Class: HexaPDF::Content::CanvasComposer

Inherits:
Object
  • Object
show all
Defined in:
lib/hexapdf/content/canvas_composer.rb

Overview

The CanvasComposer class allows using the document layout functionality for a single canvas. It works in a similar manner as the HexaPDF::Composer class.

See: HexaPDF::Composer, HexaPDF::Document::Layout

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(canvas, margin: 0) ⇒ CanvasComposer

Creates a new CanvasComposer instance for the given canvas.

The margin can be any value allowed by HexaPDF::Layout::Style::Quad#set and defines the margin that should not be used during composition. For the remaining area of the canvas a frame object will be created.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 62

def initialize(canvas, margin: 0)
  @canvas = canvas
  @document = @canvas.context.document

  box = @canvas.context.box
  margin = Layout::Style::Quad.new(margin)
  @frame = Layout::Frame.new(box.left + margin.left,
                             box.bottom + margin.bottom,
                             box.width - margin.left - margin.right,
                             box.height - margin.bottom - margin.top,
                             context: @canvas.context)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method

#method_missing(name, *args, **kwargs, &block) ⇒ Object

Draws any box that can be created using HexaPDF::Document::Layout.

This includes all named boxes defined in the ‘layout.boxes.map’ configuration option.

Examples:

#>pdf
canvas.composer(margin: 10) do |composer|
  composer.text("Some text", position: :float)
  composer.image(machu_picchu, height: 30, align: :right)
  composer.lorem_ipsum(sentences: 1, margin: [0, 0, 5])
  composer.list(item_spacing: 2) do |list|
    composer.document.config['layout.boxes.map'].each do |name, klass|
      list.formatted_text([{text: name.to_s, fill_color: "hp-blue-dark"},
                           {text: "\n#{klass}"}], font_size: 6)
    end
  end
end

See: HexaPDF::Document::Layout#box



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# File 'lib/hexapdf/content/canvas_composer.rb', line 128

def method_missing(name, *args, **kwargs, &block)
  if @document.layout.box_creation_method?(name)
    draw_box(@document.layout.send(name, *args, **kwargs, &block))
  else
    super
  end
end

Instance Attribute Details

#canvas ⇒ Object (readonly)

The associated canvas.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 49

def canvas
  @canvas
end

#document ⇒ Object (readonly)

The associated HexaPDF::Document instance.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 52

def document
  @document
end

#frame ⇒ Object (readonly)

The HexaPDF::Layout::Frame instance into which the boxes are laid out.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 55

def frame
  @frame
end

Instance Method Details

#draw_box(box) ⇒ Object

Draws the given HexaPDF::Layout::Box and returns the last drawn box.

The box is drawn into the frame. If it doesn’t fit, the box is split. If it still doesn’t fit, a new region of the frame is determined and then the process starts again.

If none or only some parts of the box fit into the frame, an exception is thrown.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 87

def draw_box(box)
  while true
    result = @frame.fit(box)
    if result.success?
      @frame.draw(@canvas, result)
      break
    elsif @frame.full?
      raise HexaPDF::Error, "Frame for canvas composer is full and box doesn't fit anymore"
    else
      draw_box, box = @frame.split(result)
      if draw_box
        @frame.draw(@canvas, result)
        (box = draw_box; break) unless box
      elsif !@frame.find_next_region
        raise HexaPDF::Error, "Frame for canvas composer is full and box doesn't fit anymore"
      end
    end
  end
  box
end

#respond_to_missing?(name, _private) ⇒ Boolean

:nodoc:

Returns:

  • (Boolean) 


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# File 'lib/hexapdf/content/canvas_composer.rb', line 136

def respond_to_missing?(name, _private) # :nodoc:
  @document.layout.box_creation_method?(name) || super
end

#style(name, base: :base, **properties) ⇒ Object

Invokes HexaPDF::Document::Layout#style with the given arguments to create/update and return a style object.



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# File 'lib/hexapdf/content/canvas_composer.rb', line 77

def style(name, base: :base, **properties)
  @document.layout.style(name, base: base, **properties)
end