c# - 使用 Unity 5 UI 进行双指缩放

Question

我正在尝试在基于 Unity UI 的应用程序中重新实现双指缩放系统。大约六个月前，我能够通过使 UI Canvas 成为常规 GameObject 的子对象并操纵该对象的变换来破解一个，但自从更新到 Unity 5.5+ 后，我发现这不起作用。我能得到的最接近的允许捏手势改变 Canvas 的比例因子，这 a) 可以使图像、面板等根据它们的对齐方式不正确地调整大小，并且 b) 不允许我在缩放后平移。

我目前的情况是这样的:

public class PinchToZoomScaler : MonoBehaviour {

    public Canvas canvas; // The canvas
    public float zoomSpeed = 0.5f;        // The rate of change of the canvas scale factor

    public float _resetDuration = 3.0f;
    float _durationTimer = 0.0f;

    float _startScale = 0.0f;

    void Start() {
        _startScale = canvas.scaleFactor;
    }

    void Update()
    {
            // If there are two touches on the device...
            if (Input.touchCount == 2) {
                // Store both touches.
                Touch touchZero = Input.GetTouch (0);
                Touch touchOne = Input.GetTouch (1);

                // Find the position in the previous frame of each touch.
                Vector2 touchZeroPrevPos = touchZero.position - touchZero.deltaPosition;
                Vector2 touchOnePrevPos = touchOne.position - touchOne.deltaPosition;

                // Find the magnitude of the vector (the distance) between the touches in each frame.
                float prevTouchDeltaMag = (touchZeroPrevPos - touchOnePrevPos).magnitude;
                float touchDeltaMag = (touchZero.position - touchOne.position).magnitude;

                // Find the difference in the distances between each frame.
                float deltaMagnitudeDiff = prevTouchDeltaMag - touchDeltaMag;

                // ... change the canvas size based on the change in distance between the touches.
                canvas.scaleFactor -= deltaMagnitudeDiff * zoomSpeed;

                // Make sure the canvas size never drops below 0.1
                canvas.scaleFactor = Mathf.Max (canvas.scaleFactor, _startScale);
                canvas.scaleFactor = Mathf.Min (canvas.scaleFactor, _startScale * 3.0f);

                _durationTimer = 0.0f;
            } else {
                _durationTimer += Time.deltaTime;

                if (_durationTimer >= _resetDuration) {
                    canvas.scaleFactor = _startScale;
                }
            }
    }
}

正如我所说，这在一定程度上起作用，但不能给我很好的均匀缩放，也不能让我平移 Canvas 。在此先感谢您的帮助。

Answer 1

将此脚本附加到要缩放的 Canvas 对象中

using UnityEngine;
using UnityEngine.EventSystems;

public class ObjectScalling : MonoBehaviour, IPointerDownHandler, IPointerUpHandler 
{
    private bool _isDragging;
    private float _currentScale;
    public float minScale, maxScale;
    private float _temp = 0;
    private float _scalingRate = 2;

    private void Start() 
    {
        _currentScale = transform.localScale.x;
    }

    public void OnPointerDown(PointerEventData eventData) 
    {
        if (Input.touchCount == 1) 
        {
            _isDragging = true;
        }
    }


    public void OnPointerUp(PointerEventData eventData) 
    {
        _isDragging = false;
    }


    private void Update() 
    {
        if (_isDragging)
            if (Input.touchCount == 2) 
            {
                transform.localScale = new Vector2(_currentScale, _currentScale);
                float distance = Vector3.Distance(Input.GetTouch(0).position, Input.GetTouch(1).position);
                if (_temp > distance) 
                {
                    if (_currentScale < minScale)
                        return;
                    _currentScale -= (Time.deltaTime) * _scalingRate;
                }

                else if (_temp < distance) 
                {
                    if (_currentScale > maxScale)
                        return;
                    _currentScale += (Time.deltaTime) * _scalingRate;
                }

                _temp = distance;
            }
    }
}

提醒:此脚本仅适用于 Canvas 对象