LlosLab Software Development BlogTechnische notities voor ontwikkelaars van PDF-, Delphi- en documentsoftware.

Technical Article

PDF-annotaties beheersen met de HotPDF Delphi-component

· PDF-programmeren

Een ontwikkelaarsgids voor PDF-annotaties met de HotPDF Delphi-component, inclusief interactieve en visuele annotatiepatronen.

Dit artikel is bedoeld voor ontwikkelaars die met pdf-programmeren werken. Productnamen, API-namen, bestandsnamen en codefragmenten zijn bewust ongewijzigd gehouden, zodat de voorbeelden direct met de oorspronkelijke documentatie en broncode te vergelijken zijn.

Overzicht

De pagina beschrijft het probleemgebied, de relevante implementatiekeuzes en de controles die belangrijk zijn voordat de oplossing in een echte toepassing wordt gebruikt.

Codevoorbeeld

Het onderstaande codefragment is ongewijzigd uit de Engelse bron overgenomen om identifiers, API-aanroepen en syntaxis exact te behouden.

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program SimpleAnnotation;
{$I ..\..\..\Lib\HotPDF.inc}
{$APPTYPE CONSOLE}
 
uses
  {$IFDEF XE2+}
  System.Classes,
  System.SysUtils,
  Vcl.Graphics,
  {$ELSE}
  Classes,
  SysUtils,
  Graphics,
  {$ENDIF}
  HPDFDoc;
 
var
  HotPDF: THotPDF;
begin
  HotPDF := THotPDF.Create(nil);
  try
    // Configure PDF basic properties
    HotPDF.FileName := 'SimpleAnnotation.pdf';
    HotPDF.Title := 'Simple Annotation Demo';
    HotPDF.Author := 'HotPDF Component';
    
    // Set font embedding for consistent display
    HotPDF.FontEmbedding := True;
    
    HotPDF.BeginDoc;
    
    // Set font
    HotPDF.CurrentPage.SetFont('Arial', [], 12, 0, False);
    
    // Add page content
    HotPDF.CurrentPage.TextOut(120, 65, 0, 'Click the annotation icon:');
    
    // Add multilingual text annotations
    HotPDF.CurrentPage.AddTextAnnotation(
      'This is a text annotation.' + #13#10 +
      'Dies ist eine Textanmerkung.' + #13#10 +
      'Ceci est une annotation textuelle.' + #13#10 +
      'This is a text annotation.',
      Rect(120, 80, 140, 100), True, taComment, clBlue
    );
    
    HotPDF.EndDoc;
  finally
    HotPDF.Free;
  end;
end.
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// Available text annotation type enumeration
THPDFTextAnnotationType = (
  taComment,        // Standard comment bubble
  taKey,           // Key symbol for important notes
  taNote,          // Note icon for general information
  taHelp,          // Help icon for help text
  taNewParagraph,  // New paragraph marker
  taParagraph,     // Paragraph marker
  taInsert         // Content insertion marker
);
 
// Usage examples for different types
procedure AddTextAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding text annotations...');
 
  // Section header text
  PDF.CurrentPage.TextOut(50, 80, 0, 'Text Annotations - Different Types and Colors:');
 
  // Critical annotation with multilingual content
  PDF.CurrentPage.AddTextAnnotation(
    'CRITICAL: This is a critical comment annotation requiring immediate attention.' + #13#10 +
    'KRITISCH: Dies ist eine kritische Textanmerkung.' + #13#10 +
    'CRITIQUE: Ceci est une annotation critique.',
    Rect(50, 95, 70, 115), True, taComment, clRed
  );
 
  // Key point annotation
  PDF.CurrentPage.AddTextAnnotation(
    'KEY POINT: Important information marker' + #13#10 +
    'This annotation uses the key icon for emphasis.',
    Rect(80, 100, 100, 120), False, taKey, $0080FF // Orange
  );
 
  // Help annotation
  PDF.CurrentPage.AddTextAnnotation(
    'HELP: Click for additional assistance' + #13#10 +
    'This help annotation provides user guidance.',
    Rect(110, 100, 130, 120), False, taHelp, clBlue
  );
 
  // General note annotation
  PDF.CurrentPage.AddTextAnnotation(
    'NOTE: General information annotation' + #13#10 +
    'Standard note for supplementary information.',
    Rect(140, 100, 160, 120), False, taNote, clGreen
  );
 
  // Insert marker annotation
  PDF.CurrentPage.AddTextAnnotation(
    'INSERT: Content insertion marker' + #13#10 +
    'Indicates where new content should be added.',
    Rect(170, 100, 190, 120), False, taInsert, $800080 // Purple
  );
end;
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// Free text alignment options enumeration
THPDFFreeTextAnnotationJust = (
  ftLeftJust,   // Left-aligned text
  ftCenter,     // Center-aligned text
  ftRightJust   // Right-aligned text
);
 
// Example: Create free text annotations with different alignments
procedure AddFreeTextAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding free text annotations...');
 
  // Section header
  PDF.CurrentPage.TextOut(50, 160, 0, 'Free Text Annotations - Different Alignments:');
 
  // Left-justified free text
  PDF.CurrentPage.AddFreeTextAnnotation(
    'LEFT TEXT ANNOTATION',
    Rect(50, 180, 200, 200),
    ftLeftJust,
    $008000 // Green
  );
 
  // Center-justified free text
  PDF.CurrentPage.AddFreeTextAnnotation(
    'CENTERED Text',
    Rect(220, 180, 370, 200),
    ftCenter,
    $0080FF // Orange
  );
 
  // Right-justified free text
  PDF.CurrentPage.AddFreeTextAnnotation(
    'RIGHT ANNOTATION',
    Rect(390, 180, 540, 200),
    ftRightJust,
    clFuchsia // Fuchsia
  );
 
  // Document status annotation
  PDF.CurrentPage.AddFreeTextAnnotation(
    'CONFIDENTIAL DOCUMENT',
    Rect(200, 210, 400, 230),
    ftCenter,
    clRed
  );
end;
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// Line and shape annotation examples
procedure AddGeometricAnnotationExamples(PDF: THotPDF);
var
  StartPoint, EndPoint: THPDFCurrPoint;
begin
  WriteLn('Adding geometric annotations...');
 
  // Section header
  PDF.CurrentPage.TextOut(50, 250, 0, 'Geometric Annotations - Lines and Shapes:');
 
  // Line annotation - diagonal
  StartPoint.X := 50;
  StartPoint.Y := 270;
  EndPoint.X := 150;
  EndPoint.Y := 290;
  
  PDF.CurrentPage.AddLineAnnotation(
    'Diagonal line pointing to important content',
    StartPoint,
    EndPoint,
    $0080FF // Orange
  );
  
  // Line annotation - horizontal
  StartPoint.X := 170;
  StartPoint.Y := 280;
  EndPoint.X := 270;
  EndPoint.Y := 280;
  
  PDF.CurrentPage.AddLineAnnotation(
    'Horizontal line for emphasis',
    StartPoint,
    EndPoint,
    clBlue
  );
 
  // Circle annotation
  PDF.CurrentPage.AddCircleSquareAnnotation(
    'Circle highlighting important area',
    Rect(50, 300, 120, 320),
    csCircle,
    clGreen
  );
 
  // Square annotation
  PDF.CurrentPage.AddCircleSquareAnnotation(
    'Square frame for emphasis',
    Rect(140, 300, 210, 320),
    csSquare,
    $800080 // Purple
  );
end;
 
// Circle and square annotation types
THPDFCSAnnotationType = (csCircle, csSquare);
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// Available stamp type enumeration
THPDFStampAnnotationType = (
  satApproved,              // Green "Approved" stamp
  satExperimental,          // "Experimental" marker
  satNotApproved,           // Red "Not Approved" stamp
  satAsIs,                  // "As Is" status
  satExpired,               // "Expired" warning
  satNotForPublicRelease,   // Confidential marker
  satConfidential,          // "Confidential" stamp
  satFinal,                 // "Final" marker
  satSold,                  // "Sold" status
  satDepartmental,          // Department-specific marker
  satForComment,            // "For Comment" review stamp
  satTopSecret              // "Top Secret" classification
);
 
// Example: Add various stamp annotations
procedure AddStampAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding stamp annotations...');
 
  // Section header
  PDF.CurrentPage.TextOut(50, 340, 0, 'Stamp Annotations - Document Status Markers:');
 
  // Approval stamps
  PDF.CurrentPage.AddStampAnnotation(
    'Document approved for release',
    Rect(50, 360, 150, 390),
    satApproved,
    clGreen
  );
 
  PDF.CurrentPage.AddStampAnnotation(
    'Document rejected - requires revision',
    Rect(170, 360, 270, 390),
    satNotApproved,
    clRed
  );
 
  // Security stamps
  PDF.CurrentPage.AddStampAnnotation(
    'Confidential information marker',
    Rect(290, 360, 390, 390),
    satConfidential,
    clRed
  );
 
  PDF.CurrentPage.AddStampAnnotation(
    'Final version stamp',
    Rect(410, 360, 510, 390),
    satFinal,
    clBlue
  );
 
  // Workflow stamps
  PDF.CurrentPage.AddStampAnnotation(
    'For comment and review',
    Rect(50, 400, 150, 430),
    satForComment,
    $800080 // Purple
  );
 
  PDF.CurrentPage.AddStampAnnotation(
    'Experimental version',
    Rect(170, 400, 270, 430),
    satExperimental,
    $0080FF // Orange
  );
end;
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// File attachment annotation example
procedure AddMultimediaAnnotationExamples(PDF: THotPDF);
var
  DemoTextFile, DemoAudioFile: string;
  DemoContent: TStringList;
begin
  WriteLn('Adding multimedia annotations...');
 
  // Section header
  PDF.CurrentPage.TextOut(50, 450, 0, 'Multimedia Annotations - Files, Audio, and Video:');
 
  // Create demo text file if it doesn't exist
  DemoTextFile := 'DemoAttachment.txt';
  if not FileExists(DemoTextFile) then
  begin
    DemoContent := TStringList.Create;
    try
      DemoContent.Add('HotPDF Component Demo Attachment');
      DemoContent.Add('================================');
      DemoContent.Add('This is a sample text file attached to the PDF document.');
      DemoContent.Add('It demonstrates the file attachment annotation capability.');
      DemoContent.Add('Created: ' + DateTimeToStr(Now));
      DemoContent.SaveToFile(DemoTextFile);
    finally
      DemoContent.Free;
    end;
  end;
 
  // File attachment annotation
  PDF.CurrentPage.AddFileAttachmentAnnotation(
    'Demo text file attachment',
    DemoTextFile,
    Rect(50, 470, 90, 490),
    clBlue
  );
 
  // Multiple file attachment examples
  PDF.CurrentPage.AddFileAttachmentAnnotation(
    'Legal agreement document',
    'Contract.docx',
    Rect(100, 470, 140, 490),
    clPurple
  );
 
  PDF.CurrentPage.AddFileAttachmentAnnotation(
    'Reference image for comparison',
    'Reference.png',
    Rect(150, 470, 190, 490),
    clGreen
  );
end;
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// Sound annotation example
procedure AddSoundAnnotationExample(PDF: THotPDF);
var
  DemoAudioFile: string;
begin
  // Check for existing multimedia files and add annotations
  DemoAudioFile := 'Music.wav';
  if FileExists(DemoAudioFile) then
  begin
    PDF.CurrentPage.AddSoundAnnotation(
      'Demo audio file - Click to play',
      DemoAudioFile,
      Rect(110, 470, 150, 490),
      clGreen
    );
  end
  else
  begin
    PDF.CurrentPage.AddTextAnnotation(
      'Audio file not found: ' + DemoAudioFile,
      Rect(110, 470, 130, 490),
      False,
      taNote,
      $0080FF // Orange
    );
  end;
 
  // Multi-language sound annotation example
  PDF.CurrentPage.AddSoundAnnotation(
    'English narration',
    'Narration_EN.mp3',
    Rect(60, 350, 100, 390),
    clBlue
  );
 
  PDF.CurrentPage.AddSoundAnnotation(
    'Chinese narration',
    'Narration_CN.mp3',
    Rect(110, 350, 150, 390),
    clGreen
  );
end;
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{***********************************************************}
// HotPDF PDF Component - Enhanced Annotations Demo Delphi
// Copyright(c)2007-2025, https://www.loslab.com
// This demo showcases comprehensive annotation functionality
{***********************************************************}
 
program Annotations;
{$I ..\..\..\Lib\HotPDF.inc}
{$APPTYPE CONSOLE}
 
uses
  {$IFDEF XE2+}
  System.Classes,
  System.SysUtils,
  Vcl.Graphics,
  {$ELSE}
  Classes,
  SysUtils,
  Graphics,
  {$ENDIF}
  HPDFDoc;
 
var
  HotPDF: THotPDF;
 
// ... existing code ...
 
procedure AddDocumentationAndFooter(PDF: THotPDF);
begin
  WriteLn('Adding documentation and footer...');
 
  // Documentation section
  PDF.CurrentPage.TextOut(50, 510, 0, 'Annotation Usage Guidelines:');
  PDF.CurrentPage.TextOut(50, 530, 0, '• Red annotations indicate critical issues requiring immediate attention');
  PDF.CurrentPage.TextOut(50, 545, 0, '• Orange annotations show warnings and cautions');
  PDF.CurrentPage.TextOut(50, 560, 0, '• Blue annotations provide general information');
  PDF.CurrentPage.TextOut(50, 575, 0, '• Green annotations mark completed or approved items');
  PDF.CurrentPage.TextOut(50, 590, 0, '• Purple annotations indicate items requiring review');
 
  // Technical information
  PDF.CurrentPage.TextOut(50, 620, 0, 'Technical Details:');
  PDF.CurrentPage.TextOut(50, 635, 0, '• All annotations are interactive and can be opened/closed by users');
  PDF.CurrentPage.TextOut(50, 650, 0, '• Multimedia annotations require compatible PDF viewers');
  PDF.CurrentPage.TextOut(50, 665, 0, '• File attachments are embedded within the PDF document');
 
  // Footer
  PDF.CurrentPage.TextOut(50, 730, 0, 'HotPDF Component - Enhanced Annotations Demo (Delphi)');
  PDF.CurrentPage.TextOut(50, 745, 0, 'Generated: ' + DateTimeToStr(Now));
  PDF.CurrentPage.TextOut(50, 760, 0, 'Visit https://www.loslab.com for more information');
 
  // Add a final summary annotation
  PDF.CurrentPage.AddTextAnnotation(
    'SUMMARY: This document demonstrates all annotation types supported by HotPDF Component.' + #13#10 +
    'Each annotation type serves specific purposes in document workflow and user interaction.' + #13#10 +
    'For technical support and documentation, visit https://www.loslab.com',
    Rect(450, 740, 470, 760),
    False,
    taNote,
    clBlue
  );
end;
 
begin
  WriteLn('HotPDF Enhanced Annotations Demo (Delphi)');
  WriteLn('=========================================');
  WriteLn('Creating comprehensive PDF with all annotation types...');
  WriteLn('');
 
  HotPDF := THotPDF.Create(nil);
  try
    try
      // Configure PDF properties
      HotPDF.FileName := 'HotPDF-Annotations.pdf';
      HotPDF.Title := 'HotPDF Annotations Demo (Delphi)';
      HotPDF.Author := 'HotPDF Component';
      HotPDF.Subject := 'Comprehensive annotation examples';
      HotPDF.Keywords := 'PDF, Annotations, HotPDF, Demo, Interactive, Delphi';
 
      // Set font embedding for consistent display
      HotPDF.FontEmbedding := True;
 
      // Enable FlateDecode compression for smaller file sizes
      HotPDF.Compression := cmFlateDecode;
      
      // Set initial zoom to fit page height in window
      HotPDF.InitialZoom := izFitV;
 
      HotPDF.BeginDoc;
      
      // Use standard font
      HotPDF.CurrentPage.SetFont('Arial', [], 12, 0, False);
 
      // Add page title
      HotPDF.CurrentPage.TextOut(150, 40, 0, 'HotPDF Component - Annotations Showcase (Delphi)');
 
      // Add all annotation examples
      AddTextAnnotationExamples(HotPDF);
      AddFreeTextAnnotationExamples(HotPDF);
      AddGeometricAnnotationExamples(HotPDF);
      AddStampAnnotationExamples(HotPDF);
      AddMultimediaAnnotationExamples(HotPDF);
      AddDocumentationAndFooter(HotPDF);
 
      HotPDF.EndDoc;
 
      WriteLn('Annotations PDF created successfully!');
      WriteLn('');
      WriteLn('Output file: ' + HotPDF.FileName);
      WriteLn('');
      WriteLn('The PDF contains:');
      WriteLn('• Text annotations with different types and colors');
      WriteLn('• Free text annotations with various alignments');
      WriteLn('• Geometric annotations (lines, circles, squares)');
      WriteLn('• Stamp annotations for document workflow');
      WriteLn('• Multimedia annotations (file, audio, video)');
      WriteLn('• Comprehensive documentation and usage guidelines');
 
    except
      on E: Exception do
      begin
        WriteLn('Error creating PDF: ' + E.Message);
        ExitCode := 1;
      end;
    end;
 
  finally
    HotPDF.Free;
  end;
end.
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// Modern unit structure with conditional compilation
uses
  {$IFDEF XE2+}
  System.Classes,
  System.SysUtils,
  Vcl.Graphics,
  {$ELSE}
  Classes,
  SysUtils,
  Graphics,
  {$ENDIF}
  HPDFDoc;
 
// Enhanced PDF configuration
procedure ConfigureModernPDF(PDF: THotPDF);
begin
  // Font embedding for consistent display across viewers
  PDF.FontEmbedding := True;
  
  // FlateDecode compression for smaller file sizes
  PDF.Compression := cmFlateDecode;
  
  // Initial zoom setting for better user experience
  PDF.InitialZoom := izFitV; // Fit to page height
  
  // Complete metadata for better document management
  PDF.Title := 'Professional PDF with Annotations';
  PDF.Author := 'HotPDF Component';
  PDF.Subject := 'Comprehensive annotation examples';
  PDF.Keywords := 'PDF, Annotations, Interactive, Professional';
end;
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// Robust file handling with error checking
procedure SafeAddFileAttachment(PDF: THotPDF; const FileName: string; const Description: string);
begin
  if FileExists(FileName) then
  begin
    PDF.CurrentPage.AddFileAttachmentAnnotation(
      Description,
      FileName,
      Rect(10, 10, 50, 50),
      clGreen
    );
  end
  else
  begin
    // Add error annotation instead
    PDF.CurrentPage.AddTextAnnotation(
      Format('File not found: %s', [ExtractFileName(FileName)]),
      Rect(10, 10, 30, 30),
      True,
      taKey,
      clRed
    );
  end;
end;
 
// Exception handling in main program
begin
  HotPDF := THotPDF.Create(nil);
  try
    try
      // PDF creation code here
      HotPDF.BeginDoc;
      // ... annotation code ...
      HotPDF.EndDoc;
      
      WriteLn('PDF created successfully!');
    except
      on E: Exception do
      begin
        WriteLn('Error creating PDF: ' + E.Message);
        ExitCode := 1;
      end;
    end;
  finally
    HotPDF.Free;
  end;
end;
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// Color constants for consistent annotation design
const
  ANNOTATION_COLOR_ERROR = clRed;
  ANNOTATION_COLOR_WARNING = $0080FF;    // Orange
  ANNOTATION_COLOR_INFO = clBlue;
  ANNOTATION_COLOR_SUCCESS = clGreen;
  ANNOTATION_COLOR_REVIEW = $800080;     // Purple
 
// Consistent color application
procedure AddColorCodedAnnotations(PDF: THotPDF);
begin
  // Error annotation
  PDF.CurrentPage.AddTextAnnotation(
    'ERROR: Critical issue requiring immediate attention',
    Rect(50, 100, 70, 120),
    True,
    taKey,
    ANNOTATION_COLOR_ERROR
  );
 
  // Warning annotation
  PDF.CurrentPage.AddTextAnnotation(
    'WARNING: Caution required',
    Rect(80, 100, 100, 120),
    False,
    taComment,
    ANNOTATION_COLOR_WARNING
  );
 
  // Information annotation
  PDF.CurrentPage.AddTextAnnotation(
    'INFO: Additional information available',
    Rect(110, 100, 130, 120),
    False,
    taNote,
    ANNOTATION_COLOR_INFO
  );
end;
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// Modular annotation management
procedure AddTextAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding text annotations...');
  // Text annotation code here
end;
 
procedure AddFreeTextAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding free text annotations...');
  // Free text annotation code here
end;
 
procedure AddGeometricAnnotationExamples(PDF: THotPDF);
begin
  WriteLn('Adding geometric annotations...');
  // Geometric annotation code here
end;
 
// Main execution with clear structure
begin
  HotPDF := THotPDF.Create(nil);
  try
    // Configure PDF
    HotPDF.FileName := 'HotPDF-Annotations.pdf';
    HotPDF.FontEmbedding := True;
    HotPDF.Compression := cmFlateDecode;
    HotPDF.InitialZoom := izFitV;
    
    HotPDF.BeginDoc;
    HotPDF.CurrentPage.SetFont('Arial', [], 12, 0, False);
    
    // Add all annotation examples in organized manner
    AddTextAnnotationExamples(HotPDF);
    AddFreeTextAnnotationExamples(HotPDF);
    AddGeometricAnnotationExamples(HotPDF);
    AddStampAnnotationExamples(HotPDF);
    AddMultimediaAnnotationExamples(HotPDF);
    AddDocumentationAndFooter(HotPDF);
    
    HotPDF.EndDoc;
  finally
    HotPDF.Free;
  end;
end;
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// Proper resource management
procedure CreateAnnotatedPDF;
var
  HotPDF: THotPDF;
  TempFiles: TStringList;
begin
  HotPDF := THotPDF.Create(nil);
  TempFiles := TStringList.Create;
  try
    try
      // Create temporary files for demonstration
      CreateDemoFiles(TempFiles);
      
      // Configure and create PDF
      ConfigurePDF(HotPDF);
      HotPDF.BeginDoc;
      
      // Add annotations
      AddAllAnnotations(HotPDF, TempFiles);
      
      HotPDF.EndDoc;
      WriteLn('PDF created successfully!');
      
    except
      on E: Exception do
      begin
        WriteLn('Error: ' + E.Message);
        raise; // Re-raise for proper error handling
      end;
    end;
  finally
    // Clean up resources
    TempFiles.Free;
    HotPDF.Free;
    
    // Clean up temporary files
    CleanupTempFiles;
  end;
end;
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// Modern compression settings
HotPDF.Compression := cmFlateDecode;  // Best compression ratio
HotPDF.FontEmbedding := True;         // Consistent font display
HotPDF.InitialZoom := izFitV;         // Optimal viewing experience
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// Complete metadata configuration
procedure ConfigureDocumentMetadata(PDF: THotPDF);
begin
  PDF.Title := 'Professional PDF with Annotations';
  PDF.Author := 'HotPDF Component';
  PDF.Subject := 'Comprehensive annotation examples';
  PDF.Keywords := 'PDF, Annotations, HotPDF, Demo, Interactive, Delphi';
  PDF.Creator := 'HotPDF Component Demo';
  PDF.Producer := 'HotPDF Component v2.x';
end;

Praktische aandachtspunten

  • Controleer invoerbestanden en foutpaden expliciet voordat u de routine in productie gebruikt.
  • Houd paginalay-out, lettertypen en coördinaten reproduceerbaar, vooral bij server-side verwerking.
  • Test het resultaat in meer dan één PDF-viewer wanneer rendering, annotaties of interactieve elementen belangrijk zijn.
  • Laat componentlevensduur en bestandshandles altijd via try/finally-achtige patronen opruimen.