path: root/doc.go

/*
 * Copyright (c) 2013-2014 Kurt Jung (Gmail: kurt.w.jung)
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
Package gofpdf implements a PDF document generator with high level support for
text, drawing and images.

Features

• Choice of measurement unit, page format and margins

• Page header and footer management

• Automatic page breaks, line breaks, and text justification

• Inclusion of JPEG, PNG, GIF and basic path-only SVG images

• Colors, gradients and alpha channel transparency

• Outline bookmarks

• Internal and external links

• TrueType, Type1 and encoding support

• Page compression

• Lines, Bézier curves, arcs, and ellipses

• Rotation, scaling, skewing, translation, and mirroring

• Clipping

• Document protection

gofpdf has no dependencies other than the Go standard library. All tests pass
on Linux, Mac and Windows platforms. Like FPDF version 1.7, from which gofpdf
is derived, this package does not yet support UTF-8 fonts. However, support is
provided to translate UTF-8 runes to code page encodings.

Acknowledgments

This package's code and documentation are closely derived from the FPDF library
created by Olivier Plathey, and a number of font and image resources are copied
directly from it. Drawing support is adapted from the FPDF geometric figures
script by David Hernández Sanz. Transparency support is adapted from the FPDF
transparency script by Martin Hall-May. Support for gradients and clipping is
adapted from FPDF scripts by Andreas Würmser. Support for outline bookmarks is
adapted from Olivier Plathey by Manuel Cornes. Support for transformations is
adapted from the FPDF transformation script by Moritz Wagner and Andreas
Würmser. PDF protection is adapted from the work of Klemen Vodopivec for the
FPDF product. Lawrence Kesteloot provided code to allow an image's extent to be
determined prior to placement. Support for vertical alignment within a cell was
provided by Stefan Schroeder. Ivan Daniluk generalized the font and image
loading code to use the Reader interface while maintaining backward
compatibility. Bruno Michel has provided valuable assistance with the code.

The FPDF website is http://www.fpdf.org/.

License

gofpdf is copyrighted by Kurt Jung and is released under the MIT License.

Installation

To install the package on your system, run

	go get code.google.com/p/gofpdf

Later, to receive updates, run

	go get -u code.google.com/p/gofpdf

Quick Start

The following Go code generates a simple PDF.

	pdf := gofpdf.New("P", "mm", "A4", "../font")
	pdf.AddPage()
	pdf.SetFont("Arial", "B", 16)
	pdf.Cell(40, 10, "Hello, world")
	pdf.Output(os.Stdout)

See the tutorials in the fpdf_test.go file (shown as examples in this
documentation) for more advanced PDF examples.

Errors

If an error occurs in an Fpdf method, an internal error field is set. After
this occurs, Fpdf method calls typically return without performing any
operations and the error state is retained. This error management scheme
facilitates PDF generation since individual method calls do not need to be
examined for failure; it is generally sufficient to wait until after Output()
is called. For the same reason, if an error occurs in the calling application
during PDF generation, it may be desirable for the application to transfer the
error to the Fpdf instance by calling the SetError() method or the SetErrorf()
method. At any time during the life cycle of the Fpdf instance, the error state
can be determined with a call to Ok() or Err(). The error itself can be
retrieved with a call to Error().

Conversion Notes

This package is a relatively straightforward translation from the original FPDF
library written in PHP (despite the caveat in the introduction to Effective
Go). The API names have been retained even though the Go idiom would suggest
otherwise (for example, pdf.GetX() is used rather than simply pdf.X()). The
similarity of the two libraries makes the original FPDF website a good source
of information. It includes a forum and FAQ.

However, some internal changes have been made. Page content is built up using
buffers (of type bytes.Buffer) rather than repeated string concatenation.
Errors are handled as explained above rather than panicking. Output is
generated through an interface of type io.Writer or io.WriteCloser. A number of
the original PHP methods behave differently based on the type of the arguments
that are passed to them; in these cases additional methods have been exported
to provide similar functionality. Font definition files are produced in JSON
rather than PHP.

Tutorials

A side effect of running "go test" is the production of the tutorial PDFs.
These can be found in the gofpdf/pdf directory after the tests complete.

Nonstandard Fonts

Nothing special is required to use the standard PDF fonts (courier, helvetica,
times, zapfdingbats) in your documents other than calling SetFont().

In order to use a different TrueType or Type1 font, you will need to generate a
font definition file and, if the font will be embedded into PDFs, a compressed
version of the font file. This is done by calling the MakeFont function or
using the included makefont command line utility. To create the utility, cd
into the makefont subdirectory and run "go build". This will produce a
standalone executable named makefont. Select the appropriate encoding file from
the font subdirectory and run the command as in the following example.

	./makefont --embed --enc=../font/cp1252.map --dst=../font ../font/calligra.ttf

In your PDF generation code, call AddFont() to load the font and, as with the
standard fonts, SetFont() to begin using it. See tutorial 7 for an example.
Good sources of free, open-source fonts include http://www.google.com/fonts/
and http://dejavu-fonts.org/.

Roadmap

• Handle UTF-8 source text natively. Until then, automatic translation of
UTF-8 runes to code page bytes is provided.

• Improve test coverage as reported by the coverage tool.

*/
package gofpdf