[
Can I get a logic/code for highlighting just the selected value from this list view which is inside a container and it is scrollable also that the axis is set to Horizontal.
I have used a list view builder to align the same and also generated the list of numbers.
Please check the sample image of the widget attached.
Blockquote
]1
It's hard to tell you exactly how to do it without any code examples, and I'm also not sure what you mean by selected. Is that already decided before building the list, or is it decided when the user selects from the list?
If it is already decided, you can pass a value from the parent component that tells the list to highlight a certain value.
If a user is selecting the value to highlight, you can use a combination of setState and onTap with GestureDetector. Here's a potential rough skeleton:
int selectedIndex?;
ListView.builder(
itemCount: litems.length,
itemBuilder: (BuildContext ctx, int index) {
return GestureDetector(
onTap: () {
setState(() {
selectedIndex = index;
});
},
child: Container(
backgroundColor: selectedIndex == index ? highlightedColor : undefined;
child: {{child content}}
),
);
}
)
Related
Basically, I have two nested ListView. Builders inside a third ListView builder. The two nested listview builders build two rows of custom buttons; the contents of the second row of buttons depend on the selected button in the two rows. The first row works entirely as intended, but the second row causes an issue.
Whenever a button from the second row is pressed, it affects the state of all the other buttons (and the data those lists are built on), as if calling the same function on all elements on the list. The strangest thing, though, is that it only seems to call PART of that function:
void toggleSubcategoryPanelButton(int panelNum, int subCategoryIndex) {
App()
.panelNames[panelNum]
.panelSettings
.categories[
App().panelNames[panelNum].panelSettings.activeCategoryIndex]
.activeSubcategory =
App()
.panelNames[panelNum]
.panelSettings
.categories[
App().panelNames[panelNum].panelSettings.activeCategoryIndex]
.subcategories[subCategoryIndex];
rerollName(panelNum);
saveSettingstoPrefs();
notifyListeners();
}
App() is a singleton that holds pretty much all the data for this lightweight app. The purpose of this function is to set a new index for activeSubcategory for only the 'panel' from which the function was called (given via panelNum). Instead, the function sets activeSubcategory of to the same index for all of the elements of panelNames in their categories at the current activeCategoryIndex.
Then, rerollName() seems to only be called for the panelNum provided.
The problem can be seen here. The top row's selection is set correctly.
[![Different function][1]][1]
You can (hopefully) see in this gif that the application correctly identifies the panelNum as it is displayed in the terminal (index of 1).
The ListView in question:
SizedBox(
height: 30.0,
child: ListView.builder(
shrinkWrap: true,
scrollDirection: Axis.horizontal,
physics:
const NeverScrollableScrollPhysics(),
itemCount: widget
.panelSettings
.categories[widget.panelSettings
.activeCategoryIndex]
.subcategories
.length,
itemBuilder: ((context, index) {
return Consumer(
builder: (context, value, child) {
return PanelButtonToggleable(
icon: widget
.panelSettings
.categories[widget
.panelSettings
.activeCategoryIndex]
.subcategories[index]
.icon,
tooltip: widget
.panelSettings
.categories[widget
.panelSettings
.activeCategoryIndex]
.subcategories[index]
.getName(),
buttonBehavior: () =>
_onToggleSubcategoryClick(
index),
toggled: widget
.panelSettings
.categories[widget
.panelSettings
.activeCategoryIndex]
.subcategories[index]
.getName() ==
widget
.panelSettings
.categories[widget
.panelSettings
.activeCategoryIndex]
.activeSubcategory
.getName(),
);
},
);
}),
),
),
https://github.com/trevclaridge/Name-Generator-Extension
[1]: https://i.stack.imgur.com/Z2tg8.gif
I discovered that my issue actually had nothing to do with the ListViews at all. Rather the objects pointed to by widget.panelSettings.categories were actually the same instance of a List. Thus, assigning the entry for activeSubcategory was assigning it for all the objects that pointed to the categories list.
Confirm this in your own projects using Dart's identical method. Link here.
To solve this, I created a new class Categories with an empty constructor to hold the list, so every initialization of the list was from a new object.
I can a little bit confuse on how should I implement the delete function.
By tapping the bottom button will add a Custom Card widget to the widget list that shows up on the top
This is the function for that
onTap: () {
setState(() {
_variationCards.add(VariationCard(
key: UniqueKey(),
variation: Variation.empty,
index: _variationCards.length,
onRemoveCard: (index) {
setState(() {
_variationCards.removeAt(index);
});
},
));
});
},
The problems of the current setup are
Lets say I delete the second Card, now that the third Card became the second Card, but the index I passed to the third Card widget is still 2 when it is actually 1 now.
I need the index in the Card widget because I need to have additional widget for the first card, but now If I delete the first card, the second card index value will not be updated.
I think I am heading to the wrong path to implement this. Any help would be much appreciated.
Thank you in advanced.
Maybe you could use "removeWhere" method. Something like:
onTap: () {
_variationCards.add(VariationCard(
key: UniqueKey(),
variation: Variation.empty,
index: _variationCards.length,
onRemoveCard: (index) {
setState(() {
_variationCards.removeWhere((card) => card.SomeId == _someId);
});
},
));
},
The leading information should rather be a list of your defined class / model instead of widgets. You want widgets to update (rebuild) according to the underlying information / state in your app. Currently your widgets are created and added to your list on gestures (like onTap) and won't update themselves - that's why the indices are "wrong" in your case.
I would suggest a combination of a class / model representing a card while making use of the ListView.builder variant:
Class representing your card:
/// Currently only holds the Variation enum value, add whatever
/// defines your cards later on
class VariationModel {
Variation variation;
VariationModel(this.variation)
}
Your widget which displays the cards in a list:
/// Need to be filled with instances of this class, maybe passed
/// down directly to this widget or grabbed from something like
/// GetIt or Provider etc.
List<VariationModel> _variations;
#override
Widget build(BuildContext context) {
...
ListView.builder(
/// +1 to include the button to add a new card at the end
itemCount: _variations.length + 1,
itemBuilder: (context, index) => index < _variations.length ?
VariationCard(
key: UniqueKey(),
variation: _variations[index].variation,
index: index,
onRemoveCard: () {
setState(() {
_variations.removeAt(index);
});
},
/// Add your widget (card) here which is used to add a new
/// new card (in this case a new VariationModel instance)
) : Card(
...
onTap: () {
setState(() {
_variations.add(VariationModel(Variation.empty));
});
},
),
),
}
Since this approach is using the ListView.builder widget which builds the children (your card widgets) dynamically and the index is properly being updated since the widgets are going to rebuild now, it should work as you intend to.
I made a little app using GetX with your requirements (I think so at least), it maybe be of help to you:
The code is here.
Dears,
it could be just a mistake of mine but ...it's driving me crazy ;)
I have a ListView inside my statefulwidget:
Expanded(
child: ListView.builder(
padding: EdgeInsets.all(10.0),
itemCount: searchableFoodList.length,
itemBuilder: (BuildContext context, int index) {
print('4 - SFL - ${searchableFoodList[index].id} - ${searchableFoodList[index].name}');
return
FoodItem(
id: searchableFoodList[index].id,
baseUnit: searchableFoodList[index].baseUnit,
baseUnitS: searchableFoodList[index].baseUnitS,
baseVal: searchableFoodList[index].baseVal,
baseValCal: searchableFoodList[index].baseValCal,
mediumVal: searchableFoodList[index].mediumVal,
mediumValCal: searchableFoodList[index].mediumValCal,
name: searchableFoodList[index].name,
note: searchableFoodList[index].note
);
},
),
searchableFoodList is modified (according user selection) inside a setState().
Let say that we have a 3 FoodItem(s), so my searchableFoodList is [FoodItem-1, FoodItem-2, FoodItem-3] and everything is working fine.
If I select a single item in my list, let say "FoodItem-2", the searchableFoodList becomes [FoodItem-2] and the list displayed contains (correctly) just one item but it is FoodItem-1.
Note that I inserted a print ...and it prints "FoodItem-2"
I guess that the problem is that it is considered the "original list" and it is changed only the length of the list but the list itself is not re-generated.
I have no more ideas ...any suggestions to solve this problem?
P.S.
FoodItem is stateful widget as well (an animated one). I did something similar with using stateless widget and I didn't have any problem
I am have an animated list in my flutter project.
For every element in that list I have a grid of buttons that are placed dynamically from a Firestore stream. Sometimes that will come back with 10 items in the grid but other times that will comeback with 0 items.
When a button on the grid in a list element is pushed it will search firestore and create a new grid of buttons in the next list element below.
The problem that I have is when it comes back with 0 grid buttons I don't want it to create a new list element (an empty list element with no grid buttons). I tried returning a container with 0 size as a work around but animated list still gives it some height so you can see there is a problem. I also understand that this would be bad practice as you have non visible empty list elements in the list.
I start with a list of foods as strings:
List foodListGrids = ['breads','drinks']
I then have an animated list:
AnimatedList(
shrinkWrap: true,
physics: NeverScrollableScrollPhysics(),
key: _FoodandDrinkKey,
initialItemCount: foodListGrids.length,
itemBuilder: (context, index, animation) {
return SizeTransition(
sizeFactor: animation,
child: buildButtonGridItemsMenu(index),
);
},
),
I set the AnimatedList size to the length of the foods list.
I set the child of the Animated List to a class that searches firebase and returns a card with the grid of buttons on it like this:
StreamBuilder(
stream: Firestore.instance
.collection(widget.categoryType)
.where(widget.relationship, isEqualTo: widget.searchString)
.snapshots(),
builder: (BuildContext context, AsyncSnapshot snapshot) {
if (!snapshot.hasData) {
return Container(width: 0, height: 0,);
} else if (snapshot.hasData) {
List<Widget> widgetList = [];
List<DocumentSnapshot> documentList = snapshot.data.documents;
if (documentList.length > 0) {
for (int i = 0; i < documentList.length; i++) {
widgetList.add(ButtonTheme(
minWidth: 16,
height: 30,
child: GridButton(snapshot, i, widget.listIndex),
));
}
return Container(
width: double.infinity,
child: Wrap(
children: widgetList,
alignment: WrapAlignment.center,
));
} else{
return Text('NO DATA BECAUSE NUMBER OF GRID ITEMS IS 0');
}
} else {
return Text('NO DATA BECAUSE GRID ITEMS CALL IS NULL');
}
},
),
then in the on pressed method for each grid button I add a new list element like this:
void _insertCategoryGridItem(String id, int index) {
if (!foodListGrids.contains(id)) {
foodListGrids.add(id);
_FoodandDrinkKey.currentState.insertItem(index + 1);
}
}
The problem is a chicken or the egg problem I will try to show below:
List item is generated from the index 0 in the food list and all stream data is if from food list index 0 firebase results.
On pressed for a grid item in the first list row is pressed to add a new list row with a new set of grid items. This will then update the food list array and the call for the list to add new row of grid buttons. The issue is because this is in the onpressed for the first rows grid there is no knowledge of what will be returned for the next row so there is no way of knowing if it will return a grid of size 0 in the next list row in the current way it is setup.
I have tried returning null, container of 0 width and height but have had no luck. I am not sure what I can do to fix it.
Thanks for your help
I'm not sure if I get you right but seems that I faced the same problem with AnimatedList and stream of data from the Firestore. The problem is in initialItemCount: property of the AnimatedList.
In my case I wanted to change AnimtedList in two ways:
I wanted to manually add an item and to show it with animation.
I want that if the list is changed due to a new portion of data from the stream - I want the list to be updated without animation of inserting and without errors (out of range).
To solve this I did a dirty hack: when there is an update from the stream I reinit the key of the list, in your case it's _FoodandDrinkKey. So BEFORE you build the AnmatedList just reinit your key _listKeyUserNotes = GlobalKey(); that's how the List will "forget" about it's initialItemCount and will render a new data without any out-of-range errors.
When you want to add a new item manually with animation - use insert().
key: _FoodandDrinkKey,
initialItemCount: foodListGrids.length,
Hope this makes sense.
I have two listview screen on my app. User can navigate between them using BottomNavigationBar control.
On listview.builder function, I return something like this
return ListView.builder(
itemCount: snapshot.data.length,
itemBuilder: (context, index) {
return ListTile(
title: Text('...'),
subtitle: Text('...'),
onTap: () {
...
}
)
});
I found onTap handler seems mixed between those 2 listviews.
When I open first list view, flutter serve the correct onTap,but when I switch to second listview, flutter still serving the first listview onTap.
Seems the onTap is cached by flutter (title & subtitle seems okay). Any idea?
Sample source code: https://github.com/jazarja/flutter_app
The problem is in your compararing transition values. Because you are first reversing the animation transition of current view.
In your botton_nav.dart, change this:
return aValue.compareTo(bValue);
to this:
return bValue.compareTo(aValue);
Yes the problem is that the animations haven't completed by the time the comparison is being done so the widget at the top of the stack is always 1 tab selection behind. You actually don't need to build a stack at all, just replace Center(child: _buildTransitionStack()) here with _navigationViews[_currentIndex].transition(_type, context) and it should work.