java - 自定义形状旋转问题

Question

我尝试围绕其中心旋转自定义形状，但无法获得预期的结果。

我想要的是

*形状应绕其中心旋转而不移动自身。*

我的解决方案目前正在做的是 围绕其中心旋转整个形状，每次旋转都会改变其位置。

我有多个形状，因此我创建了一个类来封装形状及其在以下类中的转换

public abstract class Shoe implements Shape, ShoeShape {

    // variable declaration

    /**
     * 
     */
    public Shoe() {
        position = new Point();
        lastPosition = new Point();
    }




    public void draw(Graphics2D g2, AffineTransform transform, boolean firstTime) {

        AffineTransform af = firstTime ? getInitTransform()
                : getCompositeTransform();

        if (af != null) {


                Shape s = af.createTransformedShape(this);

                if (getFillColor() != null) {
                    g2.setColor(getFillColor());
                    g2.fill(s);
                } else {
                    g2.draw(s);
                }
            }

        }



    }




    public AffineTransform getCompositeTransform() {
            AffineTransform af = new AffineTransform();
        af.setToIdentity();
        af.translate(position.getX(), position.getY());
        Point2D centerP = calculateShapeCenter();
        af.rotate(orientation, centerP.getX(), centerP.getY());
        return af;
    }







    public void onMouseDrag(MouseEvent me, Rectangle2D canvasBoundary,
            int selectionOperation) {

        // shape operation can be either resize , rotate , translate ,
        switch (selectionOperation) {
        case MmgShoeViewer.SHAPE_OPERATION_MOVE:
            // MOVEMENT
            break;
        case MmgShoeViewer.SHAPE_OPERATION_ROTATE:

            Point2D origin = calculateShapeCenter();
            Point2D.Double starting = new Point2D.Double(me.getX(), me.getY());
            currentAngle = RotationHelper.getAngle(origin, starting);
            rotationAngle = currentAngle - startingAngle;
            rotate(rotationAngle);
            break;
        case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
            break;
        default:
            System.out.println(" invalid select operation");
        }
    }



    public void onMousePress(MouseEvent me, Rectangle2D canvasBoundary,
            int selectionOperation) {

        // shape operation can be either resize , rotate , translate ,
        switch (selectionOperation) {
        case MmgShoeViewer.SHAPE_OPERATION_MOVE:
            break;
        case MmgShoeViewer.SHAPE_OPERATION_ROTATE:
            Point2D origin =  calculateShapeCenter();
            Point2D.Double starting = new Point2D.Double(me.getX(), me.getY());
            startingAngle = RotationHelper.getAngle(origin, starting);
            setShapeOperation(selectionOperation);
            break;
        case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
            break;
        default:
            System.out.println(" invalid select operation");
        }
    }

    public void onMouseRelease(MouseEvent me, Rectangle2D canvasBoundary,
            int selectionOperation) {

        // shape operation can be either resize , rotate , translate ,
        switch (selectionOperation) {
        case MmgShoeViewer.SHAPE_OPERATION_MOVE:
            break;
        case MmgShoeViewer.SHAPE_OPERATION_ROTATE:
            // FIXME rotation angle computation
            setShapeOperation(-1);
            break;
        case MmgShoeViewer.SHAPE_OPERATION_RESIZE:
            break;
        default:
            System.out.println(" invalid select operation");
        }
    }

    public void rotate(double angle) {
        orientation = (float) angle;
    }


    public void translate(double deltaX, double deltaY) {

        position.setLocation(deltaX, deltaY);
        lastPosition.setLocation(deltaX, deltaY);
    }







    // another getter and setter

我正在使用以下方法计算旋转角度

public static double getAngle(Point2D origin, Point2D other) {

        double dy = other.getY() - origin.getY();
        double dx = other.getX() - origin.getX();
        double angle;

        if (dx == 0) {// special case
            angle = dy >= 0 ? Math.PI / 2 : -Math.PI / 2;
        } else {
            angle = Math.atan(dy / dx);
            if (dx < 0) // hemisphere correction
                angle += Math.PI;
        }
        // all between 0 and 2PI
        if (angle < 0) // between -PI/2 and 0
            angle += 2 * Math.PI;
        return angle;
    }

在 Canvas 鼠标监听器的鼠标按下事件中

selectedShape.onMousePress(me, canvasBoundary, shoeViewer
                .getShapeOperation());

我只是调用所选形状的 onMousePress 方法

在 Canvas 鼠标监听器的鼠标拖动方法中，我只是调用所选形状的 onMouseDrag 方法，该方法更新旋转角度，正如您从第一类中看到的那样

selectedShape.onMouseDrag(me, canvasBoundary, shoeViewer
                .getShapeOperation());

你可以看到单个形状的绘制方法，根据当前变换绘制形状，我从paintComponent调用，如

Iterator<Shoe> shoeIter = shoeShapeMap.values().iterator();

        while (shoeIter.hasNext()) {

            Shoe shoe = shoeIter.next();
            shoe.draw(g2, firstTime);

        }

其中shoeShapeMap包含当前 Canvas 上的所有自定义形状。

我在计算角度或确定 anchor 时犯了错误吗？我当前的解决方案通过检查所有条件 [90 度等] 将形状旋转 360 度，如您在上述方法中看到的。

我希望形状围绕其中心旋转而不调整其位置大小？用这个词来说，很难解释，所以请建议我有更好的方法来在这里展示我想要完成的任务吗？

我想我已经提到了与此问题相关的所有内容。如果您有任何疑问，请随时询问我。

我在这里找到了 2 个相关帖子，但我无法从中找到太多信息。

Answer 1

我认为解决方案可能是(或/或):

• 反转 AffineTransform 上的操作顺序，将平移放在旋转之后
• 使用 -x 和 -y 作为翻译值