Skip an item in gridview without leaving a hole - flutter

Question

I'm building a gridview displaying thumbnails and do not want to show the items at index 0. I have a different widget where I show thumbnails using a listview with the Visibility widget. That works!
Like so:
ListView.separated(
separatorBuilder: (BuildContext context, int index) =>
SizedBox(
width: mainElementSize * 0.02,
),
scrollDirection: Axis.horizontal,
controller: paneController,
physics: const BouncingScrollPhysics(
parent: AlwaysScrollableScrollPhysics()),
addAutomaticKeepAlives: true,
reverse: true,
itemCount: mainElementList.mainElementList.length,
//
itemBuilder: (BuildContext context, int index) {
return Visibility(
visible: index > 0,
child: UnconstrainedBox(
child: HistoryThumb(
index: index,
),
),
);
}),
The gridview does work with Visibility, but different. Instead of just skipping the object, it leaves a whole in the grid. Code:
GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4,
mainAxisSpacing: gridheight * 0.015,
crossAxisSpacing: gridWidth * 0.015,
),
padding: EdgeInsets.symmetric(
horizontal: 0,
),
physics: const BouncingScrollPhysics(
parent: AlwaysScrollableScrollPhysics()),
itemCount:
Provider.of<MainElementList>(context).mainElementList.length,
//
itemBuilder: (context, index) => Visibility(
visible: index > 0,
child: UnconstrainedBox(
child: HistoryThumb(
index: index,
),
),
)),
Screenshot:
Any way to not have it do that? I found a similar topic here: How to skip build in item builder gridview.builder Flutter Firebase Stream Builder
But I do not want to build a seperate list and duplicate all my objects just to display the thumbnails. Isn't there something more elegant for skipping certain items?

Answer 1

Instead of using Visibility widget you can apply ternary operator and pass SizedBox at index 0:-
index == 0 ? SizedBox() : UnconstrainedBox(
child: HistoryThumb(
index: index,
),
),
Can you try like this:-
GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4,
mainAxisSpacing: gridheight * 0.015,
crossAxisSpacing: gridWidth * 0.015,
),
padding: EdgeInsets.symmetric(
horizontal: 0,
),
physics: const BouncingScrollPhysics(
parent: AlwaysScrollableScrollPhysics()),
itemCount:
Provider.of<MainElementList>(context).mainElementList.length - 1,
//
itemBuilder: (context, index) => Visibility(
visible: index > 0,
child: UnconstrainedBox(
child: HistoryThumb(
index: index+1,
),
),
)),
subtract 1 from itemCount and add 1 in Index history Thumb. I think we can't skip an certain item in the build but we can achieve what you want from this!!

Answer 2

You can achieve your required behaviour by moving your particular item to the end of the list; then you can simply hide that last item in the grid view.
This way, you wont see any whitespace in middle of the grid view.
For example:
List<String> list = [
"mustafa",
"hawari",
"ravi",
"shyam"
];
int indexOfItem = list.indexOf("hawari");
String itemTobeAddedAtLast = list[indexOfItem];
list.removeAt(indexOfItem);
list.insert(list.length, itemTobeAddedAtLast);
print(list);
// this returns
// [mustafa, ravi, shyam, hawari]

Answer 3

You can use a condition on the builder
GridView.builder(
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 4,
mainAxisSpacing: gridheight * 0.015,
crossAxisSpacing: gridWidth * 0.015,
),
padding: EdgeInsets.symmetric(
horizontal: 0,
),
physics: const BouncingScrollPhysics(
parent: AlwaysScrollableScrollPhysics()),
itemCount:
Provider.of<MainElementList>(context).mainElementList.length,
//
itemBuilder: (context, index) => {
if(index == 0) {
return --- What you want to return at index 0 --;
} else {
return --- the actual builder that you are using normally ---;
}
}