ApplyOcrSearchLayer - TPdf - PDFium Delphi Component

Component: TPdf · Unit: PDFium

Adds an invisible searchable text layer to scanned pages through an application OCR provider

Syntax

function ApplyOcrSearchLayer(
  const Provider: IPdfOcrProvider;
  const Options: TPdfOcrOptions;
  out Report: TPdfOcrReport;
  const CancellationToken: IPdfCancellationToken = nil): Boolean;

Provider contract

The library renders each selected page through PDFium and passes a compact top-down popfBgra32 image to IPdfOcrProvider.RecognizePage

The provider returns TPdfOcrWord values whose Quad coordinates use pixel units with the origin at the image top left

Text confidence must be in the range 0 through 1 and quadrilateral points must remain inside the supplied image

Output behaviour

Native FPDF_DeviceToPage mapping preserves page boxes and intrinsic rotation
Accepted words become native text objects with FPDF_TEXTRENDERMODE_INVISIBLE
Existing page images and vector content are not decoded or re-encoded
Each page is committed once and failed insertions are removed before the method continues
The returned TPdfOcrReport totals ProcessedPageCount, FailedPageCount, DetectedWordCount, InsertedWordCount, RejectedWordCount, and TotalRenderedPixels, while each TPdfOcrPageReport entry adds per-page ImageWidth, ImageHeight, DetectedWordCount, InsertedWordCount, and RejectedWordCount
The previously active page is restored before the method returns

Options and budgets

FirstPage and LastPage select an inclusive range, while zero selects the document boundary

SkipPagesWithText avoids duplicating an existing searchable layer and ContinueOnError controls page-level recovery

Budgets enforced fail-closed before page mutation cover MaxPixelsPerPage and MaxTotalPixels pixels, MaxWordsPerPage and MaxTotalWords words, MaxWordCharacters characters per word, plus confidence and DPI

Example

var
  Options: TPdfOcrOptions;
  Report: TPdfOcrReport;
begin
  Options := TPdfOcrOptions.Default;
  Options.Dpi := 300;
  Options.MinConfidence := 0.75;
  if Pdf1.ApplyOcrSearchLayer(OcrProvider, Options, Report) then
    Pdf1.SaveAs('searchable.pdf');
end;

ApplyOcrSearchLayer method