THPDFViewerHighlight Record

Stores a single page-anchored highlight rectangle and its colour in the viewer model

Declaration

THPDFViewerHighlight= record
  PageIndex: Integer;
  PageRect: THPDFRectangle;
  Color: TColor;
end;

HPDFViewerModel

Field	Purpose
`PageIndex`	Zero-based index of the page to which the highlight is anchored
`PageRect`	Rectangle in PDF user space; `AddHighlightRegion` normalises it and clamps it to the page MediaBox before storing it
`Color`	TColor used when drawing the highlight; `clYellow` by default

Create highlights with THPDFViewerModel.AddHighlightRegion, read them back with TryGetHighlightRegion and remove them with RemoveHighlightRegion or ClearHighlightRegions
Rectangles that collapse once clamped to the MediaBox are rejected, and AddHighlightRegion returns -1
Each change fires the model's OnHighlightChange event so that hosts can repaint