Class: WhirledPeas::Graphics::Canvas

Inherits:
Object
  • Object
show all
Defined in:
lib/whirled_peas/graphics/canvas.rb

Overview

Canvas represent the area of the screen a painter can paint on.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(left, top, width, height) ⇒ Canvas

Returns a new instance of Canvas.



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# File 'lib/whirled_peas/graphics/canvas.rb', line 13

def initialize(left, top, width, height)
  @left = left
  @top = top
  @width = width
  @height = height
end

Instance Attribute Details

#height ⇒ Object (readonly)

Returns the value of attribute height.



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# File 'lib/whirled_peas/graphics/canvas.rb', line 7

def height
  @height
end

#left ⇒ Object (readonly)

Returns the value of attribute left.



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# File 'lib/whirled_peas/graphics/canvas.rb', line 7

def left
  @left
end

#top ⇒ Object (readonly)

Returns the value of attribute top.



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# File 'lib/whirled_peas/graphics/canvas.rb', line 7

def top
  @top
end

#width ⇒ Object (readonly)

Returns the value of attribute width.



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# File 'lib/whirled_peas/graphics/canvas.rb', line 7

def width
  @width
end

Class Method Details

.unwritable ⇒ Object 



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# File 'lib/whirled_peas/graphics/canvas.rb', line 9

def self.unwritable
  new(-1, -1, 0, 0)
end

Instance Method Details

#==(other) ⇒ Object 



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# File 'lib/whirled_peas/graphics/canvas.rb', line 109

def ==(other)
  other.is_a?(self.class) && hash == other.hash
end

#child(child_left, child_top, child_width, child_height) ⇒ Object 



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# File 'lib/whirled_peas/graphics/canvas.rb', line 24

def child(child_left, child_top, child_width, child_height)
  Graphics.debugger(
    proc do
      "Create child: #{self.inspect}.child(left=#{child_left}, top=#{child_top}, width=#{child_width}, height=#{child_height})"
    end
  )
  if child_left >= left + width
    self.class.unwritable
  elsif child_left + child_width <= left
    self.class.unwritable
  elsif child_top >= top + height
    self.class.unwritable
  elsif child_top + child_height <= top
    self.class.unwritable
  else
    if child_left < left
      child_width -= left - child_left
      child_left = left
    end
    child_width = [width - (child_left - left), child_width].min
    if child_top < top
      child_height -= top - child_top
      child_top = top
    end
    child_height = [height - (child_top - top), child_height].min
    child_canvas = self.class.new(
      child_left,
      child_top,
      child_width,
      child_height,
    )
    Graphics.debugger(proc { "  -> #{child_canvas.inspect}" })
    child_canvas
  end
end

#hash ⇒ Object 



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# File 'lib/whirled_peas/graphics/canvas.rb', line 105

def hash
  [left, top, width, height].hash
end

#inspect ⇒ Object 



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# File 'lib/whirled_peas/graphics/canvas.rb', line 113

def inspect
  "Canvas(left=#{left}, top=#{top}, width=#{width}, height=#{height})"
end

#stroke(stroke_left, stroke_top, raw, formatting = []) {|stroke_left, stroke_top, fstring| ... } ⇒ Object

Yields a single line of formatted characters positioned on the canvas, verifying only characters within the canvas are included.

Yields:

  • (stroke_left, stroke_top, fstring) 


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# File 'lib/whirled_peas/graphics/canvas.rb', line 62

def stroke(stroke_left, stroke_top, raw, formatting=[], &block)
  Graphics.debugger(
    proc do
      "Stroke: #{self.inspect}.stroke(left=#{stroke_left}, top=#{stroke_top}, length=#{raw.length})"
    end
  )
  if stroke_left >= left + width
    # The stroke starts to the right of the canvas
    fstring = Utils::FormattedString.blank
  elsif stroke_left + raw.length <= left
    # The stroke ends to the left of the canvas
    fstring = Utils::FormattedString.blank
  elsif stroke_top < top
    # The stroke is above the canvas
    fstring = Utils::FormattedString.blank
  elsif stroke_top >= top + height
    # The stroke is below the canvas
    fstring = Utils::FormattedString.blank
  else
    # In this section, we know that at least part of the stroke should be visible
    # on the canvas. Chop off parts of the raw string that aren't within the
    # canvas boundary and ensure the stroke start position is also within the
    # canvas boundary

    # If the stroke starts to the left of the canvas, set the start index to the
    # first value that will be on the canvas, then update stroke_left to be on
    # the canvas
    start_index = stroke_left < left ? left - stroke_left : 0
    stroke_left = left if stroke_left <= left

    # Determine how many characters from the stroke will fit on the canvas
    visible_length = [raw.length, width - (stroke_left - left)].min
    end_index = start_index + visible_length - 1
    fstring = Utils::FormattedString.new(raw[start_index..end_index], formatting)
  end
  Graphics.debugger(
    proc do
      "  -> Stroke(left=#{stroke_left}, top=#{stroke_top}, length=#{fstring.length})"
    end
  )
  yield stroke_left, stroke_top, fstring
end

#writable? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/whirled_peas/graphics/canvas.rb', line 20

def writable?
  width > 0 || height > 0
end