/*
 * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * 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.
 *
 * This code 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 General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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.
/**
     * .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();
    }
}