This commit introduces a detailed migration plan to replace the
`PDF.js` rendering engine with `DxPdfViewer` in the receiver
signing experience (`EnvelopeReceiverPage.razor`). The migration
preserves the existing signing workflow and behavior while
introducing a new rendering layer.
Key changes:
- Replaced `PDF.js` rendering surface with `DxPdfViewer`.
- Preserved page-level orchestration for authorization, document
loading, signature handling, and toolbar interactions.
- Introduced a custom overlay adapter for signature placeholders
and applied signature overlays.
- Centralized page/zoom geometry acquisition for overlay alignment.
- Maintained signature navigation logic and thumbnail sidebar
behavior.
- Updated `pdf-viewer.js` to separate engine-specific logic and
adapt it for `DxPdfViewer`.
- Updated styles in `envelope-viewer.css` to support the new viewer.
This migration ensures that all existing workflow behaviors remain
functional, including navigation, zoom, signature placement, and
validation, while transitioning to the new rendering engine.
Added `RECEIVER_PDF_VIEWER_CONTEXT.md` to the `src` project, documenting the current implementation and behavior of the receiver-side PDF viewing and signing experience in the `EnvelopeGenerator` project.
The document outlines the use of `PDF.js` as the current rendering engine, the planned migration to `DxPdfViewer`, and the functional capabilities that must be preserved. Key features include single-page PDF viewing, navigation, zoom, signature overlays, and metadata validation.
This addition ensures clarity for future development and emphasizes the importance of maintaining existing workflows during the migration or other changes.
