Flutter 创建可调整大小的视图,该视图在颤振中从角落和侧面挤压或拖动时可调整大小

Flutter 创建可调整大小的视图,该视图在颤振中从角落和侧面挤压或拖动时可调整大小,flutter,resize,flutter-layout,image-resizing,window-resize,Flutter,Resize,Flutter Layout,Image Resizing,Window Resize,我目前正在开发一个屏幕视图,其功能包括可拖动和可调整大小的视图,包括角和边,如上图所示。我现在的问题是,我想通过角落里的触摸手势来调整视图的大小。因此,我想到了一个在选择时添加到视图中的点,可以通过拖动该点来调整选定视图的大小。答案更新 可调整大小的小部件演示: 修改的可行示例: import 'package:flutter/material.dart'; class ResizeWidget extends StatefulWidget { @override _R

我目前正在开发一个屏幕视图,其功能包括可拖动和可调整大小的视图,包括角和边,如上图所示。我现在的问题是,我想通过角落里的触摸手势来调整视图的大小。因此,我想到了一个在选择时添加到视图中的点,可以通过拖动该点来调整选定视图的大小。答案更新

可调整大小的小部件演示:

修改的可行示例:

  import 'package:flutter/material.dart';

  class ResizeWidget extends StatefulWidget {
    @override
    _ResizeWidgetState createState() => _ResizeWidgetState();
  }

  class _ResizeWidgetState extends State<ResizeWidget> {
    @override
    Widget build(BuildContext context) {
      return MaterialApp(
        home: Scaffold(
          backgroundColor: Colors.black,
          body: Container(
            // padding: EdgeInsets.only(top: 50),
            child: ResizebleWidget(
              child: Container(
                padding: EdgeInsets.all(10),
                child: Text(
                  'Waao!! you can really dance.',
                  style: TextStyle(
                      color: Colors.white,
                      fontStyle: FontStyle.italic,
                      fontSize: 18),
                ),
              ),
            ),
          ),
        ),
      );
    }
  }

  class ResizebleWidget extends StatefulWidget {
    ResizebleWidget({this.child});

    final Widget child;
    @override
    _ResizebleWidgetState createState() => _ResizebleWidgetState();
  }

  const ballDiameter = 10.0;

  class _ResizebleWidgetState extends State<ResizebleWidget> {
    double height = 100;
    double width = 200;
    bool isCorner = false;

    double top = 0;
    double left = 0;

    @override
    Widget build(BuildContext context) {
      return Stack(
        children: <Widget>[
          Positioned(
            top: top,
            left: left,
            child: Container(
              height: height,
              width: width,

              decoration: BoxDecoration(
                color: Colors.blueGrey,
                border: Border.all(
                  width: 2,
                  color: Colors.white70,
                ),
                borderRadius: BorderRadius.circular(0.0),
              ),

              // need tp check if draggable is done from corner or sides
              child: isCorner
                  ? FittedBox(
                      child: widget.child,
                    )
                  : Center(
                      child: widget.child,
                    ),
            ),
          ),
          // top left
          Positioned(
            top: top - ballDiameter / 2,
            left: left - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var mid = (dx + dy) / 2;
                var newHeight = height - 2 * mid;
                var newWidth = width - 2 * mid;

                setState(() {
                  isCorner = true;
                  height = newHeight > 0 ? newHeight : 0;
                  width = newWidth > 0 ? newWidth : 0;
                  top = top + mid;
                  left = left + mid;
                });
              },
              handlerWidget: HandlerWidget.VERTICAL,
            ),
          ),
          // top middle
          Positioned(
            top: top - ballDiameter / 2,
            left: left + width / 2 - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var newHeight = height - dy;

                setState(() {
                  isCorner = false;

                  height = newHeight > 0 ? newHeight : 0;
                  top = top + dy;
                });
              },
              handlerWidget: HandlerWidget.HORIZONTAL,
            ),
          ),
          // top right
          Positioned(
            top: top - ballDiameter / 2,
            left: left + width - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var mid = (dx + (dy * -1)) / 2;

                var newHeight = height + 2 * mid;
                var newWidth = width + 2 * mid;

                setState(() {
                  isCorner = true;
                  height = newHeight > 0 ? newHeight : 0;
                  width = newWidth > 0 ? newWidth : 0;
                  top = top - mid;
                  left = left - mid;
                });
              },
              handlerWidget: HandlerWidget.VERTICAL,
            ),
          ),
          // center right
          Positioned(
            top: top + height / 2 - ballDiameter / 2,
            left: left + width - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var newWidth = width + dx;

                setState(() {
                  isCorner = false;

                  width = newWidth > 0 ? newWidth : 0;
                });
              },
              handlerWidget: HandlerWidget.HORIZONTAL,
            ),
          ),
          // bottom right
          Positioned(
            top: top + height - ballDiameter / 2,
            left: left + width - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var mid = (dx + dy) / 2;

                var newHeight = height + 2 * mid;
                var newWidth = width + 2 * mid;

                setState(() {
                  isCorner = true;

                  height = newHeight > 0 ? newHeight : 0;
                  width = newWidth > 0 ? newWidth : 0;
                  top = top - mid;
                  left = left - mid;
                });
              },
              handlerWidget: HandlerWidget.VERTICAL,
            ),
          ),
          // bottom center
          Positioned(
            top: top + height - ballDiameter / 2,
            left: left + width / 2 - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var newHeight = height + dy;

                setState(() {
                  isCorner = false;

                  height = newHeight > 0 ? newHeight : 0;
                });
              },
              handlerWidget: HandlerWidget.HORIZONTAL,
            ),
          ),
          // bottom left
          Positioned(
            top: top + height - ballDiameter / 2,
            left: left - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var mid = ((dx * -1) + dy) / 2;

                var newHeight = height + 2 * mid;
                var newWidth = width + 2 * mid;

                setState(() {
                  isCorner = true;

                  height = newHeight > 0 ? newHeight : 0;
                  width = newWidth > 0 ? newWidth : 0;
                  top = top - mid;
                  left = left - mid;
                });
              },
              handlerWidget: HandlerWidget.VERTICAL,
            ),
          ),
          //left center
          Positioned(
            top: top + height / 2 - ballDiameter / 2,
            left: left - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                var newWidth = width - dx;

                setState(() {
                  isCorner = false;

                  width = newWidth > 0 ? newWidth : 0;
                  left = left + dx;
                });
              },
              handlerWidget: HandlerWidget.HORIZONTAL,
            ),
          ),
          // center center
          Positioned(
            top: top + height / 2 - ballDiameter / 2,
            left: left + width / 2 - ballDiameter / 2,
            child: ManipulatingBall(
              onDrag: (dx, dy) {
                setState(() {
                  isCorner = false;

                  top = top + dy;
                  left = left + dx;
                });
              },
              handlerWidget: HandlerWidget.VERTICAL,
            ),
          ),
        ],
      );
    }
  }

  class ManipulatingBall extends StatefulWidget {
    ManipulatingBall({Key key, this.onDrag, this.handlerWidget});

    final Function onDrag;
    final HandlerWidget handlerWidget;

    @override
    _ManipulatingBallState createState() => _ManipulatingBallState();
  }

  enum HandlerWidget { HORIZONTAL, VERTICAL }

  class _ManipulatingBallState extends State<ManipulatingBall> {
    double initX;
    double initY;

    _handleDrag(details) {
      setState(() {
        initX = details.globalPosition.dx;
        initY = details.globalPosition.dy;
      });
    }

    _handleUpdate(details) {
      var dx = details.globalPosition.dx - initX;
      var dy = details.globalPosition.dy - initY;
      initX = details.globalPosition.dx;
      initY = details.globalPosition.dy;
      widget.onDrag(dx, dy);
    }

    @override
    Widget build(BuildContext context) {
      return GestureDetector(
        onPanStart: _handleDrag,
        onPanUpdate: _handleUpdate,
        child: Container(
          width: ballDiameter,
          height: ballDiameter,
          decoration: BoxDecoration(
            color: Colors.white,
            shape: this.widget.handlerWidget == HandlerWidget.VERTICAL
                ? BoxShape.circle
                : BoxShape.rectangle,
          ),
        ),
      );
    }
  }
导入“包装:颤振/材料.省道”;
类ResizeWidget扩展StatefulWidget{
@凌驾
_ResizeWidgetState createState();
}
类_ResizeWidgetState扩展状态{
@凌驾
小部件构建(构建上下文){
返回材料PP(
家:脚手架(
背景颜色:Colors.black,
主体:容器(
//填充:仅限边缘设置(顶部:50),
孩子:ResizebleWidget(
子:容器(
填充:边缘设置。全部(10),
子:文本(
“哇!!你真会跳舞。”,
样式:TextStyle(
颜色:颜色,白色,
fontStyle:fontStyle.italic,
尺寸:18),,
),
),
),
),
),
);
}
}
类ResizebleWidget扩展StatefulWidget{
ResizebleWidget({this.child});
最后一个孩子;
@凌驾
_ResizebleWidgetState createState()=>\u ResizebleWidgetState();
}
恒球直径=10.0;
类_ResizebleWidgetState扩展状态{
双倍高度=100;
双倍宽度=200;
bool-isCorner=false;
双层顶=0;
左双=0;
@凌驾
小部件构建(构建上下文){
返回堆栈(
儿童:[
定位(
顶:顶,,
左:左,,
子:容器(
高度:高度,,
宽度:宽度,
装饰:盒子装饰(
颜色:颜色。蓝灰色,
边界:边界(
宽度:2,
颜色:颜色。白色70,
),
边界半径:边界半径。圆形(0.0),
),
//需要tp检查是否从角落或侧面进行牵引
孩子:伊斯科纳
?装配箱(
child:widget.child,
)
:中心(
child:widget.child,
),
),
),
//左上角
定位(
顶部:顶部-球径/2,
左:左-球径/2,
孩子:操纵球(
onDrag:(dx,dy){
var-mid=(dx+dy)/2;
var newHeight=高度-2*mid;
var newWidth=宽度-2*mid;
设置状态(){
isCorner=true;
高度=新高度>0?新高度:0;
宽度=新宽度>0?新宽度:0;
顶部=顶部+中间;
左=左+中;
});
},
handlerWidget:handlerWidget.VERTICAL,
),
),
//中上部
定位(
顶部:顶部-球径/2,
左:左+宽度/2-球径/2,
孩子:操纵球(
onDrag:(dx,dy){
var newHeight=高度-dy;
设置状态(){
isCorner=假;
高度=新高度>0?新高度:0;
top=top+dy;
});
},
handlerWidget:handlerWidget.HORIZONTAL,
),
),
//右上角
定位(
顶部:顶部-球径/2,
左:左+宽-球径/2,
孩子:操纵球(
onDrag:(dx,dy){
var-mid=(dx+(dy*-1))/2;
var newHeight=高度+2*mid;
var newWidth=width+2*mid;
设置状态(){
isCorner=true;
高度=新高度>0?新高度:0;
宽度=新宽度>0?新宽度:0;
顶部=顶部-中部;
左=左-中;
});
},
handlerWidget:handlerWidget.VERTICAL,
),
),
//中右翼
定位(
顶部:顶部+高度/2-球径/2,
左:左+宽-球径/2,
孩子:操纵球(
onDrag:(dx,dy){
var newWidth=width+dx;
设置状态(){
isCorner=假;
宽度=新宽度>0?新宽度:0;
});
},
handlerWidget:handlerWidget.HORIZONTAL,
),
),
//右下角
定位(
顶部:顶部+高度-球径/2,
左:左+宽-球径/2,
孩子:操纵球(
onDrag:(dx,dy){
var-mid=(dx+dy)/2;
var newHeight=高度+2*mid;
var newWidth=width+2*mid;
设置状态(){
isCorner=true;
高度=新高度>0?新高度:0;
宽度=新宽度>0?新宽度:0;
顶部=顶部-中部;
左=左-中;
});
},
handlerWidget:handlerWidget.VERTICAL,
),
),
//底部中心
定位(
顶部:顶部+高度-球径/2
    import 'package:flutter/material.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Text Overflow Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: Scaffold(
        body: Demo(),
      ),
    );
  }
}

class Demo extends StatefulWidget {
  @override
  _DemoState createState() => _DemoState();
}

class _DemoState extends State<Demo> {
  @override
  Widget build(BuildContext context) {
    return Container(
      padding: EdgeInsets.all(60),
      child: ResizebleWidget(
        child: Text(
'''I've just did simple prototype to show main idea.
  1. Draw size handlers with container;
  2. Use GestureDetector to get new variables of sizes
  3. Refresh the main container size.''',
        ),
      ),
    );
  }
}

class ResizebleWidget extends StatefulWidget {
  ResizebleWidget({this.child});

  final Widget child;
  @override
  _ResizebleWidgetState createState() => _ResizebleWidgetState();
}

const ballDiameter = 30.0;

class _ResizebleWidgetState extends State<ResizebleWidget> {
  double height = 400;
  double width = 200;

  double top = 0;
  double left = 0;

  void onDrag(double dx, double dy) {
    var newHeight = height + dy;
    var newWidth = width + dx;

    setState(() {
      height = newHeight > 0 ? newHeight : 0;
      width = newWidth > 0 ? newWidth : 0;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Positioned(
          top: top,
          left: left,
          child: Container(
            height: height,
            width: width,
            color: Colors.red[100],
            child: widget.child,
          ),
        ),
        // top left
        Positioned(
          top: top - ballDiameter / 2,
          left: left - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var mid = (dx + dy) / 2;
              var newHeight = height - 2 * mid;
              var newWidth = width - 2 * mid;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
                width = newWidth > 0 ? newWidth : 0;
                top = top + mid;
                left = left + mid;
              });
            },
          ),
        ),
        // top middle
        Positioned(
          top: top - ballDiameter / 2,
          left: left + width / 2 - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var newHeight = height - dy;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
                top = top + dy;
              });
            },
          ),
        ),
        // top right
        Positioned(
          top: top - ballDiameter / 2,
          left: left + width - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var mid = (dx + (dy * -1)) / 2;

              var newHeight = height + 2 * mid;
              var newWidth = width + 2 * mid;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
                width = newWidth > 0 ? newWidth : 0;
                top = top - mid;
                left = left - mid;
              });
            },
          ),
        ),
        // center right
        Positioned(
          top: top + height / 2 - ballDiameter / 2,
          left: left + width - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var newWidth = width + dx;

              setState(() {
                width = newWidth > 0 ? newWidth : 0;
              });
            },
          ),
        ),
        // bottom right
        Positioned(
          top: top + height - ballDiameter / 2,
          left: left + width - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var mid = (dx + dy) / 2;

              var newHeight = height + 2 * mid;
              var newWidth = width + 2 * mid;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
                width = newWidth > 0 ? newWidth : 0;
                top = top - mid;
                left = left - mid;
              });
            },
          ),
        ),
        // bottom center
        Positioned(
          top: top + height - ballDiameter / 2,
          left: left + width / 2 - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var newHeight = height + dy;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
              });
            },
          ),
        ),
        // bottom left
        Positioned(
          top: top + height - ballDiameter / 2,
          left: left - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var mid = ((dx * -1) + dy) / 2;

              var newHeight = height + 2 * mid;
              var newWidth = width + 2 * mid;

              setState(() {
                height = newHeight > 0 ? newHeight : 0;
                width = newWidth > 0 ? newWidth : 0;
                top = top - mid;
                left = left - mid;
              });
            },
          ),
        ),
        //left center
        Positioned(
          top: top + height / 2 - ballDiameter / 2,
          left: left - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              var newWidth = width - dx;

              setState(() {
                width = newWidth > 0 ? newWidth : 0;
                left = left + dx;
              });
            },
          ),
        ),
        // center center
        Positioned(
          top: top + height / 2 - ballDiameter / 2,
          left: left + width / 2 - ballDiameter / 2,
          child: ManipulatingBall(
            onDrag: (dx, dy) {
              setState(() {
                top = top + dy;
                left = left + dx;
              });
            },
          ),
        ),
      ],
    );
  }
}

class ManipulatingBall extends StatefulWidget {
  ManipulatingBall({Key key, this.onDrag});

  final Function onDrag;

  @override
  _ManipulatingBallState createState() => _ManipulatingBallState();
}

class _ManipulatingBallState extends State<ManipulatingBall> {
  double initX;
  double initY;

  _handleDrag(details) {
    setState(() {
      initX = details.globalPosition.dx;
      initY = details.globalPosition.dy;
    });
  }

  _handleUpdate(details) {
    var dx = details.globalPosition.dx - initX;
    var dy = details.globalPosition.dy - initY;
    initX = details.globalPosition.dx;
    initY = details.globalPosition.dy;
    widget.onDrag(dx, dy);
  }

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onPanStart: _handleDrag,
      onPanUpdate: _handleUpdate,
      child: Container(
        width: ballDiameter,
        height: ballDiameter,
        decoration: BoxDecoration(
          color: Colors.blue.withOpacity(0.5),
          shape: BoxShape.circle,
        ),
      ),
    );
  }
}