java - 如何在Java中放大/移动多边形？

Question

所以我有以下代码:

import java.awt.*;

public class Triangle extends Point {
    protected int size;
    private int p1x, p2x, p3x, p1y, p2y, p3y;

    //Create a new triangle
    public Triangle()
    {
        super();
        size = 100;
        yPos = 100;
    }


    public void reSize(int newSize) {
        size = size + newSize;
    }

    //Draw the triangle with current specifications on screen.
    public void display(Graphics g) {
        p1x = (size / 3);
        p2x = (size / 2);
        p3x = ((2 * size) / 3);
        p1y = ((2 * size) / 3);
        p2y = (size / 3);
        p3y = ((2 * size) / 3);
        int[] xPoints = { p1x, p2x, p3x };
        int[] yPoints = { p1y, p2y, p3y };
        int npoints = 3;
        g.fillPolygon(xPoints, yPoints, npoints);
    }
}

下面的代码用于放大/缩小三角形:

    if (e.getSource() == makeBigger) {
          aShape.reSize(20);
    }

    else if (e.getSource() == makeSmaller) {
          aShape.reSize(-20);
    }

问题是，我还希望能够使用以下代码拖动它:

    this.addMouseListener(new MouseAdapter() {
    public void mouseReleased(MouseEvent me) {
        shapeColor = Color.black;
        repaint();
    }

    public void mouseDragged(MouseEvent me) {
        shapeColor = Color.lightGray;
        aShape.moveXY(me.getX(), me.getY());
        repaint();
    }
});

    this.addMouseMotionListener(new MouseAdapter() {
    public void mouseReleased(MouseEvent me) {
        shapeColor = Color.black;
        repaint();
    }

    public void mouseDragged(MouseEvent me) {
        shapeColor = Color.lightGray;
        aShape.moveXY(me.getX(), me.getY());
        repaint();
    }
});

我能看到它的唯一方法是我可以选择其中之一。我如何将其结合起来才能拥有这两种功能？目前它可以完美地调整大小，但是假设我将 x/y 坐标中的变量大小更改为 yPos/xPos，我将能够拖动三角形但无法 reshape 它的形状。

谢谢!

Answer 1

您需要添加 xOffset 和 yOffset 成员，并在计算角点时添加它们:

public class Triangle extends Point {
    protected int size;
    private int p1x, p2x, p3x, p1y, p2y, p3y;
    private int xOffset=0;
    private int yOffset=0;

    // ...

    //Draw the triangle with current specifications on screen.
    public void display(Graphics g) {
        p1x = (size / 3) + xOffset;
        p2x = (size / 2) + xOffset;
        p3x = ((2 * size) / 3) + xOffset;
        p1y = ((2 * size) / 3) + yOffset;
        p2y = (size / 3) + yOffset;
        p3y = ((2 * size) / 3) + yOffset;
        int[] xPoints = { p1x, p2x, p3x };
        int[] yPoints = { p1y, p2y, p3y };
        int npoints = 3;
        g.fillPolygon(xPoints, yPoints, npoints);
    }

    public void moveXY(int deltaX, int deltaY) {
        xOffset += deltaX;
        yOffset += deltaY;
    }
}

这应该可以让您平移多边形。但请注意，上述 moveXY 方法期望参数包含与之前的差异，而不是绝对位置。如果您想要一个绝对位置，这很容易实现，并且可以作为练习。 ;)