如何获取点击位置 (GestureDetector)？

Question

我正在尝试在我的 zoomable_images plugin but the GestureTapCallback 中实现双击缩放，但未提供点击位置信息。

理想情况下，偏移量将由回调返回。还有另一个 API 吗？

Answer 1

你可以提供一个GestureTapDownCallback callback as the onTapDown argument of the GestureDetector constructor. The GestureTapDownCallback takes a TapDownDetails argument that includes the global position of the tap. You can then convert it to relative coordinates using BuildContext.findRenderObject and RenderBox.globalToLocal:

Offset _tapPosition;

void _handleTapDown(TapDownDetails details) {
  final RenderBox referenceBox = context.findRenderObject();
  setState(() {
    _tapPosition = referenceBox.globalToLocal(details.globalPosition);
  });
}

@override
Widget build(BuildContext context) {
  return new GestureDetector(
     /* ... */
     onTapDown: _handleTapDown,
  );
}

在您的 onDoubleTap 处理程序中，您可以参考 _tapPosition 以找出最近点击的位置。

有关此操作的示例，请参阅 InkWell。

Answer 2

截至 [✓] Flutter (Channel stable, 2.5.3)

GestureDetector(
      onTapDown: (details) {

        var position = details.globalPosition;
        // you can also check out details.localPosition; 

        if (position.dx < MediaQuery.of(context).size.width / 2){
          // tap left side
        } else {
          // tap rigth size
        }
      },
      child: SomeChildWidget(),
),

Answer 3

如果你想处理双击，你需要存储来自onDoubleTapDown的点击位置，然后使用onDoubleTap:

late Offset _doubleTapPosition;
...
onDoubleTap: () {
    //do your stuff with _doubleTapPosition here
},
onDoubleTapDown: (details) {
    final RenderBox box = context.findRenderObject() as RenderBox;
    _doubleTapPosition = box.globalToLocal(details.globalPosition);
},