THotPDF Loaded Form Field Editing Methods

Updates field constraints and widget appearance dictionaries in an existing AcroForm with correct incremental saving

Methods

SetLoadedFormFieldFlags  SetLoadedFormFieldMaxLength  SetLoadedFormFieldJustification
GetLoadedFormFieldWidgetCount  GetLoadedFormFieldWidgetRect  SetLoadedFormFieldWidgetRect
SetLoadedFormFieldRotation  SetLoadedFormFieldBorderColor  SetLoadedFormFieldVisibility

• SetLoadedFormFieldFlags replaces the complete PDF /Ff bit mask
• SetLoadedFormFieldMaxLength writes /MaxLen; zero or a negative value removes the limit
• THPDFFormFieldJustification contains ffjLeft, ffjCenter, and ffjRight for PDF /Q values 0 through 2

Widget geometry

function GetLoadedFormFieldWidgetCount(FieldIndex: Integer): Integer;
function GetLoadedFormFieldWidgetRect(FieldIndex, WidgetIndex: Integer;
  out ARect: THPDFRect): boolean;
procedure SetLoadedFormFieldWidgetRect(FieldIndex, WidgetIndex: Integer;
  X1, Y1, X2, Y2: Single);

• Field and widget indexes are zero based
• Widget enumeration exposes every /Kids entry of radio groups and other multi-widget fields
• Rectangle endpoints use raw PDF user-space points and are normalised before writing

Widget appearance and visibility

procedure SetLoadedFormFieldRotation(FieldIndex, ADegrees: Integer);
procedure SetLoadedFormFieldBorderColor(FieldIndex: Integer;
  ARed, AGreen, ABlue: Single);
procedure SetLoadedFormFieldVisibility(FieldIndex: Integer;
  AVisible, APrintable: boolean);
procedure SetLoadedFormFieldBorderWidth(FieldIndex: Integer; AWidth: Single);
procedure SetLoadedFormFieldBackgroundColor(FieldIndex: Integer;
  ARed, AGreen, ABlue: Single);

• Rotation accepts positive or negative multiples of 90 degrees and stores the normalised /MK /R value
• Border and background RGB components are clamped to the PDF DeviceRGB range from 0 through 1
• Appearance and visibility setters update every widget belonging to the selected field
• Visibility preserves unrelated annotation flags while controlling Hidden, NoView, and Print

Incremental update behaviour

• Field, widget, /MK, and /BS dictionaries are marked dirty at the level where each value is stored
• Visual changes invalidate only the affected page's cached DPI variants
• Invalid field or widget indexes leave the document unchanged

Example

PDF.BeginIncrementalUpdate('input.pdf');
PDF.SetLoadedFormFieldMaxLength(0, 40);
PDF.SetLoadedFormFieldJustification(0, ffjCenter);
PDF.SetLoadedFormFieldRotation(0, 90);
PDF.SetLoadedFormFieldBorderColor(0, 0.1, 0.4, 0.8);
PDF.SetLoadedFormFieldWidgetRect(1, 1, 80, 150, 100, 170);
PDF.SaveIncrementalUpdate('updated.pdf');

Related APIs

Loaded form field methods · Loaded document toolkit · THotPDF