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# frozen_string_literal: true
require 'prawn/manual_builder'
Prawn::ManualBuilder::Chapter.new do
title 'Origin'
text do
prose <<~TEXT
This is the most important concept you need to learn about Prawn:
PDF documents have the origin <code>[0,0]</code> at the bottom-left corner
of the page.
A bounding box is a structure which provides boundaries for inserting
content. A bounding box also has the property of relocating the origin to
its relative bottom-left corner. However, be aware that the location
specified when creating a bounding box is its top-left corner, not
bottom-left (hence the <code>[100, 300]</code> coordinates below).
Even if you never create a bounding box explicitly, each document already
comes with one called the margin box. This initial bounding box is the
one responsible for the document margins.
So practically speaking the origin of a page on a default generated
document isn't the absolute bottom left corner but the bottom left corner
of the margin box.
The following snippet strokes a circle on the margin box origin. Then
strokes the boundaries of a bounding box and a circle on its origin.
TEXT
end
example axes: true do
stroke_circle [0, 0], 10
bounding_box([100, 200], width: 300, height: 100) do
stroke_bounds
stroke_circle [0, 0], 10
end
end
end
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