[英]How to rotate an image using touch
任何人都可以告诉我,如何根据用户给出的触摸旋转视图....
我的意思是我想像旧电话那样做出类似的外观(按下并旋转拨号......)......
我很清楚如何旋转,但根据这种情况无法旋转.....
您只需要一个只有拨号图像的视图。
This view has a center C(x,y)
First, the view will be touched at coordinate T0(x,y)
if the x and y is within the circle do the tracking:
Then the finger will move to coordinate Tn(x,y)
Find the angle made up by Tn(x,y) C(x,y) T0(x,y) //(See below for a reference)
and do the rotation using that angle as you already know ;)
else
do nothing since the touch is not in the dial
参考: 如何从三个点计算角度
计算起始触摸和刻度盘中心之间的角度( atan2f(y - yc, x - xc)
),并将其用作基准角度,以确定每个后续触摸事件所需的旋转。
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