知道 Mac OS X 下手指在触控板上的位置

Question

我正在开发一个 Mac 应用程序，我想知道触摸时手指在触控板上的位置。

有可能吗？如果有，怎么可能？

Answer 1

您的视图需要设置为接受触摸（[self setAcceptsTouchEvents:YES]）。当您收到像 -touchesBeganWithEvent: 这样的触摸事件时，您可以通过查看其 normalizedPosition 来确定手指所在的位置（范围为 [0.0, 1.0] x [0.0, 1.0]），因为它的 deviceSize 是大点（每英寸有 72 bp）。触控板的左下角被视为零原点。

因此，例如：（

- (id)initWithFrame:(NSRect)frameRect {
   self = [super initWithFrame:frameRect];
   if (!self) return nil;

   /* You need to set this to receive any touch event messages. */
   [self setAcceptsTouchEvents:YES];

   /* You only need to set this if you actually want resting touches.
    * If you don't, a touch will "end" when it starts resting and
    * "begin" again if it starts moving again. */
   [self setWantsRestingTouches:YES]
   return self;
}

/* One of many touch event handling methods. */
- (void)touchesBeganWithEvent:(NSEvent *)ev {
   NSSet *touches = [ev touchesMatchingPhase:NSTouchPhaseBegan inView:self];

   for (NSTouch *touch in touches) {
      /* Once you have a touch, getting the position is dead simple. */
      NSPoint fraction = touch.normalizedPosition;
      NSSize whole = touch.deviceSize;
      NSPoint wholeInches = {whole.width / 72.0, whole.height / 72.0};
      NSPoint pos = wholeInches;
      pos.x *= fraction.x;
      pos.y *= fraction.y;
      NSLog(@"%s: Finger is touching %g inches right and %g inches up "
            @"from lower left corner of trackpad.", __func__, pos.x, pos.y);
   }
}

将此代码视为示例，而不是经过验证的真实示例代码；我只是将其直接写到注释框中。）

Answer 2

Swift 3：

我编写了一个 NSTouch 扩展，它返回相对于 NSView 的触控板触摸位置：

extension NSTouch {
    /**
     * Returns the relative position of the touch to the view
     * NOTE: the normalizedTouch is the relative location on the trackpad. values range from 0-1. And are y-flipped
     * TODO: debug if the touch area is working with a rect with a green stroke
     */
    func pos(_ view:NSView) -> CGPoint{
        let w = view.frame.size.width
        let h = view.frame.size.height
        let touchPos:CGPoint = CGPoint(self.normalizedPosition.x,1 + (self.normalizedPosition.y * -1))/*flip the touch coordinates*/
        let deviceSize:CGSize = self.deviceSize
        let deviceRatio:CGFloat = deviceSize.width/deviceSize.height/*find the ratio of the device*/
        let viewRatio:CGFloat = w/h
        var touchArea:CGSize = CGSize(w,h)
        /*Uniform-shrink the device to the view frame*/
        if(deviceRatio > viewRatio){/*device is wider than view*/
            touchArea.height = h/viewRatio
            touchArea.width = w
        }else if(deviceRatio < viewRatio){/*view is wider than device*/
            touchArea.height = h
            touchArea.width = w/deviceRatio
        }/*else ratios are the same*/
        let touchAreaPos:CGPoint = CGPoint((w - touchArea.width)/2,(h - touchArea.height)/2)/*we center the touchArea to the View*/
        return CGPoint(touchPos.x * touchArea.width,touchPos.y * touchArea.height) + touchAreaPos
    }
}

这是我写的一篇关于 macOS 中的 GestureHUD 类的文章。还包含指向现成扩展的链接：http://eon. codes/blog/2017/03/15/Gesture-HUD/

示例：

Answer 3

我不知道是否有 ObjC 接口，但您可能会找到 C HID 类设备接口 有趣。

Answer 4

在 Cocoa（Obj-C 级别）尝试以下操作 - 尽管请记住许多用户仍在使用鼠标控制。

http://developer.apple.com/ mac/library/documentation/cocoa/conceptual/EventOverview/HandlingTouchEvents/HandlingTouchEvents.html