paper.js/src/path/PathItem.js

/*
 * Paper.js - The Swiss Army Knife of Vector Graphics Scripting.
 * http://paperjs.org/
 *
 * Copyright (c) 2011 - 2013, Juerg Lehni & Jonathan Puckey
 * http://lehni.org/ & http://jonathanpuckey.com/
 *
 * Distributed under the MIT license. See LICENSE file for details.
 *
 * All rights reserved.
 */

/**
 * @name PathItem
 *
 * @class The PathItem class is the base for any items that describe paths
 * and offer standardised methods for drawing and path manipulation, such as
 * {@link Path} and {@link CompoundPath}.
 *
 * @extends Item
 */
var PathItem = Item.extend(/** @lends PathItem# */{
	initialize: function PathItem() {
		Item.apply(this, arguments);
	},

	/**
	 * Returns all intersections between two {@link PathItem} items as an array
	 * of {@link CurveLocation} objects. {@link CompoundPath} items are also
	 * supported.
	 *
	 * @param {PathItem} path the other item to find the intersections to.
	 * @return {CurveLocation[]} the locations of all intersection between the
	 * paths
	 * @example {@paperscript}
	 * // Create a rectangular path with its top-left point at
	 * // {x: 30, y: 25} and a size of {width: 50, height: 50}:
	 * var path = new Path.Rectangle(new Point(30, 25), new Size(50, 50));
	 * path.strokeColor = 'black';
	 *
	 * var secondPath = path.clone();
	 * var intersectionGroup = new Group();
	 *
	 * function onFrame(event) {
	 * 	secondPath.rotate(3);
	 *
	 * 	var intersections = path.getIntersections(secondPath);
	 * 	intersectionGroup.removeChildren();
	 *
	 * 	for (var i = 0; i < intersections.length; i++) {
	 * 		var intersectionPath = new Path.Circle({
	 * 			center: intersections[i].point,
	 * 			radius: 4,
	 * 			fillColor: 'red'
	 * 		});
	 * 		intersectionGroup.addChild(intersectionPath);
	 * 	}
	 * }
	 */
	getIntersections: function(path) {
		// First check the bounds of the two paths. If they don't intersect,
		// we don't need to iterate through their curves.
		if (!this.getBounds().touches(path.getBounds()))
			return [];
		var locations = [],
			curves1 = this.getCurves(),
			curves2 = path.getCurves(),
			length2 = curves2.length,
			values2 = [];
		for (var i = 0; i < length2; i++)
			values2[i] = curves2[i].getValues();
		for (var i = 0, l = curves1.length; i < l; i++) {
			var curve1 = curves1[i],
				values1 = curve1.getValues();
			for (var j = 0; j < length2; j++)
				Curve.getIntersections(values1, values2[j], curve1, curves2[j],
						locations);
		}
		return locations;
	},

	setPathData: function(data) {
		// This is a very compact SVG Path Data parser that works both for Path
		// and CompoundPath.

		var parts = data.match(/[a-z][^a-z]*/ig),
			coords,
			relative = false,
			control,
			current = new Point(); // the current position

		function getCoord(index, coord, update) {
			var val = parseFloat(coords[index]);
			if (relative)
				val += current[coord];
			if (update)
				current[coord] = val;
			return val;
		}

		function getPoint(index, update) {
			return new Point(
				getCoord(index, 'x', update),
				getCoord(index + 1, 'y', update)
			);
		}

		// First clear the previous content
		if (this._type === 'path')
			this.removeSegments();
		else
			this.removeChildren();

		for (var i = 0, l = parts.length; i < l; i++) {
			var part = parts[i];
				cmd = part[0],
				lower = cmd.toLowerCase();
			// Split at white-space, commas but also before signs.
			// Use positive lookahead to include signs.
			coords = part.slice(1).trim().split(/[\s,]+|(?=[+-])/);
			relative = cmd === lower;
			var length = coords.length;
			switch (lower) {
			case 'm':
			case 'l':
				for (var j = 0; j < length; j += 2)
					this[j === 0 && lower === 'm' ? 'moveTo' : 'lineTo'](
							getPoint(j, true));
				break;
			case 'h':
			case 'v':
				var coord = lower == 'h' ? 'x' : 'y';
				for (var j = 0; j < length; j++) {
					getCoord(j, coord, true);
					this.lineTo(current);
				}
				break;
			case 'c':
				for (var j = 0; j < length; j += 6) {
					this.cubicCurveTo(
							getPoint(j),
							control = getPoint(j + 2),
							getPoint(j + 4, true));
				}
				break;
			case 's':
				// Shorthand cubic bezierCurveTo, absolute
				for (var j = 0; j < length; j += 4) {
					this.cubicCurveTo(
							// Calculate reflection of previous control points
							current.multiply(2).subtract(control),
							control = getPoint(j),
							getPoint(j + 2, true));
				}
				break;
			case 'q':
				for (var j = 0; j < length; j += 4) {
					this.quadraticCurveTo(
							control = getPoint(j),
							getPoint(j + 2, true));
				}
				break;
			case 't':
				for (var j = 0; j < length; j += 2) {
					this.quadraticCurveTo(
							// Calculate reflection of previous control points
							control = current.multiply(2).subtract(control),
							getPoint(j, true));
				}
				break;
			case 'a':
				// TODO: Implement Arcs!
				break;
			case 'z':
				this.closePath();
				break;
			}
		}
	},

	/**
	 * Smooth bezier curves without changing the amount of segments or their
	 * points, by only smoothing and adjusting their handle points, for both
	 * open ended and closed paths.
	 *
	 * @name PathItem#smooth
	 * @function
	 *
	 * @example {@paperscript}
	 * // Smoothing a closed shape:
	 *
	 * // Create a rectangular path with its top-left point at
	 * // {x: 30, y: 25} and a size of {width: 50, height: 50}:
	 * var path = new Path.Rectangle(new Point(30, 25), new Size(50, 50));
	 * path.strokeColor = 'black';
	 *
	 * // Select the path, so we can see its handles:
	 * path.fullySelected = true;
	 *
	 * // Create a copy of the path and move it 100pt to the right:
	 * var copy = path.clone();
	 * copy.position.x += 100;
	 *
	 * // Smooth the segments of the copy:
	 * copy.smooth();
	 *
	 * @example {@paperscript height=220}
	 * var path = new Path();
	 * path.strokeColor = 'black';
	 *
	 * path.add(new Point(30, 50));
	 *
	 * var y = 5;
	 * var x = 3;
	 *
	 * for (var i = 0; i < 28; i++) {
	 *     y *= -1.1;
	 *     x *= 1.1;
	 *     path.lineBy(x, y);
	 * }
	 *
	 * // Create a copy of the path and move it 100pt down:
	 * var copy = path.clone();
	 * copy.position.y += 120;
	 *
	 * // Set its stroke color to red:
	 * copy.strokeColor = 'red';
	 *
	 * // Smooth the segments of the copy:
	 * copy.smooth();
	 */

	/**
	 * {@grouptitle Postscript Style Drawing Commands}
	 *
	 * On a normal empty {@link Path}, the point is simply added as the path's
	 * first segment. If called on a {@link CompoundPath}, a new {@link Path} is
	 * created as a child and the point is added as its first segment.
	 *
	 * @name PathItem#moveTo
	 * @function
	 * @param {Point} point
	 */

	// DOCS: Document #lineTo()
	/**
	 * @name PathItem#lineTo
	 * @function
	 * @param {Point} point
	 */

	/**
	 * Adds a cubic bezier curve to the path, defined by two handles and a to
	 * point.
	 *
	 * @name PathItem#cubicCurveTo
	 * @function
	 * @param {Point} handle1
	 * @param {Point} handle2
	 * @param {Point} to
	 */

	/**
	 * Adds a quadratic bezier curve to the path, defined by a handle and a to
	 * point.
	 *
	 * @name PathItem#quadraticCurveTo
	 * @function
	 * @param {Point} handle
	 * @param {Point} to
	 */

	// DOCS: Document PathItem#curveTo() 'paramater' param.
	/**
	 * Draws a curve from the position of the last segment point in the path
	 * that goes through the specified {@code through} point, to the specified
	 * {@code to} point by adding one segment to the path.
	 *
	 * @name PathItem#curveTo
	 * @function
	 * @param {Point} through the point through which the curve should go
	 * @param {Point} to the point where the curve should end
	 * @param {Number} [parameter=0.5]
	 *
	 * @example {@paperscript height=300}
	 * // Interactive example. Move your mouse around the view below:
	 *
	 * var myPath;
	 * function onMouseMove(event) {
	 * 	// If we created a path before, remove it:
	 * 	if (myPath) {
	 * 		myPath.remove();
	 * 	}
	 *
	 * 	// Create a new path and add a segment point to it
	 * 	// at {x: 150, y: 150):
	 * 	myPath = new Path();
	 * 	myPath.add(150, 150);
	 *
	 * 	// Draw a curve through the position of the mouse to 'toPoint'
	 * 	var toPoint = new Point(350, 150);
	 * 	myPath.curveTo(event.point, toPoint);
	 *
	 * 	// Select the path, so we can see its segments:
	 * 	myPath.selected = true;
	 * }
	 */

	/**
	 * Draws an arc from the position of the last segment point in the path that
	 * goes through the specified {@code through} point, to the specified
	 * {@code to} point by adding one or more segments to the path.
	 *
	 * @name PathItem#arcTo
	 * @function
	 * @param {Point} through the point where the arc should pass through
	 * @param {Point} to the point where the arc should end
	 *
	 * @example {@paperscript}
	 * var path = new Path();
	 * path.strokeColor = 'black';
	 *
	 * var firstPoint = new Point(30, 75);
	 * path.add(firstPoint);
	 *
	 * // The point through which we will create the arc:
	 * var throughPoint = new Point(40, 40);
	 *
	 * // The point at which the arc will end:
	 * var toPoint = new Point(130, 75);
	 *
	 * // Draw an arc through 'throughPoint' to 'toPoint'
	 * path.arcTo(throughPoint, toPoint);
	 *
	 * // Add a red circle shaped path at the position of 'throughPoint':
	 * var circle = new Path.Circle(throughPoint, 3);
	 * circle.fillColor = 'red';
	 *
	 * @example {@paperscript height=300}
	 * // Interactive example. Click and drag in the view below:
	 *
	 * var myPath;
	 * function onMouseDrag(event) {
	 * 	// If we created a path before, remove it:
	 * 	if (myPath) {
	 * 	    myPath.remove();
	 * 	}
	 *
	 * 	// Create a new path and add a segment point to it
	 * 	// at {x: 150, y: 150):
	 * 	myPath = new Path();
	 * 	myPath.add(150, 150);
	 *
	 * 	// Draw an arc through the position of the mouse to 'toPoint'
	 * 	var toPoint = new Point(350, 150);
	 * 	myPath.arcTo(event.point, toPoint);
	 *
	 * 	// Select the path, so we can see its segments:
	 * 	myPath.selected = true;
	 * }
	 *
	 * // When the mouse is released, deselect the path
	 * // and fill it with black.
	 * function onMouseUp(event) {
	 * 	myPath.selected = false;
	 * 	myPath.fillColor = 'black';
	 * }
	 */
	/**
	 * Draws an arc from the position of the last segment point in the path to
	 * the specified point by adding one or more segments to the path.
	 *
	 * @name PathItem#arcTo
	 * @function
	 * @param {Point} to the point where the arc should end
	 * @param {Boolean} [clockwise=true] specifies whether the arc should be
	 *        drawn in clockwise direction.
	 *
	 * @example {@paperscript}
	 * var path = new Path();
	 * path.strokeColor = 'black';
	 *
	 * path.add(new Point(30, 75));
	 * path.arcTo(new Point(130, 75));
	 *
	 * var path2 = new Path();
	 * path2.strokeColor = 'red';
	 * path2.add(new Point(180, 25));
	 *
	 * // To draw an arc in anticlockwise direction,
	 * // we pass 'false' as the second argument to arcTo:
	 * path2.arcTo(new Point(280, 25), false);
	 *
	 * @example {@paperscript height=300}
	 * // Interactive example. Click and drag in the view below:
	 * var myPath;
	 *
	 * // The mouse has to move at least 20 points before
	 * // the next mouse drag event is fired:
	 * tool.minDistance = 20;
	 *
	 * // When the user clicks, create a new path and add
	 * // the current mouse position to it as its first segment:
	 * function onMouseDown(event) {
	 * 	myPath = new Path();
	 * 	myPath.strokeColor = 'black';
	 * 	myPath.add(event.point);
	 * }
	 *
	 * // On each mouse drag event, draw an arc to the current
	 * // position of the mouse:
	 * function onMouseDrag(event) {
	 * 	myPath.arcTo(event.point);
	 * }
	 */

	/**
	 * Closes the path. When closed, Paper.js connects the first and last
	 * segments.
	 *
	 * @name PathItem#closePath
	 * @function
	 * @see Path#closed
	 */

	/**
	 * {@grouptitle Relative Drawing Commands}
	 *
	 * If called on a {@link CompoundPath}, a new {@link Path} is created as a
	 * child and a point is added as its first segment relative to the
	 * position of the last segment of the current path.
	 *
	 * @name PathItem#moveBy
	 * @function
	 * @param {Point} vector
	 */

	/**
	 * Adds a segment relative to the last segment point of the path.
	 *
	 * @name PathItem#lineBy
	 * @function
	 * @param {Point} vector The vector which is added to the position of the
	 *        last segment of the path, to become the new segment.
	 *
	 * @example {@paperscript}
	 * var path = new Path();
	 * path.strokeColor = 'black';
	 *
	 * // Add a segment at {x: 50, y: 50}
	 * path.add(25, 25);
	 *
	 * // Add a segment relative to the last segment of the path.
	 * // 50 in x direction and 0 in y direction, becomes {x: 75, y: 25}
	 * path.lineBy(50, 0);
	 *
	 * // 0 in x direction and 50 in y direction, becomes {x: 75, y: 75}
	 * path.lineBy(0, 50);
	 *
	 * @example {@paperscript height=300}
	 * // Drawing a spiral using lineBy:
	 * var path = new Path();
	 * path.strokeColor = 'black';
	 *
	 * // Add the first segment at {x: 50, y: 50}
	 * path.add(view.center);
	 *
	 * // Loop 500 times:
	 * for (var i = 0; i < 500; i++) {
	 * 	// Create a vector with an ever increasing length
	 * 	// and an angle in increments of 45 degrees
	 * 	var vector = new Point({
	 * 	    angle: i * 45,
	 * 	    length: i / 2
	 * 	});
	 * 	// Add the vector relatively to the last segment point:
	 * 	path.lineBy(vector);
	 * }
	 *
	 * // Smooth the handles of the path:
	 * path.smooth();
	 *
	 * // Uncomment the following line and click on 'run' to see
	 * // the construction of the path:
	 * // path.selected = true;
	 */

	// DOCS: Document Path#curveBy()
	/**
	 * @name PathItem#curveBy
	 * @function
	 * @param {Point} throughVector
	 * @param {Point} toVector
	 * @param {Number} [parameter=0.5]
	 */

	// DOCS: Document Path#arcBy()
	/**
	 * @name PathItem#arcBy
	 * @function
	 * @param {Point} throughVector
	 * @param {Point} toVector
	 */
});