android/graphics/RoundRectangle.java

/*
 * Copyright (C) 2016 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.graphics;

import java.awt.geom.AffineTransform;
import java.awt.geom.PathIterator;
import java.awt.geom.Rectangle2D;
import java.awt.geom.RectangularShape;
import java.awt.geom.RoundRectangle2D;
import java.util.EnumSet;
import java.util.NoSuchElementException;

/**
 * Defines a rectangle with rounded corners, where the sizes of the corners
 * are potentially different.
 */
public class RoundRectangle extends RectangularShape {
    public double x;
    public double y;
    public double width;
    public double height;
    public double ulWidth;
    public double ulHeight;
    public double urWidth;
    public double urHeight;
    public double lrWidth;
    public double lrHeight;
    public double llWidth;
    public double llHeight;

    private enum Zone {
        CLOSE_OUTSIDE,
        CLOSE_INSIDE,
        MIDDLE,
        FAR_INSIDE,
        FAR_OUTSIDE
    }

    private final EnumSet<Zone> close = EnumSet.of(Zone.CLOSE_OUTSIDE, Zone.CLOSE_INSIDE);
    private final EnumSet<Zone> far = EnumSet.of(Zone.FAR_OUTSIDE, Zone.FAR_INSIDE);

    /**
     * @param cornerDimensions array of 8 floating-point number corresponding to the width and
     * the height of each corner in the following order: upper-left, upper-right, lower-right,
     * lower-left. It assumes for the size the same convention as {@link RoundRectangle2D}, that
     * is that the width and height of a corner correspond to the total width and height of the
     * ellipse that corner is a quarter of.
     */
    public RoundRectangle(float x, float y, float width, float height, float[] cornerDimensions) {
        assert cornerDimensions.length == 8 : "The array of corner dimensions must have eight " +
                    "elements";

        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;

        float[] dimensions = cornerDimensions.clone();
        // If a value is negative, the corresponding corner is squared
        for (int i = 0; i < dimensions.length; i += 2) {
            if (dimensions[i] < 0 || dimensions[i + 1] < 0) {
                dimensions[i] = 0;
                dimensions[i + 1] = 0;
            }
        }

        double topCornerWidth = (dimensions[0] + dimensions[2]) / 2d;
        double bottomCornerWidth = (dimensions[4] + dimensions[6]) / 2d;
        double leftCornerHeight = (dimensions[1] + dimensions[7]) / 2d;
        double rightCornerHeight = (dimensions[3] + dimensions[5]) / 2d;

        // Rescale the corner dimensions if they are bigger than the rectangle
        double scale = Math.min(1.0, width / topCornerWidth);
        scale = Math.min(scale, width / bottomCornerWidth);
        scale = Math.min(scale, height / leftCornerHeight);
        scale = Math.min(scale, height / rightCornerHeight);

        this.ulWidth = dimensions[0] * scale;
        this.ulHeight = dimensions[1] * scale;
        this.urWidth = dimensions[2] * scale;
        this.urHeight = dimensions[3] * scale;
        this.lrWidth = dimensions[4] * scale;
        this.lrHeight = dimensions[5] * scale;
        this.llWidth = dimensions[6] * scale;
        this.llHeight = dimensions[7] * scale;
    }

    @Override
    public double getX() {
        return x;
    }

    @Override
    public double getY() {
        return y;
    }

    @Override
    public double getWidth() {
        return width;
    }

    @Override
    public double getHeight() {
        return height;
    }

    @Override
    public boolean isEmpty() {
        return (width <= 0d) || (height <= 0d);
    }

    @Override
    public void setFrame(double x, double y, double w, double h) {
        this.x = x;
        this.y = y;
        this.width = w;
        this.height = h;
    }

    @Override
    public Rectangle2D getBounds2D() {
        return new Rectangle2D.Double(x, y, width, height);
    }

    @Override
    public boolean contains(double x, double y) {
        if (isEmpty()) {
            return false;
        }

        double x0 = getX();
        double y0 = getY();
        double x1 = x0 + getWidth();
        double y1 = y0 + getHeight();
        // Check for trivial rejection - point is outside bounding rectangle
        if (x < x0 || y < y0 || x >= x1 || y >= y1) {
            return false;
        }

        double insideTopX0 = x0 + ulWidth / 2d;
        double insideLeftY0 = y0 + ulHeight / 2d;
        if (x < insideTopX0 && y < insideLeftY0) {
            // In the upper-left corner
            return isInsideCorner(x - insideTopX0, y - insideLeftY0, ulWidth / 2d, ulHeight / 2d);
        }

        double insideTopX1 = x1 - urWidth / 2d;
        double insideRightY0 = y0 + urHeight / 2d;
        if (x > insideTopX1 && y < insideRightY0) {
            // In the upper-right corner
            return isInsideCorner(x - insideTopX1, y - insideRightY0, urWidth / 2d, urHeight / 2d);
        }

        double insideBottomX1 = x1 - lrWidth / 2d;
        double insideRightY1 = y1 - lrHeight / 2d;
        if (x > insideBottomX1 && y > insideRightY1) {
            // In the lower-right corner
            return isInsideCorner(x - insideBottomX1, y - insideRightY1, lrWidth / 2d,
                    lrHeight / 2d);
        }

        double insideBottomX0 = x0 + llWidth / 2d;
        double insideLeftY1 = y1 - llHeight / 2d;
        if (x < insideBottomX0 && y > insideLeftY1) {
            // In the lower-left corner
            return isInsideCorner(x - insideBottomX0, y - insideLeftY1, llWidth / 2d,
                    llHeight / 2d);
        }

        // In the central part of the rectangle
        return true;
    }

    private boolean isInsideCorner(double x, double y, double width, double height) {
        double squareDist = height * height * x * x + width * width * y * y;
        return squareDist <= width * width * height * height;
    }

    private Zone classify(double coord, double side1, double arcSize1, double side2,
            double arcSize2) {
        if (coord < side1) {
            return Zone.CLOSE_OUTSIDE;
        } else if (coord < side1 + arcSize1) {
            return Zone.CLOSE_INSIDE;
        } else if (coord < side2 - arcSize2) {
            return Zone.MIDDLE;
        } else if (coord < side2) {
            return Zone.FAR_INSIDE;
        } else {
            return Zone.FAR_OUTSIDE;
        }
    }

    public boolean intersects(double x, double y, double w, double h) {
        if (isEmpty() || w <= 0 || h <= 0) {
            return false;
        }
        double x0 = getX();
        double y0 = getY();
        double x1 = x0 + getWidth();
        double y1 = y0 + getHeight();
        // Check for trivial rejection - bounding rectangles do not intersect
        if (x + w <= x0 || x >= x1 || y + h <= y0 || y >= y1) {
            return false;
        }

        double maxLeftCornerWidth = Math.max(ulWidth, llWidth) / 2d;
        double maxRightCornerWidth = Math.max(urWidth, lrWidth) / 2d;
        double maxUpperCornerHeight = Math.max(ulHeight, urHeight) / 2d;
        double maxLowerCornerHeight = Math.max(llHeight, lrHeight) / 2d;
        Zone x0class = classify(x, x0, maxLeftCornerWidth, x1, maxRightCornerWidth);
        Zone x1class = classify(x + w, x0, maxLeftCornerWidth, x1, maxRightCornerWidth);
        Zone y0class = classify(y, y0, maxUpperCornerHeight, y1, maxLowerCornerHeight);
        Zone y1class = classify(y + h, y0, maxUpperCornerHeight, y1, maxLowerCornerHeight);

        // Trivially accept if any point is inside inner rectangle
        if (x0class == Zone.MIDDLE || x1class == Zone.MIDDLE || y0class == Zone.MIDDLE || y1class == Zone.MIDDLE) {
            return true;
        }
        // Trivially accept if either edge spans inner rectangle
        if ((close.contains(x0class) && far.contains(x1class)) || (close.contains(y0class) &&
                far.contains(y1class))) {
            return true;
        }

        // Since neither edge spans the center, then one of the corners
        // must be in one of the rounded edges.  We detect this case if
        // a [xy]0class is 3 or a [xy]1class is 1.  One of those two cases
        // must be true for each direction.
        // We now find a "nearest point" to test for being inside a rounded
        // corner.
        if (x1class == Zone.CLOSE_INSIDE && y1class == Zone.CLOSE_INSIDE) {
            // Potentially in upper-left corner
            x = x + w - x0 - ulWidth / 2d;
            y = y + h - y0 - ulHeight / 2d;
            return x > 0 || y > 0 || isInsideCorner(x, y, ulWidth / 2d, ulHeight / 2d);
        }
        if (x1class == Zone.CLOSE_INSIDE) {
            // Potentially in lower-left corner
            x = x + w - x0 - llWidth / 2d;
            y = y - y1 + llHeight / 2d;
            return x > 0 || y < 0 || isInsideCorner(x, y, llWidth / 2d, llHeight / 2d);
        }
        if (y1class == Zone.CLOSE_INSIDE) {
            //Potentially in the upper-right corner
            x = x - x1 + urWidth / 2d;
            y = y + h - y0 - urHeight / 2d;
            return x < 0 || y > 0 || isInsideCorner(x, y, urWidth / 2d, urHeight / 2d);
        }
        // Potentially in the lower-right corner
        x = x - x1 + lrWidth / 2d;
        y = y - y1 + lrHeight / 2d;
        return x < 0 || y < 0 || isInsideCorner(x, y, lrWidth / 2d, lrHeight / 2d);
    }

    @Override
    public boolean contains(double x, double y, double w, double h) {
        if (isEmpty() || w <= 0 || h <= 0) {
            return false;
        }
        return (contains(x, y) &&
                contains(x + w, y) &&
                contains(x, y + h) &&
                contains(x + w, y + h));
    }

    @Override
    public PathIterator getPathIterator(final AffineTransform at) {
        return new PathIterator() {
            int index;

            // ArcIterator.btan(Math.PI/2)
            public static final double CtrlVal = 0.5522847498307933;
            private final double ncv = 1.0 - CtrlVal;

            // Coordinates of control points for Bezier curves approximating the straight lines
            // and corners of the rounded rectangle.
            private final double[][] ctrlpts = {
                    {0.0, 0.0, 0.0, ulHeight},
                    {0.0, 0.0, 1.0, -llHeight},
                    {0.0, 0.0, 1.0, -llHeight * ncv, 0.0, ncv * llWidth, 1.0, 0.0, 0.0, llWidth,
                            1.0, 0.0},
                    {1.0, -lrWidth, 1.0, 0.0},
                    {1.0, -lrWidth * ncv, 1.0, 0.0, 1.0, 0.0, 1.0, -lrHeight * ncv, 1.0, 0.0, 1.0,
                            -lrHeight},
                    {1.0, 0.0, 0.0, urHeight},
                    {1.0, 0.0, 0.0, ncv * urHeight, 1.0, -urWidth * ncv, 0.0, 0.0, 1.0, -urWidth,
                            0.0, 0.0},
                    {0.0, ulWidth, 0.0, 0.0},
                    {0.0, ncv * ulWidth, 0.0, 0.0, 0.0, 0.0, 0.0, ncv * ulHeight, 0.0, 0.0, 0.0,
                            ulHeight},
                    {}
            };
            private final int[] types = {
                    SEG_MOVETO,
                    SEG_LINETO, SEG_CUBICTO,
                    SEG_LINETO, SEG_CUBICTO,
                    SEG_LINETO, SEG_CUBICTO,
                    SEG_LINETO, SEG_CUBICTO,
                    SEG_CLOSE,
            };

            @Override
            public int getWindingRule() {
                return WIND_NON_ZERO;
            }

            @Override
            public boolean isDone() {
                return index >= ctrlpts.length;
            }

            @Override
            public void next() {
                index++;
            }

            @Override
            public int currentSegment(float[] coords) {
                if (isDone()) {
                    throw new NoSuchElementException("roundrect iterator out of bounds");
                }
                int nc = 0;
                double ctrls[] = ctrlpts[index];
                for (int i = 0; i < ctrls.length; i += 4) {
                    coords[nc++] = (float) (x + ctrls[i] * width + ctrls[i + 1] / 2d);
                    coords[nc++] = (float) (y + ctrls[i + 2] * height + ctrls[i + 3] / 2d);
                }
                if (at != null) {
                    at.transform(coords, 0, coords, 0, nc / 2);
                }
                return types[index];
            }

            @Override
            public int currentSegment(double[] coords) {
                if (isDone()) {
                    throw new NoSuchElementException("roundrect iterator out of bounds");
                }
                int nc = 0;
                double ctrls[] = ctrlpts[index];
                for (int i = 0; i < ctrls.length; i += 4) {
                    coords[nc++] = x + ctrls[i] * width + ctrls[i + 1] / 2d;
                    coords[nc++] = y + ctrls[i + 2] * height + ctrls[i + 3] / 2d;
                }
                if (at != null) {
                    at.transform(coords, 0, coords, 0, nc / 2);
                }
                return types[index];
            }
        };
    }
}