Generating PDF files cross-platform with ease

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Thursday, December 22, 2016

With the new 1.7 release of the TMS FNC UI Pack we've added a completely new PDF library built from the ground up, that is capable of generating PDF files on all supported frameworks (FMX, VCL, LCL). Via all supported frameworks, you can easily target minimum 5 different operating systems: Windows, macOS, iOS, Android, Linux (&Raspbian),.. To introduce this new PDF library I've written a small tutorial to start generating your own PDF files.

Getting Started

To get started with the PDF library, add the FMX.TMSFNCPDFLib, VCL.TMSFNCPDFLib or LCLTMSFNCPDFLib depending on the chosen framework. The PDF library class is called TTMSFNCPDFLib, and the code is shareable between the three supported frameworks.

Starting a new document

Starting a new document can be file-based, or TMemoryStream-based. To start a new document, call the BeginDocument function. The BeginDocument always needs to be paired with EndDocument, which is responsible for writing the contents to a file or TMemoryStream. When the AFileName parameter in the BeginDocument call is empty, the contents will be written to a TMemoryStream, returned by the EndDocument call. The EndDocument call also has an additional parameter to allow opening the generated PDF file in the default PDF reader application.

procedure TForm1.GeneratePDF(AFileName: string);
var
  p: TTMSFNCPDFLib;
begin
  p := TTMSFNCPDFLib.Create;
  try
    p.BeginDocument(AFileName);
    p.EndDocument;
  finally
    p.Free;
  end;
end;

Adding pages

Adding pages can be done by calling the NewPage function. The NewPage is responsible for starting a new page content stream on which the graphics / text can be written. Each NewPage call will clear the content buffer and allow you to start with new text and graphics. Please note though that all appearance settings such as fill, stroke and font are stored for the entire document, so starting a new page will allow you to continue in the same appearance settings as the previous page.

procedure TForm1.GeneratePDF(AFileName: string);
var
  p: TTMSFNCPDFLib;
begin
  p := TTMSFNCPDFLib.Create;
  try
    p.BeginDocument(AFileName);
    p.NewPage;
    p.EndDocument;
  finally
    p.Free;
  end;
end;

Drawing content on a page

After adding a new page, the page can be filled with content such as HTML formatted text, plain text as well as some basic drawing primitives such as rectangles, circles and lines. To starting drawing content, the pdf library has a Graphics property that provides access to the drawing functionality. The following sample uses the Fill and Stroke properties to generate a PDF with a gradient rectangle and a dotted border.

procedure TForm1.GeneratePDF(AFileName: string);
var
  p: TTMSFNCPDFLib;
begin
  p := TTMSFNCPDFLib.Create;
  try
    p.BeginDocument(AFileName);
    p.NewPage;
    p.Graphics.Stroke.Color := gcRed;
    p.Graphics.Stroke.Width := 3;
    p.Graphics.Stroke.Kind := gskDashDotDot;
    p.Graphics.Fill.Kind := gfkGradient;
    p.Graphics.Fill.Color := gcBlue;
    p.Graphics.Fill.ColorTo := gcOrange;
    p.Graphics.DrawRectangle(RectF(10, 50, 100, 150));
    p.EndDocument(True);
  finally
    p.Free;
  end;
end;

Drawing Text

Drawing text on a PDF page is done via the DrawText function. The DrawText has a set of parameters to allow drawing wordwrapped text in a rectangle, or simply as-is at a specific position. The DrawText function has a set of overloads that also supports column drawing. Each call to DrawText returns a value that can either contain the calculated text rectangle or the amount of left-over characters after an overflow is detected when drawing text in a column. The font that is used when drawing text can be controlled separately via the Font property. With this property, the font name, size, color and style can be set.

procedure TForm1.GeneratePDF(AFileName: string);
var
    p: TTMSFNCPDFLib;
begin
    p := TTMSFNCPDFLib.Create;
  try
    p.BeginDocument(AFileName);
    p.NewPage;
    p.Graphics.Font.Name := 'Segoe UI';
    p.Graphics.Font.Size := 16;
    p.Graphics.Font.Color := gcRed;
    p.Graphics.Font.Style := [TFontStyle.fsBold];
    p.Graphics.DrawText('Hello World !', PointF(10, 50));
    p.EndDocument(True);
  finally
    p.Free;
  end;
end;

HTML formatted text

HTML formatted text is also supported by using the DrawHTMLText call. When passing a TMSFNCBitmapContainer reference it can even draw images referenced by the <IMG> tag. HTML support is based on the miniHTML reference.

procedure TForm1.GeneratePDF(AFileName: string);
var
  p: TTMSFNCPDFLib;
  s: string;
  r: TRectF;
begin
  p := TTMSFNCPDFLib.Create;
  try
    s := 'Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum     has been the industry''s standard dummy'+
'text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book. '+
'It has survived not only five centuries, but also the leap into electronic typeset'+
'ting, 
remaining essentially unchanged. It'+ ' was popularised in the 1960s with the release of Letraset sheets containing Lorem Ipsum passages, and more recently with des'+ 'ktop publishing software like Aldus PageMaker including versions of Lorem Ipsum.'; p.BitmapContainer := TMSFNCBitmapContainer1; p.BeginDocument(AFileName); p.NewPage; p.Graphics.Font.Name := 'Arial'; p.Graphics.Font.Size := 10; p.Graphics.Fill.Color := gcNull; r := RectF(10, 50, 300, 400); p.Graphics.DrawHTMLText(s, r); p.EndDocument(True); finally p.Free; end; end;

The PDF library supports more than simple text and graphics. More information on the PDF library and the features can be found at the following page https://www.tmssoftware.com/site/tmsfncuipack.asp?s=fncpdf#features.

The PDF library is also available in the TMS FMX UI Pack and is coming to the TMS Component Pack at the beginning of 2017!

Pieter Scheldeman


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