HexaPDF 0.24.0 - Document Layout Update Published on

The focus of this release was to provide a major improvement in document layout and creation. Nearly all classes in HexaPDF::Layout were adapted or refactored which also resulted in some breaking changes.

Column and List Boxes

The most user visible changes are the addition of HexaPDF::Layout::ColumnBox for laying out boxes in columns and HexaPDF::Layout::ListBox for creating ordered or unordered lists:

ColumBox in action ListBox in action

These two new box classes represent a major step forward since they are container boxes, i.e. boxes that contain other boxes. For such classes to work flawlessly with the rest of the layout engine, the class HexaPDF::Layout::BoxFitter was introduced. It allows fitting multiple boxes into one or more (temporary) frames and storing the results for later use; exactly what is needed for container boxes.

The container boxes can be used like any other box which means they can also be split. And they can be nested in one another, like having a column box inside a list box inside a column box:

Container boxes used together

Since the container boxes internally rely on the same layout engine that is used everywhere else, they can also recognize and flow around cut-outs, like the black box in the image above.

One of the nice advantages of having this system of individual box classes which represent certain parts of a document is that it allows for adding additional information later on. For example, adding support for tagged PDF (i.e. providing accessibility related information) should not be much of a problem in the future.

More Convenient Box and Document Creation

There was also much work done to improve the document layout API to make it easier to use.

The new HexaPDF::Document::Layout class, accessible through HexaPDF::Document#layout, is now the central hub for creating box objects. It allows for the easy instantiation of all built-in box classes as well as user-provided ones.

Additionally, that class contains a central style registry which allows one to associate names to specific box styles and reference those styles later by their given name.

The HexaPDF::Composer class from which most of the methods in HexaPDF::Document::Layout came from, uses this new class and can now concentrate on the special behaviour needed when creating whole documents. It is now also possible to easily define the children of container boxes:

require 'hexapdf'

HexaPDF::Composer.create("list.pdf") do |composer|
  composer.text("Hello World!", font_size: 30, align: :center, padding: [0, 0, 20])
  composer.box(:list, item_spacing: 20) do |list|
    list.image('examples/machupicchu.jpg', height: 100)
    list.box(:list, item_type: :decimal) do |sub_list|
      sub_list.text("Item 1")
      sub_list.text("Another item")

Example composer document

Other Changes

The code base and test suite have been adapted so that all tests now pass on Linux, macOS and Windows using Ruby versions 2.6, 2.7, 3.0, 3.1 and the current Ruby head version.

There were also some other, smaller changes, like the ability to move pages around in a document. And as usual there were several bug fixes

As always, have a look at the changelog for an overview of all changes.