一个简单的缩放拖动实现

最新推荐文章于 2025-06-04 09:06:46 发布

原创最新推荐文章于 2025-06-04 09:06:46 发布 · 725 阅读

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本文详细阐述了触摸屏设备上手势识别的工作原理，并通过一个简单的类实例展示了如何使用手势来控制应用程序的移动、拖动、缩放和旋转。重点介绍了手势识别过程中的关键参数和状态管理，以及手势识别后的响应动作。

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public class Gesture {
    private boolean isFirst;
    private int mode;
    private static final int DRAG = 1;
    private static final int MOVE = 2;
    private static final int NONE = 0;
    private float oldDis;
    private float newDis;
    private IGesture gesture;
    private float oldX;
    private float oldY;
    private float newX;
    private float newY;
    private boolean result;
    private int status;
    private static final int LEFT = 1;
    private static final int BOTTOM = 4;
    private static final int UP = 3;
    private static final int RIGHT = 2;
    private static final int ZOOMIN = 5;
    private static final int ZOOMOUT = 6;


    public Gesture(IGesture gesture) {
        this.gesture = gesture;
    }

    public boolean gesture(MotionEvent event) {
        switch (event.getAction() & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
                mode = DRAG;
                oldX = event.getRawX();
                oldY = event.getRawY();
                result = true;
                break;
            case MotionEvent.ACTION_UP:
                if (mode == MOVE) {

                } else {
                    switch (status) {
                        case 0:

                            break;
                        case LEFT:
                            gesture.stopLeft();
                            break;
                        case RIGHT:
                            gesture.stopRight();
                            break;
                        case BOTTOM:
                            gesture.stopBottom();
                            break;
                        case UP:
                            gesture.stopUp();
                            break;

                    }
                    isFirst = true;


                }
                mode=NONE;
                result = true;
                break;
            case MotionEvent.ACTION_POINTER_DOWN:
                mode = MOVE;
                oldDis = spacing(event);
                result = true;
                break;
            case MotionEvent.ACTION_POINTER_UP:
                switch (status) {
                    case ZOOMIN:
                        gesture.stopZoomIn();
                        break;
                    case ZOOMOUT:
                        gesture.stopZoomOut();
                        break;

                }
                mode = NONE;
                result = true;
                break;
            case MotionEvent.ACTION_MOVE:
                if (isFirst) {


                    switch (mode) {
                        case NONE:

                            break;
                        case DRAG:
                            newX = event.getRawX();
                            newY = event.getRawY();

                            if (newX - oldX > 0 && Math.abs(newX - oldX) > Math.abs(newY - oldY)) {
                                //toRight
                                gesture.moveRight();
                                status = RIGHT;


                            } else if (newX - oldX < 0 && Math.abs(newX - oldX) > Math.abs(newY - oldY)) {
                                //toLeft
                                gesture.moveLeft();
                                status = LEFT;


                            } else if (newY - oldY > 0 && Math.abs(newY - oldY) > Math.abs(newX - oldX)) {
                                //toBottom
                                gesture.moveBottom();
                                status = BOTTOM;

                            } else if (newY - oldY < 0 && Math.abs(newY - oldY) > Math.abs(newX - oldX)) {
                                gesture.moveUp();
                                status = UP;

                            }


                            break;
                        case MOVE:
                            newDis = spacing(event);
                            if (newDis - oldDis > 1) {
                                status = ZOOMOUT;
                                gesture.zoomOut();
                            } else if (oldDis - newDis > 1) {
                                status = ZOOMIN;
                                gesture.zoomIn();
                            }
                            break;


                    }
                    isFirst = false;
                    result = true;
                    break;
                } else {
                    //只需要接受第一次move即可 后面的move都被忽略
                }
        }
        return result;
    }

    private float spacing(MotionEvent event) {
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return (float) Math.sqrt(x * x + y * y);
    }
}

IGesture

public interface IGesture {
    void moveUp();
    void moveBottom();
    void moveLeft();
    void moveRight();
    void zoomIn();
    void zoomOut();
    void stopUp();
    void stopBottom();
    void stopLeft();
    void stopRight();
    void stopZoomIn();
    void stopZoomOut();
}