检测iphone上的特殊触摸 [英] Detecting Special touch on the iphone

问题描述

我问自己是否有在线示例，其中包括如何检测触摸手势中的形状。

例如矩形或圆形复杂的心...）

或确定滑动速度（随着时间的推移，我正在刷我的iPhone对50英里每小时））

对于非常简单的手势（水平或垂直滑动），计算两次触摸之间的x和y之差。

  dy = abs（y2  -  y1）
 dx = abs（x2  -  x1）
f = dy / dx 
  

接近零的水平滑动。接近1的f是对角滑动。一个非常大的f是一个垂直滑动（请记住，dx可能为零，因此上面的内容不会为所有x和y产生有效的结果）。

如果你对速度感兴趣，pythagoras可以帮助。两次触摸之间移动的距离长度为：

  l = sqrt（dx * dx + dy * dy）
  

如果触摸发生在时间t1和t2，速度为：

  tdiff = abs（t2  -  t1）
s = l / tdiff 
  

由你决定哪个值可以解释为快或慢。

您可以扩展这种方法以获得更复杂的图形，例如您的正方形可以是水平/垂直/水平/垂直滑动，其中前一次滑动已停止的开始/结束点。

对于更复杂的数字，具有理想化的形状。可以考虑多边形形状作为理想，并检查是否触摸范围

1. 与其最近的距离

p>您可以从那里进一步细化。

I was asking myself if there are examples online which covers how you can for instance detect shapes in touch gestures.

for example a rectangle or a circle (or more complex a heart .. )

or determine the speed of swiping (over time ( like i'm swiping my iphone against 50mph ))

解决方案

For very simple gestures (horizontal vs. vertical swipe), calculate the difference in x and y between two touches.

dy = abs(y2 - y1)
dx = abs(x2 - x1)
f = dy/dx

An f close to zero is a horizontal swipe. An f close to 1 is a diagonal swipe. And a very large f is a vertical swipe (keep in mind that dx could be zero, so the above won't yield valid results for all x and y).

If you're interested in speed, pythagoras can help. The length of the distance travelled between two touches is:

l = sqrt(dx*dx + dy*dy)

If the touches happened at times t1 and t2, the speed is:

tdiff = abs(t2 - t1)
s = l/tdiff

It's up to you to determine which value of s you interpret as fast or slow.

You can extend this approach for more complex figures, e.g. your square shape could be a horizontal/vertical/horizontal/vertical swipe with start/end points where the previous swipe stopped.

For more complex figures, it's probably better to work with an idealized shape. One could consider a polygon shape as the ideal, and check if a range of touches

1. don't have too high a distance to their closest point on the pologyon's outline, and
2. all touches follow the same direction along the polygon's outline.

You can refine things further from there.

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