//=======================================================================
//TODO: implement arc to ***
/*
* public void arc_to(double rx, double ry,
* double angle,
* bool large_arc_flag,
* bool sweep_flag,
* double x, double y)
* {
* if(m_vertices.total_vertices() && is_vertex(m_vertices.last_command()))
* {
* double epsilon = 1e-30;
* double x0 = 0.0;
* double y0 = 0.0;
* m_vertices.last_vertex(&x0, &y0);
*
* rx = fabs(rx);
* ry = fabs(ry);
*
* // Ensure radii are valid
* //-------------------------
* if(rx < epsilon || ry < epsilon)
* {
* line_to(x, y);
* return;
* }
*
* if(calc_distance(x0, y0, x, y) < epsilon)
* {
* // If the endpoints (x, y) and (x0, y0) are identical, then this
* // is equivalent to omitting the elliptical arc segment entirely.
* return;
* }
* bezier_arc_svg a(x0, y0, rx, ry, angle, large_arc_flag, sweep_flag, x, y);
* if(a.radii_ok())
* {
* join_path(a);
* }
* else
* {
* line_to(x, y);
* }
* }
* else
* {
* move_to(x, y);
* }
* }
* public void arc_rel(double rx, double ry,
* double angle,
* bool large_arc_flag,
* bool sweep_flag,
* double dx, double dy)
* {
* rel_to_abs(&dx, &dy);
* arc_to(rx, ry, angle, large_arc_flag, sweep_flag, dx, dy);
* }
*/
//=======================================================================
/// <summary>
/// approximate arc with curve4, cubic curve
/// </summary>
/// <param name="r1"></param>
/// <param name="r2"></param>
/// <param name="xAxisRotation"></param>
/// <param name="largeArcFlag"></param>
/// <param name="sweepFlags"></param>
/// <param name="x"></param>
/// <param name="y"></param>
/// <param name="isRelative"></param>
public static void SvgArcToCurve4(this PathWriter _writer, float r1, float r2, float xAxisRotation, int largeArcFlag, int sweepFlags, float x, float y, bool isRelative)
{
using (VectorToolBox.Borrow(out SvgArcSegment svgArc))
{
if (isRelative)
{
svgArc.Set(
(float)_writer.CurrentX, (float)_writer.CurrentY,
r1, r2,
xAxisRotation,
(SvgArcSize)largeArcFlag,
(SvgArcSweep)sweepFlags,
(float)(_writer.CurrentX + x), (float)(_writer.CurrentY + y));
//
svgArc.AddToPath(_writer);
}
else
{
//approximate with bezier curve
svgArc.Set(
(float)_writer.CurrentX, (float)_writer.CurrentY,
r1, r2,
xAxisRotation,
(SvgArcSize)largeArcFlag,
(SvgArcSweep)sweepFlags,
x, y);
//
svgArc.AddToPath(_writer);
}
}
}
public static void CatmullRomToCurve4Rel(this PathWriter _writer, double dx0, double dy0, double dx1, double dy1, double dx2, double dy2, double dx3, double dy3)
{
//https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
//relative point
double curX = _writer.CurrentX;
double curY = _writer.CurrentY;
CatmullRomSegmentToCurve4(_writer, curX + dx0, curY + dy0, curX + dx1, curY + dy1, curX + dx2, curY + dy2, curX + dx3, curY + dy3);
}
static TempContext <PixelFarm.CpuBlit.PathWriter> Borrow(out PixelFarm.CpuBlit.PathWriter pathWriter)
{
if (!Temp <PixelFarm.CpuBlit.PathWriter> .IsInit())
{
Temp <PixelFarm.CpuBlit.PathWriter> .SetNewHandler(
() => new PixelFarm.CpuBlit.PathWriter(),
w => w.UnbindVxs());
}
return(Temp <PixelFarm.CpuBlit.PathWriter> .Borrow(out pathWriter));
}
public static bool CatmullRomSegmentToCurve4(this PathWriter _writer,
double x0, double y0, //p0 //explicit x0 y0
double x1, double y1, //p1
double x2, double y2, //p2
double x3, double y3) //p3
{
//just experiment only,
//not correct now
//https://en.wikipedia.org/wiki/Centripetal_Catmull%E2%80%93Rom_spline
//https://stackoverflow.com/questions/30748316/catmull-rom-interpolation-on-svg-paths
double t0 = 0.0f,
t1 = CatmullRomGetT(t0, x0, y0, x1, y1),
t2 = CatmullRomGetT(t1, x1, y1, x2, y2),
t3 = CatmullRomGetT(t2, x2, y2, x3, y3);
if ((t0 == t1) || (t1 == t2) || (t2 == t3))
{
//invalid
_writer.LineTo(x1, y1);
_writer.LineTo(x2, y2);
return(false);
}
double c1 = (t2 - t1) / (t2 - t0),
c2 = (t1 - t0) / (t2 - t0),
d1 = (t3 - t2) / (t3 - t1),
d2 = (t2 - t1) / (t3 - t1);
double m1x = (t2 - t1) * (c1 * (x1 - x0) / (t1 - t0) + c2 * (x2 - x1) / (t2 - t1));
double m2x = (t2 - t1) * (d1 * (x2 - x1) / (t2 - t1) + d2 * (x3 - x2) / (t3 - t2));
double m1y = (t2 - t1) * (c1 * (y1 - y0) / (t1 - t0) + c2 * (y2 - y1) / (t2 - t1));
double m2y = (t2 - t1) * (d1 * (y2 - y1) / (t2 - t1) + d2 * (y3 - y2) / (t3 - t2));
//Q0 = P1
//Q1 = P1 + M1 / 3
//Q2 = P2 - M2 / 3
//Q3 = P2
_writer.LineTo(x1, y1);
_writer.Curve4(x1 + m1x / 3, y1 + m1y / 3, x2 - m2x / 3, y2 - m2y / 3, x2, y2);
return(true);
}
public static void UnsafeDirectGetData(
PathWriter pathStore,
out int m_allocated_vertices,
out int m_num_vertices,
out double[] m_coord_xy,
out byte[] m_CommandAndFlags)
{
VertexStore.UnsafeDirectGetData(
pathStore.Vxs,
out m_allocated_vertices,
out m_num_vertices,
out m_coord_xy,
out m_CommandAndFlags);
}
/// <summary>
/// Draws a Cardinal spline (cubic) defined by a point collection.
/// The cardinal spline passes through each point in the collection.
/// </summary>
/// <param name="bmp">The WriteableBitmap.</param>
/// <param name="points">The points for the curve in x and y pairs, therefore the array is interpreted as (x1, y1, x2, y2, x3, y3, x4, y4, x1, x2 ..., xn, yn).</param>
/// <param name="tension">The tension of the curve defines the shape. Usually between 0 and 1. 0 would be a straight line.</param>
/// <param name="color">The color for the spline.</param>
public static void DrawCurve(this PathWriter writer, float[] points, float tension)
{
// First segment
SplineCurveSegment(writer, points[0], points[1], points[0], points[1], points[2], points[3], points[4], points[5], tension);
// Middle segments
int i = 2;
for (; i < points.Length - 4; i += 2)
{
SplineCurveSegment(writer, points[i - 2], points[i - 1], points[i], points[i + 1], points[i + 2], points[i + 3], points[i + 4], points[i + 5], tension);
}
// Last segment
SplineCurveSegment(writer, points[i - 2], points[i - 1], points[i], points[i + 1], points[i + 2], points[i + 3], points[i + 2], points[i + 3], tension);
}
public static void Hermite(this PathWriter pw, double[] xyCoords)
{
Curve4Points curve4_points = pw._c4_points;
pw.MoveTo(xyCoords[0], xyCoords[1]);
for (int i = 0; i < xyCoords.Length - (4 * 2);)
{
Curves.HermiteToBezier(
xyCoords[i], xyCoords[i + 1],
xyCoords[i + 2], xyCoords[i + 3],
xyCoords[i + 4], xyCoords[i + 5],
xyCoords[i + 6], xyCoords[i + 7],
curve4_points
);
pw.Curve4(curve4_points.x1, curve4_points.y1,
curve4_points.x2, curve4_points.y2,
curve4_points.x3, curve4_points.y3
);
i += 2;
}
}
public static void CatmulRom(this PathWriter pw, double[] xyCoords)
{
Curve4Points curve4_points = pw._c4_points;
pw.MoveTo(xyCoords[2], xyCoords[3]);//***
for (int i = 0; i < xyCoords.Length - (4 * 2);)
{
Curves.CatromToBezier(
xyCoords[i], xyCoords[i + 1],
xyCoords[i + 2], xyCoords[i + 3],
xyCoords[i + 4], xyCoords[i + 5],
xyCoords[i + 6], xyCoords[i + 7],
pw._c4_points
);
pw.Curve4(curve4_points.x1, curve4_points.y1,
curve4_points.x2, curve4_points.y2,
curve4_points.x3, curve4_points.y3
);
i += 2;
}
}
public static TempContext <PathWriter> BorrowPathWriter(VertexStore vxs, out PathWriter pathWriter) => VectorToolBox.Borrow(vxs, out pathWriter);
public static TempContext <PixelFarm.CpuBlit.PathWriter> Borrow(VertexStore vxs, out PixelFarm.CpuBlit.PathWriter pathWriter)
{
var tmpPw = Borrow(out pathWriter);
tmpPw._tool.BindVxs(vxs);
return(tmpPw);
}
static void SplineCurveSegment(
PathWriter writer,
double x1, double y1,
double x2, double y2,
double x3, double y3,
double x4, double y4,
float tension)
{
//from SplineExtensions.cs
//MIT, 2009-2015, Rene Schulte and WriteableBitmapEx Contributors, https://github.com/teichgraf/WriteableBitmapEx
//
// Project: WriteableBitmapEx - WriteableBitmap extensions
// Description: Collection of draw spline extension methods for the WriteableBitmap class.
//
// Changed by: $Author: unknown $
// Changed on: $Date: 2015-03-05 18:18:24 +0100 (Do, 05 Mrz 2015) $
// Changed in: $Revision: 113191 $
// Project: $URL: https://writeablebitmapex.svn.codeplex.com/svn/trunk/Source/WriteableBitmapEx/WriteableBitmapSplineExtensions.cs $
// Id: $Id: WriteableBitmapSplineExtensions.cs 113191 2015-03-05 17:18:24Z unknown $
//
//
// Copyright © 2009-2015 Rene Schulte and WriteableBitmapEx Contributors
// Determine distances between controls points (bounding rect) to find the optimal stepsize
double minX = Math.Min(x1, Math.Min(x2, Math.Min(x3, x4)));
double minY = Math.Min(y1, Math.Min(y2, Math.Min(y3, y4)));
double maxX = Math.Max(x1, Math.Max(x2, Math.Max(x3, x4)));
double maxY = Math.Max(y1, Math.Max(y2, Math.Max(y3, y4)));
// Get slope
double lenx = maxX - minX;
double len = maxY - minY;
if (lenx > len)
{
len = lenx;
}
// Prevent division by zero
if (len != 0)
{
// Init vars
double step = STEP_FACTOR / len;
double tx1 = x2;
double ty1 = y2;
// Calculate factors
double sx1 = tension * (x3 - x1);
double sy1 = tension * (y3 - y1);
double sx2 = tension * (x4 - x2);
double sy2 = tension * (y4 - y2);
double ax = sx1 + sx2 + 2 * x2 - 2 * x3;
double ay = sy1 + sy2 + 2 * y2 - 2 * y3;
double bx = -2 * sx1 - sx2 - 3 * x2 + 3 * x3;
double by = -2 * sy1 - sy2 - 3 * y2 + 3 * y3;
// Interpolate
writer.LineTo(tx1, ty1);
double tx2, ty2;
for (double t = step; t <= 1; t += step)
{
double tSq = t * t;
tx2 = (ax * tSq * t + bx * tSq + sx1 * t + x2);
ty2 = (ay * tSq * t + by * tSq + sy1 * t + y2);
// Draw line //
//DrawLine(context, w, h, tx1, ty1, tx2, ty2, color);
writer.LineTo(tx2, ty2);
tx1 = tx2;
ty1 = ty2;
}
// Prevent rounding gap
writer.LineTo(x3, y3);
//DrawLine(context, w, h, tx1, ty1, x3, y3, color);
}
}
