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Lines with rounded corners #158

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Lines with rounded corners #158

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d194f14
Preliminary support for Lines with rounded corners
macfreek Nov 15, 2012
8c48884
Check if the rounded corner fits
macfreek Nov 16, 2012
12019cc
Replace arcTo() with arc()
macfreek Nov 22, 2012
56ba4e8
Special case for rounded corners: 180° turn
macfreek Nov 24, 2012
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90 changes: 90 additions & 0 deletions src/shapes/Line.js
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,96 @@ Kinetic.Line.prototype = {
var lastY = this.attrs.points[n - 1].y;
this._dashedLine(context, lastX, lastY, x, y, this.attrs.dashArray);
}
else if(this.attrs.cornerRadius && n+1 < this.attrs.points.length) {
// draw line with rounded corner
var radius = this.attrs.cornerRadius
var lastX = this.attrs.points[n - 1].x;
var lastY = this.attrs.points[n - 1].y;
var nextX = this.attrs.points[n + 1].x;
var nextY = this.attrs.points[n + 1].y;
var lastXD = x - lastX
var lastYD = y - lastY
var nextXD = nextX - x
var nextYD = nextY - y

// Warning: the angle system for atan2() and arc() in the
// HTML5 canvas is different.
// For atan2(), south is 0°, counter clockwise, range -π to π
// For arc(), east is 0°, clockwise, range 0 to 2π
var lastangle = Math.atan2(lastXD, lastYD);
var nextangle = Math.atan2(nextXD, nextYD);
var anglediff = nextangle - lastangle
if (anglediff < -Math.PI) {
anglediff += 2*Math.PI
var clockwise = false;
// Direction of the normal line bisecting the two line segments
var normangle = (lastangle + nextangle - Math.PI)/2 // Value is between -1.5 π and 0.5 π
// Relative angle between normal line and either line segment
var halfangle = (Math.PI - anglediff)/2 // Value is between 0 and π/2 (0 and 90°).
// Direction in arc() coordinates, not in atan2() coordinates.
var startangle = Math.PI - lastangle // lastangle + 90 degrees clockwise, other angle system.
var endangle = Math.PI - nextangle // nextangle + 90 degrees clockwise, other angle system.
} else if (anglediff < 0) {
var clockwise = true;
// Direction of the normal line bisecting the two line segments
var normangle = (lastangle + nextangle - Math.PI)/2 // Value is between -1.5 π and 0.5 π
// Relative angle between normal line and either line segment
var halfangle = (anglediff + Math.PI)/2 // Value is between 0 and π/2 (0 and 90°).
var startangle = -lastangle // lastangle + 90 degrees counter clockwise, other angle system.
var endangle = -nextangle // nextangle + 90 degrees counter clockwise, other angle system.
} else if (anglediff < Math.PI) {
var clockwise = false;
// Direction of the normal line bisecting the two line segments
var normangle = (lastangle + nextangle + Math.PI)/2 // Value is between -0.5 π and 1.5 π
// Relative angle between normal line and either line segment
var halfangle = (Math.PI - anglediff)/2 // Value is between 0 and π/2 (0 and 90°).
var startangle = Math.PI - lastangle // lastangle + 90 degrees clockwise, other angle system.
var endangle = Math.PI - nextangle // nextangle + 90 degrees clockwise, other angle system.
} else {
anglediff -= 2*Math.PI
var clockwise = true;
// Direction of the normal line bisecting the two line segments
var normangle = (lastangle + nextangle + Math.PI)/2 // Value is between -0.5 π and 1.5 π
// Relative angle between normal line and either line segment
var halfangle = (anglediff + Math.PI)/2 // Value is between 0 and π/2 (0 and 90°).
var startangle = -lastangle // lastangle + 90 degrees counter clockwise, other angle system.
var endangle = -nextangle // nextangle + 90 degrees counter clockwise, other angle system.
}
if (radius * Math.cos(halfangle) < 0.5) {
// less than half a pixel of a corner to draw. Don't bother.
// This also prevents tan(halfang) to reach infinity.
context.lineTo(x, y);
radius = 0
} else {
if (n == 1) {
lastlen = Math.sqrt(lastXD*lastXD + lastYD*lastYD);
} else {
lastlen = Math.sqrt(lastXD*lastXD + lastYD*lastYD)/2;
}
if (n+1 == this.attrs.points.length) {
nextlen = Math.sqrt(nextXD*nextXD + nextYD*nextYD);
} else {
nextlen = Math.sqrt(nextXD*nextXD + nextYD*nextYD)/2;
}
// no worries that tan(halfang) is infinite; that is caught above
// Reduce the radius if there is not enough space
radius = Math.min(radius, Math.min(lastlen, nextlen) * Math.tan(halfangle))

if (radius <= 0) {
// special case: the line segments make a 180° turn
var arcdist = Math.min(lastlen, nextlen)
var arcX = x + arcdist*Math.sin(normangle)
var arcY = y + arcdist*Math.cos(normangle)
context.lineTo(arcX, arcY);
} else {
// distance from x,y to center of the arc
var arcdist = radius/Math.sin(halfangle)
var arcX = x + arcdist*Math.sin(normangle)
var arcY = y + arcdist*Math.cos(normangle)
context.arc(arcX, arcY, radius, startangle, endangle, !clockwise);
}
}
}
else {
// draw normal line
context.lineTo(x, y);
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