⚠️ Technical Insight: Unlike image editors that "paint" pixels, PDF Watermarking creates a
floating vector layer on top of the existing content stream.
⚙️ The Overlay Algorithm
1. Coordinate Calculation
The engine first calculates the viewport matrix of the page (UserUnit). It determines the precise center (x, y) coordinates relative to the rotation of the existing page.
2. Alpha Blending (Opacity)
We use an Alpha Channel value between 0.0 and 1.0. This ensures the text behind the watermark remains readable, essential for legal documents.
3. Vector Injection
The text "CONFIDENTIAL" is injected as a vector path, not an image. This means even if you zoom in 5000%, the watermark remains crisp.