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La fenêtre verticale a reçu une hauteur illimitée

Je suis nouveau à flutter. Il suffit de centrer ma vue de grille:

 enter image description here

Voici le code que j'ai essayé:

  @override
  Widget build(BuildContext context) {
    return new Material(
      color: Colors.deepPurpleAccent,
      child: new Column(
       mainAxisAlignment: MainAxisAlignment.center,
          children:<Widget>[new GridView.count(crossAxisCount: _column,children: new List.generate(_row*_column, (index) {
            return new Center(
                child: new CellWidget()
            );
          }),)]
      )
    );
  }

Exception comme suit:

    I/flutter ( 9925): ══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter ( 9925): The following assertion was thrown during performResize():
I/flutter ( 9925): Vertical viewport was given unbounded height.
I/flutter ( 9925): Viewports expand in the scrolling direction to fill their container.In this case, a vertical
I/flutter ( 9925): viewport was given an unlimited amount of vertical space in which to expand. This situation
I/flutter ( 9925): typically happens when a scrollable widget is nested inside another scrollable widget.
I/flutter ( 9925): If this widget is always nested in a scrollable widget there is no need to use a viewport because
I/flutter ( 9925): there will always be enough vertical space for the children. In this case, consider using a Column
I/flutter ( 9925): instead. Otherwise, consider using the "shrinkWrap" property (or a ShrinkWrappingViewport) to size
I/flutter ( 9925): the height of the viewport to the sum of the heights of its children.
I/flutter ( 9925): 
I/flutter ( 9925): When the exception was thrown, this was the stack:
I/flutter ( 9925): #0      RenderViewport.performResize.<anonymous closure> (package:flutter/src/rendering/viewport.Dart:827:15)
I/flutter ( 9925): #1      RenderViewport.performResize (package:flutter/src/rendering/viewport.Dart:880:6)
I/flutter ( 9925): #2      RenderObject.layout (package:flutter/src/rendering/object.Dart:1555:9)

Merci d'avance!

flutterflutter-layout
4
pallav bohara

mettre la vue de grille dans le widget Flexible ou Expanded

return new Material(
    color: Colors.deepPurpleAccent,
    child: new Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children:<Widget>[
         Flexible(
          child:  GridView.count(crossAxisCount: _column,children: new List.generate(_row*_column, (index) {
          return new Center(
             child: new CellWidget(),
          );
        }),))]
    )
);
9
Manoj Kumar

N'utilisez pas Column pour l'alignement d'un enfant unique. Utilisez Align à la place. 

    new Align(
      alignment: Alignment.topCenter,
      child: new GridView(),
    )
3
Rémi Rousselet

en ajoutant ces deux lignes 

ListView.builder(
    scrollDirection: Axis.vertical,
    shrinkWrap: true,
...
2
BloodLoss

Votre colonne ne sait pas combien de hauteur cela va prendre ..__ Utilisez Flexible pour envelopper votre colonne avec ce qui lui permettra d’agrandir pour remplir l’espace disponible dans l’axe principal.

  @override
  Widget build(BuildContext context) {
    return new Material(
        color: Colors.deepPurpleAccent,
        child: Flexible(
            child: new Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children:<Widget>[new GridView.count(crossAxisCount: _column,children: new List.generate(_row*_column, (index) {
                  return new Center(
                      child: new CellWidget()
                  );
                }),)]
            )
        )
    );
  }
0
dmarquina