scratchfoundation/paper.js
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Begin implementing Path#getStrokeBounds().

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This commit is contained in:
Jürg Lehni 2011-03-06 10:09:37 +00:00
parent 1607d744ef
commit 3a51acec88
1 changed files with 26 additions and 12 deletions
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38
src/path/Path.js
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@ -416,14 +416,14 @@ var Path = this.Path = PathItem.extend({
} }
}, new function() { // Inject methods that require scoped privates }, new function() { // Inject methods that require scoped privates
function calculateBounds(that, includeStroke) { function calculateBounds(that, strokeRadius) {
// Code ported and further optimised from: // Code ported and further optimised from:
// http://blog.hackers-cafe.net/2009/06/how-to-calculate-bezier-curves-bounding.html // http://blog.hackers-cafe.net/2009/06/how-to-calculate-bezier-curves-bounding.html
var segments = that._segments, first = segments[0], prev = first; var segments = that._segments, first = segments[0];
if (!first) if (!first)
return null; return null;
var min = first.point.clone(), max = min.clone(); var min = first.point.clone(), max = min.clone(),
var coords = ['x', 'y']; coords = ['x', 'y'], prev = first;
function processSegment(segment) { function processSegment(segment) {
for (var i = 0; i < 2; i++) { for (var i = 0; i < 2; i++) {
var coord = coords[i]; var coord = coords[i];
@ -434,6 +434,7 @@ var Path = this.Path = PathItem.extend({
v2 = v3 + segment.handleIn[coord]; v2 = v3 + segment.handleIn[coord];
function add(value, t) { function add(value, t) {
var radius = 0;
if (value == null) { if (value == null) {
// Calculate bezier polynomial at t // Calculate bezier polynomial at t
var u = 1 - t; var u = 1 - t;
@ -441,14 +442,20 @@ var Path = this.Path = PathItem.extend({
+ 3 * u * u * t * v1 + 3 * u * u * t * v1
+ 3 * u * t * t * v2 + 3 * u * t * t * v2
+ t * t * t * v3; + t * t * t * v3;
// Only add strokeWidth to bounds for points which lie
// within 0 < t < 1. The corner cases for cap and join
// are handled in getStrokeBounds()
radius = strokeRadius;
} }
if (value < min[coord]) { var left = value - radius,
min[coord] = value; right = value + radius;
} else if (value > max[coord]) { if (left < min[coord])
max[coord] = value; min[coord] = left;
} if (right > max[coord])
max[coord] = right;
} }
add(v3); add(v3, null);
// Calculate derivative of our bezier polynomial, divided by 3. // Calculate derivative of our bezier polynomial, divided by 3.
// Dividing by 3 allows for simpler calculations of a, b, c and // Dividing by 3 allows for simpler calculations of a, b, c and
@ -531,14 +538,21 @@ var Path = this.Path = PathItem.extend({
* The bounding rectangle of the item excluding stroke width. * The bounding rectangle of the item excluding stroke width.
*/ */
getBounds: function() { getBounds: function() {
return calculateBounds(this, false); return calculateBounds(this, 0);
}, },
/** /**
* The bounding rectangle of the item including stroke width. * The bounding rectangle of the item including stroke width.
*/ */
getStrokeBounds: function() { getStrokeBounds: function() {
return calculateBounds(this, true); var width = this.getStrokeWidth(),
radius = width / 2,
join = this.getStrokeJoin(),
cap = this.getStrokeCap(),
miter = this.getMiterLimit();
var bounds = calculateBounds(this, radius);
// TODO: Handle cap and join
return bounds;
}, },
/** /**