PDFium Component: annotation review UI в Delphi

Встраивайте workflow PDFium VCL Component в приложения Delphi и C++Builder или workflow PDFium LCL Component в Lazarus/FPC, используя компоненты с исходным кодом для просмотра, рендеринга, форм, печати, preflight-отчетов и проверки по стандартам.

Эта статья предназначена для teams adding review, markup, approval, or quality-control panels to a Delphi PDF viewer. Она рассматривает annotation review UI как промышленную инженерию документов, а не как одиночный вызов компонента.

Практический риск состоит в том, что annotations are easy to display but hard to trust when page rotation, authorship, replies, hidden states, or coordinate conversions are not handled consistently. Поэтому процессу нужны письменный контракт, наблюдаемая диагностика и реалистичные регрессионные файлы.

Архитектурные решения

Separate review state from page rendering. which annotation types can be viewed, filtered, replied to, exported, or locked / author identity, status labels, and whether review data is stored in the PDF

which annotation types can be viewed, filtered, replied to, exported, or locked
author identity, status labels, and whether review data is stored in the PDF
coordinate conversion for rotation, zoom, crop boxes, and high-DPI displays
read-only mode for signed, protected, or externally governed documents

Порядок реализации

Index annotations before showing review actions. The order below keeps the workflow reviewable for Delphi and C++Builder teams.

load annotation metadata into a review index before painting page overlays
normalize page coordinates and keep a stable reference for every annotation
apply filters by author, status, type, page, and date without re-parsing pages
tie selection in the review list to viewport navigation and highlight behavior
export review summaries with enough context for non-viewer workflows

Доказательства проверки

Review evidence that supports collaboration. Keep these fields with the output or support record.

annotation type, author, page, bounds, status, and reply count
coordinate transform used for the current zoom, rotation, and crop box
permission decision when a user attempts to edit a locked or signed document
exported review summary with stable page references

Coordinates and intent matter

A professional review UI treats annotations as structured data with authors, dates, page locations, appearance, replies, status, and permissions. The canvas view is only one presentation of that model.

Customer-visible behavior

Users do not see internal call order. They see whether the file opens, validates, prints, edits, imports, or gets rejected. The workflow should translate annotation review UI results into states users can act on.

load annotation metadata into a review index before painting page overlays
normalize page coordinates and keep a stable reference for every annotation
apply filters by author, status, type, page, and date without re-parsing pages
rotated pages can make highlights appear detached from the original text
popup annotations and replies may be missed when only visible marks are scanned

Замечания для инженерного ревью по annotation review UI

Используйте эти замечания, чтобы убедиться, что функция вышла за рамки демо и может быть обоснована на релизе, в поддержке и при эскалации клиента

Решение: which annotation types can be viewed, filtered, replied to, exported, or locked. Точка приложения при реализации: normalize page coordinates and keep a stable reference for every annotation. Доказательство приемки: permission decision when a user attempts to edit a locked or signed document. Триггер регрессии: annotations on cropped pages need coordinates tied to the intended page box
Решение: author identity, status labels, and whether review data is stored in the PDF. Точка приложения при реализации: apply filters by author, status, type, page, and date without re-parsing pages. Доказательство приемки: exported review summary with stable page references. Триггер регрессии: rotated pages can make highlights appear detached from the original text
Решение: coordinate conversion for rotation, zoom, crop boxes, and high-DPI displays. Точка приложения при реализации: tie selection in the review list to viewport navigation and highlight behavior. Доказательство приемки: annotation type, author, page, bounds, status, and reply count. Триггер регрессии: popup annotations and replies may be missed when only visible marks are scanned
Решение: read-only mode for signed, protected, or externally governed documents. Точка приложения при реализации: export review summaries with enough context for non-viewer workflows. Доказательство приемки: coordinate transform used for the current zoom, rotation, and crop box. Триггер регрессии: read-only review must still allow selection, navigation, filtering, and export
Решение: which annotation types can be viewed, filtered, replied to, exported, or locked. Точка приложения при реализации: load annotation metadata into a review index before painting page overlays. Доказательство приемки: permission decision when a user attempts to edit a locked or signed document. Триггер регрессии: annotations on cropped pages need coordinates tied to the intended page box
Решение: author identity, status labels, and whether review data is stored in the PDF. Точка приложения при реализации: normalize page coordinates and keep a stable reference for every annotation. Доказательство приемки: exported review summary with stable page references. Триггер регрессии: rotated pages can make highlights appear detached from the original text
Решение: coordinate conversion for rotation, zoom, crop boxes, and high-DPI displays. Точка приложения при реализации: apply filters by author, status, type, page, and date without re-parsing pages. Доказательство приемки: annotation type, author, page, bounds, status, and reply count. Триггер регрессии: popup annotations and replies may be missed when only visible marks are scanned

Пограничные случаи

rotated pages can make highlights appear detached from the original text
popup annotations and replies may be missed when only visible marks are scanned
read-only review must still allow selection, navigation, filtering, and export
annotations on cropped pages need coordinates tied to the intended page box

Примечания по Delphi / C++Builder

PDFium Component should sit behind a small service boundary that receives files, streams, profiles, and credentials, then returns output paths, warnings, metrics, and validation status. Важные термины включают annotation, markup, reply, page bounds, rotation, review status.

Пример кода Delphi

Следующий эскиз Delphi показывает практическую границу сервиса для этой темы. Оставляйте проверки политики, журналирование и валидацию вне узкого блока вызова продукта, чтобы сценарий было проще тестировать.

procedure TReviewForm.LoadAnnotationQueue(const FileName: string);
var
  PageNo: Integer;
begin
  PdfView.LoadFromFile(FileName);
  FQueue.Clear;
  for PageNo := 1 to PdfView.PageCount do
    AddPageAnnotationsToQueue(PdfView, PageNo, FQueue);
  FQueue.SortByAuthorAndDate;
  ShowNextReviewItem;
end;

Производственный чек-лист

Запускайте сценарий на пустом файле, обычном клиентском файле и файле худшего случая
Открывайте сгенерированный PDF в целевом просмотрщике, валидаторе, принтере или downstream-приложении
Записывайте версию продукта, версию профиля, хэш входа, путь вывода, затраченное время и число предупреждений
Храните пароли, сертификаты, временные файлы и данные клиентов по явным правилам хранения
Добавляйте регрессионные документы, когда клиентский файл выявляет новый граничный случай

Документация по продукту

PDFium Component

Дополнительные примеры кода

A := Pdf.Annotation[Item.Index];
A.HasColor := True;
A.Color := $0000B0FF;       // amber
A.ColorAlpha := 160;
try
  Pdf.Annotation[Item.Index] := A;
except
  on EPdfError do
  begin
    // The annotation owns a pre-rendered /AP stream; the dictionary
    // color alone cannot change what viewers paint
    Item.AppearanceLocked := True;
    StatusBar.SimpleText := 'Color is fixed by the annotation appearance';
  end;
end;

Pdf.PageNumber := Item.PageNo;
Pdf.DeleteAnnotation(Item.Index);   // raises EPdfError on failure
Bmp := Pdf.RenderPage(0, 0, ViewWidth, ViewHeight, ro0, [reAnnotations]);
try
  PaintPageBitmap(Bmp);
finally
  Bmp.Free;  // RenderPage hands bitmap ownership to the caller
end;
RebuildPageEntries(Item.PageNo);  // indices after Item.Index shifted