I am building a wallpaper app and want to implement a feature of switching views, like switching from GridView to ListView on the press of an IconButton in FLutter
would look something like this:
The only way I could think of implementing this feature is by changing the crossAxisCount value in the GridView.count() method by hooking up a counter to the crossAxisCount property and controlling it through a function on click of an IconButton, this works but I have to Hot Reload my application every time the counter is incremented or decremented,
Any Suggestions or fix to this problem is welcomed.
You can simply use ternary operators and setState() to achieve what you want.
First, declare a boolean above your widget build. Then you can use ternary operators to change it from gridview to listview.
bool isGridView=true;
#override
Widget build(BuildContext context) {
Scaffold(
body: isGridView ? GridView.builder():ListView.builder(),
);
}
In your onPressed(), you can call setState():
setState(() {
isGridView=false;
});
Related
So... I have a togglebutton widget [1|2|3|4], but if another widget is checked, I need to disable some of those buttons (eg, if I'm connecting to a Tile instead of a Frob, I need to disable 2 & 4).
you can play with Visibility to hide or not the widgets you want
I found that the best way is to have the a function that returns ToggleButtons widget based on certain input parameters. So the function returns ToggleButton widgets whatever number of toggle buttons you want. In case you want 3 buttons, you would pass in a list of 3 bools, take that list and build the ToggleButtons widget with only 3 buttons...and so on. And/Or you can have a condition that builds different ToggleButtons widget based on a certain parameter:
ToggleButtons toggleButtons(
{required StateSetter setState,
required List<bool> isSelected,
required String nameOfButtons}) {
if (nameOfButtons == "shortList") {
// return ToggleButtons widget that only has 3 Toggle Buttons
return ToggleButtons(...);
} else {
// return ToggleButtons widget that only has 2 Toggle Buttons
return ToggleButtons(...);
}});
Visibility will simply hide the content of the toggle button but still allow a user to press that button. Also if you have an outline on your toggle buttons, the inside will just be blank but.
I have a problem with a BottomNavigationBar. My app has two screens and one of them has a bottom sheet that doesn't hide on disposing of the first screen when I'm tapping on the icon of the second screen. BottomNavigationBar works normally and screens switch, but how to hide the bottom sheet of the first screen when shown the second screen I have no ideas. Could you help me solve that?
Calling:
void _showForm(int id) async {
showBottomSheet(
context: context,
elevation: 5,
builder: (context) => BottomSheetSwitch(_refreshJournals, id));
}
Closing (inside bottom sheet):
Navigator.of(context).pop();
P.S. I couldn't solve that problem, so I change showBottomSheet to showModalBottomSheet like that was in: how to set showModalBottomSheet to full height?
You can try to provide a key to the stateful widget of BottomSheet. And access that key's context just use the Navigator's pop method on tap or change of the screen. It might help you.
You can use it like
Navigator.of(key.currentContext).pop();
Else call the function of your BottomSheet using the key. Like as below
Declare GlobalKey with state in your currentWidget.
GloabalKey<BottomSheetWidgetState> closeKey = GloabalKey();
Declare one function closeBottomSheet in your bottomsheet widget state.
void closeBottomSheet(){ Navigator.of(conext).pop(); }
Call the function using the key.
closeKey.currentState.closeBottomSheet();
And done.
I've been having a problem while trying to personalize the FloatingActionButton, contained in a main page, from withing a nested route for a BottomNavigation. Right now what I have is this widget tree:
As you can see the app contains a Scaffold with a BottomNavigationBar and for each index from this BottomNavigation I have a new Navigator, from which I can navigate between nested routes. The problem is that the FAB configuration for each nested routed inside these Navigators is different, and therefore I needed to know which strategy should I use to change it's options, more specifically the icon and onPress method
Solution:
In the end I thought about a simple enough solution, don't know if it is the more adequate one, but it does work quite well.
Basically what I did was to create a provider in which I would have a list containing the FAB function for each route, being called accordingly with the one being displayed at the moment.
You can make your AppScreen a stateful widget, create an int _currentIndex = 0 in the state and after clicking on any of the BottomNavigationBarItems you can call setState changing the _currentIndex.
Then, in your build method you can do something like this:
Widget fabChild;
VoidCallback fabOnPressed;
if (_currentIndex == 0) {
fabChild = ...
fabOnPressed = ...
} else if (_currentIndex == 2) {
// (...)
}
return Scaffold(
floatingActionButton: FloatingActionButton(
child: fabChild,
onPressed: fabOnPressed,
),
);
Say my App() contains some widget and to make the code look pretty, i have created classes for child widgets. Now these child widgets contain onTap functions which are supposed to replace a widget on App(), so how do i approach this type of problem ?
Some code of what you're doing would be useful or where you're trying to "replace a widget".
If by replace you mean show a different widget in the place of another then you just use a boolean to decide which one to show. These are the steps I would follow to implement this.
Make the widget in your App() stateful and create a member variable boolean called showingOriginalWidget = true;
In your child widget classes take in a Function in the parameter called onSwapWidget.
In your onTap function in your child widget call onSwapWidget()
In your App() supply the widget that's performing this action with your Function to call back to
See below
childWidget(onSwapWidget: (){
setState((){
// toggle the original widget state
showingOriginalWidget = !showOriginalWidget;
});
});
Where you're showing your widgets add a condition so that you show either one depending on the value.
example
...
child: showingOriginalWidget ? originalWidget() : swappedOutWidget()
...
That should do the trick.
I'm trying to understand the class Navigator.
A Navigator Route seem to always return a new widget but what if I want to manage the TabBar and TabBarView so that each Tab when tapped or swipe on, will be pushed to the Navigator stack, I don't find a what to do that.
On a more general case, can I react to a route change without creating a new widget but instead taking another action like scrolling to a specific item in a listView?
I've tried recreating the entire app structure every time but doing this way I don't have the nice default animation and, also, doesn't seem a good approach to me.
You can use WillPopScope widget and its onWillPop to catch the back button pressure and handle it yourself. Find more info here https://docs.flutter.io/flutter/widgets/WillPopScope-class.html
On a more general case, can I react to a route change without creating
a new widget but instead taking another action like scrolling to a
specific item in a listView?
This looks more specific rather than general. However, you do need to set a ScrollController in your ListView and let it scroll the list for you to the desired point. A simple example function returning to top:
class MyFancyClass extends StatelessWidget{
...
ScrollController _scrollController;
...
#override
Widget build(BuildContext Context){
return ....
new ListView(
...
controller: _scrollController,
...
}
void _toTop() {
_scrollController.animateTo(
0.0,
duration: const Duration(milliseconds: 500),
curve: Curves.ease,
);
}
Check https://docs.flutter.io/flutter/widgets/ScrollController-class.html for more details and behaviors. In case you want the back button to bring you to the top:
Widget build(BuildContext context) {
return new WillPopScope(
onWillPop: _onTop,
child:
...
),
);
}
Concerning the tab behavior I suggest you to read https://docs.flutter.io/flutter/material/TabController-class.html to better understand how to implement what you have in your mind.