Which bytes should be edited in a WMF hex string stored in an RTF file in order to change image dimensions?

Question

I  would like to save the WMF file with proper dimensions as they are in the editor (my saved WMFs have the dimensions of my screen resolution).  They come from a RichEdit.
Thanks.
Edit:
My goal is to convert the images that appear on a RichEdit to another format.
Here is the fragment of the RTF:
{\pict\wmetafile8\picw7407\pich9259\picwgoal4199\pichgoal5249 
010009000003703e020000005a3e02000000050000000b0200000000050000000c022b24ef1c5a
ffffffffffffff030000000000
}\cf2\lang1033\b\f1\fs23\par
For each 2 chars in this string I converted it to hex and saved it through a memory stream. Then I opened it in Paint or GIMP and there is the image.  I even can convert it to a PNG file through ImageMagick tool. But the dimensions are wrong. How to fix
this?
I am using Lazarus.
I could guess that the header is not OK, but how they can be opened by Paint and converted? So I guess the dimensions info is wrong in the header. In GIMP even the dimensions are right, here a link to the GIMP's dialogbox confirmation with the dimensions
it has encountered in the file (  http://s13.postimg.org/s536tgo9z/Metafile_in_GIMP.png  ).
So the info is there, but is wrong. When I open the images in Paint, they are wrong. Microsoft Office Picture Manager can also open them correctly, but could not convert them so. I need to do it programmatically. TMetafile Delphi class could not open these
files as well in order to be converted. So I could only edit the bytes.
My RichEdit WMF data can not be accepted by ComputeAldusChecksum routine nor get a handle from SetWinMetaFileBits API call, which would convert it to an EMF format.
procedure TMetafile.ReadWMFStream(Stream: TStream; Length: Longint);
var
WMF: TMetafileHeader;
BitMem: Pointer;
MFP: TMetaFilePict;
begin
NewImage;
Stream.Read(WMF, SizeOf(WMF));
if (WMF.Key <> WMFKEY) or (ComputeAldusChecksum(WMF) <> WMF.CheckSum) then
raise EComponentError.Create('Invalid metafile.'); // <<<<<<<<<<<<<<< exception here
Dec(Length, SizeOf(WMF));
GetMem(Bitmem, Length);
with FImage do
try
Stream.Read(BitMem^, Length);
FImage.FInch := WMF.Inch;
if WMF.Inch = 0 then
WMF.Inch := 96;
FWidth := MulDiv(WMF.Box.Right - WMF.Box.Left,25400,WMF.Inch);
FHeight := MulDiv(WMF.Box.Bottom - WMF.Box.Top,25400,WMF.Inch);
with MFP do
begin
MM := MM_ANISOTROPIC;
xExt := 0;
yExt := 0;
hmf := 0;
end;
FHandle := SetWinMetaFileBits(Length, BitMem, 0, MFP); 
if FHandle = 0 then
raise EComponentError.Create('Invalid metafile.'); // <<<<<<<<<<<<<< exception here
Enhanced := False;
finally
Freemem(BitMem, Length);
end;
end;

Answer 1

Hi Antônio G,
Based on your description, I’m afraid that it is not the correct forum for this issue, since this forum is to discuss:
Visual Studio WPF/SL Designer, Visual Studio Guidance Automation Toolkit, Developer Documentation and Help System, and Visual Studio Editor.
To make this issue clearly, would you mind letting us know more information about this issue? Which language are you using? Which kind of app are you developing?
Reference:
https://social.msdn.microsoft.com/Forums/vstudio/en-US/a9e1857d-dd5b-443b-8633-397aea6e7b8c/help-on-properly-handling-wmf-mmanisotropic-image-in-rtf-file-when-extracted?forum=csharpgeneral
https://social.msdn.microsoft.com/Forums/vstudio/en-US/5b99d331-ef56-4d60-bf12-3e3b70783376/how-to-convert-a-hex-string-save-in-a-rtf-file-into-an-image-jpg-or-bmp?forum=csharpgeneral#a9219408-f73b-4e98-a9d8-7a1e0f20cdd9
Maybe you could select the language development forum for this kind of issue. If not, please let me know more information about it, I will help you find a more appropriate forum.
Best Regards,
Jack
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