diff options
Diffstat (limited to 'src/main/java/com/kitfox/svg/pathcmd/Arc.java')
| -rw-r--r-- | src/main/java/com/kitfox/svg/pathcmd/Arc.java | 245 |
1 files changed, 245 insertions, 0 deletions
diff --git a/src/main/java/com/kitfox/svg/pathcmd/Arc.java b/src/main/java/com/kitfox/svg/pathcmd/Arc.java new file mode 100644 index 0000000..c48d149 --- /dev/null +++ b/src/main/java/com/kitfox/svg/pathcmd/Arc.java @@ -0,0 +1,245 @@ +/*
+ * MoveTo.java
+ *
+ *
+ * The Salamander Project - 2D and 3D graphics libraries in Java
+ * Copyright (C) 2004 Mark McKay
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Mark McKay can be contacted at mark@kitfox.com. Salamander and other
+ * projects can be found at http://www.kitfox.com
+ *
+ * Created on January 26, 2004, 8:40 PM
+ */
+
+package com.kitfox.svg.pathcmd;
+
+//import org.apache.batik.ext.awt.geom.ExtendedGeneralPath;
+import java.awt.*;
+import java.awt.geom.*;
+
+/**
+ * This is a little used SVG function, as most editors will save curves as
+ * Beziers. To reduce the need to rely on the Batik library, this functionallity
+ * is being bypassed for the time being. In the future, it would be nice to
+ * extend the GeneralPath command to include the arcTo ability provided by Batik.
+ *
+ * @author Mark McKay
+ * @author <a href="mailto:mark@kitfox.com">Mark McKay</a>
+ */
+public class Arc extends PathCommand
+{
+
+ public float rx = 0f;
+ public float ry = 0f;
+ public float xAxisRot = 0f;
+ public boolean largeArc = false;
+ public boolean sweep = false;
+ public float x = 0f;
+ public float y = 0f;
+
+ /** Creates a new instance of MoveTo */
+ public Arc() {
+ }
+
+ public Arc(boolean isRelative, float rx, float ry, float xAxisRot, boolean largeArc, boolean sweep, float x, float y) {
+ super(isRelative);
+ this.rx = rx;
+ this.ry = ry;
+ this.xAxisRot = xAxisRot;
+ this.largeArc = largeArc;
+ this.sweep = sweep;
+ this.x = x;
+ this.y = y;
+ }
+
+// public void appendPath(ExtendedGeneralPath path, BuildHistory hist)
+ public void appendPath(GeneralPath path, BuildHistory hist)
+ {
+ float offx = isRelative ? hist.history[0].x : 0f;
+ float offy = isRelative ? hist.history[0].y : 0f;
+
+ arcTo(path, rx, ry, xAxisRot, largeArc, sweep, x + offx, y + offy, hist.history[0].x, hist.history[0].y);
+// path.lineTo(x + offx, y + offy);
+ hist.setPoint(x + offx, y + offy);
+ }
+
+ public int getNumKnotsAdded()
+ {
+ return 6;
+ }
+
+ /**
+ * Adds an elliptical arc, defined by two radii, an angle from the
+ * x-axis, a flag to choose the large arc or not, a flag to
+ * indicate if we increase or decrease the angles and the final
+ * point of the arc.
+ *
+ * @param rx the x radius of the ellipse
+ * @param ry the y radius of the ellipse
+ *
+ * @param angle the angle from the x-axis of the current
+ * coordinate system to the x-axis of the ellipse in degrees.
+ *
+ * @param largeArcFlag the large arc flag. If true the arc
+ * spanning less than or equal to 180 degrees is chosen, otherwise
+ * the arc spanning greater than 180 degrees is chosen
+ *
+ * @param sweepFlag the sweep flag. If true the line joining
+ * center to arc sweeps through decreasing angles otherwise it
+ * sweeps through increasing angles
+ *
+ * @param x the absolute x coordinate of the final point of the arc.
+ * @param y the absolute y coordinate of the final point of the arc.
+ * @param x0 - The absolute x coordinate of the initial point of the arc.
+ * @param y0 - The absolute y coordinate of the initial point of the arc.
+ */
+ public void arcTo(GeneralPath path, float rx, float ry,
+ float angle,
+ boolean largeArcFlag,
+ boolean sweepFlag,
+ float x, float y, float x0, float y0)
+ {
+
+ // Ensure radii are valid
+ if (rx == 0 || ry == 0) {
+ path.lineTo((float) x, (float) y);
+ return;
+ }
+
+ if (x0 == x && y0 == y) {
+ // If the endpoints (x, y) and (x0, y0) are identical, then this
+ // is equivalent to omitting the elliptical arc segment entirely.
+ return;
+ }
+
+ Arc2D arc = computeArc(x0, y0, rx, ry, angle,
+ largeArcFlag, sweepFlag, x, y);
+ if (arc == null) return;
+
+ AffineTransform t = AffineTransform.getRotateInstance
+ (Math.toRadians(angle), arc.getCenterX(), arc.getCenterY());
+ Shape s = t.createTransformedShape(arc);
+ path.append(s, true);
+ }
+
+
+ /**
+ * This constructs an unrotated Arc2D from the SVG specification of an
+ * Elliptical arc. To get the final arc you need to apply a rotation
+ * transform such as:
+ *
+ * AffineTransform.getRotateInstance
+ * (angle, arc.getX()+arc.getWidth()/2, arc.getY()+arc.getHeight()/2);
+ */
+ public static Arc2D computeArc(double x0, double y0,
+ double rx, double ry,
+ double angle,
+ boolean largeArcFlag,
+ boolean sweepFlag,
+ double x, double y) {
+ //
+ // Elliptical arc implementation based on the SVG specification notes
+ //
+
+ // Compute the half distance between the current and the final point
+ double dx2 = (x0 - x) / 2.0;
+ double dy2 = (y0 - y) / 2.0;
+ // Convert angle from degrees to radians
+ angle = Math.toRadians(angle % 360.0);
+ double cosAngle = Math.cos(angle);
+ double sinAngle = Math.sin(angle);
+
+ //
+ // Step 1 : Compute (x1, y1)
+ //
+ double x1 = (cosAngle * dx2 + sinAngle * dy2);
+ double y1 = (-sinAngle * dx2 + cosAngle * dy2);
+ // Ensure radii are large enough
+ rx = Math.abs(rx);
+ ry = Math.abs(ry);
+ double Prx = rx * rx;
+ double Pry = ry * ry;
+ double Px1 = x1 * x1;
+ double Py1 = y1 * y1;
+ // check that radii are large enough
+ double radiiCheck = Px1/Prx + Py1/Pry;
+ if (radiiCheck > 1) {
+ rx = Math.sqrt(radiiCheck) * rx;
+ ry = Math.sqrt(radiiCheck) * ry;
+ Prx = rx * rx;
+ Pry = ry * ry;
+ }
+
+ //
+ // Step 2 : Compute (cx1, cy1)
+ //
+ double sign = (largeArcFlag == sweepFlag) ? -1 : 1;
+ double sq = ((Prx*Pry)-(Prx*Py1)-(Pry*Px1)) / ((Prx*Py1)+(Pry*Px1));
+ sq = (sq < 0) ? 0 : sq;
+ double coef = (sign * Math.sqrt(sq));
+ double cx1 = coef * ((rx * y1) / ry);
+ double cy1 = coef * -((ry * x1) / rx);
+
+ //
+ // Step 3 : Compute (cx, cy) from (cx1, cy1)
+ //
+ double sx2 = (x0 + x) / 2.0;
+ double sy2 = (y0 + y) / 2.0;
+ double cx = sx2 + (cosAngle * cx1 - sinAngle * cy1);
+ double cy = sy2 + (sinAngle * cx1 + cosAngle * cy1);
+
+ //
+ // Step 4 : Compute the angleStart (angle1) and the angleExtent (dangle)
+ //
+ double ux = (x1 - cx1) / rx;
+ double uy = (y1 - cy1) / ry;
+ double vx = (-x1 - cx1) / rx;
+ double vy = (-y1 - cy1) / ry;
+ double p, n;
+ // Compute the angle start
+ n = Math.sqrt((ux * ux) + (uy * uy));
+ p = ux; // (1 * ux) + (0 * uy)
+ sign = (uy < 0) ? -1d : 1d;
+ double angleStart = Math.toDegrees(sign * Math.acos(p / n));
+
+ // Compute the angle extent
+ n = Math.sqrt((ux * ux + uy * uy) * (vx * vx + vy * vy));
+ p = ux * vx + uy * vy;
+ sign = (ux * vy - uy * vx < 0) ? -1d : 1d;
+ double angleExtent = Math.toDegrees(sign * Math.acos(p / n));
+ if(!sweepFlag && angleExtent > 0) {
+ angleExtent -= 360f;
+ } else if (sweepFlag && angleExtent < 0) {
+ angleExtent += 360f;
+ }
+ angleExtent %= 360f;
+ angleStart %= 360f;
+
+ //
+ // We can now build the resulting Arc2D in double precision
+ //
+ Arc2D.Double arc = new Arc2D.Double();
+ arc.x = cx - rx;
+ arc.y = cy - ry;
+ arc.width = rx * 2.0;
+ arc.height = ry * 2.0;
+ arc.start = -angleStart;
+ arc.extent = -angleExtent;
+
+ return arc;
+ }
+}
|