THPDFViewer Coordinate Transforms

Converts points bidirectionally between PDF page space and the rendered Viewer bitmap

Point type

THPDFViewerPoint= record
  X: Single;
  Y: Single;
end;

Declarations

function PagePointToView(PageIndex: Integer;
  const PagePoint: THPDFViewerPoint; out ViewPoint: THPDFViewerPoint;
  DPI: Integer= 150): boolean;
function ViewPointToPage(PageIndex: Integer;
  const ViewPoint: THPDFViewerPoint; out PagePoint: THPDFViewerPoint;
  DPI: Integer= 150): boolean;

Coordinate spaces

• PDF page coordinates use the visible page box, the CropBox clipped to the MediaBox, and a lower-left origin
• Viewer coordinates use rendered pixels and a top-left origin
• The PDF page /Rotate value is applied before ViewRotation
• DPI values below 1 use 1; higher values remain exact so transforms match the full Viewer zoom range
• Invalid page state returns False and clears the output point

Round trip

if Model.PagePointToView(0, PagePoint, ViewPoint, 144) then
  Model.ViewPointToPage(0, ViewPoint, RestoredPoint, 144);