I want to know the direction of scrolling at the moment of scrolling up or down in the list view. but I couldn't find a solution.
I tried to use ScrollController to listen to the direction of scrolling for dealing with different work as up and down scrolls. But there is no way to listen to that with ScrollController.
Is there anyone to have dealt with this problem?
You can make use of NotificationListener<ScrollNotification>. You will need to wrap your scroll view in that widget and then listen to UserScrollNotifications:
NotificationListener<ScrollNotification>(
onNotification: (ScrollNotification notification) {
if (notification is UserScrollNotification) {
if (notification.direction == ScrollDirection.forward) {
// Handle scroll down.
} else if (notification.direction == ScrollDirection.reverse) {
// Handle scroll up.
}
}
// Returning null (or false) to
// "allow the notification to continue to be dispatched to further ancestors".
return null;
},
child: ListView(..), // Or whatever scroll view you use.
)
Related
How to make able to scroll listview inside SingleChildScrollView?
That's right, normally the list view scrolls even if the parent is a SingleChildScrollView.
But my case is special because I used
NotificationListener<ScrollNotification>(
onNotification: (ScrollNotification notification) {
if (notification is UserScrollNotification) {
if (notification.direction == ScrollDirection.forward) {
//trigger doing some event ...
...changing screen because of this event
So my Listview scrolling is absolutely doing nothing and changing the screen because of the parent event.
child: ListView.builder( ... // when scroll it doesn`t scroll and change screen because of parent
Can anyone solve this?
I think you have not provided the physics property for the list view:
Use -> physics:AlwaysScrollableScrollPhysics() for the listview to make it scrollable.
Would like get current status of 'autorotate' system setting in Flutter application. Need to identify weather it is ON or OFF.
This can be done in android with the answer mentioned in the stackoverflow question.
Android auto rotate on off status link. But need the same with Flutter which should work for both android and ios.
Apricates your suggestion.
To know the Orientation of the screen, you can use the OrientationBuilder Widget, it will determine the current Orientation and rebuild when the Orientation changes its state.
#override
Widget build(BuildContext context) {
return Scaffold(
body: OrientationBuilder(builder: (_, orientation) {
if (orientation == Orientation.portrait)
return Something(); // if orientation is portrait, do something
else
return Something(); // else do something
}),
);
}
I'm experimenting with SwiftUI and I found a weird behaviour of ScrollView when nested in a TabView. If I swipe the ScrollView down and then do a slow gesture to swipe to the next tab, it sometimes reset the scrollView Position to the start. I'm not sure how to explain it well so here is a gif:
I'm trying to understand what cause this and if there is a way to avoid it.
Here is the code I use:
var body: some View {
TabView(selection: $selectedTab,
content: {
ForEach(coreData.pageList, id: \.self) { page in
if(coreData.pageList[page] == nil) {
ProgressView().onAppear(perform: {
loadPage(page: page)
})
} else {
ScrollView {
Text("START OF PAGE ------- -----Page Number: \(page)! This is a very short text made big to simulate scrolling. This is a very short text made big to simulate scrolling. ").font(.system(size: 90))
}
}
}
})
}
Am I missing something simple, is it a bug (with workaround), am I using these views wrong?
Ultimately I just want to have something that look like a page that you swipe right left or right but having the scroll position reset so fast would not be great user experience and doesn't look great
Edit: I haven't found any solution yet, but an interesting point: if I put the ProgressView inside the scrollView the scrollview does NOT reset position but the next tab will already be scrolled with the same amount as the previews page. This is equally "bad" if not worse :-(.
Try to put it into separated view (passing all needed parameters), so SwiftUI will see that view not changed and so not rerender it, ie. it should look like
if(coreData.pageList[page] == nil) {
ProgressView().onAppear(perform: {
loadPage(page: page)
})
} else {
DetailsView(page: page) // << ScrollView inside
}
I am trying to dismiss the keyboard when the user swipes from the edge to pop route.
Currently the keyboard doesn't dismiss until the route is completely gone popped, messing up some of the other pages layout until it dismisses
I did try to use a WillPopScope to determine when the user was going to pop the route, but unfortunately this disables the swipe to pop functionality from iOS or the CupertinoPageRoute.
I just want to find out if there's anyway I can determine when the user swipes from the edge to pop or taps the back button on the appBar and dismiss the keyboard as they do so.
If possible, I am trying to dismiss keyboard as soon as they start swiping to pop, as it happens in many apps.
I am attaching attaching a gif showing the effect I'm trying to achieve.
As suggested by Ovidiu
class DismissKeyboardNavigationObserver extends NavigatorObserver {
#override
void didStartUserGesture(Route route, Route previousRoute) {
SystemChannels.textInput.invokeMethod('TextInput.hide');
super.didStartUserGesture(route, previousRoute);
}
}
and in your Material App
MaterialApp(
navigatorObservers: [DismissKeyboardNavigationObserver()],
)
You need to create a custom class extending NavigatorObserver, and pass an instance of it to the navigatorObservers property of your MaterialApp or CupertinoApp.
Within that custom class, you can override didStartUserGesture and didStopUserGesture, which will be called when the swipe gesture starts/ends. This should allow you to achieve the behavior you are looking for. Note that didStartUserGesture indicates the current route as well as the previous route, based on which you could add logic to determine whether the keyboard should be dismissed or not.
This should come naturally and you shouldn't be directly concerned with that because actually, when you pop a route with the keyboard on, it should dismiss properly.
However, if you want to detect when the user starts swiping and dismiss the keyboard along with it and then pop the current route, you can easily achieve it by wrapping your screen widget with a GestureDetector like so:
Widget build(BuildContext context) {
double dragStart = 0.0;
return GestureDetector(
onHorizontalDragStart: (details) => dragStart = details.globalPosition.dx,
onHorizontalDragUpdate: (details) {
final double screenWidth = MediaQuery.of(context).size.width;
// Here I considered a back swipe only when the user swipes until half of the screen width, but you can tweak it to your needs.
if (dragStart <= screenWidth * 0.05 && details.globalPosition.dx >= screenWidth) {
FocusScope.of(context).unfocus();
}
child: // Your other widgets...
},
this is something i wrote to handle this issue. doesnt use any external packages, you would just wrap your content in the main function at the top.
Widget swipeOffKeyboard(BuildContext context, {Widget? child}) {
return Listener(
onPointerMove: (PointerMoveEvent pointer) {
disKeyboard(pointer, context);
},
child: child, // your content should go here
);
}
void disKeyboard(PointerMoveEvent pointer, BuildContext context) {
double insets = MediaQuery.of(context).viewInsets.bottom;
double screenHeight = MediaQuery.of(context).size.height;
double position = pointer.position.dy;
double keyboardHeight = screenHeight - insets;
if (position > keyboardHeight && insets > 0) FocusManager.instance.primaryFocus?.unfocus();
}
I have an Activity that populates two views on a ViewFlipper. I added an onTouch(View v, MotionEvent event) public boolean method to the Activity. The method is implemented so that when the person taps on the screen the ViewFlipper goes to the next view. It works great but some of the text is too long so I went into my XML file and surrounded the textfield in one of my ViewFlipper views with a linearlayout and then a ScrollView. But now when I'm viewing the fields that are too long and show a scroll bar, I can't display the previous view. The onTouch method in my main activity isn't being executed. I have not been able to figure this out. I've read some posts about implementing or overriding the methods in ScrollView but I don't know where to do this in my activity. Does anyone know how I can program ScrollView to not intercept but keep its ability to scroll the view?
ScrollView myScroll;
myScroll.setOnTouchListener(new OnTouchListener){
#Override
public boolean onTouch(View v, MotionEvent touchevent) {
switch (touchevent.getAction()) {
case MotionEvent.ACTION_DOWN: {
oldTouchValue = touchevent.getX();
break;
}
case MotionEvent.ACTION_UP: {
float currentX = touchevent.getX();
if (oldTouchValue < currentX) {
//left swipe
return true;
}
if (oldTouchValue > currentX) {
//right swipe
return true;
}
return false;
}
}