and color balances the image so it can be used in ID passes. Apologies for the cryptic variable names! Cheers, Peter C type BMPfileheader = record BMPType : Smallint; Size : LongInt; Reserved1 : SmallInt; Reserved2 : SmallInt; OhFileBits : LongInt; end; Const BMP_LABEL : Integer = 19778; var v : OLEVariant; o : TOleContainer; m : TMemoryStream; i,l : Integer; p : Pointer; h : bmpfileheader; j : TJPEGImage; b : TBitmap; begin h.BMPType := BMP_LABEL; h.OhFileBits := 54; // Accounts for the size of the BMP Header and the Device Information already in the Bitmap //........Call Ole Control which returns a Device Independant Bitmap!!! m:= TMemoryStream.Create; try l:= VarArrayHighBound( v, 1 ) - VarArrayLowBound(v, 1) + 1; h.Size := l + 55; // Sets the total size of the Bitmap that will be created by Appending the DIB to the BMP Header p:= varArrayLock( v ); try m.WriteBuffer( h , 14 ); // Load Header in First m.Writebuffer( p^, l ); // Load in DIB finally varArrayUnlock( v ); end; m.Position := 0; b := TBitmap.Create; j := TJPEGImage.Create; b.LoadFromStream(m); j.Assign(b); Image1.Picture.Graphic := j; // Image1.Picture.Bitmap.LoadFromStream(m); finally m.free; b.Free; j.Free; o.DestroyObject; end; "Warrick Wilson" <warrickw (AT) mercuryonline (DOT) com> wrote in message news:452d171f$1 (AT) newsgroups (DOT) borland.com... Quote: "Peter C" <ozcelt (AT) hotmail (DOT) com> wrote in message news:4529da11 (AT) newsgroups (DOT) borland.com... Thanks Peter, This helped a lot. I had been doing something similiar, but I did not know I had to lock the array, which made all the difference. I also had to generate a 14 byte Bitmap File Header and write it too the stream before I wrote the DIB content. Everything now seems to be working fine. Thanks Again, Peter Collas Peter C, Any chance you could post your updated routine that solves the problem so that this thread becomes a complete solution? Having that will help the next guy who comes along with your question. 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