Hi GroupDocs Support,
I encountered a rendering issue using GroupDocs.Viewer when previewing a PDF document.
In the original PDF, there is some text that is intentionally hidden behind a filled rectangle or shape (used for masking or redaction purposes). When I open the document in Adobe Acrobat or Chrome PDF Viewer, the text is correctly blocked/covered and not visible.
However, when the same document is rendered using GroupDocs.Viewer, the text appears visible, because the blocking shape is rendered behind the text, not in front of it as intended. This appears to be a layering issue (Z-ordering) in the rendering engine.
It seems that GroupDocs:
- Converts the PDF content to an image (or HTML layout),
- But draws the text layer above image-based content (even if the text was originally underneath a shape).
This leads to previously hidden or intentionally blocked content becoming clearly visible, which is a major concern for confidentiality.
Steps to Reproduce:
- Open the attached PDF (
IN0001_2022-23.pdf
) in Adobe Acrobat — observe the text behind shapes is properly blocked. - Render the same document using
GroupDocs.Viewer
in HTML mode. - Observe that the blocked text becomes visible, because the overlaying shape is rendered behind the text.
IN0001_2022-23.pdf (166.9 KB)