arrowhead.js-e

## Copyright (c) 2016, Empirical Modelling Group
## All rights reserved.
##
## See LICENSE.txt

${{
	Arrowhead = function(start, end, length, width, filled) {
		this.start = start;
		this.end = end;
		this.length = length;
		this.width = width;
		this.filled = filled;
	};

	Arrowhead.prototype.toString = function () {
		return "Arrowhead(" + Eden.edenCodeForValues(this.start, this.end, this.length, this.width,
			this.filled) + ")";
	};

	Arrowhead.prototype.getEdenCode = Arrowhead.prototype.toString;

	Arrowhead.prototype.draw = function (context, scale, x1, y1, gradient1, reverse1, x2, y2, gradient2, reverse2) {
		var invGradient, len1, len2, len3, p0x, p0y, p1x, p1y, p2x, p2y, p3x, p3y;
		var lineWidth = context.lineWidth;
		var adjustment = lineWidth / 4;
		var filled = this.filled;

		var width = this.width;
		var length = this.length;

		if (length === undefined) {
			if (lineWidth <= 4) {
				length = 10 / scale;
			} else {
				length = lineWidth * 2.5 / scale;
			}
		} else {
			length = length / scale;
		}
		if (width === undefined) {
			width = length / 2;
		} else {
			width = (width / 2) / scale;
		}

		context.fillStyle = context.strokeStyle;

		if (this.start) {
			invGradient = - 1 / gradient1;
			if ((reverse1 && invGradient == Infinity) || (!reverse1 && invGradient == -Infinity)) {
				//Horizontal left
				p1x = x1 + length;
				p1y = y1 - width;
				p2x = p1x;
				p2y = y1 + width;
				p3x = x1 + adjustment;
				p3y = y1;
			} else if (gradient1 == 0) {
				//Horizontal right
				p1x = x1 - length;
				p1y = y1 - width;
				p2x = p1x;
				p2y = y1 + width;
				p3x = x1 - adjustment;
				p3y = y1;
			} else if ((reverse1 && gradient1 == -Infinity) || (!reverse1 && gradient1 == Infinity)) {
				//Vertical upward
				p1x = x1 - width;
				p1y = y1 + length;
				p2x = x1 + width;
				p2y = p1y;
				p3x = x1;
				p3y = y1 + adjustment;
			} else if (gradient1 == Infinity || gradient1 == -Infinity) {
				//Vertical downward
				p1x = x1 - width;
				p1y = y1 - length;
				p2x = x1 + width;
				p2y = p1y;
				p3x = x1;
				p3y = y1 - adjustment;
			} else {
				len1 = Math.sqrt(length * length / (1 + gradient1 * gradient1));
				if (reverse1) {
					len1 = -len1;
				}
				p0x = x1 + len1;
				p0y = y1 + len1 * gradient1;
				len2 = Math.sqrt(width * width / (1 + invGradient * invGradient));
				p1x = p0x - len2;
				p1y = p0y - len2 * invGradient;
				p2x = p0x + len2;
				p2y = p0y + len2 * invGradient;
				len3 = Math.sqrt(adjustment * adjustment / (1 + gradient1 * gradient1));
				p3x = x1 - len3;
				p3y = y1 - len3 * gradient1
			}

			context.beginPath();
			context.moveTo(p1x, p1y);
			context.lineTo(p3x, p3y);
			context.lineTo(p2x, p2y);
			if (filled) {
				context.closePath();
				context.fill();
			}
			context.stroke();
		}

		if (this.end) {
			invGradient = - 1 / gradient2;
			if ((reverse2 && invGradient == -Infinity) || (!reverse2 && invGradient == Infinity)) {
				//Horizontal left
				p1x = x2 + length;
				p1y = y2 - width;
				p2x = p1x;
				p2y = y2 + width;
				p3x = x2 + adjustment;
				p3y = y2;
			} else if (gradient2 == 0) {
				//Horizontal right
				p1x = x2 - length;
				p1y = y2 - width;
				p2x = p1x;
				p2y = y2 + width;
				p3x = x2 - adjustment;
				p3y = y2;
			} else if ((reverse2 && gradient2 == Infinity) || (!reverse2 && gradient2 == -Infinity)) {
				//Vertical upward
				p1x = x2 - width;
				p1y = y2 + length;
				p2x = x2 + width;
				p2y = p1y;
				p3x = x2;
				p3y = y2 + adjustment;
			} else if (gradient2 == Infinity || gradient2 == -Infinity) {
				//Vertical downward
				p1x = x2 - width;
				p1y = y2 - length;
				p2x = x2 + width;
				p2y = p1y;
				p3x = x2;
				p3y = y2 - adjustment;
			} else {
				len1 = Math.sqrt(length * length / (1 + gradient2 * gradient2));
				if (reverse2) {
					len1 = -len1;
				}
				p0x = x2 - len1;
				p0y = y2 - len1 * gradient2;
				len2 = Math.sqrt(width * width / (1 + invGradient * invGradient));
				p1x = p0x - len2;
				p1y = p0y - len2 * invGradient;
				p2x = p0x + len2;
				p2y = p0y + len2 * invGradient;
				len3 = Math.sqrt(adjustment * adjustment / (1 + gradient2 * gradient2));
				p3x = x2 - len3;
				p3y = y2 - len3 * gradient2
			}

			context.beginPath();
			context.moveTo(p1x, p1y);
			context.lineTo(p3x, p3y);
			context.lineTo(p2x, p2y);
			if (filled) {
				context.closePath();
				context.fill();
			}
			context.stroke();
		}
	};

}}$;

#! Create an Arrowhead line.
# @param start Whether to draw the arrowhead at the start
# @param end Whether to draw the arrowhead at the end
# @param length Length of the arrowhead
# @param width Width of the arrowhead. IF undefined, a proportional value is automatically chosen.
# @param [filled] Whether to fill the arrowhead or just draw an outline. Defaults to true.
# 
#  #canvas #arrow #arrowhead #shape #arrow #library #draw
func Arrowhead {
	${{
		var argsProcessed;
		var numArgs = arguments.length;
		var arg = arguments[0];
		var argType = typeof(arg);

		var start, end, length, width, filled;

		if ((argType == "boolean" && numArgs >= 2 &&
		 (typeof(arguments[1]) == "boolean" || arguments[1] === undefined)) ||
		 numArgs == 5
		) {
			start = arg;
			end = arguments[1];
			argsProcessed = 2;
			arg = arguments[2];
			argType = typeof(arg);
		} else {
			start = false;
			end = true;
			argsProcessed = 0;
		}

		if (argType == "number" || arg === undefined) {
			length = arg;
			argsProcessed++;
			arg = arguments[argsProcessed];
			argType = typeof(arg);
		}

		if (argType == "number" || arg === undefined) {
			width = length;
			length = arg;
			argsProcessed++;
		}

		if (argsProcessed < numArgs) {
			filled = arguments[argsProcessed];
		}

		if (filled === undefined) {
			filled = true;
		}

		return new Arrowhead(start, end, length, width, filled);
	}}$;
}