Rendering interactive Pdf forms to images issue

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   We are using QPDF version 17.11 for the document management with Delphi Xe10. The problem appears when we use PDFium engine to render Pdf interactive Form pages into images. Namely, the context of the form controls is blank on an image. Yet the only possible solution I found seems is flattening forms into plain Pdf. Is this the only way to go? 

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Vladimir Members Profile Find Members Posts Beginner Joined: 23 Feb 22 Location: Canada Status: Offline Points: 4	Post Options Post Reply Quote Vladimir Report Post Thanks(0) Quote Reply Topic: Rendering interactive Pdf forms to images issue Posted: 23 Feb 22 at 2:32PM
	We are using QPDF version 17.11 for the document management with Delphi Xe10. The problem appears when we use PDFium engine to render Pdf interactive Form pages into images. Namely, the context of the form controls is blank on an image. Yet the only possible solution I found seems is flattening forms into plain Pdf. Is this the only way to go?

Vladimir Members Profile Find Members Posts Beginner Joined: 23 Feb 22 Location: Canada Status: Offline Points: 4	Post Options Post Reply Quote Vladimir Report Post Thanks(0) Quote Reply Posted: 23 Feb 22 at 10:13PM
	It looks that flattening forms' fields (FlattenAllFormFields()) doesn't work with Delphi FoxIt library. Adding a call for SetRenderOptions() to include rendering form controls has no affect neither. The interactive AcroForm are still precented with empty fields when rendering to an Image. Something is broken there ... Any ideas?

tfrost Members Profile Find Members Posts Senior Member Joined: 06 Sep 10 Location: UK Status: Offline Points: 437	Post Options Post Reply Quote tfrost Report Post Thanks(0) Quote Reply Posted: 24 Feb 22 at 11:14AM
	I have also found that QPDF fails to render form field content for some (but not all) samples of PDF documents with form fields. We are using v18 and Delphi 10.4.2. To show form field content reliably we have to use the PDFIUM DLL, but I have not tested with the QPDF rendering option which selects the use of this DLL. When you say you use PDFIUM, do you mean that you use the QPDF option to select it, or do you instead call it directly or via the Winsoft wrapper?

Vladimir Members Profile Find Members Posts Beginner Joined: 23 Feb 22 Location: Canada Status: Offline Points: 4	Post Options Post Reply Quote Vladimir Report Post Thanks(0) Quote Reply Posted: 24 Feb 22 at 2:35PM
	Well, we built a wrapper for Foxit Quick PDF Library (DebenuPDFLibrary1711.pas etc.) with setting the rendering engine to PDFium. I tried to render at least two Pdf AcroForm docs and both show blank form fields when pages rendered to images. Neither SetRenderOptions(1, 1) (forcing the FGDIPlusSettings.RenderFormFields) nor FlattenAllFormFields() affect the result. Switching back to DPLR rendering engine brings form fields back, however with DPLR we see poor OCR results in some docs (unreadable characters). Any suggestions? Thanks!