iphone - 如何计算 iPhone、iPad 和 Android 设备上触摸点的直径？

Question

现在我知道 iPhone 中默认可以有 5 个触摸点，并且可以在不同的 SDK 上启用不同的触摸点。不过，我已经完成了注册触摸点并获取距离、触摸点的实际数量。我想知道是否有一种方法可以完成并获取特定触摸点的直径，例如与食指相比计算拇指触摸，有什么想法吗？

Answer 1

我认为苹果公司已经明确表示他们不打算让第三方开发者访问低级多点触控信息。来自Apple关于Event Handling in iOS的文档:

A finger on the screen affords a much different level of precision than a mouse pointer. When a user touches the screen, the area of contact is actually elliptical and tends to be offset below the point where the user thinks he or she touched. This “contact patch” also varies in size and shape based on which finger is touching the screen, the size of the finger, the pressure of the finger on the screen, the orientation of the finger, and other factors. The underlying Multi-Touch system analyzes all of this information for you and computes a single touch point.