Writing PNG images using streams fails in V2.0 when targeting .ods
format.
lazarus / 49-FPSpreadsheet

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Russ · 2025-09-23 12:58

There is an issue when writing PNG images to worksheets using streams
in V2.0 that didn't manifest in V1.16:

When PNG image(s) are written to a sheet using a stream through the
TsWorkSheet.WriteImage() and the resultant workbook is then written to
disk in .ods format, when attempting to open the document in Libre
Office Calc, a read error "Format error discovered in the file in sub-
document content.xml at 1,4468(row,col)" is thrown. When the image is
written using the File version of the TsWorksheet.WriteImage()
function where the image is loaded from a PNG file, then everything
works. There are no problems with .xlsx format.

The .ods archives were unpacked and the problems found are the
following:
In the Picture directory there are no images.In content.xml the field
<draw:image xlink:href="Pictures/" has no images listed.manifest.xml
has the same problem.In addition, if the user (me  ) uses the same
stream to load multiple images and forgets to clear the stream between
loading images, then the application hangs. There is a fix that stops
the app from hanging, but won't stop the wrong image from being
loaded.
  
A patch is attached.

The test project:Code: Pascal  [Select][+][-]window.onload =
function(){var x1 = document.getElementById("main_content_section");
if (x1) { var x = document.getElementsByClassName("geshi");for (var i
= 0; i program project1;uses  SysUtils, Classes, Graphics, LCLIntf,
fpSpreadsheet, fpsTypes, fpsallformats;var  wbook: TsWorkbook; 
wsheet: TsWorksheet;  image1: TPortableNetworkGraphic;  image2:
TPortableNetworkGraphic;  astream: TMemoryStream; begin  wbook :=
TsWorkbook.create;  image1 := TPortableNetworkGraphic.Create;  image2
:= TPortableNetworkGraphic.Create;  astream:= TMemoryStream.Create; 
try    (* In the target application the image is created by the app
and not loaded from a file. *)    image1.LoadFromFile('Image1.png'); 
 image2.LoadFromFile('Image2.png');     (* Writing the image to the
sheet directly from a file works for both .ods and .xlsx formats. *) 
 //wsheet := wbook.AddWorksheet('Image1');    //wsheet.WriteImage(0,
0, 'Image1.png');    //wsheet := wbook.AddWorksheet('Image2');   
//wsheet.WriteImage(0, 0, 'Image2.png');   
//wbook.WriteToFile('Test1_WriteImage(File).xlsx', true);   
//wbook.WriteToFile('Test1_WriteImage(File).ods', true);   
//wbook.clear;     (* Copying a spreadsheet containing the image from
excel to calc format works. *)   
//wbook.ReadFromFile('Test1_WriteImage(File).xlsx');   
//wbook.WriteToFile('Test2_SpreadsheetCopy.ods', true);     (*     
Writing the image to the sheet using a stream works on V1.16, but not
on V2.00.      Attempting to open image_03.ods in Calc results in an
error:      Format error discovered in the file in sub-document
content.xml at 1,4466(row,col).    *)    wbook.Clear;    wsheet :=
wbook.AddWorksheet('Image 1');    image1.SaveToStream(astream);   
wsheet.WriteImage(0, 0, astream, 1.0, 1.0);    wsheet :=
wbook.AddWorksheet('Image 2');     astream.Clear; // If this was
forgotten, the application used to hang - now loads Image1 for
Image2.    image2.SaveToStream(astream);    wsheet.WriteImage(0, 0,
astream, 1.0, 1.0);   
wbook.WriteToFile('Test3_WriteImage(Stream).xlsx', true);   
wbook.WriteToFile('Test3_WriteImage_01(Stream).ods', true);    
OpenDocument('Test3_WriteImage_01(Stream).ods');   finally   
wbook.Free;    image1.Free;    image2.Free;    astream.Free;  end;end.

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wp · 2025-09-23 20:16

Thanks for analyzing the situation and providing a patch. Applied to
ccr-svn.