org.eclipse.swt.graphics.Rectangle.java Source code

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/*******************************************************************************
 * Copyright (c) 2000, 2011 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import java.io.*;

import org.eclipse.swt.*;

/**
 * Instances of this class represent rectangular areas in an
 * (x, y) coordinate system. The top left corner of the rectangle
 * is specified by its x and y values, and the extent of the
 * rectangle is specified by its width and height.
 * <p>
 * The coordinate space for rectangles and points is considered
 * to have increasing values downward and to the right from its
 * origin making this the normal, computer graphics oriented notion
 * of (x, y) coordinates rather than the strict mathematical one.
 * </p>
 * <p>
 * The hashCode() method in this class uses the values of the public
 * fields to compute the hash value. When storing instances of the
 * class in hashed collections, do not modify these fields after the
 * object has been inserted.
 * </p>
 * <p>
 * Application code does <em>not</em> need to explicitly release the
 * resources managed by each instance when those instances are no longer
 * required, and thus no <code>dispose()</code> method is provided.
 * </p>
 *
 * @see Point
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */

public final class Rectangle implements Serializable {

    /**
     * the x coordinate of the rectangle
     */
    public int x;

    /**
     * the y coordinate of the rectangle
     */
    public int y;

    /**
     * the width of the rectangle
     */
    public int width;

    /**
     * the height of the rectangle
     */
    public int height;

    static final long serialVersionUID = 3256439218279428914L;

    /**
     * Construct a new instance of this class given the
     * x, y, width and height values.
     *
     * @param x the x coordinate of the origin of the rectangle
     * @param y the y coordinate of the origin of the rectangle
     * @param width the width of the rectangle
     * @param height the height of the rectangle
     */
    public Rectangle(int x, int y, int width, int height) {
        this.x = x;
        this.y = y;
        this.width = width;
        this.height = height;
    }

    /**
     * Destructively replaces the x, y, width and height values
     * in the receiver with ones which represent the union of the
     * rectangles specified by the receiver and the given rectangle.
     * <p>
     * The union of two rectangles is the smallest single rectangle
     * that completely covers both of the areas covered by the two
     * given rectangles.
     * </p>
     *
     * @param rect the rectangle to merge with the receiver
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     */
    public void add(Rectangle rect) {
        if (rect == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        int left = x < rect.x ? x : rect.x;
        int top = y < rect.y ? y : rect.y;
        int lhs = x + width;
        int rhs = rect.x + rect.width;
        int right = lhs > rhs ? lhs : rhs;
        lhs = y + height;
        rhs = rect.y + rect.height;
        int bottom = lhs > rhs ? lhs : rhs;
        x = left;
        y = top;
        width = right - left;
        height = bottom - top;
    }

    /**
     * Returns <code>true</code> if the point specified by the
     * arguments is inside the area specified by the receiver,
     * and <code>false</code> otherwise.
     *
     * @param x the x coordinate of the point to test for containment
     * @param y the y coordinate of the point to test for containment
     * @return <code>true</code> if the rectangle contains the point and <code>false</code> otherwise
     */
    public boolean contains(int x, int y) {
        return (x >= this.x) && (y >= this.y) && x < (this.x + width) && y < (this.y + height);
    }

    /**
     * Returns <code>true</code> if the given point is inside the
     * area specified by the receiver, and <code>false</code>
     * otherwise.
     *
     * @param pt the point to test for containment
     * @return <code>true</code> if the rectangle contains the point and <code>false</code> otherwise
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     */
    public boolean contains(Point pt) {
        if (pt == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        return contains(pt.x, pt.y);
    }

    /**
     * Compares the argument to the receiver, and returns true
     * if they represent the <em>same</em> object using a class
     * specific comparison.
     *
     * @param object the object to compare with this object
     * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
     *
     * @see #hashCode()
     */
    @Override
    public boolean equals(Object object) {
        if (object == this)
            return true;
        if (!(object instanceof Rectangle))
            return false;
        Rectangle r = (Rectangle) object;
        return (r.x == this.x) && (r.y == this.y) && (r.width == this.width) && (r.height == this.height);
    }

    /**
     * Returns an integer hash code for the receiver. Any two
     * objects that return <code>true</code> when passed to
     * <code>equals</code> must return the same value for this
     * method.
     *
     * @return the receiver's hash
     *
     * @see #equals(Object)
     */
    @Override
    public int hashCode() {
        return x ^ y ^ width ^ height;
    }

    /**
     * Destructively replaces the x, y, width and height values
     * in the receiver with ones which represent the intersection of the
     * rectangles specified by the receiver and the given rectangle.
     *
     * @param rect the rectangle to intersect with the receiver
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     *
     * since 3.0
     */
    public void intersect(Rectangle rect) {
        if (rect == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        if (this == rect)
            return;
        int left = x > rect.x ? x : rect.x;
        int top = y > rect.y ? y : rect.y;
        int lhs = x + width;
        int rhs = rect.x + rect.width;
        int right = lhs < rhs ? lhs : rhs;
        lhs = y + height;
        rhs = rect.y + rect.height;
        int bottom = lhs < rhs ? lhs : rhs;
        x = right < left ? 0 : left;
        y = bottom < top ? 0 : top;
        width = right < left ? 0 : right - left;
        height = bottom < top ? 0 : bottom - top;
    }

    /**
     * Returns a new rectangle which represents the intersection
     * of the receiver and the given rectangle.
     * <p>
     * The intersection of two rectangles is the rectangle that
     * covers the area which is contained within both rectangles.
     * </p>
     *
     * @param rect the rectangle to intersect with the receiver
     * @return the intersection of the receiver and the argument
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     */
    public Rectangle intersection(Rectangle rect) {
        if (rect == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        if (this == rect)
            return new Rectangle(x, y, width, height);
        int left = x > rect.x ? x : rect.x;
        int top = y > rect.y ? y : rect.y;
        int lhs = x + width;
        int rhs = rect.x + rect.width;
        int right = lhs < rhs ? lhs : rhs;
        lhs = y + height;
        rhs = rect.y + rect.height;
        int bottom = lhs < rhs ? lhs : rhs;
        return new Rectangle(right < left ? 0 : left, bottom < top ? 0 : top, right < left ? 0 : right - left,
                bottom < top ? 0 : bottom - top);
    }

    /**
     * Returns <code>true</code> if the rectangle described by the
     * arguments intersects with the receiver and <code>false</code>
     * otherwise.
     * <p>
     * Two rectangles intersect if the area of the rectangle
     * representing their intersection is not empty.
     * </p>
     *
     * @param x the x coordinate of the origin of the rectangle
     * @param y the y coordinate of the origin of the rectangle
     * @param width the width of the rectangle
     * @param height the height of the rectangle
     * @return <code>true</code> if the rectangle intersects with the receiver, and <code>false</code> otherwise
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     *
     * @see #intersection(Rectangle)
     * @see #isEmpty()
     *
     * @since 3.0
     */
    public boolean intersects(int x, int y, int width, int height) {
        return (x < this.x + this.width) && (y < this.y + this.height) && (x + width > this.x)
                && (y + height > this.y);
    }

    /**
     * Returns <code>true</code> if the given rectangle intersects
     * with the receiver and <code>false</code> otherwise.
     * <p>
     * Two rectangles intersect if the area of the rectangle
     * representing their intersection is not empty.
     * </p>
     *
     * @param rect the rectangle to test for intersection
     * @return <code>true</code> if the rectangle intersects with the receiver, and <code>false</code> otherwise
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     *
     * @see #intersection(Rectangle)
     * @see #isEmpty()
     */
    public boolean intersects(Rectangle rect) {
        if (rect == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        return rect == this || intersects(rect.x, rect.y, rect.width, rect.height);
    }

    /**
     * Returns <code>true</code> if the receiver does not cover any
     * area in the (x, y) coordinate plane, and <code>false</code> if
     * the receiver does cover some area in the plane.
     * <p>
     * A rectangle is considered to <em>cover area</em> in the
     * (x, y) coordinate plane if both its width and height are
     * non-zero.
     * </p>
     *
     * @return <code>true</code> if the receiver is empty, and <code>false</code> otherwise
     */
    public boolean isEmpty() {
        return (width <= 0) || (height <= 0);
    }

    /**
     * Returns a string containing a concise, human-readable
     * description of the receiver.
     *
     * @return a string representation of the rectangle
     */
    @Override
    public String toString() {
        return "Rectangle {" + x + ", " + y + ", " + width + ", " + height + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$ //$NON-NLS-5$
    }

    /**
     * Returns a new rectangle which represents the union of
     * the receiver and the given rectangle.
     * <p>
     * The union of two rectangles is the smallest single rectangle
     * that completely covers both of the areas covered by the two
     * given rectangles.
     * </p>
     *
     * @param rect the rectangle to perform union with
     * @return the union of the receiver and the argument
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_NULL_ARGUMENT - if the argument is null</li>
     * </ul>
     *
     * @see #add(Rectangle)
     */
    public Rectangle union(Rectangle rect) {
        if (rect == null)
            SWT.error(SWT.ERROR_NULL_ARGUMENT);
        int left = x < rect.x ? x : rect.x;
        int top = y < rect.y ? y : rect.y;
        int lhs = x + width;
        int rhs = rect.x + rect.width;
        int right = lhs > rhs ? lhs : rhs;
        lhs = y + height;
        rhs = rect.y + rect.height;
        int bottom = lhs > rhs ? lhs : rhs;
        return new Rectangle(left, top, right - left, bottom - top);
    }

}