I would like the body of my scaffold to change size when the bottom sheet is expanded similar to how the Google Maps app responds when it's bottomsheet is pulled up (the map shrinks to about half the height of the screen).
body: _isSheetExpanded ? _buildBodySize1() : _buildBodySize2()
In your isExpanded() [or some similar method] for the bottom sheet in expanded state:
setState(){
_isSheetExpanded = true;
}
In the isCollapsed() method:
setState(){
_isSheetExpanded = false;
}
Related
I want to implement a dashboard that has 2 widgets: a menu panel and a panel where information is displayed.
I also want that if you click the top left button, the panel would collapse and the information panel would be 100% of the screen's width.
How can I resize a widget on button click?
Wrap you sidebar with an AnimatedContainer. Then, set the width property on that container to width: isExpanded ? 200 : 0, where isExpanded is a bool that specifies whether or not the sidebar should be expanded, and 200 is the width that you want the sidebar to be when expanded.
To toggle the sidebar to be expanded or not, simply call this:
setState(() { isExpanded = !isExpanded; });
I have ListView.builder with horizontal scrolling (a custom top navigation bar). As I scroll to the right and left, the 'selectedIndex' is changing, but the UI inside this widget isn't showing this change in position. I'd like to 'Jump To' the selected index upon swiping.
Here's how my ListView is currently updating its index:
void onChanged(int index) {
pageController.jumpToPage(index);
setState(() {
this.selectedIndex = index;
});
}
How can I accomplish this? Any guidance would mean a lot.
Thanks, A.V.
You can calculate selected item offset by item width and height and then use
_gridViewController.jumpTo(calculatedOffset);
I am copying my question from here as it is the same question but for flutter
How do you know if your ListView has enough number of items so that it
can scroll?
For instance, If I have 5 items on my ListView all of it will be
displayed on a single screen. But if I have 7 or more, my ListView
begins to scroll. How do I know if my List can scroll
programmatically?
Thank you
I am adding the code I tried, in which I test if the controller is attached, to be able to get the position. I couldn't get the position because the controller is not attached until you actually scroll
Widget build(BuildContext context) {
_afterBuild();
ListView.builder(
controller: controller,
// ...
)
}
Future<void> _afterBuild () async {
if (controller.hasClients) {
print("controller.hasClients");
// here I would be able to get the position
} else {
print("controller.has no Clients");
}
}
Edit: For anyone coming here: The controller was not being attached because I had a condition under which to build the ListView
So I combined the comments with the accepted answer (which is actually the answer for the question) and solved it like this (with some pseudocode):
Widget build(BuildContext context) {
if (not loaded results from api) {
return Something()
} else {
Future(_afterBuild);
return ListView.builder(
controller: controller,
// ...
)
}
}
Future<void> _afterBuild () async {
if (controller.hasClients) {
if(controller.position.maxScrollExtent > 0){
print('it can be scrolled');
}
} else {
print("controller has no client");
}
}
Actually it's quite easy to do in Flutter. You should have a ScrollController attached to your ListView and then you can check the maxScrollExtent. If it's bigger than zero then your ListView can be scrolled. It also works for any scrolling view which uses ScrollController.
#override
void initState() {
super.initState();
WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
if(controller.position.maxScrollExtent > 0){
print('it can be scrolled');
}
});
}
Step 1 - Assign a GlobalKey
GlobalKey myKey= GlobalKey();
Step 2 - Assign key to ListView
ListView(
key: myKey,
...
)
Step 3 - In your function that checks if the ListView is scrollable, use the following code-
final RenderBox renderBoxRed = myKey.currentContext.findRenderObject();
final height = renderBoxRed.size.height; // find height of ListView
if (height > MediaQuery.of(context).size.height) { // checking if listview height is greater than page height
print("ListView is SCROLLABLE !!!");
}
I like where most of the rest of the answers are going, but they aren't getting the data the most succinctly or reliably. What you want to do is, yes, attach a ScrollController, and then look for the .position on that (which may throw if there's no single attached position). Then, ask the position for extentAfter and extentBefore, and you'll discover how much virtual view (in pixels) there is after and before the current visible portion. If those are 0, no scrolling. No need to figure out the size of the screen or the containers. Flutter already knows all that when it laid everything out!
Ive create a popup menu widget which takes two arguments :a button widget, and a menu widget . When the button is pressed the menu widget is passed to an OverlayEntry as the child which is then added to the Overlay.of(context)
I'd like the resulting display to be as such:
O (Button)
____|____
| MENU |
|_______|
I can place the menu widget inside a Positioned Widget to move it freely around the Overlay, but I dont know how to get the correct coordinates. I can get the center of the Button by finding it's Renderbox, but I cant know the size, and therefore the correct position, of the Menu until after it's draw (as it can be any widget).
Is there some soft of layout option to tell a Widget of any size to vertically or horzontally align itself with a given coordinate?
To get the size of a widget:
First give your Widget a key:
key: _key,
Then you can get the size(and position) like this:
_getSize() {
final RenderBox renderBox = _key.currentContext.findRenderObject();
final size = renderBox.size;
final position = renderBox.localToGlobal(Offset.zero);
final height = size.height; //same for width
}
If we have a Visibility widget on top of our screen and we click to display it at the end of our screen scrolling top manually, why still this hidden? Does this mean that we need to do something like this instead?:
showWidget == true ? Text("hi") : Container();
Because code above is failing as well.
Video of the error:
https://youtu.be/YQ7nZ3LAENo