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Flutter 手势系列教程---GestureDetector

Jimi 发表于 2021-09-202021-09-20T00:00:00+08:00
22 分钟阅读

GestureDetector介绍

在前面的文章中我们介绍了Listener，而GestureDetector是对Listener的封装，提供非常多的手势,包括单击、双击、拖动、混合手势等。

视频教程地址

手势系列视频教程地址

什么情况下使用GestureDetector？

当我们需要对文字需要增加点击事件时，或者需要对组件进行拖动、缩放等那我们就可以借助GestureDetector

GestureDetector构造函数

我们可以看到GestureDetector的属性非常多，接下来我们分类来一一讲解。

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GestureDetector({
    Key? key,
    this.child,
    this.onTapDown,
    this.onTapUp,
    this.onTap,
    this.onTapCancel,
    this.onSecondaryTap,
    this.onSecondaryTapDown,
    this.onSecondaryTapUp,
    this.onSecondaryTapCancel,
    this.onTertiaryTapDown,
    this.onTertiaryTapUp,
    this.onTertiaryTapCancel,
    this.onDoubleTapDown,
    this.onDoubleTap,
    this.onDoubleTapCancel,
    this.onLongPressDown,
    this.onLongPressCancel,
    this.onLongPress,
    this.onLongPressStart,
    this.onLongPressMoveUpdate,
    this.onLongPressUp,
    this.onLongPressEnd,
    this.onSecondaryLongPressDown,
    this.onSecondaryLongPressCancel,
    this.onSecondaryLongPress,
    this.onSecondaryLongPressStart,
    this.onSecondaryLongPressMoveUpdate,
    this.onSecondaryLongPressUp,
    this.onSecondaryLongPressEnd,
    this.onTertiaryLongPressDown,
    this.onTertiaryLongPressCancel,
    this.onTertiaryLongPress,
    this.onTertiaryLongPressStart,
    this.onTertiaryLongPressMoveUpdate,
    this.onTertiaryLongPressUp,
    this.onTertiaryLongPressEnd,
    this.onVerticalDragDown,
    this.onVerticalDragStart,
    this.onVerticalDragUpdate,
    this.onVerticalDragEnd,
    this.onVerticalDragCancel,
    this.onHorizontalDragDown,
    this.onHorizontalDragStart,
    this.onHorizontalDragUpdate,
    this.onHorizontalDragEnd,
    this.onHorizontalDragCancel,
    this.onForcePressStart,
    this.onForcePressPeak,
    this.onForcePressUpdate,
    this.onForcePressEnd,
    this.onPanDown,
    this.onPanStart,
    this.onPanUpdate,
    this.onPanEnd,
    this.onPanCancel,
    this.onScaleStart,
    this.onScaleUpdate,
    this.onScaleEnd,
    this.behavior,
    this.excludeFromSemantics = false,
    this.dragStartBehavior = DragStartBehavior.start,
  }) : assert(excludeFromSemantics != null),
       assert(dragStartBehavior != null),
       assert(() {
         final bool haveVerticalDrag = onVerticalDragStart != null || onVerticalDragUpdate != null || onVerticalDragEnd != null;
         final bool haveHorizontalDrag = onHorizontalDragStart != null || onHorizontalDragUpdate != null || onHorizontalDragEnd != null;
         final bool havePan = onPanStart != null || onPanUpdate != null || onPanEnd != null;
         final bool haveScale = onScaleStart != null || onScaleUpdate != null || onScaleEnd != null;
         if (havePan || haveScale) {
           if (havePan && haveScale) {
             throw FlutterError.fromParts(<DiagnosticsNode>[
               ErrorSummary('Incorrect GestureDetector arguments.'),
               ErrorDescription(
                 'Having both a pan gesture recognizer and a scale gesture recognizer is redundant; scale is a superset of pan.',
               ),
               ErrorHint('Just use the scale gesture recognizer.'),
             ]);
           }
           final String recognizer = havePan ? 'pan' : 'scale';
           if (haveVerticalDrag && haveHorizontalDrag) {
             throw FlutterError(
               'Incorrect GestureDetector arguments.\n'
               'Simultaneously having a vertical drag gesture recognizer, a horizontal drag gesture recognizer, and a $recognizer gesture recognizer '
               'will result in the $recognizer gesture recognizer being ignored, since the other two will catch all drags.',
             );
           }
         }
         return true;
       }()),
       super(key: key);

GestureDetector单击手势

单击手势总共有四种，分别如下：

字段 属性 描述
onTapDown GestureTapDownCallback 手指按下时的回调函数
onTapUp GestureTapUpCallback 手指松开时的回调函数
onTap GestureTapCallback 手指点击时的回调函数
onTapCancel GestureTapCancelCallback 手指取消点击时的回调函数

GestureDetector单击手势应用场景

单击手势一般常用于给容器添加点击事件

GestureDetector单击手势案例展示

我们在Container容器上添加了单击手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            GestureDetector(
              onTap: (){
                print("onTap");
              },
              onTapCancel: () {
                print("onTapCancel");
              },
              onTapDown: (details) {
                print("onTapDown---${details.globalPosition}---${details.localPosition}");
              },
              onTapUp: (details) {
                print("onTapUp---${details.globalPosition}---${details.localPosition}");
              },
              child: Container(
                width: 200,
                height: 200,
                color: Colors.orange,
                alignment: Alignment.center,
                child: Text("Jimi",
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 30
                  ),
                ),
              ),
            )
          ],
        ),
      ),
    );
  }
}

GestureDetector单击手势控制台输出结果

第一种：点击Container容器
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flutter: onTapDown---Offset(211.5, 317.0)---Offset(124.0, 45.5)
flutter: onTapUp---Offset(211.5, 317.0)---Offset(124.0, 45.5)
flutter: onTap
第二种：点击Container容器后不松手直接移出区域
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flutter: onTapDown---Offset(195.5, 305.5)---Offset(108.0, 34.0)
flutter: onTapCancel

GestureDetector双击手势

双击手势总共有三种，分别如下：

字段 属性 描述
onDoubleTapDown GestureTapDownCallback 手指按下时的回调函数
onDoubleTap GestureTapCallback 手指双击时的回调函数
onDoubleTapCancel GestureTapCancelCallback 手指取消时的回调函数

GestureDetector双击手势应用场景

在特定情况下需要对单一容器增加双击事件

GestureDetector双击手势案例展示

我们在Container容器上添加了三种双击手势的回调，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            GestureDetector(
              onDoubleTap: () {
                print("onTapDown");
              },
              onDoubleTapCancel: () {
                print("onDoubleTapCancel");
              },
              onDoubleTapDown: (details) {
                print("onDoubleTapDown---${details.globalPosition}---${details.localPosition}");
              },
              child: Container(
                width: 200,
                height: 200,
                color: Colors.orange,
                alignment: Alignment.center,
                child: Text("Jimi",
                  style: TextStyle(
                      color: Colors.white,
                      fontSize: 30
                  ),
                ),
              ),
            )
          ],
        ),
      ),
    );
  }
}

GestureDetector双击手势控制台输出结果

第一种：双击Container容器
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flutter: onDoubleTapDown---Offset(204.5, 317.0)---Offset(117.0, 45.5)
flutter: onTapDown
第二种：双击Container容器但不抬起手指并移出区域
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flutter: onDoubleTapDown---Offset(195.5, 283.5)---Offset(108.0, 12.0)
flutter: onDoubleTapCancel

GestureDetector长按手势

长按手势总共有七种，分别如下：

字段 属性 描述
onLongPressDown GestureLongPressDownCallback 手指按下去时的回调函数
onLongPressCancel GestureLongPressCancelCallback 手指长按取消时的回调函数
onLongPress GestureLongPressCallback 手指长按时的回调函数
onLongPressStart GestureLongPressStartCallback 手指长按并开始拖动时的回调函数
onLongPressMoveUpdate GestureLongPressMoveUpdateCallback 手指长按并移动时的回调函数
onLongPressUp GestureLongPressUpCallback 手指长按并松开时的回调函数
onLongPressEnd GestureLongPressEndCallback 手指长按结束拖动时的回调函数

GestureDetector长按手势应用场景

长按某组件需要执行特定的方法，比如按钮长按时的水波纹效果

GestureDetector长按手势案例展示

我们在Container容器上添加了长按手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            GestureDetector(
              onLongPress: (){
                print("onLongPress");
              },
              onLongPressCancel: () {
                print("onLongPressCancel");
              },
              onLongPressUp: () {
                print("onLongPressUp");
              },
              onLongPressDown: (details) {
                print("onLongPressDown---${details.globalPosition}---${details.localPosition}");
              },
              onLongPressEnd: (details) {
                print("onLongPressEnd---${details.globalPosition}---${details.localPosition}");
              },
              onLongPressStart: (details) {
                print("onLongPressStart---${details.globalPosition}---${details.localPosition}");
              },
              onLongPressMoveUpdate: (details) {
                print("onLongPressMoveUpdate---${details.globalPosition}---${details.localPosition}");
              },
              child: Container(
                width: 200,
                height: 200,
                color: Colors.orange,
                alignment: Alignment.center,
                child: Text("Jimi",
                  style: TextStyle(
                    color: Colors.white,
                    fontSize: 30
                  ),
                ),
              ),
            )
          ],
        ),
      ),
    );
  }
}

GestureDetector长按手势控制台输出结果

第一种：单击Container容器
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flutter: onLongPressDown---Offset(199.0, 336.0)---Offset(111.5, 64.5)
flutter: onLongPressCancel
第二种：长按Container容器但是手指不动后松开
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flutter: onLongPressDown---Offset(215.0, 301.0)---Offset(127.5, 29.5)
flutter: onLongPressStart---Offset(215.0, 301.0)---Offset(127.5, 29.5)
flutter: onLongPress
flutter: onLongPressEnd---Offset(215.0, 301.0)---Offset(127.5, 29.5)
flutter: onLongPressUp
第三种：长按Container容器并进行拖动最后松开手指
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flutter: onLongPressDown---Offset(169.0, 314.0)---Offset(81.5, 42.5)
flutter: onLongPressStart---Offset(169.0, 314.0)---Offset(81.5, 42.5)
flutter: onLongPress
flutter: onLongPressMoveUpdate---Offset(168.5, 314.5)---Offset(81.0, 43.0)
flutter: onLongPressMoveUpdate---Offset(165.0, 318.5)---Offset(77.5, 47.0)
flutter: onLongPressMoveUpdate---Offset(164.0, 319.0)---Offset(76.5, 47.5)
flutter: onLongPressMoveUpdate---Offset(158.5, 323.5)---Offset(71.0, 52.0)
flutter: onLongPressMoveUpdate---Offset(153.0, 329.5)---Offset(65.5, 58.0)
flutter: onLongPressMoveUpdate---Offset(148.5, 335.0)---Offset(61.0, 63.5)
flutter: onLongPressMoveUpdate---Offset(146.5, 339.0)---Offset(59.0, 67.5)
flutter: onLongPressMoveUpdate---Offset(146.5, 339.5)---Offset(59.0, 68.0)
flutter: onLongPressEnd---Offset(146.5, 339.5)---Offset(59.0, 68.0)
flutter: onLongPressUp
第四种：长按Container容器并马上移出区域
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flutter: onLongPressDown---Offset(97.0, 277.5)---Offset(9.5, 6.0)
flutter: onLongPressCancel
flutter: onLongPressDown---Offset(91.5, 275.5)---Offset(4.0, 4.0)
flutter: onLongPressCancel

GestureDetector垂直滑动手势

垂直滑动手势总共有五种，分别如下：

字段 属性 描述
onVerticalDragDown GestureDragDownCallback 手指按下时的回调函数
onVerticalDragStart GestureDragStartCallback 手指开始垂直滑动时的回调函数
onVerticalDragUpdate GestureDragUpdateCallback 手指垂直滑动时的回调函数
onVerticalDragEnd GestureDragEndCallback 手指垂直滑动结束时的回调函数
onVerticalDragCancel GestureDragCancelCallback 手指垂直滑动取消时的回调函数

GestureDetector垂直滑动手势应用场景

需要对某个组件进行垂直滑动时

GestureDetector垂直滑动手势案例展示

我们在Container容器上添加了垂直滑动手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  double _left = 0;
  double _top = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            GestureDetector(
              onVerticalDragCancel: () {
                print("onVerticalDragCancel");
              },
              onVerticalDragDown: (details) {
                print("onVerticalDragDown---${details.globalPosition}---${details.localPosition}");
              },
              onVerticalDragEnd: (details) {
                print("onVerticalDragEnd---${details.velocity}---${details.primaryVelocity}");
              },
              onVerticalDragStart: (details) {
                print("onVerticalDragStart---${details.globalPosition}---${details.localPosition}");
              },
              onVerticalDragUpdate: (details) {
                print("onVerticalDragUpdate---${details.globalPosition}---${details.localPosition}---${details.delta}");
                setState(() {
                  _top += details.delta.dy;
                });

              },
              child: Stack(
                children: [
                  Positioned(
                    left: _left,
                    top: _top,
                    child: Container(
                      width: 200,
                      height: 200,
                      color: Colors.orange,
                      alignment: Alignment.center,
                      child: Text("Jimi",
                        style: TextStyle(
                            color: Colors.white,
                            fontSize: 30
                        ),
                      ),
                    ),
                  )
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}

GestureDetector垂直滑动手势控制台输出

第一种：点击Container容器
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flutter: onVerticalDragDown---Offset(76.5, 114.5)---Offset(76.5, 38.5)
flutter: onVerticalDragStart---Offset(76.5, 114.5)---Offset(76.5, 38.5)
flutter: onVerticalDragEnd---Velocity(0.0, 0.0)---0.0
第二种：拖动Container容器
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flutter: onVerticalDragDown---Offset(185.5, 332.5)---Offset(185.5, 256.5)
flutter: onVerticalDragStart---Offset(185.5, 332.5)---Offset(185.5, 256.5)
flutter: onVerticalDragUpdate---Offset(185.5, 332.0)---Offset(185.5, 256.0)
flutter: onVerticalDragUpdate---Offset(187.5, 322.0)---Offset(187.5, 246.0)
flutter: onVerticalDragUpdate---Offset(192.0, 307.0)---Offset(192.0, 231.0)
flutter: onVerticalDragUpdate---Offset(193.5, 298.0)---Offset(193.5, 222.0)
flutter: onVerticalDragUpdate---Offset(193.5, 297.0)---Offset(193.5, 221.0)
flutter: onVerticalDragEnd---Velocity(131.3, -548.9)----548.8773895303548
第三种：拖动Container容器并马上松开
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flutter: onVerticalDragDown---Offset(10.5, 93.5)---Offset(10.5, 17.5)
flutter: onVerticalDragCancel

GestureDetector水平滑动手势

水平滑动手势总共有五种，分别如下：

字段 属性 描述
onHorizontalDragDown GestureDragDownCallback 手指按下时的回调函数
onHorizontalDragStart GestureDragStartCallback 手指开始水平滑动时的回调函数
onHorizontalDragUpdate GestureDragUpdateCallback 手指水平滑动时的回调函数
onHorizontalDragEnd GestureDragEndCallback 手指水平滑动结束时的回调函数
onHorizontalDragCancel GestureDragCancelCallback 手指水平滑动取消时的回调函数

GestureDetector水平滑动手势应用场景

需要对某个组件进行水平滑动时

GestureDetector水平滑动手势案例展示

我们在Container容器上添加了水平滑动手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  double _left = 0;
  double _top = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            /// 水平滑动
            GestureDetector(
              onHorizontalDragCancel: () {
                print("onHorizontalDragCancel");
              },
              onHorizontalDragDown: (details) {
                print("onHorizontalDragDown---${details.globalPosition}---${details.localPosition}");
              },
              onHorizontalDragEnd: (details) {
                print("onHorizontalDragEnd---${details.velocity}---${details.primaryVelocity}");
              },
              onHorizontalDragStart: (details) {
                print("onHorizontalDragStart---${details.globalPosition}---${details.localPosition}");
              },
              onHorizontalDragUpdate: (details) {
                print("onHorizontalDragUpdate---${details.globalPosition}---${details.localPosition}---${details.delta}");
                setState(() {
                  _left += details.delta.dx;
                });

              },
              child: Stack(
                children: [
                  Positioned(
                    left: _left,
                    top: _top,
                    child: Container(
                      width: 200,
                      height: 200,
                      color: Colors.orange,
                      alignment: Alignment.center,
                      child: Text("Jimi",
                        style: TextStyle(
                            color: Colors.white,
                            fontSize: 30
                        ),
                      ),
                    ),
                  )
                ],
              ),
            )

          ],
        ),
      ),
    );
  }
}

GestureDetector水平滑动控制台输出

第一种：点击Container容器
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flutter: onHorizontalDragDown---Offset(151.5, 118.0)---Offset(151.5, 42.0)
flutter: onHorizontalDragStart---Offset(151.5, 118.0)---Offset(151.5, 42.0)
flutter: onHorizontalDragEnd---Velocity(0.0, 0.0)---0.0
第二种：拖动Container容器
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flutter: onHorizontalDragDown---Offset(97.5, 135.5)---Offset(97.5, 59.5)
flutter: onHorizontalDragStart---Offset(97.5, 135.5)---Offset(97.5, 59.5)
flutter: onHorizontalDragUpdate---Offset(100.0, 136.0)---Offset(100.0, 60.0)---Offset(2.5, 0.0)
flutter: onHorizontalDragUpdate---Offset(100.5, 136.0)---Offset(100.5, 60.0)---Offset(0.5, 0.0)
flutter: onHorizontalDragUpdate---Offset(102.0, 136.0)---Offset(102.0, 60.0)---Offset(1.5, 0.0)
flutter: onHorizontalDragUpdate---Offset(105.0, 136.5)---Offset(105.0, 60.5)---Offset(3.0, 0.0)
flutter: onHorizontalDragUpdate---Offset(107.0, 137.0)---Offset(107.0, 61.0)---Offset(2.0, 0.0)
flutter: onHorizontalDragUpdate---Offset(108.5, 137.0)---Offset(108.5, 61.0)---Offset(1.5, 0.0)
flutter: onHorizontalDragUpdate---Offset(109.0, 137.0)---Offset(109.0, 61.0)---Offset(0.5, 0.0)
flutter: onHorizontalDragUpdate---Offset(110.0, 137.0)---Offset(110.0, 61.0)---Offset(1.0, 0.0)
flutter: onHorizontalDragUpdate---Offset(111.0, 137.0)---Offset(111.0, 61.0)---Offset(1.0, 0.0)
flutter: onHorizontalDragEnd---Velocity(0.0, 0.0)---0.0
第三种：拖动Container容器并马上松开
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flutter: onHorizontalDragDown---Offset(6.0, 109.0)---Offset(6.0, 33.0)
flutter: onHorizontalDragCancel

GestureDetector拖动手势

拖动手势总共有五种，分别如下：

字段 属性 描述
onPanDown GestureDragDownCallback 手指按下时的回调函数
onPanStart GestureDragStartCallback 手指开始拖动时的回调函数
onPanUpdate GestureDragUpdateCallback 手指移动时的回调函数
onPanEnd GestureDragEndCallback 手指抬起时的回调函数
onPanCancel GestureDragCancelCallback 手指取消拖动时的回调函数

GestureDetector拖动手势应用场景

如微信的全局悬浮按钮

GestureDetector拖动手势案例展示

我们在Container容器上添加了拖动手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  double _left = 0;
  double _top = 0;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [

            // 拖动手势
            GestureDetector(
              onPanCancel: () {
                print("onPanCancel");
              },
              onPanDown: (details) {
                print("onPanDown---${details.globalPosition}---${details.localPosition}");
              },
              onPanEnd: (details) {
                print("onPanEnd---${details.velocity}---${details.primaryVelocity}");
              },
              onPanStart: (details) {
                print("onPanStart---${details.globalPosition}---${details.localPosition}");
              },
              onPanUpdate: (details) {
                print("onPanUpdate---${details.globalPosition}---${details.localPosition}---${details.delta}");
                setState(() {
                  _left += details.delta.dx;
                  _top += details.delta.dy;
                });
              },
              child: Stack(
                children: [
                  Positioned(
                    left: _left,
                    top: _top,
                    child: Container(
                      width: 200,
                      height: 200,
                      color: Colors.orange,
                      alignment: Alignment.center,
                      child: Text("Jimi",
                        style: TextStyle(
                            color: Colors.white,
                            fontSize: 30
                        ),
                      ),
                    ),
                  )
                ],
              ),
            )
          ],
        ),
      ),
    );
  }
}

GestureDetector拖动手势控制台输出

第一种：点击Container容器
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flutter: onPanDown---Offset(161.0, 233.0)---Offset(161.0, 157.0)
flutter: onPanStart---Offset(161.0, 233.0)---Offset(161.0, 157.0)
flutter: onPanEnd---Velocity(0.0, 0.0)---0.0
第二种：拖动Container容器
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flutter: onPanDown---Offset(123.5, 193.5)---Offset(123.5, 117.5)
flutter: onPanStart---Offset(123.5, 193.5)---Offset(123.5, 117.5)
flutter: onPanUpdate---Offset(123.5, 193.0)---Offset(123.5, 117.0)---Offset(0.0, -0.5)
flutter: onPanUpdate---Offset(124.0, 193.0)---Offset(124.0, 117.0)---Offset(0.5, 0.0)
flutter: onPanUpdate---Offset(124.5, 192.0)---Offset(124.5, 116.0)---Offset(0.5, -1.0)
flutter: onPanUpdate---Offset(125.5, 190.5)---Offset(125.5, 114.5)---Offset(1.0, -1.5)
flutter: onPanUpdate---Offset(126.0, 190.0)---Offset(126.0, 114.0)---Offset(0.5, -0.5)
flutter: onPanUpdate---Offset(126.5, 189.5)---Offset(126.5, 113.5)---Offset(0.5, -0.5)
flutter: onPanUpdate---Offset(127.0, 189.0)---Offset(127.0, 113.0)---Offset(0.5, -0.5)
flutter: onPanEnd---Velocity(0.0, 0.0)---0.0
第三种：拖动Container容器并马上松开
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flutter: onPanDown---Offset(5.5, 162.5)---Offset(5.5, 86.5)
flutter: onPanCancel

GestureDetector缩放手势

缩放手势总共有三种，分别如下：

字段 属性 描述
onScaleStart GestureScaleStartCallback 开始缩放时的回调函数
onScaleUpdate GestureScaleUpdateCallback 缩放移动时的回调函数
onScaleEnd GestureScaleEndCallback 缩放结束时的回调函数

GestureDetector缩放手势应用场景

如查看图片需要对图片进行缩小或放大时

GestureDetector缩放手势案例展示

我们在Container容器上添加了缩放手势，代码如下：

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import 'package:flutter/material.dart';

class GestureDetectorExample extends StatefulWidget {
  @override
  _GestureDetectorExampleState createState() => _GestureDetectorExampleState();
}

class _GestureDetectorExampleState extends State<GestureDetectorExample> {

  double _left = 0;
  double _top = 0;
  double _widthAndHeight = 200;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text("GestureDetector"),
      ),
      body: Center(
        child: Stack(
          children: [
            /// 缩放手势
            GestureDetector(
              onScaleEnd: (details) {
                print("onScaleEnd---${details.velocity}---${details.pointerCount}");
              },
              onScaleStart: (details) {
                print("onScaleStart---${details.focalPoint}---${details.pointerCount}");
              },
              onScaleUpdate: (details) {
                print("onScaleUpdate---${details.scale}---${details.scale.clamp(0.1, 1.2)}");
                setState(() {
                  _widthAndHeight = 200 * details.scale.clamp(0.3, 1.8);
                });
              },
              child: Container(
                width: _widthAndHeight,
                height: _widthAndHeight,
                color: Colors.orange,
                alignment: Alignment.center,
                child: Text("Jimi",
                  style: TextStyle(
                      color: Colors.white,
                      fontSize: 30
                  ),
                ),
              ),
            )

          ],
        ),
      ),
    );
  }
}
第一种：点击Container容器
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flutter: onScaleStart---Offset(149.5, 348.0)---1
flutter: onScaleEnd---Velocity(0.0, 0.0)---0
第二种：单指拖动Container容器
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flutter: onScaleStart---Offset(178.0, 304.5)---1
flutter: onScaleUpdate---1.0---1.0
flutter: onScaleUpdate---1.0---1.0
flutter: onScaleUpdate---1.0---1.0
flutter: onScaleUpdate---1.0---1.0
flutter: onScaleEnd---Velocity(0.0, 0.0)---0
第三种：双指缩放Container容器
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flutter: onScaleStart---Offset(187.5, 333.5)---2
flutter: onScaleUpdate---1.0055027720002572---1.0055027720002572
flutter: onScaleUpdate---1.0110087715145855---1.0110087715145855
flutter: onScaleUpdate---1.0293231946761667---1.0293231946761667
flutter: onScaleUpdate---1.04763763435052---1.04763763435052
flutter: onScaleUpdate---1.0531463022961167---1.0531463022961167
flutter: onScaleEnd---Velocity(0.0, 0.0)---1

GestureDetector其他手势

带有3D Touch功能压力设备触发手势

总共有4个手势

字段 属性 描述
onForcePressStart GestureForcePressStartCallback 手指强制按下时的回调函数
onForcePressPeak GestureForcePressPeakCallback 手指按压力度最大时的回调函数
onForcePressUpdate GestureForcePressUpdateCallback 手指按下后移动时的回调函数
onForcePressEnd GestureForcePressEndCallback 手指离开时的回调函数

辅助按钮触发手势

字段 属性 描述
onSecondaryTap GestureTapCallback 辅助按钮单击时的回调函数
onSecondaryTapDown GestureTapDownCallback 辅助按钮按下时的回调函数
onSecondaryTapUp GestureTapUpCallback 辅助按钮松开时的回调函数
onSecondaryTapCancel GestureTapCancelCallback 辅助按钮取消点击时的回调函数
onSecondaryLongPressDown GestureLongPressDownCallback 辅助按钮按下去时的回调函数
onSecondaryLongPressCancel GestureLongPressCancelCallback 辅助按钮长按取消时的回调函数
onSecondaryLongPress GestureLongPressCallback 辅助按钮长按时的回调函数
onSecondaryLongPressStart GestureLongPressStartCallback 辅助按钮长按并开始拖动时的回调函数
onSecondaryLongPressMoveUpdate GestureLongPressMoveUpdateCallback 辅助按钮长按并移动时的回调函数
onSecondaryLongPressUp GestureLongPressUpCallback 辅助按钮长按并松开时的回调函数
onSecondaryLongPressEnd GestureLongPressEndCallback 辅助按钮长按结束拖动时的回调函数

三指触发手势

字段 属性 描述
onTertiaryTapDown GestureTapDownCallback 三指按下时的回调函数
onTertiaryTapUp GestureTapUpCallback 三指点击时的回调函数
onTertiaryTapCancel GestureTapCancelCallback 三指取消时的回调函数
onTertiaryLongPressDown GestureLongPressDownCallback 三指按下去时的回调函数
onTertiaryLongPressCancel GestureLongPressCancelCallback 三指长按取消时的回调函数
onTertiaryLongPress GestureLongPressCallback 三指长按时的回调函数
onTertiaryLongPressStart GestureLongPressStartCallback 三指长按并开始拖动时的回调函数
onTertiaryLongPressMoveUpdate GestureLongPressMoveUpdateCallback 三指长按并移动时的回调函数
onTertiaryLongPressUp GestureLongPressUpCallback 三指长按并松开时的回调函数
onTertiaryLongPressEnd GestureLongPressEndCallback 三指长按结束拖动时的回调函数

其他属性

字段 属性 描述
child Widget 子组件
behavior HitTestBehavior 在命中测试期间如何表现
excludeFromSemantics bool 是否从语义树中排除这些手势，默认false
dragStartBehavior DragStartBehavior 拖拽行为的处理方式

总结

我们对GestureDetector的 单击、双击、长按、拖动、缩放 用案例来展示出他们的用法以及应用场景，还有其他如压力设备手势、辅助按钮、三指等手势对其属性进行了描述，手势是学Flutter必须掌握的一个组件，能实现很多效果，如给容器添加手势、全局悬浮按钮、图片缩放等功能。

flutter, 手势系列教程
flutter Flutter手势
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