使用PanResponder进行锁定运动

Question

使用react native PanResponder,当屏幕触摸坐标超出某个值范围时,如何阻止移动？

例如,如何阻止用户将组件移动到屏幕上某个y位置以下？

PanResponder使用手势响应系统.

我正在仔细阅读文档,但我找不到答案.

任何帮助是极大的赞赏.

Answer 1

查看您提供的PanResponder文档页面(https://facebook.github.io/react-native/docs/panresponder.html),我认为您可以修改示例以满足您的需求.

负责响应手势采取操作的函数是PanResponder的一个属性,名为onPanResponderMove,在示例代码中看起来像这样:

_handlePanResponderMove: function(e: Object, gestureState: Object) {
    this._circleStyles.style.left = this._previousLeft + gestureState.dx;
    this._circleStyles.style.top = this._previousTop + gestureState.dy;
    this._updateNativeStyles();
},

gestureState对象的位置如下所示:

stateID - ID of the gestureState- persisted as long as there at least one touch on screen
moveX - the latest screen coordinates of the recently-moved touch
moveY - the latest screen coordinates of the recently-moved touch
x0 - the screen coordinates of the responder grant
y0 - the screen coordinates of the responder grant
dx - accumulated distance of the gesture since the touch started
dy - accumulated distance of the gesture since the touch started
vx - current velocity of the gesture
vy - current velocity of the gesture
numberActiveTouches - Number of touches currently on screen

您可以在_handlePanResponderMove中添加条件检查以确定gestureState.y0是否低于某个阈值,并且只应用更改