Class: Vedeu::Output::Viewport

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Defined in:
lib/vedeu/output/viewport.rb

Overview

A Viewport is the visible part of the content within an interface.

When a buffer has more lines than the defined height, or more columns than the defined width of the interface, this class provides ‘scrolling’ via the cursor’s position.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(view) ⇒ Vedeu::Output::Viewport

Returns an instance of Vedeu::Output::Viewport.



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# File 'lib/vedeu/output/viewport.rb', line 39

def initialize(view)
  @view = view
end

Instance Attribute Details

#view ⇒ Vedeu::Views::View (readonly, protected) 



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# File 'lib/vedeu/output/viewport.rb', line 62

def view
  @view
end

Class Method Details

.render(view) ⇒ Array<Array<String>>|NilClass 



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# File 'lib/vedeu/output/viewport.rb', line 31

def self.render(view)
  new(view).render
end

Instance Method Details

#border ⇒ Object (private)

Return the border associated with the interface/view we are drawing.



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# File 'lib/vedeu/output/viewport.rb', line 152

def border
  @border ||= Vedeu.borders.by_name(name)
end

#bx ⇒ Fixnum (private) 



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# File 'lib/vedeu/output/viewport.rb', line 157

def bx
  @bx ||= border.bx
end

#by ⇒ Fixnum (private) 



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# File 'lib/vedeu/output/viewport.rb', line 162

def by
  @by ||= border.by
end

#columns ⇒ Range (private)

Note:

The width is reduced by one as #columns is a range of Array elements.

Using the current cursor’s x position, return a range of visible columns.

Scrolls the content horizontally when the stored cursor’s x position for the interface is outside of the visible area.



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# File 'lib/vedeu/output/viewport.rb', line 121

def columns
  left...(left + width)
end

#content_offset(offset, dimension) ⇒ Fixnum (private)

Returns the offset for the content (the number of rows or columns to change the viewport by on either the y or x axis) determined by the offset (the cursor’s y or x offset position.



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# File 'lib/vedeu/output/viewport.rb', line 142

def content_offset(offset, dimension)
  return 0 unless offset >= dimension

  offset - dimension
end

#cursor ⇒ Vedeu::Cursors::Cursor (private)

See Also:

  • Cursors::Repository#by_name


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# File 'lib/vedeu/output/viewport.rb', line 168

def cursor
  @cursor ||= Vedeu.cursors.by_name(name)
end

#left ⇒ Fixnum (private) 



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# File 'lib/vedeu/output/viewport.rb', line 126

def left
  @left ||= content_offset(ox, width)
end

#output ⇒ Array<Array<Vedeu::Views::Char>> (private) 



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# File 'lib/vedeu/output/viewport.rb', line 67

def output
  Vedeu.timer("Rendering content: '#{name}'".freeze) do
    out = []

    show.each_with_index do |line, iy|
      line.each_with_index do |column, ix|
        column.position = [by + iy, bx + ix]
        out << column
      end
    end

    out
  end
end

#render ⇒ Array<Array<String>>|NilClass

Returns the content for the view.



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# File 'lib/vedeu/output/viewport.rb', line 46

def render
  Vedeu.render_output(output) if visible?
end

#rows ⇒ Range (private)

Note:

The height is reduced by one as #rows is a range of Array elements.

Using the current cursor’s y position, return a range of visible lines.

Scrolls the content vertically when the stored cursor’s y position for the interface is outside of the visible area.



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# File 'lib/vedeu/output/viewport.rb', line 106

def rows
  top...(top + height)
end

#show ⇒ Array (private)

Note:

If there are no lines of content, we return an empty array. If there are no more columns of content we return a space enclosed in an array; this prevents a weird line hopping bug which occurs when the current line has no more content, but subsequent lines do.

Returns the visible content for the view.



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# File 'lib/vedeu/output/viewport.rb', line 91

def show
  (lines[rows] || []).map { |line| (line.chars[columns] || []) }
end

#to_s ⇒ String Also known as: to_str

Returns a string representation of the viewport.



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# File 'lib/vedeu/output/viewport.rb', line 53

def to_s
  Array(render).map(&:to_s).join("\n")
end

#top ⇒ Fixnum (private) 



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# File 'lib/vedeu/output/viewport.rb', line 131

def top
  @top ||= content_offset(oy, height)
end