Class: HexaPDF::Layout::PageStyle

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/layout/page_style.rb

Overview

A PageStyle defines the dimensions of a page, its initial look, the Frame for object placement and which page style should be used next.

This class is used by HexaPDF::Composer to style the individual pages.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(page_size: :A4, orientation: :portrait, next_style: nil, &block) ⇒ PageStyle

Creates a new page style instance for the given page size, orientation and next style values. If a block is given, it is used as #template for defining the initial content of a page.

Example:

PageStyle.new(page_size: :Letter) do |canvas, style|
  style.frame = style.create_frame(canvas.context, 72)
  style.next_style = :other
  canvas.fill_color("fd0") { canvas.circle(100, 100, 50).fill }
end



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# File 'lib/hexapdf/layout/page_style.rb', line 114

def initialize(page_size: :A4, orientation: :portrait, next_style: nil, &block)
  @page_size = page_size
  @orientation = orientation
  @template = block
  @frame = nil
  @next_style = next_style
end

Instance Attribute Details

#frame ⇒ Object

The Frame object that defines the area for the last page created with #create_page where content should be placed.

This value is usually updated during execution of the #template. If the value is not updated, a frame covering the page except for a default margin on all sides is set during #create_page.



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# File 'lib/hexapdf/layout/page_style.rb', line 94

def frame
  @frame
end

#next_style ⇒ Object

Defines the name of the page style that should be used for the next page.

Note that this value can be different each time a new page is created via #create_page.

If this attribute is nil (the default), it means that this style should be used again.



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# File 'lib/hexapdf/layout/page_style.rb', line 101

def next_style
  @next_style
end

#orientation ⇒ Object

The page orientation, either :portrait or :landscape.

Only used if #page_size is one of the predefined page sizes and not an array.



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# File 'lib/hexapdf/layout/page_style.rb', line 64

def orientation
  @orientation
end

#page_size ⇒ Object

The page size.

Can be any valid predefined page size (see HexaPDF::Type::Page::PAPER_SIZE) or an array

llx, lly, urx, ury

specifying a custom page size.

Example:

style.page_size = :A4
style.page_size = [0, 0, 200, 200]



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# File 'lib/hexapdf/layout/page_style.rb', line 59

def page_size
  @page_size
end

#template ⇒ Object

A callable object that defines the initial content of a page created with #create_page.

The callable object is given a canvas and the page style as arguments. It needs to draw the initial content of the page. Note that the graphics state of the canvas is not saved before executing the template code and restored afterwards. If this is needed, the object needs to do it itself. The #next_style attribute can optionally be set.

Furthermore, the callable object should set the #frame that defines the area on the page where content should be placed. The #create_frame method can be used for easily creating a rectangular frame.

Example:

page_style.template = lambda do |canvas, style|
  box = canvas.context.box
  canvas.fill_color("fd0") do
    canvas.rectangle(0, 0, box.width, box.height).fill
  end
  style.frame = style.create_frame(canvas.context, 72)
end



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# File 'lib/hexapdf/layout/page_style.rb', line 86

def template
  @template
end

Instance Method Details

#create_frame(page, margin = 36) ⇒ Object

Creates a frame based on the given page’s box and margin.

The margin can be any value allowed by HexaPDF::Layout::Style::Quad#set.

Note: This is a helper method for use inside the #template callable.



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# File 'lib/hexapdf/layout/page_style.rb', line 139

def create_frame(page, margin = 36)
  box = page.box
  margin = Layout::Style::Quad.new(margin)
  Layout::Frame.new(box.left + margin.left,
                    box.bottom + margin.bottom,
                    box.width - margin.left - margin.right,
                    box.height - margin.bottom - margin.top,
                    context: page)
end

#create_page(document) ⇒ Object

Creates a new page in the given document using this page style and returns it.

If the #frame has not changed during execution of the #template, a default frame covering the whole page except a margin of 36 is assigned.



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# File 'lib/hexapdf/layout/page_style.rb', line 126

def create_page(document)
  frame_before = @frame
  page = document.pages.create(media_box: page_size, orientation: orientation)
  template&.call(page.canvas, self)
  self.frame = create_frame(page, 36) if @frame.equal?(frame_before)
  page
end