com.sun.javafx.sg.prism.NGCircle Maven / Gradle / Ivy
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
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package com.sun.javafx.sg.prism;
import com.sun.javafx.geom.Ellipse2D;
import com.sun.javafx.geom.RectBounds;
import com.sun.javafx.geom.Shape;
import com.sun.prism.Graphics;
import com.sun.prism.shape.ShapeRep;
/**
*
*/
public class NGCircle extends NGShape {
/**
* .5 * 1/Math.sqrt(2). If you multiply this value by the diameter of the
* circle, then you will get half the length of the side of the square which
* is inscribed within the circle. This is used when computing the opaque region
* of the circle and ellipse. This value has been precomputed and stored
* as a constant to make the resulting math faster. It is low in precision
* to compute a conservative inscribed square.
*/
static final float HALF_SQRT_HALF = .353f; // really .35355339059327...
private Ellipse2D ellipse = new Ellipse2D();
private float cx, cy;
public void updateCircle(float cx, float cy, float r) {
ellipse.x = cx - r;
ellipse.y = cy - r;
ellipse.width = r * 2f;
ellipse.height = ellipse.width;
this.cx = cx;
this.cy = cy;
geometryChanged();
}
@Override
public Shape getShape() {
return ellipse;
}
@Override protected boolean supportsOpaqueRegions() { return true; }
@Override
protected boolean hasOpaqueRegion() {
// Since this is a circle, both ellipse.width & ellipse.height are the
// same, so I can just get away with checking one of them.
// Although a circle with a very small radius won't produce a very large
// opaque region on its own, it might be subsequently scaled in which
// case even a very small radius (like .00001) could become something
// significant.
return super.hasOpaqueRegion() && ellipse.width > 0;
}
@Override
protected RectBounds computeOpaqueRegion(RectBounds opaqueRegion) {
final float halfSquareLength = ellipse.width * HALF_SQRT_HALF;
return (RectBounds) opaqueRegion.deriveWithNewBounds(
cx - halfSquareLength,
cy - halfSquareLength, 0,
cx + halfSquareLength,
cy + halfSquareLength, 0);
}
@Override
protected ShapeRep createShapeRep(Graphics g) {
return g.getResourceFactory().createEllipseRep();
}
}