Catalyst 转换的 Mac 应用程序中的滚轮事件捕获

Question

在使用使用 Catalyst 从 iOS 转换而来的 Mac 应用程序时，为 Mac 捕获鼠标滚轮 activity 的常用方法，例如

(void)scrollWheel:(NSEvent *)event;

不工作，因为在构建 Catalyst 转换的应用程序时显然不支持 NSEvent。

我需要控制的对象在常规图像容器中，而不是在滚动视图容器中。我只是想使用滚轮来更改加载的图像。触控板 activity 工作正常，但到目前为止捕获滚轮一直难以捉摸。

谢谢！

Answer 1

使用 UIPanGestureRecognizer 并将 allowedScrollTypesMask 设置为 UIScrollTypeMaskDiscrete：

    // pan gesture to recognize mouse-wheel scrolling (zoom)
    UIPanGestureRecognizer * scrollWheelGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handleScrollWheelGesture:)];
    scrollWheelGesture.allowedScrollTypesMask = UIScrollTypeMaskDiscrete;   // only accept scroll-wheel, not track-pad
    scrollWheelGesture.maximumNumberOfTouches = 0;
    [self.view addGestureRecognizer:scrollWheelGesture];

然后

- (void)handleScrollWheelGesture:(UIPanGestureRecognizer *)pan
{
    CGPoint delta = [pan translationInView:self.view];
    CGFloat zoom = (1000 + delta.y) / 1000;
    [self adjustZoomBy:zoom];
}

Answer 2

Swift 5:

func setupScrollWheel() {
    let scrollWheelGesture = UIPanGestureRecognizer(target: self, action: #selector(scrollWheelGestureRecognizer(_:)))
    scrollWheelGesture.allowedScrollTypesMask = .discrete
    scrollWheelGesture.maximumNumberOfTouches = 0
    view.addGestureRecognizer(scrollWheelGesture)
}

@objc func scrollWheelGestureRecognizer(_ recognizer: UIPanGestureRecognizer) {
    let delta = recognizer.translation(in: view)      
}

Catalyst 转换的 Mac 应用程序中的滚轮事件捕获

Scroll Wheel event capture in a Catalyst-converted Mac app

macos

mac-catalyst