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Merge pull request #328 from Lehonti/improvement12
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Simple refactorings of `LineCurveSeriesEngine`
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@cameronwhite
cameronwhite authored Aug 10, 2023
2 parents ac9d70c + fb105ac commit 5081289
Showing 1 changed file with 87 additions and 92 deletions.
179 changes: 87 additions & 92 deletions Pinta.Tools/Editable/Shapes/LineCurveSeriesEngine.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,7 +30,7 @@

namespace Pinta.Tools
{
public class LineCurveSeriesEngine : ShapeEngine
public sealed class LineCurveSeriesEngine : ShapeEngine
{
public Arrow Arrow1 = new (), Arrow2 = new ();

Expand Down Expand Up @@ -71,96 +71,97 @@ public override ShapeEngine Clone ()
/// </summary>
public override void GeneratePoints (int brush_width)
{
if (ControlPoints.Count < 2) {
GeneratedPoints = new[] { new GeneratedPoint (ControlPoints[0].Position, 0) };
return;
}

List<GeneratedPoint> generatedPoints = new List<GeneratedPoint> ();

if (ControlPoints.Count < 2) {
generatedPoints.Add (new GeneratedPoint (ControlPoints[0].Position, 0));
//Generate tangents for each of the smaller cubic Bezier curves that make up each segment of the resulting curve.

//The tension calculated for each point is a gradient between the previous
//control point's tension and the following control point's tension.

//Stores all of the tangent values.
List<PointD> bezierTangents = new List<PointD> ();

int pointCount = ControlPoints.Count - 1;
double pointCountDouble = (double) pointCount;
double tensionForPoint;

//Calculate the first tangent.
if (Closed) {
bezierTangents.Add (new PointD (
ControlPoints[0].Tension * (ControlPoints[1].Position.X - ControlPoints[pointCount].Position.X),
ControlPoints[0].Tension * (ControlPoints[1].Position.Y - ControlPoints[pointCount].Position.Y)));
} else {
bezierTangents.Add (new PointD (
ControlPoints[0].Tension * (ControlPoints[1].Position.X - ControlPoints[0].Position.X),
ControlPoints[0].Tension * (ControlPoints[1].Position.Y - ControlPoints[0].Position.Y)));
}

//Calculate all of the middle tangents.
for (int i = 1; i < pointCount; ++i) {
tensionForPoint = ControlPoints[i].Tension * (double) i / pointCountDouble;

bezierTangents.Add (new PointD (
tensionForPoint *
(ControlPoints[i + 1].Position.X - ControlPoints[i - 1].Position.X),
tensionForPoint *
(ControlPoints[i + 1].Position.Y - ControlPoints[i - 1].Position.Y)));
}

//Calculate the last tangent.
if (Closed) {
bezierTangents.Add (new PointD (
ControlPoints[pointCount].Tension *
(ControlPoints[0].Position.X - ControlPoints[pointCount - 1].Position.X),
ControlPoints[pointCount].Tension *
(ControlPoints[0].Position.Y - ControlPoints[pointCount - 1].Position.Y)));
} else {
//Generate tangents for each of the smaller cubic Bezier curves that make up each segment of the resulting curve.

//The tension calculated for each point is a gradient between the previous
//control point's tension and the following control point's tension.

//Stores all of the tangent values.
List<PointD> bezierTangents = new List<PointD> ();

int pointCount = ControlPoints.Count - 1;
double pointCountDouble = (double) pointCount;
double tensionForPoint;

//Calculate the first tangent.
if (Closed) {
bezierTangents.Add (new PointD (
ControlPoints[0].Tension * (ControlPoints[1].Position.X - ControlPoints[pointCount].Position.X),
ControlPoints[0].Tension * (ControlPoints[1].Position.Y - ControlPoints[pointCount].Position.Y)));
} else {
bezierTangents.Add (new PointD (
ControlPoints[0].Tension * (ControlPoints[1].Position.X - ControlPoints[0].Position.X),
ControlPoints[0].Tension * (ControlPoints[1].Position.Y - ControlPoints[0].Position.Y)));
}

//Calculate all of the middle tangents.
for (int i = 1; i < pointCount; ++i) {
tensionForPoint = ControlPoints[i].Tension * (double) i / pointCountDouble;

bezierTangents.Add (new PointD (
tensionForPoint *
(ControlPoints[i + 1].Position.X - ControlPoints[i - 1].Position.X),
tensionForPoint *
(ControlPoints[i + 1].Position.Y - ControlPoints[i - 1].Position.Y)));
}

//Calculate the last tangent.
if (Closed) {
bezierTangents.Add (new PointD (
ControlPoints[pointCount].Tension *
(ControlPoints[0].Position.X - ControlPoints[pointCount - 1].Position.X),
ControlPoints[pointCount].Tension *
(ControlPoints[0].Position.Y - ControlPoints[pointCount - 1].Position.Y)));
} else {
bezierTangents.Add (new PointD (
ControlPoints[pointCount].Tension *
(ControlPoints[pointCount].Position.X - ControlPoints[pointCount - 1].Position.X),
ControlPoints[pointCount].Tension *
(ControlPoints[pointCount].Position.Y - ControlPoints[pointCount - 1].Position.Y)));
}


int iMinusOne;

//Generate the resulting curve's points with consecutive cubic Bezier curves that
//use the given points as end points and the calculated tangents as control points.
for (int i = 1; i < ControlPoints.Count; ++i) {
iMinusOne = i - 1;

generatedPoints.AddRange (GenerateCubicBezierCurvePoints (
bezierTangents.Add (new PointD (
ControlPoints[pointCount].Tension *
(ControlPoints[pointCount].Position.X - ControlPoints[pointCount - 1].Position.X),
ControlPoints[pointCount].Tension *
(ControlPoints[pointCount].Position.Y - ControlPoints[pointCount - 1].Position.Y)));
}


int iMinusOne;

//Generate the resulting curve's points with consecutive cubic Bezier curves that
//use the given points as end points and the calculated tangents as control points.
for (int i = 1; i < ControlPoints.Count; ++i) {
iMinusOne = i - 1;

generatedPoints.AddRange (GenerateCubicBezierCurvePoints (
ControlPoints[iMinusOne].Position,
new PointD (
ControlPoints[iMinusOne].Position.X + bezierTangents[iMinusOne].X,
ControlPoints[iMinusOne].Position.Y + bezierTangents[iMinusOne].Y),
new PointD (
ControlPoints[i].Position.X - bezierTangents[i].X,
ControlPoints[i].Position.Y - bezierTangents[i].Y),
ControlPoints[i].Position,
i));
}

if (Closed) {
// Close the shape.

iMinusOne = ControlPoints.Count - 1;

generatedPoints.AddRange (GenerateCubicBezierCurvePoints (
ControlPoints[iMinusOne].Position,
new PointD (
ControlPoints[iMinusOne].Position.X + bezierTangents[iMinusOne].X,
ControlPoints[iMinusOne].Position.Y + bezierTangents[iMinusOne].Y),
new PointD (
ControlPoints[i].Position.X - bezierTangents[i].X,
ControlPoints[i].Position.Y - bezierTangents[i].Y),
ControlPoints[i].Position,
i));
}

if (Closed) {
// Close the shape.

iMinusOne = ControlPoints.Count - 1;

generatedPoints.AddRange (GenerateCubicBezierCurvePoints (
ControlPoints[iMinusOne].Position,
new PointD (
ControlPoints[iMinusOne].Position.X + bezierTangents[iMinusOne].X,
ControlPoints[iMinusOne].Position.Y + bezierTangents[iMinusOne].Y),
new PointD (
ControlPoints[0].Position.X - bezierTangents[0].X,
ControlPoints[0].Position.Y - bezierTangents[0].Y),
ControlPoints[0].Position,
0));
}
ControlPoints[0].Position.X - bezierTangents[0].X,
ControlPoints[0].Position.Y - bezierTangents[0].Y),
ControlPoints[0].Position,
0));
}

GeneratedPoints = generatedPoints.ToArray ();
Expand All @@ -175,11 +176,8 @@ public override void GeneratePoints (int brush_width)
/// <param name="p3">The second end point that the curve passes through.</param>
/// <param name="cPIndex">The index of the previous ControlPoint to the generated points.</param>
/// <returns>The List of generated points.</returns>
protected static List<GeneratedPoint> GenerateCubicBezierCurvePoints (PointD p0, PointD p1, PointD p2, PointD p3, int cPIndex)
private static IEnumerable<GeneratedPoint> GenerateCubicBezierCurvePoints (PointD p0, PointD p1, PointD p2, PointD p3, int cPIndex)
{
List<GeneratedPoint> resultList = new List<GeneratedPoint> ();


//Note: this must be low enough for mouse clicks to be properly considered on/off the curve at any given point.
double tInterval = .025d;

Expand Down Expand Up @@ -220,14 +218,11 @@ protected static List<GeneratedPoint> GenerateCubicBezierCurvePoints (PointD p0,
//This is done for both the X and Y given a value t going from 0d to 1d at a very small interval
//and given 4 points p0, p1, p2, and p3, where p0 and p3 are end points and p1 and p2 are control points.

resultList.Add (new GeneratedPoint (new PointD (
yield return new GeneratedPoint (new PointD (
oneMinusTCubed * p0.X + oneMinusTSquaredTimesTTimesThree * p1.X + oneMinusTTimesTSquaredTimesThree * p2.X + tCubed * p3.X,
oneMinusTCubed * p0.Y + oneMinusTSquaredTimesTTimesThree * p1.Y + oneMinusTTimesTSquaredTimesThree * p2.Y + tCubed * p3.Y),
cPIndex));
cPIndex);
}


return resultList;
}
}
}

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