[[Raku PDF Project]](https://pdf-raku.github.io)
 / [PDF::API6](https://pdf-raku.github.io/PDF-API6)
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PDF::API6 - A Raku PDF API
===

- [NAME](#name)
- [DESCRIPTION](#description)
- [EXAMPLE](#example)
- [DIFFERENCES BETWEEN PDF::API2 AND PDF::API6](#differences-between-pdfapi2-and-pdfapi6)
   - [PDF::API6](#pdfapi6)
   - [TODO](#todo)
- [SYNOPSIS](#synopsis)
- [SECTION I: Input/Output Methods (inherited from PDF)](#section-i-inputoutput-methods-inherited-from-pdf)
   - [Input/Output](#inputoutput)
       - [new](#new)
       - [open](#open)
       - [update](#update)
       - [save-as](#save-as)
       - [encrypt](#encrypt)
       - [is-encrypted](#is-encrypted)
   - [Serialization Methods](#serialization-methods)
       - [Str, Blob](#str-blob)
       - [ast](#ast)
- [SECTION II: Content Methods (inherited from PDF::Class)](#section-ii-content-methods-inherited-from-pdfclass)
   - [Pages](#pages)
       - [page-count](#page-count)
       - [page](#page)
       - [iterate-pages](#iterate-pages)
       - [add-page](#add-page)
       - [delete-page](#delete-page)
   - [Page Methods](#page-methods)
       - [to-xobject](#to-xobject)
       - [images](#images)
       - [media-box, crop-box, trim-box, bleed-box, art-box, bleed](#media-box-crop-box-trim-box-bleed-box-art-box-bleed)
       - [rotate](#rotate)
   - [Graphics Constructor](#graphics-constructor)
       - [gfx](#gfx)
   - [Text Methods](#text-methods)
       - [text](#text)
       - [font, core-font](#font-core-font)
       - [text-position](#text-position)
       - [text-transform](#text-transform)
       - [base-coords](#base-coords)
       - [print](#print)
       - [say](#say)
   - [Graphics Methods](#graphics-methods)
       - [graphics](#graphics)
       - [transform](#transform)
       - [paint](#paint)
   - [Image Methods](#image-methods)
       - [load-image](#load-image)
       - [do](#do)
   - [XObject Forms](#xobject-forms)
       - [xobject-form](#xobject-form)
   - [Patterns](#patterns)
       - [tiling-pattern](#tiling-pattern)
       - [use-pattern](#use-pattern)
   - [Low Level Graphics](#low-level-graphics)
   - [Basic Colors](#basic-colors)
       - [FillColor, FillAlpha](#fillcolor-fillalpha)
       - [StrokeColor, StrokeAlpha](#strokecolor-strokealpha)
       - [Named Colors](#named-colors)
       - [Text Modes](#text-modes)
   - [Rendering Methods](#rendering-methods)
       - [render: :&callback](#render-callback)
       - [html-canvas()](#html-canvas)
   - [AcroForm Fields](#acroform-fields)
- [SECTION III: PDF::API6 Specific Methods](#section-iii-pdfapi6-specific-methods)
   - [Metadata Methods](#metadata-methods)
       - [info](#info)
       - [xmp-metadata](#xmp-metadata)
   - [Settings Methods](#settings-methods)
       - [preferences](#preferences)
       - [version](#version)
   - [Color Management](#color-management)
       - [color-separation](#color-separation)
       - [color-devicen](#color-devicen)
   - [Interactive Features](#interactive-features)
       - [Outlines](#outlines)
       - [Page Labels](#page-labels)
       - [Annotations](#annotations)
       - [Named Destinations](#named-destinations)
   - [Tagged Content](#tagged-content)
       - [tag](#tag)
       - [mark](#mark)
- [APPENDIX](#appendix)
   - [Appendix I: Graphics](#appendix-i-graphics)
       - [Graphics Variables](#graphics-variables)
       - [Graphic Operators](#graphic-operators)
       - [Graphics State](#graphics-state)
       - [Text Operators](#text-operators)
       - [Path Construction Operators](#path-construction-operators)
       - [Path Painting Operators](#path-painting-operators)
       - [Path Clipping](#path-clipping)
       - [Marked Content](#marked-content)
       - [Graphics Introspection Methods](#graphics-introspection-methods)
       - [Graphics Tracing](#graphics-tracing)
   - [Appendix II: Text Rendering Modes](#appendix-ii-text-rendering-modes)
   - [Appendix III: Module Overview](#appendix-iii-module-overview)


# NAME

PDF::API6 - Facilitates the creation and modification of PDF files

# DESCRIPTION

A Raku PDF module; reminiscent of Perl 5's PDF::API2.

This module is a work in progress in replicating, or mapping the functionality of Perl 5's PDF::API2 tool-chain.

# EXAMPLE

```Raku
use v6;
use PDF::API6;
use PDF::Page;
use PDF::XObject::Image;
use PDF::Content::FontObj;

my PDF::API6 $pdf .= new;
$pdf.media-box = [0, 0, 200, 100];
my PDF::Page $page = $pdf.add-page;
constant Padding = 10;

$page.graphics: {
    enum <x0 y0 x1 y1>;
    my PDF::Content::FontObj $font = .core-font: :family<Helvetica>, :weight<bold>, :style<italic>;
    my @box = .say: 'Hello, world', :$font, :position[10, 10];

    my PDF::XObject::Image $img = .load-image: "t/images/lightbulb.png";
    .do: $img, :position[@box[x1] + Padding, 10];
}

$pdf.save-as: "tmp/hello-world.pdf";
```

![example.pdf](https://raw.githubusercontent.com/pdf-raku/PDF-API6/master/tmp/.previews/hello-world-001.png)

# DIFFERENCES BETWEEN PDF::API2 AND PDF::API6

## PDF::API6

- Has a Graphics State engine. This is based on the graphics operators and variables as described PDF 32000 chapter 8 "Graphics and the operators".

- Supports the creation and manipulation of XObject Forms and Patterns.

- Implements an Object Graph model for data access. A PDF file is modelled as an object tree of Dictionaries (Hashes) and Arrays that contain simpler
values such as Integers, Reals and Strings.

## TODO

PDF::API2 features that are not yet available in PDF::API6 include:

- Images. PDF::API6 supports PNG, JPEG and GIF images

    - currently not supported are: TIFF and PNM images.

- Fonts. A variety of formats are handled by the [PDF::Font::Loader](https://pdf-raku.github.io/PDF-Font-Loader-raku/) module (available on CPAN).

   - Font sub-setting (to reduces file sizes) is experimental. See [HarfBuzz::Subset](https://harfbuzz-raku.github.io/HarfBuzz-Subset-raku/)
   - Synthetic fonts are NYI (wanted: module PDF::Font::Synthetic)


# SYNOPSIS

```raku
use PDF::API6;
# Create a blank PDF file
my PDF::API6 $pdf .= new();

# Open an existing PDF file
my PDF::API6 $pdf .= open('some.pdf');

# Add a blank page
use PDF::Page;
my PDF::Page $page = $pdf.add-page();

# Retrieve an existing page
use PDF::Page;
my PDF::Page $page_2 = $pdf.page(2);

# Set the default page size for all pages
use PDF::Content::Page :PageSizes;
$pdf.media-box = A4;

# Set the size of a specific page
use PDF::Content::Page :PageSizes;
$page.media-box = Letter;

# Use a standard PDF core font
use PDF::Content::FontObj;
constant FontObj = PDF::Content::FontObj;
my FontObj $font = $pdf.core-font('Helvetica-Bold');
$font = $pdf.core-font: :family<Helvetica>, :weight<Bold>;

# Add an external TrueType font to the PDF
# (requires PDF::Font::Loader module to be installed)
use PDF::Font::Loader;
$font = PDF::Font::Loader.load-font: :file</path/to/font.ttf>;
# (requires both PDF::Font::Loader module and fontconfig package)
$font = PDF::Font::Loader.load-font: :family<Vera>, :weight<Bold>;

# Add some text to the page
$page.text: {
    .font = $font, 20;
    .text-position = 200, 700;
    .say('Hello World!');
}

# Save the PDF
$pdf.save-as('/path/to/new.pdf');
```

# SECTION I: Input/Output Methods (inherited from PDF)

## Input/Output

### new

Creates a new PDF object.

```raku
my PDF::API6 $pdf .= new();
#...
dd $pdf.Str;
$fh.write: $pdf.Blob;

$pdf = PDF::API6.new();
#...
$pdf.save-as('our/new.pdf');
```

### open

Opens an existing PDF or JSON file.

```raku
my PDF::API6 $pdf .= open('our/old.pdf');
#...
$pdf.save-as('our/new.pdf');

# open from a stream
my PDF::API6 $pdf2 .= open($pdf.Blob);
```

Open an encrypted document:
```raku
PDF::API6.open( "enc.pdf", :password<sshh!> );
```

Open a PDF, ignoring indices and stream lengths:
```raku
PDF::API6.open( "damaged-or-edited.pdf", :repair );
```
### update

In-place update of a PDF file
```raku
my PDF::API6 $pdf .= open('our/to/be/updated.pdf');
#...
$pdf.update();
```
### save-as

Save a new or updated PDF document to a file
```raku
my PDF::API6 $pdf .= new;
#...
$pdf.save-as: 'our/new.pdf';
```
The `:preserve` option (default True) keeps the original PDF structure, then applies incremental updates. This is generally faster and also ensures that digital signatures are not invalidated.
```raku
PDF::API6 $pdf .= open("our/original.pdf");
$pdf.save-as: 'our/updated.pdf', :!preserve;
```
The `:rebuild` option (default False) rewrites the PDF. This may be useful, if there have been a substantial number of updates.

The `:compress` option is used to ensure stream objects (which generally make up the bulk of a PDF) are compressed. This is useful when maximum compaction is needed.
```raku
PDF::API6 $pdf .= open("our/original.pdf");
$pdf.save-as: 'our/updated.pdf', :rebuild, :compress;
```
The reverse flag, `:!compress` is useful when you want to optimise for human-readability of the output PDF. It will uncompress `Flate`, `LZW`, `ASCIIHex` and `ASCII85` encoded streams.

The `:stream` option writes the PDF file progressively, starting as early as possible.

A PDF file can also be saved as, and opened from an intermediate JSON representation, by saving to, or reading from, files with a `.json` extension
```raku
PDF::API6 $pdf .= new;
#...
$pdf.save-as: 'our/ast.json';
# ...
$pdf.open: 'our/ast.json';
```
### encrypt

Encrypt a PDF:
```raku
$pdf.encrypt( :owner-pass<ssh1>, :user-pass<abc>, :aes );
```
### is-encrypted

Check if document is encrypted
```raku
if $pdf.is-encrypted { ... }
```
## Serialization Methods

### Str, Blob

Return a binary representation of a PDF as a string, or binary Blob
```raku
my Str $pdf-byte-string = $pdf.Str; # returns a string of latin-1 characters
my blob8 $bytes = $pdf.Blob;         # returns a Blob[uint8]
```
### ast

Return an AST tree representation of a PDF.

```raku
use PDF::IO::Writer;
my %cos = $pdf.ast;   # returns a nested Hash representation of the PDF
# write it to a file
my $pdf-byte-string = PDF::IO::Writer.new.write: |%cos;
"/tmp/out.pdf".IO.spurt(:bin, $pdf-byte-string);
```

# SECTION II: Content Methods (inherited from PDF::Class)

## Pages

### page-count
```raku
my UInt $pages = $pdf.page-count;
```
Returns the number of pages in a PDF.

### page
```raku
use PDF::Page;
my PDF::Page $second-page = $pdf.page(2);
```
Returns the nth page from the PDF


### iterate-pages
```raku
for $pdf.iterate-pages -> PDF::Page $page { ... }
my PDF::Page @all-pages = $pdf.iterate-pages;
my $page-iterator = $pdf.iterate-pages;
$page-iterator.pull-one for ^$pdf.page-count;
```
Returns an iterator that traverses all pages in sequence.

### add-page

Synopsis: `$pdf.add-page($page-object?)`
```raku
my PDF::Page page = $pdf.add-page;
```
Adds a page to the end of a PDF. Creates a new blank page by default.

### delete-page

Deletes a page, by page-number
```raku
my PDF::Page $moved-page = $pdf.delete-page(2);
# re-add the to the end of the PDF
$pdf.add-page($moved-page);
```

## Page Methods

### to-xobject

Converts a page to an [XObject Form](#xobject-forms).

This is useful if you want to transpose the imported page somewhat differently onto a page (e.g. two-up, four-up, etc.).

Example:
```raku
use PDF::API6;
use PDF::Page;
use PDF::XObject;
use PDF::Content;
my PDF::API6 $old .= open('our/old.pdf');
my PDF::API6 $pdf .= new;
my PDF::Page $page = $pdf.add-page;
my PDF::Content $gfx = $page.gfx;

# Import Page 2 from the old PDF
my PDF::XObject $xo = $pdf.page(2).to-xobject;

# Add it to the new PDF's first page at 1/2 scale
my $width = $xo.width / 2;
my $bottom = 5;
my $left = 10;
$gfx.do($xo, :position[$bottom, $left], :$width);

$pdf.save-as('our/new.pdf');
```
### images

Synopsis: `my PDF::XObject::Image @images = $gfx.images: :inline;`

This method extracts image objects for a given page, or other graphical element:

The `:inline` flag will check for any image objects in the graphical content stream.

### media-box, crop-box, trim-box, bleed-box, art-box, bleed

A page has several different bounding boxes:

- crop-box -- the region of the PDF that is displayed or printed
- media-box -- width and height of the printed page
- trim-box -- the intended dimensions of the finished page
- bleed-box -- the region to which the page contents needs to be clipped when output in a production environment.
- art-box -- for general use

`bleed` is a convenience method for setting up or showing a bleed gutter area surrounding the trim-box. It should usually be set up after the trim box.

Example:
```Raku
use PDF::API6;
use PDF::Page;
use PDF::Content::Page :PageSizes;
sub postfix:<mm>(Numeric $v){ ($v * 2.83).round(1) };

my PDF::API6 $pdf .= new;
my PDF::Page $page = $pdf.add-page;

# set-up Letter-size trim-box with symmetrical 3mm bleed

$page.trim-box = Letter;
$page.bleed = 3mm;
##  $page.bleed = 3mm, 3mm, 3mm, 3mm; # same as above
say $page.bleed;     # (8 8 8 8)
say $page.trim-box;  # [0 0 612 792]
say $page.bleed-box; # [-8 -8 620 800]
```

### rotate

    $page.rotate = 90;

Read/write accessor to rotate the page, clockwise. Angles must be multiples of 90 degrees.

## Graphics Constructor

### gfx

Synopsis: `$page.gfx: :&render, :!strict, :trace, :comment`

Options:
    - `:&render` install a rendering call-back (see [Rendering below](#rendering-methods))
    - `:!strict` turn off some warnings, regarding out-of-sequence operations,
       incorrect nesting or un-closed Save, Text or Marked content blocks.

Debugging options:
    - `:trace` print debugging information to $*ERR
    - `:comment` write explanatory comments into the content stream, including
       operator mnemonics and original un-encoded text. These may make it a bit
       easier for developers to interpret the content stream within the PDF. Note
       that setting both :comment` and `:trace` options will direct the trace output
       output to the content stream as comments.

Graphics form the basis of PDF rendering and display. This includes text, images, graphics, colors and painting.

Pages, XObject Forms and Tiling Patterns all have associated graphics. These can be accessed by the`.gfx` method.

```Raku
use v6;
use PDF::API6;
use PDF::Content;

my PDF::API6 $pdf .= open("tmp/hello-world.pdf");
# dump existing graphics on page 1
my $page = $pdf.page(1);
my PDF::Content $gfx = $page.gfx;
dd $gfx.content-dump; # dump existing graphics operations

# add some more text to the page
$gfx.font = $gfx.core-font: :family<Courier>;
$gfx.text: {
    .text-position = (10, 30);
    .say("Demo added text");
}

```

See also [Patterns](#patterns) and [XObject Forms](#xobject-forms) which also have associated graphics.

## Text Methods

Text-blocks are designed to construct one or more paragraphs of
text. The [print](#print) method can be used to add text to a line. The [say](#say) methods adds text then advances to the start of the next line.

```raku
use PDF::API6;
use PDF::Content::FontObj;
use PDF::Page;

my PDF::API6 $pdf .= new;
my PDF::Content::FontObj $header-font = $pdf.core-font: :family<Helvetica>, :weight<bold>;
my PDF::Content::FontObj $body-font = $pdf.core-font: :family<Helvetica>;

my PDF::Page $page = $pdf.add-page;
my @curpos;
$page.gfx.graphics: -> $gfx {
    $gfx.text: {
        $gfx.say: 'My first novel', :position[10, 200], :font($header-font); # output a line
        $gfx.print: 'It was a dark and stormy', :font($body-font); # start a line
        $gfx.say: ' night.', :font($header-font); # finish it
        @curpos = $gfx.text-position.List; # save current position.
    }
}
```

There are a number of [text variables](#text-state-variables) (e.g. WordSpacing) and [graphics variables](#general-graphics---common-state-variables) (e.g. FillColor) that can be set to affect the appearance of the displayed text.

Please note that text variables and `text-position` are scoped to a text block. You will need to set them up again when starting a new text block.

### text

Synopsis: `$gfx.text: &block`

This is a convenience method, that executes code in a text block. Text blocks
cannot be nested. Nor can they contain a graphics block.
```raku
$page.text: {
    .text-position = 30, 50;
    .WordSpacing = 5;
    .say "hi";
}
```
is equivalent to:
```raku
given $page.gfx {
    .BeginText;
    .text-position = 30, 50;
    .WordSpacing = 5;
    .say "hi";
    .EndText;
}
```
Where `BeginText` and `EndText` are text graphics operators [1].

The following should only be used within a text block:

- text methods, such as: `font()`,`text-position()` and text-transform()
- text state variables: CharSpacing, WordSpacing, HorizScaling, TextLeading, TextRender, TextRise [1].

`print()` and `say()` can be used outside of a text block, but you
need to at least pass a `:$font` option and will likely need a `:$text-position` method (if the text is not at 0, 0 in current user coordinates).

[1] see [Appendix I: Graphics / Text Operators](#text-operators).

### font, core-font

```raku
$gfx.font = $gfx.core-font( :family<Helvetica>, :weight<bold>, :style<italic> );
$gfx.font = $gfx.core-font('Times-Bold');
$gfx.font = $gfx.core-font('ZapfDingbats');
```
Read/write accessor to set, or get the current font.

Note: other fonts can be loaded via the PDF::Font::Loader module:
```raku
use PDF::Font::Loader :load-font;
$gfx.font = load-font( :file</usr/share/fonts/truetype/tlwg/Garuda-BoldOblique.ttf> );
# this also requires the fontconfig package on your system
$gfx.font = load-font( :family<Garuda>, :weight<bold>, :slant<oblique> );
```
### text-position
```raku
$page.text: {
    .text-position = 10,20;
    .say('text @10,20');
}
```
Gets or sets the current text output position. Origin `(0, 0)` is at the bottom left corner.

### text-transform

Synopsis: `$gfx.text-transform: :$matrix, :translate[$x,$y], :rotate($rad), :scale[$s, $sy?], :skew[$x,y];`

Applies text transforms, such as translation, rotation, scaling, and skew.
```raku
$gfx.text-transform: :translate[110, 10], :rotate(.1);
```
- Text transforms are applied after any [Graphics Transform](#transform).

- This replaces any existing text positioning or transforms.

### base-coords

Synopsis:
```raku
my ($x-o, $y-o, ...) = $gfx.base-coords(
                           $x-t, $y-t, ...,
                           :$user=True,    # map to user default coordinates
                           :$text=False);  # un-map text matrix
```
Options:

- `:text` -  Treat as a text position on the page, i.e. un-transform against the current `TextMatrix` before un-transforming against the graphics matrix (`CTM`).

- `:!user` - Treat at a text position relative to current graphics, i.e. un-transform only the current `TextMatrix`

This method maps transformed pairs of x-y coordinates back to original coordinates.
```raku
$gfx.transform: :translate($x,$y), :scale(.8);
my @image-region = $gfx.do($my-image, :align<middle>, :position[20, 30]);
my @position-on-page = $gfx.base-coords(|@image-region);
```
### print
```raku
$gfx.WordSpacing = 2; # add extra spacing between words
my $font = $gfx.core-font( :family<Helvetica>, :weight<bold> );
my $font-size = 16;
my $text = "Hello.  Ting, ting-ting. Attention! … ATTENTION! ";

my ($x0, $x1, $y1, $y1) = $gfx.print: $text, :$font, :$font-size, :width(120);

note "text block has size {$x1 - $x0} X {$y1 - $y0};
```
Synopsis: `my @rect = print(
                 $text-str-or-chunks-or-block,
                 :align<left|center|right>, :valign<top|center|bottom>,
                 :$font, :$font-size,
                 :$.WordSpacing, :$.CharSpacing, :$.HorizScaling, :$.TextRise
                 :baseline-shift<top|middle|bottom|alphabetic|ideographic|hanging>,
                 :kern, :squish, :$leading, :$width, :$height, :nl)`

Renders a text string, or [Text Box](https://pdf-raku.github.io/PDF-Content-raku/#pdfcontenttextbox).

### say

Takes the same parameters as `print`. Sets the final text position (`$.text-position`) to the start pf the next line.

## Graphics Methods

These methods are applicable to objects that perform the `PDF::Content::Canvas` role: `PDF::Page`, `PDF::XObject::Form`, and `PDF::Pattern::Tiling`

### graphics

Synopsis: `$gfx.graphics: &block`

This is a convenience method, that executes code in a nested Save/Restore block.
```raku
$page.graphics: {
    .Rectangle(10,20,100,50);
    .Fill;
}
```
is equivalent to:
```raku
given $page.gfx {
    .Save;
    .Rectangle(10,20,100,50);
    .Fill;
    .Restore;
}
```

### transform

Synopsis: `$gfx.transform: :$matrix, :translate[$x,$y], :rotate($rad), :scale[$s, $sy?], :skew[$x,y];`

Applies a graphics transform, such as translation, rotation, scaling, etc.
```raku
$gfx.transform: :rotate(pi/4), :scale(2);
```
Unlike [Text Transforms](#text-transform), Graphics Transforms accumulate; and are applied in addition to any existing transforms.

### paint

Synopsis: `$gfx.paint( &block?, :close, :stroke, :fill, :even-odd)`

`paint` is a general purpose method for closing, stroking and filling shapes.

`paint` takes an optional block which may contain operations
to set up the graphics state and ends with one or more path
construction operations:

```raku
use PDF::Content::Color :rgb;
# fill and stroke a colored rectangle

$gfx.paint: :fill, :stroke, {
    .FillColor = rgb(.7, .7, .9);
    .StrokeColor = rgb(.9, .5, .5);
    .LineWidth = 2.5; # set stroking line-width
    .Rectangle(0, 20, 100, 250);
}
```
The graphics state is saved and restored if the optional block is provided. The above example is equivalent to:

```raku
use PDF::Content::Color :rgb;
given $gfx: {
    .Save;
    .FillColor = rgb(.7, .7, .9);
    .StrokeColor = rgb(.9, .5, .5);
    .LineWidth = 2.5; # set stroking line-width
    .Rectangle(0, 20, 100, 250);
    .FillStroke;
    .Restore;
}
```

## Image Methods

### load-image

Loads an image in a supported format (currently PNG, GIF and JPEG).
```raku
 my PDF::XObject::Image $img = $gfx.load-image("t/images/lightbulb.png");
 note "image has size {$img.width} X {$image.height}";
```
### do
```raku
$gfx.do($img, :position[10, 20])
```
Synopsis: `my Numeric @region[4] = $gfx.do(
                       $xobject, $x = 0, $y = 0,
                       :$width, :$height, :inline,
                       :align<left center right> = 'left',
                       :valign<top center bottom> = 'bottom')`

Displays an XObject Image or Form.

## XObject Forms

A Form is a graphical sub-element. Its usage is the same as an image.

XObject form construction is similar to pages; both perform the
PDF::Context::Graphics role, which provides methods such as
`gfx`, `pre-gfx`, `graphics`, `text` and `render`.

### xobject-form

This graphical method is used to create a new, empty form object:
```Raku
use v6;
use PDF::API6;
use PDF::Page;
use PDF::XObject::Form;
use PDF::Content::Color :rgb;

my PDF::API6 $pdf .= new;
my PDF::Page $page = $pdf.add-page;
$page.media-box = [0, 0, 275, 100];

# create a new XObject form of size 120 x 50
my @BBox = [0, 0, 120, 50];
my PDF::XObject::Form $form = $page.xobject-form: :@BBox;

$form.graphics: {
    # color the entire form
    .FillColor = rgb(.9, .8, .8);
    .Rectangle: |@BBox;
    .paint: :fill, :stroke;
}

$form.text: {
    # add some sample text
    .font = .core-font('Helvetica');
    .text-position = 10, 10;
    .say: "Sample form";
}

# display the form a couple of times
$page.graphics: {
    .transform: :translate(10, 10);
    .do($form);
    .transform: :translate(130, 0), :rotate(.1);
    .do($form);
}

$pdf.save-as: "tmp/sample-form.pdf";
```

![example.pdf](https://raw.githubusercontent.com/pdf-raku/PDF-API6/master/tmp/.previews/sample-form-001.png)


## Patterns

A Pattern is a graphical object. Its construction is similar to a form; its usage is the same as a color.

```Raku
use PDF::API6;
use PDF::Pattern::Tiling;
use PDF::Content::Color :rgb;

my PDF::API6 $pdf .= new;
$pdf.media-box = [0, 0, 250, 100];
my $page = $pdf.add-page;

$page.graphics: -> $gfx {
    # create a new tiling pattern
    my PDF::Pattern::Tiling $pattern = $page.tiling-pattern(:BBox[0, 0, 25, 25], );
    $pattern.graphics: {
        .FillColor = rgb(.7, .7, .9);
        .Rectangle(|$pattern<BBox>);
        .Fill;
        my $img = .load-image("t/images/lightbulb.png");
        .do($img, :position[5, 5] );
    }
    # set our pattern as the fill color
    $gfx.StrokeColor = rgb(.3, .3, .9);
    $gfx.StrokeAlpha = .5;
    $gfx.FillColor = $gfx.use-pattern($pattern);

    $gfx.FillAlpha = .6; # semitransparent
    # create a couple of overlapping semi-transparent filled rectangles
    $gfx.Rectangle(30, 30, 110, 50);
    $gfx.paint: :fill, :stroke;

    $gfx.transform: :translate[50, 0], :rotate(.25);
    $gfx.Rectangle(30, 2, 110, 50);
    $gfx.paint: :fill, :stroke;
}
$pdf.save-as: "tmp/patterns.pdf";
```

![patterns.pdf](https://raw.githubusercontent.com/pdf-raku/PDF-API6/master/tmp/.previews/patterns-001.png)

Patterns are typically used to achieve textured colors or tiling effects.


### tiling-pattern

Synopsis: `my PDF::Pattern::Tiling $pattern = $gfx.tiling-pattern( :@BBox, :@Matrix, :$XStep, :$YStep, :$group = True)`

Creates a new empty tiling pattern.

### use-pattern

Synopsis: `$gfx.FillColor = $gfx.use-pattern($pattern)`

Use a pattern; registering it as graphics resource. This method should be used to place the pattern after it has been fully constructed.

## Low Level Graphics

PDF::API6 fully supports the PDF graphics instruction set, both for reading and
writing PDF files. Direct calls to instructions are camel-cased, such as:
```raku
$gfx.TextMove(10,20);
```
It is also possible to directly call the TextMove operator 'Td':
```raku
use PDF::Content::Ops :OpCode
$gfx.op(OpCode::TextMove, 10,20);
$gfx.op('Td', 10,20);  # TextMove
```
A number of graphics variables are tracked as the instructions are executed. For example,
to set the line-width for stroking operations:
```raku
$gfx.LineWidth = 2.5;
```
This is equivalent to:
```raku
$gfx.SetLineWidth(2.5)
     unless $gfx.LineWidth == 2.5;
```
The `Save` and `Restore` operators may be used to save and restore graphics variables.
```raku
$gfx.LineWidth = 1.5;
$gfx.Save;
$gfx.LineWidth = 2.5;
#...
$gfx.Restore;
say $gfx.LineWidth; # 1.5
```
The `graphics` method simply adds `Save` and `Restore` operators
```raku
$gfx.LineWidth = 1.5;
$gfx.graphics: {
    .LineWidth = 2.5;
    #...
}
say $gfx.LineWidth; # 1.5
```
## Basic Colors

The PDF Model maintains two separate color states; for filling and stroking.

They are applicable to general graphics as well as displayed text.

### FillColor, FillAlpha

To set an RGB color for filling, or for displaying text:
```raku
$gfx.FillColorSpace = 'DeviceRGB';
$gfx.FillColorN = [1.0, .5, .5];
```
Alternatives:
```raku
$gfx.FillColor = :DeviceRGB[1.0, .5, .5];

use PDF::Content::Color :rgb;
$gfx.FillColor = rgb(1.0, .5, .5);
```
There are also Gray and CMYK color-spaces
```raku
$gfx.FillColor = :DeviceGray[.7];
$gfx.FillColor = :DeviceCMYK[.3, .2, .2, .15];

use PDF::Content::Color :gray, :cmyk;
$gfx.FillColor = gray(.7);
$gfx.FillColor = cmyk(.3, .2, .2, .15);
```
Also settable is the `FillAlpha`. This is a value between 0.0 (fully transparent) and
1.0 (fully opaque).

Note that `FillAlpha` can also be used to draw semi-transparent images:
```raku
$gfx.FillAlpha = .3;  # make the fill color semi-transparent
$gfx.Rectangle(10,10,50,75);
$gfx.Fill; # fill, semi-transparently
$gfx.do($image, 20,20);  # overlay image, semi-transparently
```
### StrokeColor, StrokeAlpha

These are identical to `FillColor`, and `FillAlpha`, except that they are applied to stroking colors:
```raku
# draw a semi-transparent rectangle with red border
use PDF::Content::Color :rgb;
$gfx.StrokeAlpha = .5;  # make the stroke color semi-transparent
$gfx.StrokeColor = rgb(.9, .1, .1);
$gfx.Rectangle(10,10,50,75);
$gfx.Stroke;
```
### Named Colors

The PDF::Content::Color `:ColorName` and `color` exports provide a selection of built in named colors.

-  Aqua, Black, Blue, Fuchsia, Gray, Green, Lime, Maroon Navy, Olive Orange, Purple,
   Red, Silver, Teal, Yellow, Cyan, Magenta

A wider selection of named colors is available via the `Color::Named` module.
```raku
use PDF::Content::Color :ColorName, :color;
use Color::Named;
$gfx.FillColor = color Blue; # a PDF::Content named color
$gfx.StrokeColor = color Color::Named.new( :name<azure> );
```    
### Text Modes

By default text is drawn solidly using the current fill color. There are other text rendering modes that alter how text is stroked and filled. For example, the FillOutLineText rendering mode strokes the text using the current StrokeColor to a thickness determined by the current LineWidth then fills it using the current FillColor.

Setting the same `FillColor` and `StrokeColor` with `TextMode::OutlineText`
artificially increasing the font weight by `LineWidth`.

```Raku
use v6;
use PDF::API6;
use PDF::Content::Color :ColorName, :color;
use PDF::Content::Ops :TextMode;

my PDF::API6 $pdf .= new;
$pdf.media-box = [0, 0, 200, 100];
my PDF::Page $page = $pdf.add-page;
my $font = $page.core-font( :family<Helvetica> );

$page.graphics: {
    .text: {
        .font = $font, 20;
        .FillColor = color Blue;
        .StrokeColor = color Red;
        .LineWidth = .6;

        .text-position = 10, 75;
        .say: "Filled/Solid";

        .TextRender = TextMode::OutlineText;
        .say: "Outlined";

        .TextRender = TextMode::FillOutlineText;
        .say: "Filled/Stroked";

        .StrokeColor = .FillColor;
        .LineWidth = 1;
        .say: "Bolded Text";
    }
}

$pdf.save-as: "tmp/text-render-modes.pdf";
```

![example.pdf](https://raw.githubusercontent.com/pdf-raku/PDF-API6/master/tmp/.previews/text-render-modes-001.png)

See [Appendix II: Text Rendering Modes](#appendix-ii-text-rendering-modes)

## Rendering Methods

### render: :&callback 

This method is used to process graphics; normally after installing
callbacks. Callback invocations have access to the graphics state via
the `$*gfx` dynamic variable.

```Raku
use PDF::API6;
use PDF::Content;
use PDF::Content::Ops :OpCode;
use PDF::Page;
my PDF::API6 $pdf .= open: "t/basic.pdf";
my PDF::Page $page = $pdf.page: 1;

my sub callback($op, *@args) {
   given $op {
       when TextMove|TextMoveSet|SetTextMatrix {
           note "Text matrix updated by $op to {$*gfx.TextMatrix}";
       }
   }
}

my PDF::Content $gfx = $page.render( :&callback);
```

### html-canvas

The optional [HTML::Canvas::To::PDF](https://pdf-raku.github.io/HTML-Canvas-To-PDF-raku/) module needs to be installed before using this method. It adds a rendering back-end to enable HTML5 Canvas like graphics construction on Pages or XObject Forms (which perform the PDF::Content::Canvas role).

In this mode, fonts are registered via [CSS:Font::Descriptor](https://css-raku.github.io/CSS-Properties-raku/CSS/Font/Descriptor) objects.

```
use PDF::API6;
use PDF::Content::Canvas;
use CSS::Font::Descriptor;

my PDF::API6 $pdf .= new;
my PDF::Content::Canvas $page = $pdf.add-page;
my CSS::Font::Descriptor $arial .= new: :font-family<arial>, :src<url(resources/font/FreeMono.ttf)>;
$page.html-canvas: :font-face[$arial], {
    .beginPath();
    .arc(95, 50, 40, 0, 2 * pi);
    .stroke();
    .font = "30px Arial";
    .fillText("Hello World", 10, 50);
}

$pdf.save-as: "tmp/html-canvas.pdf";
```

## AcroForm Fields

PDF::API6 has some experimental abilities to read and manipulate AcroFields.

The individual fields are returned as PDF::Field sub-roles (see PDF::Class).

Displayed fields are also a subclass of PDF::Annot, most commonly PDF::Annot::Widget.
```Raku
use PDF::API6;
use PDF::Field;
use PDF::Field::Button;
use PDF::Field::Choice;
use PDF::Field::Text;
use PDF::Field::Signature;
use PDF::Annot::Widget;

my PDF::API6 $pdf .= open: "t/pdf/OoPdfFormExample.pdf";
my PDF::Field @fields = $pdf.fields;
# display field names and values
for @fields -> $field {
    my $field-type = do given $field {
       when PDF::Field::Button { 'button' }
       when PDF::Field::Choice { 'button' }
       when PDF::Field::Text   { 'text' }
       when PDF::Field::Signature   { 'signature' }
       default { 'unknown' }
    }
    my $annot-type = do given $field {
       when PDF::Annot::Widget {'widget'}
       when PDF::Annot {'annot'}
       default {'hidden'}
    }
    say "{$field.key}: {$field.value} is of type $field-type $annot-type";
}
```

- The `fields` method returns all fields in the PDF as an array.
- The `fields-hash` method returns fields hashed on each fields `.key()` value

There are also PDF::Page `fields`, and `fields-hash` methods that return all fields on a given page.
```raku
my PDF::API6 $pdf .= open: "my-form.pdf";
my PDF::Field @page-1-fields = $pdf.page(1).fields;
```
More work needs to be done in PDF::Class to fully support all possible field types;

# SECTION III: PDF::API6 Specific Methods

## Metadata Methods

### info
```raku
use PDF::Info;
my PDF::Info $info := $pdf.info;
```
Gets/sets the info for the document
```raku
$pdf.info.Title = 'Some Publication';
```
Standard `Info` fields include: `Title`, `Author`, `Subject`, `Keywords`, `Creator`, `Producer`, `CreationDate` and `ModDate`.

### xmp-metadata

    Str $xml = $pdf.xmp-metadata;

Gets/sets the XMP XML data stream.

Example:
```raku
my $xml = q:to<EOT>;
    <?xpacket begin='' id='W5M0MpCehiHzreSzNTczkc9d'?>
    <?adobe-xap-filters esc="CRLF"?>
    <x:xmpmeta
      xmlns:x='adobe:ns:meta/'
      x:xmptk='XMP toolkit 2.9.1-14, framework 1.6'>
        <rdf:RDF
          xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'
          xmlns:iX='http://ns.adobe.com/iX/1.0/'>
            <rdf:Description
              rdf:about='uuid:b8659d3a-369e-11d9-b951-000393c97fd8'
              xmlns:pdf='http://ns.adobe.com/pdf/1.3/'
              pdf:Producer='Raku PDF::API6 version 0.0.1'></rdf:Description>
            </rdf:Description>
        </rdf:RDF>
    </x:xmpmeta>
    <?xpacket end='w'?>
    EOT

$pdf.xmp-metadata = $xml
```

## Settings Methods

### preferences
```raku
use PDF::Destination :Fit;
given $pdf.preferences {
    .HideToolBar = True;
    .OpenAction = $pdf.destination( :page(2), :fit(FitWindow) );
}
```
Controls viewing preferences for the PDF. Options are:

#### `$prefs.PageMode = 'FullScreen'`

Full-screen mode, with no menu bar, window controls, or any other window visible.

#### `$prefs.PageMode = 'UseThumbs'`

Thumbnail images visible.

#### `$prefs.PageMode = 'UseOutlines'`

Make document outlines visible.

#### `$prefs.PageLayout = 'SinglePage'`

Display one page at a time.

#### `$prefs.PageLayout = 'OneColumn'`

Display the pages in one column.

#### `$prefs.PageLayout = 'TwoColumnLeft'`

Display the pages in two columns, with odd numbered pages on the left.

#### `$prefs.PageLayout = 'TwoColumnRight'`

Display the pages in two columns, with odd numbered pages on the right.

#### `$prefs.direction = 'r2l';`

The predominant reading order for text:

- `l2r` Left to right

- `r2l` Right to left (vertical writing systems, such as Chinese, Japanese, and Korean)


#### `$prefs.HideToolbar = True`

Specifying whether to hide tool bars.

#### `$prefs.HideMenubar = True`

Specifying whether to hide menu bars.

#### `$prefs.WindowUI = True`

Specifying whether to hide user interface elements.

#### `$prefs.CenterWindow = True`

Specifying whether to position the document's window in the center of the screen.

#### `$prefs.DisplayDocTitle = True`

Specifying whether the window's title bar should display the
document title taken from the Title entry of the document information
dictionary.

#### `$prefs.after-fullscreen = 'UseThumbs'`

Thumbnail images visible after Full-screen mode.

#### `$prefs.after-fullscreen = 'UseOutlines'`

Document outline visible after Full-screen mode.

#### `$prefs.PrintScaling = 'None'`

Set the default print setting for page scaling to none.

#### `$prefs.Duplex = 'Simplex'`

Print single-sided by default.

#### `$prefs.Duplex = 'DuplexFlipShortEdge'`

Print duplex by default and flip on the short edge of the sheet.

#### `$prefs.Duplex = 'DuplexFlipLongEdge'`

Print duplex by default and flip on the long edge of the sheet.

#### `$prefs.OpenAction = $pdf.destination( :$page, :fit(FitWindow));

Specifying the page (either a page number or a page object) to be
displayed by a PDF viewer, plus one of the following options:

#### `destination()` Options:

##### `:fit(FitWindow)`

Display the page designated by page, with its contents magnified just
enough to fit the entire page within the window both horizontally and
vertically. If the required horizontal and vertical magnification
factors are different, use the smaller of the two, centering the page
within the window in the other dimension.

##### `:fit(FitHoriz), :$top`

Display the page designated by page, with the vertical coordinate top
positioned at the top edge of the window and the contents of the page
magnified just enough to fit the entire width of the page within the
window.

##### `:fit(FitVert), :$left`

Display the page designated by page, with the horizontal coordinate
left positioned at the left edge of the window and the contents of the
page magnified just enough to fit the entire height of the page within
the window.

##### `:fit(FitRect), :$left, :$bottom, :$right, :$top`

Display the page designated by page, with its contents magnified just
enough to fit the rectangle specified by the coordinates left, bottom,
right, and top entirely within the window both horizontally and
vertically. If the required horizontal and vertical magnification
factors are different, use the smaller of the two, centering the
rectangle within the window in the other dimension.

##### `:fit(FitBoxHoriz), :$top`

Display the page designated by page, with its contents magnified just
enough to fit its bounding box entirely within the window both
horizontally and vertically. If the required horizontal and vertical
magnification factors are different, use the smaller of the two,
centering the bounding box within the window in the other dimension.

##### `:fit(FitBox)`

Display the page designated by page, with the vertical coordinate top
positioned at the top edge of the window and the contents of the page
magnified just enough to fit the entire width of its bounding box
within the window.

##### `:fit(FitBoxVert), :$left`

Display the page designated by page, with the horizontal coordinate
left positioned at the left edge of the window and the contents of the
page magnified just enough to fit the entire height of its bounding
box within the window.

##### `:fit(FitXYZoom), :$left, :$top, :$zoom`

Display the page designated by page, with the coordinates (left, top)
positioned at the top-left corner of the window and the contents of
the page magnified by the factor zoom. A zero (0) value for any of the
parameters left, top, or zoom specifies that the current value of that
parameter is to be retained unchanged.

see also [examples/pdf-preferences.raku](examples/pdf-preferences.raku)

### version

    $pdf.version = v1.5;

Get or set the PDF Version

## Color Management

### color-separation
```Raku
use PDF::API6;
use PDF::Content::Color :color;
use PDF::ColorSpace::Separation;
constant CS = PDF::ColorSpace::Separation;
my PDF::API6 $pdf .= new;
$pdf.add-page.graphics: -> $gfx {
    my CS $c = $pdf.color-separation('Cyan',    color '%f000');
    my CS $m = $pdf.color-separation('Magenta', color '%0f00');
    my CS $y = $pdf.color-separation('Yellow',  color '%00f0');
    my CS $k = $pdf.color-separation('Black',   color '%000f');

    # use a separation color directly
    my CS $pms023 = $pdf.color-separation('PANTONE 032CV', color '%0ff0');
    $gfx.FillColor = $pms023 => .75;
}
```
### color-devicen
```raku
# create a DeviceN color-space for color mixing
use PDF::ColorSpace::DeviceN;
my PDF::ColorSpace::DeviceN $color-mix = $pdf.color-devicen( [ $c, $m, $y, $k, $pms023 ] );
# apply it
$gfx.FillColor = $color-mix => [0, 0, 0, .25, .75];
```
The current version of PDF::API6 only supports CMYK separations as DeviceN
components.

## Interactive Features

### Outlines

Outlines (or bookmarks) are commonly used by viewers for navigation of PDF documents.

For example, the following sets up a simple table-of-contents that will typically appear
in the navigation pane of a PDF viewer.

```Raku
use PDF::API6;
my PDF::API6 $pdf .= new;
$pdf.add-page for 1 .. 7;
use PDF::Destination :Fit;

sub dest(|c) { :Dest($pdf.destination(|c)) }

$pdf.outlines.kids = [
          %( :Title('1. Purpose of this Document'), dest(:page(1))),
          %( :Title('2. Pre-requisites'),           dest(:page(2))),
          %( :Title('3. Compiler Speed-up'),        dest(:page(3))),
          %( :Title('4. Recompiling the Kernel for Modules'), dest(:page(4)),
             :kids[
                %( :Title('5.1. Configuring Debian or RedHat for Modules'),
                   dest(:page(5), :fit(FitXYZoom), :top(798)) ),
                %( :Title('5.2. Configuring Slackware for Modules'),
                   dest(:page(5), :fit(FitXYZoom), :top(400)) ),
                %( :Title('5.3. Configuring Other Distributions for Module'),
                   dest(:page(5), :fit(FitXYZoom), :top(200)) ),
             ],
           ),
          %( :Title('Appendix'), dest(:page(7))),
         ];

```

See also: `pdf-toc.raku`, installed with PDF::Class. This can be used to view the outlines for a PDF.

### Page Labels

Get or sets page numbers to identify each page number, for display or printing:

page-labels is an array of ascending integer indexes. Each is followed by a page numbering scheme. For example
```raku
constant PageLabel = PDF::API6::PageLabel;
$pdf.page-labels = 0  => 'i',   # Roman lowercase: i, ii, iii, ...
                   4  => '1',   # Plain Decimal Numbering: 1, 2, 3, ...
                  32  => 'A-1', # Decimal: A-1, A-2, ...
                  36  => 'B-1', # Decimal: B-1, B-2, ...
                  # equivalent to 'C-1'
                  40  => { :numbering-style(PageLabel::RomanUpper), :start(1), :prefix<C-> };
```
### Annotations

An annotation associates a 'clickable' region on a page with an object such as a text note, destination page or URI. PDF::API6 currently supports a small number of commonly used annotations:

- Links
  - pages within the PDF
  - pages from another other PDF files
  - external URIs
- File Attachments
- Text Annotations (or "sticky notes")

Synopsis:
```raku
use PDF::Annot::Link;
use PDF::Annot::FileAttachment;
use PDF::Annot::Text;

my PDF::Annot::Link $page-link = $pdf.annotation: :$page, :$action, |%props;
my PDF::Annot::Link $dest-link = $pdf.annotation: :$page, :$destination, |%props;
my PDF::Annot::FileAttachment $attachment = $pdf.annotation: :$page, :$attachment, :icon-name<Paperclip|GraphPushPin>, :$text-label, |%props;
my PDF::Annot::Text $sticky-note = $pdf.annotation: :$page, :$content, :$Open, |%props;
```
Where:

    %props {              # common annotation options
        :@color,          # color for the annotation 3 values
                          # (rgb), 1 value (gray) or 4 values (cmyk)
        :@rect, :$text,   # rectangle or text to print and highlight
        :$border-style,   # style the annotation border
    }

Examples:

```Raku
use v6;
use PDF::API6;
use PDF::Destination :Fit;
use PDF::Annot::Link;
use PDF::Content::Color :ColorName;
use PDF::Border :BorderStyle;
use PDF::Annot::Text;
use PDF::Filespec;
use PDF::Content;

my PDF::API6 $pdf .= new;

$pdf.add-page for 1 .. 2;

sub dest(|c) { :Dest($pdf.destination(|c)) }
sub action(|c) { :action($pdf.action(|c)) }

my PDF::Content $gfx = $pdf.page(1).gfx;
$gfx.text: {
    .font = .core-font: 'Times-Roman';

    #-- create a link from a region on Page 1 to Page 2 --
    .text-position = 377, 545;
    my PDF::Annot::Link $link = $pdf.annotation(
                     :page(1),
                     :text("see page 2"),
                     |dest(:page(2)),
                     :color(Blue),
                 );

    #-- Link to an URI --
    .text-position = 377, 515;
    $link = $pdf.annotation(
                     :page(1),
                     :text("Raku"),
                     |action(:uri<https://raku.org>),
                     :color(Orange),
                 );

    #-- Link to a Page in another PDF --

    # display the annotation with a 2pt dashed border
    my $border-style = {
        :width(2),  # 2 point width
        # 3 point dashes, alternating with 2-point gaps
        :style(BorderStyle::Dashed),
        :dash-pattern[3, 2],
    };

    .text-position = 377, 485;
    $link = $pdf.annotation(
                     :page(1),
                     :text("Example PDF Form"),
                     |action(
                         :file<../t/pdf/OoPdfFormExample.pdf>,
                         :page(1), :fit(FitXYZoom), :top(400),
                     ),
                     :color(Green),
                     :$border-style,
                 );
}

#-- Create a Text annotation --
my Str $content = q:to<END-QUOTE>;
    To be, or not to be: that is the question: Whether 'tis
    nobler in the mind to suffer the slings and arrows of
    outrageous fortune, or to take arms against a sea of
    troubles, and by opposing end them?
END-QUOTE

my PDF::Annot::Text $note = $pdf.annotation(
             :page(1),
             :$content,
             :rect[ 377, 455, 455, 467 ],
             :color[0, 0, 1],
         );

#--  Add a File Attachment annotation
my PDF::Filespec $attachment = $pdf.attachment("t/images/lightbulb.png");
$content = 'Click on the paperclip to see an image as an example image attachment';
$pdf.annotation(
             :page(1),
             :$attachment,
             :text-label("Light Bulb"),
             :$content,
             :icon-name<Paperclip>,
             :rect[ 377, 395, 425, 412 ],
         );

```

### Named Destinations

The `destination()` method (above), also accepts an optional `:$name` argument.

This causes the PDF to keep a table that maps names to destinations. So for example:

    ```
    $pdf.destination: :page(99), :name<appendix-i-graphics>;
    $pdf.save-as: "doc.pdf";

Is enough to create a named declaration. This may have several benefits in browsers and other third-party software:

- major browsers support opening PDF's to named declarations. Opening url "file://doc.pdf#appendix-i-graphics" will open the PDF at page 99.

- PDF::API can then also locate pages by name: `$pdf.open("doc.pdf").page('appendix-i-graphics')` will open page 99.

Note that destinations can be combined with link annotations to create
links that are both internally and externally accessible.

```
    .text-position = 377, 545;
    my PDF::Annot::Link $link = $pdf.annotation(
                     :page(1), # linking from page 1 [this could also be a name]
                     :text("see Appendix I - graphics"),
                     :destination(:page(99), :name<appendix-i-graphics>),
                     :color(Blue),
                 );

```
## Tagged Content

PDF::API6 has some basic ability to tag graphical content.

See also
the [PDF::Tags](https://pdf-raku.github.io/PDF-Tags-raku/) module,
which can be used with PDF::API and provides more functionality.

### tag

    my PDF::Content::Tag $tag = $gfx.tag($tag-name, &block?, *%attrs);
    $gfx.tag: 'Span', {
        .print: 'Hasta la vista.';
    }, :Lang<es-MX>;

Create a local tag in a content stream, if a code block is given. The block is
marked, otherwise a marked point is made in the content stream.

### mark

    my PDF::Content::Tag $mark = $gfx.mark($tag-name, &block?, *%attrs);
    say $mark.mcid;

Similar to the `tag` method, but allocates a marked content identifier (MCID)
for marked content that forms part of a document's logical structure. See also
the [PDF::Tags](https://pdf-raku.github.io/PDF-Tags-raku/) module.

# APPENDIX

## Appendix I: Graphics

The PDF standard defines a state machine for rendering graphics. There are
a set of graphics operations that are used to construct content, or affect the
graphics state. These are short codes that appear in a content stream (e.g. 'cm'). [PDF::Content](https://pdf-raku.github.io/PDF-Content-raku/) implements a graphics engine that can execute these operations and maintain graphics state.

The operations and graphics variables accessors are mapped to (camel-cased) mnemonics that can be executed as methods on the [PDF::Content](https://pdf-raku.github.io/PDF-Content-raku/) `$gfx` object.

For example 'cm' is mapped to the `ConcatMatrix` mnemonic. Its takes a matrix array as an argument and updates the `CTM` graphics state variable.

Graphics are used to construct page content, as well as Form XObjects and Tiling Patterns.

Graphics operations and variables sometimes need to be used directly. In particular,

- [Text State Variables](#text-state-variables) - for advanced text effects
- [General Graphics](#general-graphics---common-state-variables) - for lines and colors
- [Path Construction Operands](#path-construction-operators) - for drawing curves and lines

There are some nesting and sequencing rules for operations, including:

- There are three types of block structures, [graphics](#graphics), [text](#text) and [marked content](#marked-content).
- [Text blocks](#text) don't nest, or contain graphics blocks.
- [Text state variables](#text-state-variables) should only be used in a [text block](#text) and are scoped to it.
- Other Graphics state variables should be used in a [graphics block](#graphics) (possibly nested) and are scoped to the innermost graphics block.
- [Font](#font-core-font) and [text position](#text-position) should be set before rendering text.
- A sequence of [path construction operands](#path-construction-operators) should be followed by a [path painting operand](#path-painting-operators).

PDF::Content will warn if there are any problems with operator sequencing or block structure.

### Graphics Variables

#### Text State Variables

These are scoped to text blocks and influence the appearance
and layout of text.

Accessor | Code | Description | Default | Example Setters | Notes
-------- | ------ | ----------- | ------- | ------- | ---
TextMatrix | Tm | Text transformation matrix | [1,0,0,1,0,0] | `.TextMatrix = :scale(1.5);` | [1]
CharSpacing | Tc | Character spacing adjustment | 0.0 | `.CharSpacing = 1.0`
WordSpacing | Tw | Word spacing adjustment | 0.0 | `.WordSpacing = 2.5`
HorizScaling | Th | Horizontal scaling (percent) | 100 | `.HorizScaling = 150`
TextLeading | Tl | Text line height | 0.0 | `.TextLeading = 12;`
Font | [Tf, Tfs] | Text font and size | | `.font = [ .core-font( :family<Helvetica> ), 12 ]` | [2]
TextRender | Tmode | Text rendering mode | 0 | `.TextRender = TextMode::OutlineText` | [3]
TextRise | Trise | Text rise | 0.0 | `.TextRise = 3`

[1] See also the [text-transform](#text-transform) method

[2] See also the [font](#font-core-font) method.

[3] See [Appendix II: Text Rendering Modes](#appendix-ii-text-rendering-modes)

#### General Graphics - Common State Variables

These variables affect the appearance of lines and set stroke and fill colors

Accessor | Code | Description | Default | Example Setters | Notes
-------- | ------ | ----------- | ------- | ------- | ---
CTM |  | The current transformation matrix | [1,0,0,1,0,0] | `.ConcatMatrix: :scale(1.5);` | [1]
DashPattern | D |  A description of the dash pattern to be used when paths are stroked | solid | `.DashPattern = [[3, 5], 6];`
FillAlpha | ca | The constant shape or constant opacity value to be used for other painting operations | 1.0 | `.FillAlpha = 0.25`
FillColor| | current fill color-space and color | :DeviceGray[0.0] | `.FillColor = :DeviceCMYK[.7,.2,.2,.1]`
LineCap  |  LC | A code specifying the shape of the endpoints for any open path that is stroked | 0 (butt) | `.LineCap = LineCaps::RoundCaps;`
LineJoin | LJ | A code specifying the shape of joints between connected segments of a stroked path | 0 (miter) | `.LineJoin = LineJoin::RoundJoin`
LineWidth | w | Stroke line-width | 1.0 | `.LineWidth = 2.5`
StrokeAlpha | CA | The constant shape or constant opacity value to be used when paths are stroked | 1.0 | `.StrokeAlpha = 0.5;`
StrokeColor| | current stroke color-space and color | :DeviceGray[0.0] | `.StrokeColor = :DeviceRGB[.7,.2,.2]`

[1] See also the [transform](#transform) method

#### General Graphics - Advanced State Variables

Accessor | Code | Description | Default
-------- | ------ | ----------- | -------
AlphaSource | AIS | A flag specifying whether the current soft mask and alpha constant parameters are interpreted as shape values or opacity values. This flag also governs the interpretation of the SMask entry | false |
BlackGenerationFunction | BG2 | A function that calculates the level of the black colour component to use when converting RGB colours to CMYK
BlendMode | BM | The current blend mode to be used in the transparent imaging model |
Flatness | FT | The precision with which curves are rendered on the output device. The value of this parameter gives the maximum error tolerance, measured in output device pixels; smaller numbers give smoother curves at the expense of more computation | 1.0 
Halftone | HT |  A halftone screen for gray and colour rendering
MiterLimit | ML | number The maximum length of mitered line joins for stroked paths |
OverPrintMode | OPM | A flag specifying whether painting in one set of colorants should cause the corresponding areas of other colorants to be erased or left unchanged | false
OverPrintPaint | OP | A code specifying whether a colour component value of 0 in a DeviceCMYK colour space should erase that component (0) or leave it unchanged (1) when overprinting | 0
OverPrintStroke | OP | " | 0
RenderingIntent | RI | The rendering intent to be used when converting CIE-based colours to device colours | RelativeColorimetric
SmoothnessTolerance | ST | The precision with which colour gradients are to be rendered on the output device. The value of this parameter (0 to 1.0) gives the maximum error tolerance, expressed as a fraction of the range of each colour component; smaller numbers give smoother colour transitions at the expense of more computation and memory use.
SoftMask | SMask | A soft-mask dictionary specifying the mask shape or mask opacity values to be used in the transparent imaging model, or the name: None | None
StrokeAdjust | SA | A flag specifying whether to compensate for possible rasterization effects when stroking a path with a line | false
TransferFunction | TR2 |  A function that adjusts device gray or colour component levels to compensate for nonlinear response in a particular output device
UndercolorRemovalFunction | UCR2 | A function that calculates the reduction in the levels of the cyan, magenta, and yellow colour components to compensate for the amount of black added by black generation

### Graphic Operators

#### Color Operators

Low level setters for [FillColor](#fillcolor-fillalpha) and [StrokeColor](#strokecolor-strokealpha).

Method | Code | Description
--- | --- | ---
SetStrokeColorSpace(name) | CS | Set the current space to use for stroking operations. This can be a standard name, such as 'DeviceGray', 'DeviceRGB', 'DeviceCMYK', or a name declared in the parent's Resource<ColorSpace> dictionary.
SetStrokeColorSpace(name) | cs | Same but for non-stroking operations.
SetStrokeColor(c1, ..., cn) | SC | Set the colours to use for stroking operations in a device. The number of operands required and their interpretation depends on the current stroking colour space: DeviceGray, CalGray, and Indexed colour spaces, have one operand. DeviceRGB, CalRGB, and Lab colour spaces, three operands. DeviceCMYK has four operands.
SetStrokeColorN(c1, ..., cn [,pattern-name]) | SCN | Same as SetStrokeColor but also supports Pattern, Separation, DeviceN, ICCBased colour spaces and patterns.
SetFillColor(c1, ..., cn) | sc | Same as SetStrokeColor, but for non-stroking operations.
SetFillColorN(c1, ..., cn [,pattern-name]) | scn | Same as SetStrokeColorN, but for non-stroking operations.
SetStrokeGray(level) | G | Set the stroking colour space to DeviceGray and set the gray level to use for stroking operations, between 0.0 (black) and 1.0 (white).
SetFillGray(level) | g | Same as G but used for non-stroking operations.
SetStrokeRGB(r, g, b) | RG | Set the stroking colour space to DeviceRGB and set the colour to use for stroking operations. Each operand is a number between 0.0 (minimum intensity) and 1.0 (maximum intensity).
SetFillRGB(r, g, b) | rg | Same as RG but used for non-stroking operations.
SetFillCMYK(c, m, y, k) | K | Set the stroking colour space to DeviceCMYK and set the colour to use for stroking operations. Each operand is a number between 0.0 (zero concentration) and 1.0 (maximum concentration). The behaviour of this operator is affected by the OverprintMode graphics state.
SetStrokeCMYK(c, m, y, k) | k | Same as K but used for non-stroking operations.

### Graphics State

Method | Code | Description | Notes
--- | --- | --- | ---
Save() | q | Save the current graphics state on the graphics state stack | [1]
Restore() | Q | Restore the graphics state by removing the most recently saved state from the stack and making it the current state. | [1]
ConcatMatrix(a, b, c, d, e, f) | cm | Modify the current transformation matrix (CTM) by concatenating the specified matrix | [2]
SetLineWidth(width) | w | Set the line width in the graphics state
SetLineCap(cap-style) | J | Set the line cap style in the graphics state (see LineCap enum)
SetLineJoin(join-style) | j | Set the line join style in the graphics state (see LineJoin enum)
SetMiterLimit(ratio) | M | Set the miter limit in the graphics state
SetDashPattern(dashArray, dashPhase) | d | Set the line dash pattern in the graphics state
SetRenderingIntent(intent) | ri | Set the colour rendering intent in the graphics state: AbsoluteColorimetric, RelativeColormetric, Saturation, or Perceptual
SetFlatness(flat) | i | Set the flatness tolerance in the graphics state. flatness is a number in the range 0 to 100; 0 specifies the output device’s default flatness tolerance.
SetGraphics(dictName) | gs | Set the specified parameters in the graphics state. dictName is the name of a graphics state parameter dictionary in the ExtGState resource sub-dictionary | [3]

[1] See also the [graphics](#graphics) method

[2] See also the [transform](#transform) method

[3] See also [Advanced State Variables](#general-graphics---advanced-state-variables)

### Text Operators

Method | Code | Description | Notes
--- | --- | --- | ---
BeginText() | BT | Begin a text object, initializing $.TextMatrix, to the identity matrix. Text objects cannot be nested. | [1]
EndText() | ET | End a text object, discarding the text matrix. | [1]
TextMove(tx, ty) | Td | Move to the start of the next line, offset from the start of the current line by (tx, ty ); where tx and ty are expressed in unscaled text space units. | [2]
TextMoveSet(tx, ty) | TD | Move to the start of the next line, offset from the start of the current line by (tx, ty ). Set $.TextLeading to ty.
SetTextMatrix(a, b, c, d, e, f) | Tm | Set $.TextMatrix | [3]
TextNextLine| T* | Move to the start of the next line
ShowText(string) | Tj | Show a text string | [4][5]
MoveShowText(string) | ' | Move to the next line and show a text string. | [4][5]
MoveSetShowText(aw, ac, string) | " | Move to the next line and show a text string, after setting $.WordSpacing to  aw and $.CharSpacing to ac | [4][5]
ShowSpacetext(array) |  TJ | Show one or more text strings, allowing individual glyph positioning. Each element of array is either a string or a number. If the element is a string, show it. If it is a number, adjust the text position by that amount | [4][5]

[1] See also the [text](#text) method

[2] See also the [text-position](#text-position) method

[3] See also the [text-transform](#text-transform) method

[4] See also the [print](#print) and [say](#say) methods

[5] `string` arguments should be encoded using the current font. For example:

    $gfx.ShowText: $gfx.font.encode("Sample Text", :str)

### Path Construction Operators

Method | Code | Description | Notes
--- | --- | --- | ---
MoveTo(x, y) | m | Begin a new sub-path by moving the current point to coordinates (x, y), omitting any connecting line segment. If the previous path construction operator in the current path was also m, the new m overrides it. | [1]
LineTo(x, y) | l | Append a straight line segment from the current point to the point (x, y). The new current point is (x, y). | [1]
CurveTo(x1, y1, x2, y2, x3, y3) | c | Append a cubic Bézier curve to the current path. The curve extends from the current point to the point (x3, y3 ), using (x1 , y1 ) and (x2, y2 ) as the Bézier control points. The new current point is (x3, y3 ). | [1]
Rectangle(x, y, width, Height) | re | Append a rectangle to the current path as a complete sub-path, with lower-left corner (x, y) and dimensions `width` and `height`. | [1]
ClosePath | h | Close the current sub-path by appending a straight line segment from the current point to the starting point of the sub-path. | [1]

[1] The [current-point](#method-current-point) accessor can be used to obtain the Current Point.

### Path Painting Operators

Method | Code | Description | Notes
--- | --- | --- | ---
Stroke() | S | Stroke the path. | [1]
CloseStroke() | s | Close and stroke the path. Same as: $.ClosePath; $.Stroke | [1]
Fill() | f | Fill the path, using the nonzero winding number rule to determine the region. Any open sub-paths are implicitly closed before being filled. | [1]
EOFill() | f* | Fill the path, using the even-odd rule to determine the region to fill | [1]
FillStroke() | B | Fill and then stroke the path, using the nonzero winding number rule to determine the region to fill. | [1]
EOFillStroke() | B* | Fill and then stroke the path, using the even-odd rule to determine the region to fill. | [1]
CloseFillStroke() | b | Close, fill, and then stroke the path, using the nonzero winding number rule to determine the region to fill. | [1]
CloseEOFillStroke() | b* | Close, fill, and then stroke the path, using the even-odd rule to determine the region to fill. | [1]
EndPath() | n | End the path object without filling or stroking it. This operator is a path-painting no-op, used primarily for the side effect of changing the current clipping path. | [1]

[1] See also [paint](#paint) method, which encapsulates the operators in this section. For example:

    $gfx.paint(:close, :fill, :stroke);   # equivalent to $gfx.CloseFillStroke
    $gfx.paint(:close, :fill);            # equivalent to $gfx.ClosePath; $gfx.Fill

### Path Clipping

Method | Code | Description
 --- | --- | ---
Clip() | W | Modify the current clipping path by intersecting it with the current path, using the nonzero winding number rule to determine which regions lie inside the clipping path. |
EOClip() | W* | Modify the current clipping path by intersecting it with the current path, using the even-odd rule to determine which regions lie inside the clipping path. |

### Marked Content

Method | Code | Description | Notes
--- | --- | --- | ---
MarkPoint(tag) | MP | Designate a marked-content point. | [1]
MarkPointDict(tag,props) | DP | Designate a marked-content point with an associated property dictionary. | [1]
BeginMarkContent(tag) | BMC |  Begin a marked-content sequence terminated by a balancing `EMC` (EndMarkedContent) operator. | [1]
BeginMarkedContentDict(tag,props) |  BDC |  Begin a marked-content sequence with an associated property dictionary | [1]
EndMarkContent | EMC | End a marked-content sequence begun by a BMC (BeginMarkedContent) or BDC (BeginMarkedContentDict) operator. | [1]

[1] See also  [tag](#tag) and [mark](#mark) methods

### Graphics Introspection Methods


#### Method graphics-state()

Synopsis: `my %gstate = $gfx.graphics-state: :delta`

Returns a snapshot of the current graphics state. Summarising the values of all of the graphics variables described above. The `:delta` option returns only those values that have been updated since the last `.Save()` ('q' operator).

#### Method gsaves()

Synopsis: `my Hash @gstates = $gfx.gsaves: :delta`

A summary of all currently saved graphics states. This corresponds to the the number of open Save ('q') operations that have not been closed with a Restore ('Q') operation.

The `:delta` option returns the differences from the current graphics state to the last gsave, and the difference between each previously saved graphics state.

#### Method context()

Synopsis: `my $ctxt  = $gfx.context()`

Returns the current graphics state context. As defined in the PDF::Content::Ops::GraphicsContext enumeration. One of: Path, Text, Clipping, Page, Shading or Image.

#### Method ops()

Synopsis: `my Pair @ops = $gfx.ops(); PDF::IO::Writer.write-content(@ops);`

Returns a raw list of operations to date.

#### Method content-dump()

Synopsis: `my Str @lines = .content-dump()`

Returns a serialized content stream to-date as a list of lines

#### Method open-tags()

Synopsis: `my PDF::Content::Tag @tags = .open-tags();`

Returns any currently open marked-content tags.

#### Method tags()

Synopsis: `my PDF::Content::Tag @closed-tags = .tags()`

Returns previously closed marked content tags

### Method current-point()

Returns the Current Point coordinates during path construction, as a two element list (`x` and `y`). Returns `(Numeric, Numeric)` if a path is not being constructed.

### Graphics Tracing

The `gfx :trace` option enables tracing as graphics operations are executed. For example:

    use PDF::API6;
    use PDF::Page;
    use PDF::Content;
    my PDF::API6 $pdf .= new;
    my PDF::Page $page = $pdf.add-page;
    my PDF::Content $gfx = $page.gfx: :trace;
    $gfx.text: {
        .font = $page.core-font: 'Times-Roman';
        .print: "Hello World";
    };

Produces:

    BT	% BeginText
      /F1 16 Tf	% SetFont	{"Font":[{"BaseFont":"Courier","Encoding":"WinAnsiEncoding","Subtype":"Type1","Type":"Font"},16]}
      (Hello World) Tj	% ShowText
    ET	% EndText

To break this down:
- The `text()` method is adding a BeginText (BT) graphics operation
  on block entry and a EndText (ET) method on exit.
- The `font()` method sets the current font object and size. Behind the scenes it has also set up a font dictionary, registered as /F1 for the font
- The `print()` command is displaying text using thew ShowText (Tj) operator


The following methods give an overview of the current state of the graphics engine:

## Appendix II: Text Rendering Modes

Text is filled using the current `FillColor` and/or stroked using the
current `StrokeColor`, depending on the current `TextRender` mode
as listed below.

Enumerations can be imported via `use PDF::Content::Ops :TextMode`

Mode | Enumeration | Description
---- | ----------- | -----------
0 | FillText | Fill text (default).
1 | OutlineText | Stroke text.
2 | FillOutlineText | Fill, then stroke text.
3 | InvisableText | Neither fill nor stroke text (invisible).
4 | FillClipText | Fill text and add to path for clipping
5 | OutlineClipText | Stroke text and add to path for clipping.
6 | FillOutlineClipText | Fill, then stroke text and add to path for clipping.
7 |ClipText | Add text to path for clipping.

## Appendix III: Module Overview


                               PDF::API6
                                  ^
                                  |
                                  |
    3.       PDF::Lite         PDF::Class
                |                 |
                |                 | ..<... PDF::Tags
                |                 |
                +-----------------+
                        ^
    2.                  | --<--- PDF::Content
                        |
                        | ..<... PDF::Font::Loader
                        |
                        ^                FDF
                        |                 |
                        +-----------------+
                        |
    1.                 PDF
                        |
                        | --<--- PDF::Grammar


There are three levels underlying PDF::API6. From bottom to top, these are:

1. *PDF* handles the
physical structure of a PDF, including object indexes, encryption, data
dictionaries and arrays and the packing and unpacking of stream content.
PDF files can be created read and updated.

As well as loading PDF files, the *PDF* module can load FDF files, which are
a closely related, but simpler format with the same syntax, commonly used to maintain
form data associated with a PDF. There is an unreleased *FDF* module than is analogous to, but much simpler than *PDF::Class*.

2. *PDF::Content* is a set of roles that both *PDF::Class* and
*PDF::Lite* use to implement basic PDF content and graphics.
This includes methods for page manipulation, images, xobject forms, graphics,
simple colors (RGB, CMYK and Gray-scale) and core-fonts.

The optional *PDF::Font::Loader* can be used to load Type-1 and Free-Type fonts
for use by either *PDF::Class*, or *PDF::Lite*.

3. *PDF::Class* is a comprehensive set of classes that understand most of
the commonly used objects in a PDF, including fonts, interactive features, tagged
PDF, AcroForm fields and annotations.

*PDF::Lite* understands content only, including pages and xobjects (forms and images). 

The optional *PDF::Tags* module is applicable to PDF files that are 'Tagged'. It
presents DOM like interface for reading document structure elements.

*PDF::API6* is a lightweight class that inherits from *PDF::Class*. It provides
sugar and extra functionality for common use cases such as colors, outlines
(table of contents) and preferences.

