# A basic vectorial 2D canvas that can output SVG
#
# See Part 4.
module canvas

# A basic canvas
class Canvas
	# All the drawing elements
	var items = new Array[Line]

	# Add a line in the canvas
	fun add_line(x1,y1,x2,y2: Float) do items.add new Line(x1,y1,x2,y2)

	# Return a full SVG for the canvas
	fun to_svg: String do
		var res = """
<?xml version="1.0" encoding="UTF-8" ?>
<svg xmlns="http://www.w3.org/2000/svg" version="1.1" height="200" width="500">
		"""
		for i in items do res += i.to_svg + "\n"
		res += "</svg>"
		return res
	end
end

# A line on a canvas
class Line
	# x coordinate of the first point
	var x1: Float

	# y coordinate of the first point
	var y1: Float

	# x coordinate of the second point
	var x2: Float

	# y coordinate of the second point
	var y2: Float

	# The `line` SVG element
	fun to_svg: String do
		return """<line x1="{{{x1}}}" y1="{{{y1}}}" x2="{{{x2}}}" y2="{{{y2}}}" style="stroke:black;stroke-width:3"/>"""
	end
end