I have a list of image paths and I am using the List.generate method to display images and a cross icon to remove image from list. Upload method is called on each image and when I remove the image from the list the method still keeps running until the image is uploaded. The behavior I am expecting is when I remove the image from the list the method should also stop running. I am using a future builder to display the circular progress bar and error icons while uploading an image.
What should I be doing to make sure the future method associated to the current widget also stops when I remove the widget from the list?
This is the code where I am creating a list
List.generate(
files.length,
(index) {
var image = files[index];
return Container(
height: itemSize,
width: itemSize,
child: Stack(
children: <Widget>[
Container(
getImagePreview(image, itemSize)
),
Row(
mainAxisAlignment: MainAxisAlignment.end,
children: [
uploadHandler(image, field),
InkWell(
onTap: () => removeFileAtIndex(index, field),
child: Container(
margin: EdgeInsets.all(3),
decoration: BoxDecoration(
color: Colors.grey.withOpacity(.7),
shape: BoxShape.circle,
),
alignment: Alignment.center,
height: 22,
width: 22,
child: Icon(Icons.close, size: 18, color: Colors.white),
),
),
],
),
],
),
);
},
)
This is Upload Handler method.
Widget uploadHandler(file, field) {
return FutureBuilder(
future: upload(file),
builder: (context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.data.statusCode == 201) {
return doneUpload();
} else {
logger.d(snapshot.error);
return error();
}
} else {
return uploading();
}
},
);
}
The lifecycle of the widget isn't attached to the async functions invoked by the widget.
You can check the mounted variable to check if the widget still mounted from your async function.
Related
I have List View and I have inside each item in the list a button called "Delete item". When I press that button inside each item I want to delete only that item from the list.
But it does not delete item, it just display Toast message that I have specified.
How I can solve this?
This is the code:
Widget build(BuildContext context) {
listItems = buildVCsFromAPI(context);
return Container(
child: ListView.builder(
itemBuilder: (context, index) =>
_buildListItem(context, listItems[index], index),
itemCount: listItems.length,
physics: AlwaysScrollableScrollPhysics()),
);
}
Widget _buildListItem(
BuildContext context, _VerifiableCredentialListItem cert, int index) {
return GestureDetector(
child: AnimatedAlign(
curve: Curves.ease,
duration: Duration(milliseconds: 500),
heightFactor: selectedPosition == index ? factorMax : factorMin,
alignment: Alignment.topCenter,
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(10)), //here
color: Colors.white,
boxShadow: [
BoxShadow(
color: Colors.grey.withOpacity(0.5),
offset: Offset(0, -1),
blurRadius: 10.0)
]),
child: Column(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
HeadingRow(title: cert.fullTitle, appIcon: cert.appIcon),
displayListItem(index, selectedPosition, cert)
],
),
),
),
}
Column displayListItem(
int index, int selectedIndex, _VerifiableCredentialListItem cert) {
CredentialListGroupType groupType = cert.groupType;
return Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: [
SizedBox(
height: UIConstants.s2,
),
buildAnotherWidget(),
SizedBox(
height: UIConstants.s3,
),
buildDeleteAndExportButtons(),
],
);
}
Column buildDeleteAndExportButtons() {
return Column(
children: [
Padding(
padding: EdgeInsets.symmetric(
vertical: UIConstants.s1, horizontal: UIConstants.s2),
child: Row(
children: [
Expanded(
flex: 1,
child: BlueButtonWithIcon(
text: 'Delete item',
icon: 'assets/icons/delete-icon.svg',
onPressed: () {
setState(() {
AppToaster.pop(ToasterType.info, "Delete");
listItems.removeAt(0);
});
},
),
),
SizedBox(width: UIConstants.s1),
Expanded(
flex: 1,
child: BlueButtonWithIcon(
text: 'Export',
icon: 'assets/icons/export.svg',
onPressed: null,
),
)
],
),
),
SizedBox(height: UIConstants.s1)
],
);
}
Calling setState doesn't mean that flutter would actually full repaint the screen it means that it will check your widget tree with the last rendered widget tree and it will paint only the differences and it first compares widgets type and then widget keys to find that there is a difference between the current widget and the previous one and because of this when you remove an item from your list of items flutter checks your returned widgets to the currently rendered widget it doesn't found any difference and it won't repaint the screen and continues showing the last render
So for you to tell the flutter that one of the items in the listView is changed you could assign a uniqueKey key for each list item widget note that for this topic your keys should be unique to the data of that widget otherwise you will face performance issues because if your widget key is changed without any change in the representation of that widget in next time that builds method is called which could happen frequently flutter compares widgets key with the previous widgets key which is rendered to the screen and exist on the render tree and it founds that the keys are different and it repaints that widget which is a redundant operation because your widgets UI and representation are the same
For example, assign a unique id base on the index or content of your data to each data model in the listItems and use that to create a ValueKey() for the widget that is represented by that data
here is a working example of the list which when you click on the list item first list item will be removed
class ListItemDataModel {
final String id;
final Color color;
ListItemDataModel(this.id, this.color);
}
class _MyHomePageState extends State<MyHomePage> {
List<ListItemDataModel> items = [];
#override
void initState() {
super.initState();
items = [
ListItemDataModel("A", Colors.red),
ListItemDataModel("B", Colors.amber),
ListItemDataModel("C", Colors.green),
ListItemDataModel("D", Colors.lightBlueAccent),
ListItemDataModel("E", Colors.pink),
];
}
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Container(
child: ListView.builder(
itemBuilder: (context, index) {
return GestureDetector(
key: ValueKey(items[index].id),
//Tap to Remove first item from list
onTap: () {
items.removeAt(0);
setState(() {});
},
child: Container(
height: 60,
color: items[index].color,
child: Center(
child: Text(
"This is a unique item with id = ${items[index].id}"),
),
),
);
},
itemCount: items.length,
),
),
);
}
}
So,
We don't have acces to the code above.. so.. where does listItems came from?
Maybe you are retrieving the value of listItems after the init state? if so it's normal that you are retrieving always the same result..
What you should do is the following:
get listItems value from params, global vars, databse ecc
display the list
when you delete a single item you should update the original list
on state updated now the list will be loaded with updated values
If you delete an item from a list but the list is then reloaded in its original form your updates will be lost
I have a ListView inside of a FutureBuilder. This FutureBuilder loads a list from disk and once loaded, shows a ListView. This ListView has a custom ItemTile to show for each loaded item. Each ItemTile has a button to copy itself (i.e. writing a copy of itself to memory). How can I now inform the ListView to be rebuild?
This is how my ItemTile is implemented (I only included the relevant code).
#override
Widget build(BuildContext context) {
return InkWell(
child: Card(
semanticContainer: false,
//This flag should be false if the card contains multiple different types of content.
child: Container(
height: 200,
width: double.infinity,
child:
Align(
alignment: Alignment.topRight,
child: getPopUpMenuButton(context),
)
),
),
);
}
PopupMenuButton<String> getPopUpMenuButton(BuildContext context) {
return PopupMenuButton(
onSelected: (str) {
switch (str) {
case 'MAKECOPY':
{
Item newItem = Item.clone(this.item, sameUID: false);
Scaffold.of(context).setState(() {
_itemManager.save(newItem);
});
}
}
},
icon: Icon(Icons.more_vert),
itemBuilder: (_) => <PopupMenuItem<String>>[
new PopupMenuItem<String>(
value: 'MAKECOPY',
child: Text(AppLocalizations.of(context).get('edit_as_copy'))),
],
);
}
I assumed the Scaffold.of(context).setState would do the trick but it does not. How do I correctly call a rebuild of the ListView/FutureBuilder from a list item?
I have a list of chats, and I want to show on each chat card, if there's a new message that the user hasn't read.
The list is in a StatefulWidget, the list contains refactored cards that are also StatefulWidgets, I also made the code to work with Firestore to check if the user has read the message, but still I don't know what's happening, because it doesn't update the icon of unread messages.
The data changes in the database, but it doesn't in the chat card. If I reload the app, because the cards are rebuilt, then it does change.
Here's the chat card code:
bool hasUnreadMessages = false;
void unreadMessagesVerifier() {
setState(() {
_firestore.collection('chatRoom').document(_chatRoomID).get().then((data) async {
hasUnreadMessages = await data['hasUnreadMessages'];
});
});
}
#override
Widget build(BuildContext context) {
unreadMessagesVerifier();
return GestureDetector(
child: Stack(
children: <Widget>[
Container(
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: <Widget>[
Flexible(
child: Container(
width: double.infinity,
child: Text(
widget.lastMessage,
),
),
),
hasUnreadMessages
? Container(
margin: EdgeInsets.fromLTRB(10, 0, 5, 0),
child: CircleAvatar(
radius: 7,
backgroundColor: Colors.blue,
),
)
: SizedBox(),
],
),
),
],
),
onTap: widget.onTap,
); // ChatCard
}
If more info is needed, do let me know!
========================================================================
EDIT:
Fixed thanks to #Pedro R.
I just had to move the SetState() and check the mounted
void unreadMessagesVerifier() {
_firestore.collection('chatRoom').document(_chatRoomID).get().then((data) async {
if (mounted) {
setState(() {
hasUnreadMessages = data['hasUnreadMessages'];
});
}
});
}
I think your problem lies in the way you are calling setState.
Try calling it after the future finishes.
Like this:
void unreadMessagesVerifier() {
_firestore.collection('chatRoom').document(_chatRoomID).get().then((data) =>
data['hasUnreadMessages'].then(result){
setState((){
hasUnreadMessages = result;
});
});
}
Sorry for the formatting by the way.
Consider using StatefulBuilder class, it rebuilds the particular Widget which it wraps based upon the value getting updated
So, hasUnreadMessage will be used to update the Container(). Do something like this
StatefulBuilder(
builder: (BuildContext context, StateSetter setState){
// here you return the data based upon your bool value
return hasUnreadMessages ? Container(
margin: EdgeInsets.fromLTRB(10, 0, 5, 0),
child: CircleAvatar(
radius: 7,
backgroundColor: Colors.blue,
)
) : SizedBox();
}
)
I am building an app in Flutter,that supposed to be a social network app-similar to faceboook.
I have implemented a like button-when pressed is sending the server the request,and then depending on the status code it sets the state.My problem begins when the setState() is rendering again the avatar picture,or creating it again from scratch(the avatar is stored in a 64base String).
the likePress is a future that sends the request and then sets the boolean isLiked accordingly.
this is the creating of the like button:
buildLikeButton(int ownerId, int postId) {
return RepaintBoundary(
child: FutureBuilder<bool>(
future: getLike(ownerId, postId),
builder: (BuildContext context, AsyncSnapshot<bool> snapshot) {
IconButton likeButton;
if (snapshot.hasData) {
isLiked = snapshot.data;
likeButton = createLikeButton(ownerId, postId);
} else if (snapshot.hasError) {
isLiked = false;
likeButton = createLikeButton(ownerId, postId);
print('the snapshot has an error ${snapshot.error}');
} else {
isLiked = false;
likeButton = createLikeButton(ownerId, postId);
}
return likeButton;
}));
}
createLikeButton(int ownerId, int postId) {
return IconButton(
icon: returnLikeIcon(isLiked),
color: Theme.of(context).accentColor,
onPressed: () async {
if (this.mounted) {
setState(() {
Future lol = likePress(ownerId, postId).then((onValue) {});
});
}
},
);
}
and this is the creation of the avatar:
createAvatar(BuildContext context, avatar_base64, int ownerId) {
Uint8List bytes = base64Decode(avatar_base64.split(',').last);
return RepaintBoundary(
child: CircleAvatar(
radius: 25.0,
backgroundImage: MemoryImage(bytes),
backgroundColor: Colors.transparent,
));
}
The widget that displays them together is the Post widget which i have created for this project,and this is it's build function:
Widget build(BuildContext context) {
return InkWell(
borderRadius: BorderRadius.circular(0.2),
child: Container(
decoration: BoxDecoration(boxShadow: [
BoxShadow(
color: Theme.of(context).primaryColor,
blurRadius: 1.0,
spreadRadius: 1.0, // has the effect of extending the shadow
offset: Offset(
5.0, // horizontal, move right 10
5.0, // vertical, move down 10
),
),
]),
child: Card(
elevation: 10.0,
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Flexible(
fit: FlexFit.loose,
child: postInfo(context, time, ownerId)),
Divider(
thickness: 1.0,
height: 10.0,
indent: 10.0,
endIndent: 10.0,
),
postContent(content),
Divider(
thickness: 1.0,
height: 10.0,
indent: 10.0,
endIndent: 10.0,
),
createButtonBar(ownerId, postId),
],
)),
));
}
postInfo is just a FutureBuilder that builds the ListTile that adds up the avatar and the name, and createButtonBar creates the like button and 2 more buttons.
I would like to change the icon when the user presses the like button,but only if the server has responded with the right status code and without rendering and creating the whole Post widget over again.Thank you for the trouble!
This means that the avatar is beneath the point where you are calling setState(() {}). In your case, the method is probably inside that particular widget and the widget is being rebuilt.
I suggest for you to solve the problem to move the creation of the avatar above. In this way, if you need to rebuild the object the avatar will not be created anew but simply placed within the new widget. Place some debugPrints around to speed up the process and try to refactor the code to see if you missed something.
After taking a better look at my code,I decided to create a different Widget for each part of the post,so I can initialize everything that will not be built again outside of the build method.
so if you want to exclude a widget from the setState() method, you need to move it outside the current widget(by creating a widget for it) and just create an instance of it as a parameter in the constructor.
In more detail,I created a class named PostHeader and there i created the avatar and the ListTile containing it,then i created an instance of it inside the Post class,so it is not created inside the build method of the Post class.
In my Flutter pr project, I am using Image Picker plugin to select images from the android mobile gallery or capture images with the camera and show them one after another with a delete icon below each image. On tapping the RaisedButton for selecting images from the gallery, the method imageSelectorGallery() is called. There inside the setState() method , I add a SizedBox and a delete icon to the List namely images_captured. I expect the images_captured to be rendered inside the Column in SingleChildScrollView.
But after selecting an image from the gallery, nothing happens. I also want to tap on the delete icon and remove the image above it. But flutter has no data binding mechanism as I know to correlate the image with the delete button.
Code follows:
class PrescriptionScreen extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return new UserOptionsState();
}
}
class UserOptionsState extends State<PrescriptionScreen> {
//save the result of gallery fileUserOptions
File galleryFile;
//save the result of camera file
File cameraFile;
#override
Widget build(BuildContext context) {
var images_captured=List<Widget>();
//display image selected from gallery
imageSelectorGallery() async {
galleryFile = await ImagePicker.pickImage(
source: ImageSource.gallery,
// maxHeight: 50.0,
// maxWidth: 50.0,
);
print("You selected gallery image : " + galleryFile.path);
setState(() {
var sized_box_indiv= new SizedBox(
height: 200.0,
width: 300.0,
//child: new Card(child: new Text(''+galleryFile.toString())),
//child: new Image.file(galleryFile),
child: galleryFile == null
? new Text('Sorry nothing selected from gallery!!')
: new Image.file(galleryFile),
);
images_captured.add(sized_box_indiv);
var delete_button = IconButton(icon: Icon(Icons.delete), onPressed: () {});
images_captured.add(delete_button);
});
}
//display image selected from camera
imageSelectorCamera() async {
cameraFile = await ImagePicker.pickImage(
source: ImageSource.camera,
//maxHeight: 50.0,
//maxWidth: 50.0,
);
print("You selected camera image : " + cameraFile.path);
setState(() {});
}
return new SingleChildScrollView(
child:Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
new RaisedButton(
child: new Text('Select Image from Gallery'),
onPressed: imageSelectorGallery,
),
new RaisedButton(
child: new Text('Select Image from Camera'),
onPressed: imageSelectorCamera,
),
Column(
children: images_captured
),
],
),
);
/* },
),
);*/
}
}
How to show the images selected from gallery one after another with a delete icon button below each of them?
How to remove the corresponding image on tapping the delete icon button?
I think if I can accomplish it for gallery, I can do it for camera capturing as well.
I used the answer by jJuice and the images after being selected showed overflow error. The screenshot is given below:
My code is:
class UserOptionsState extends State<PrescriptionScreen> {
//save the result of gallery fileUserOptions
File galleryFile;
//save the result of camera file
File cameraFile;
var images_captured=List<Widget>();
List<File> images = List<File>();
#override
Widget build(BuildContext context) {
//display image selected from gallery
imageSelectorGallery() async {
galleryFile = await ImagePicker.pickImage(
source: ImageSource.gallery,
// maxHeight: 50.0,
// maxWidth: 50.0,
);
images.add(galleryFile);
print("You selected gallery image : " + galleryFile.path);
setState(() {
});
}
//display image selected from camera
imageSelectorCamera() async {
cameraFile = await ImagePicker.pickImage(
source: ImageSource.camera,
//maxHeight: 50.0,
//maxWidth: 50.0,
);
print("You selected camera image : " + cameraFile.path);
setState(() {});
}
return new SingleChildScrollView(
child:Column(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
new RaisedButton(
child: new Text('Select Image from Gallery'),
onPressed: imageSelectorGallery,
),
new RaisedButton(
child: new Text('Select Image from Camera'),
onPressed: imageSelectorCamera,
),
new Container(
// new Column(
// children: <Widget>[
height: 1200,
child:GridView.count(
crossAxisSpacing: 6,
mainAxisSpacing: 6,
crossAxisCount: 3,
children: List.generate(images.length, (index) {
return Column(
children: <Widget>[
Container(
height: 200,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10),
),
child: ClipRRect(
child: Image.file(images[index], fit: BoxFit.cover),
borderRadius: BorderRadius.circular(10),
)
),
GestureDetector(
onTap: () {
setState(() {
images.removeAt(index);
});
},
child: Padding(
padding: const EdgeInsets.all(3.0),
child: Align(
alignment: Alignment.bottomCenter,
child: Icon(Icons.clear, color: Colors.black, size: 20),
),
),
),
]
);
}
),
),
// ]
)
/*displaySelectedFile(galleryFile),
displaySelectedFile(cameraFile)*/
],
),
);
}
Widget displaySelectedFile(File file) {
return new SizedBox(
height: 200.0,
width: 300.0,
//child: new Card(child: new Text(''+galleryFile.toString())),
//child: new Image.file(galleryFile),
child: file == null
? new Text('Sorry nothing selected!!')
: new Image.file(file),
);
}
}
Question 1: You first need to store the images picked by using ImagePicker (or MultiImagePicker plugin) in a collection. Here's an example on how to do that:
List<File> images = List<File>();
images.add(await ImagePicker.pickImage(source: ImageSource.gallery, imageQuality: 20););
When you want to show those images on the screen, you can use several different widgets, like ListView, GridView, Row, Column.
Here's an example where I use a GridView:
child: Container(
height: 1200,
child: GridView.count(
crossAxisSpacing: 6,
mainAxisSpacing: 6,
crossAxisCount: 3,
children: List.generate(images.length, (index) {
return Column(
children: <Widget>[
Container(
height: 200,
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(10),
),
child: ClipRRect(
child: Image.file(images[index], fit: BoxFit.cover),
borderRadius: BorderRadius.circular(10),
)
),
GestureDetector(
onTap: () {
setState(() {
images.removeAt(index);
});
},
child: Padding(
padding: const EdgeInsets.all(3.0),
child: Align(
alignment: Alignment.bottomCenter,
child: Icon(Icons.clear, color: Colors.white, size: 20),
),
),
),
]
),
}
),
),
I think using a Stack widget works best in this case. A Stack can be used to show Widgets, layered on top of each other. So in this case, a widget showing the image, with a Icon widget on top of it that is the button for your delete action.
Question 2:
You could delete the image by calling the removeAt method available on collections like a List. See the code inside the onTap method of the GestureDetector. By calling setState the page gets rebuild once the image has been deleted.
EDIT
Sorry, I misread your question and see that you want to show a button below the image, instead of on top of it. A Column widget could be used for this purpose. I edited the code accordingly.