Y 轴在应该形成矩形的代码中反转

Question

所以我的代码由 3 个部分组成 2 classes 和测试想法是 2 classes 使用来自测试的输入形成一个矩形。这是测试代码

@Test
    public void testRectangle1() {
        Point center = new Point(20, 30);
        Rectangle rect = new Rectangle(center, 20, 20);
        assertAll(
                () -> assertEquals(10, rect.getTopLeft().getX()),
                () -> assertEquals(20, rect.getTopLeft().getY()),
                () -> assertEquals(30, rect.getBottomRight().getX()),
                () -> assertEquals(40, rect.getBottomRight().getY()),
                () -> assertEquals(20, rect.getWidth()),
                () -> assertEquals(20, rect.getHeight())
        );
    }

首先 class 调用了 Point 它工作正常。

public class Point {

    private int x, y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public Point() {
        this(0, 0);
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

    public void moveTo(int newX, int newY) {
        x = newX;
        y = newY;
    }

    public void moveRel(int dx, int dy) {
        x += dx;
        y += dy;
    }

    @Override
    public int hashCode() {
        final int prime = 31;
        int result = 1;
        result = prime * result + x;
        result = prime * result + y;
        return result;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        if (obj == null)
            return false;
        if (getClass() != obj.getClass())
            return false;
        Point other = (Point) obj;
        if (x != other.x)
            return false;
        if (y != other.y)
            return false;
        return true;
    }
}

所以这是第二个 class 形成了 recatangle 本身。它由一些用于形成我的矩形的附加方法的构造函数组成

public class Rectangle {
    public int width = 0;
    public int height = 0;
    public Point center;

    public Rectangle(Point center, int width, int height) {
        int x = 0;
        int y = 0;
        this.width=width;
        this.height=height;
        this.center=center;
    }

    public Point getTopLeft() {
        Point point = new Point(center.getX(), center.getY());
        point.moveRel(- width / 2, height / 2);
        return point;
    }

    public Point getBottomRight() {
        Point point = new Point(center.getX(), center.getY());
        point.moveRel(width / 2, - height / 2);
        return point;
    }

    public int getWidth() {

        return width;
    }


    public int getHeight() {

        return height;
    }
}

所以问题是 y 轴似乎是倒转的，因为当我运行测试它时 returns 错误的值， () -> assertEquals(20, rect.getTopLeft().getY())，其中 returns 40 而不是 20 并进行测试 () -> assertEquals(40, rect.getBottomRight().getY()), returns 2o 而不是 40。所以看起来左上角和右下角在 y 轴上是倒置的。

Answer 1

您在 moveRel 中添加 height/2 以获得 topLeft。因此，您得到 40 而不是 20 是正常的。

高度参数前似乎有符号错误：

public Point getTopLeft() {
    Point point = new Point(center.getX(), center.getY());
    point.moveRel(- width / 2, height / 2);
    return point;
}

public Point getBottomRight() {
    Point point = new Point(center.getX(), center.getY());
    point.moveRel(width / 2, - height / 2);
    return point;
}

Y 轴在应该形成矩形的代码中反转

Y axis inverted in code that should form a rectangle

java

rectangles