When you run this code from the main() method it is probably a timing issue. You can try something like import “package:polymer/polymer.dart”; main() { initPolymer().run(() { // code here works most of the time Polymer.onReady.then((e) { // some things must wait until onReady callback is called }); }); } see also how to implement a … Read more
() => expression or () { statements } creates a closure or inline function. This way you create inline a function that is passed as argument to be called in case of the event onPressed by the widget you pass it to. The expression or statements have the context where they were created available and … Read more
Unfortunately, ListView has no built-in approach to a scrollToIndex() function. You’ll have to develop your own way to measure to that element’s offset for animateTo() or jumpTo(), or you can search through these suggested solutions/plugins or from other posts like Flutter: Scrolling to a widget in ListView (the general scrollToIndex issue is discussed at flutter/issues/12319 … Read more
I just changed my code as follows, import ‘dart:convert’; List<int> imageBytes = widget.fileData.readAsBytesSync(); print(imageBytes); String base64Image = base64Encode(imageBytes); and this is working fine now. It is better to read it asynchronously as the image can be very large which may cause blocking of the main thread List<int> imageBytes = await widget.fileData.readAsBytes();
There are a few different options for this. The most basic is hopefully something you’ve already done, but I’ll list it anyways: 1: Create a class for your drawer Your widget should be its own stateful or stateless widget. This way, you just have to instantiate it each time. class MyDrawer extends StatelessWidget { @override … Read more
as and show are two different concepts. With as you are giving the imported library a name. It’s usually done to prevent a library from polluting your namespace if it has a lot of global functions. If you use as you can access all functions and classes of said library by accessing them the way … Read more
A StatelessWidget will never rebuild by itself (but can from external events). A StatefulWidget can. That is the golden rule. BUT any kind of widget can be repainted any times. Stateless only means that all of its properties are immutable and that the only way to change them is to create a new instance of … Read more
Flutter is based around immutable data. Meaning that if the reference to an object didn’t change, the content didn’t either. The problem is, in your case you always send to ListView the same array, and instead mutate its content. But this leads to ListView assuming the list didn’t change and therefore prevent useless render. You … Read more
To check for keyboard visibility, just check for the viewInsets property anywhere in the widget tree. The keyboard is hidden when viewInsets.bottom is equal to zero. You can check for the viewInsets with MediaQuery like: MediaQuery.of(context).viewInsets.bottom
You can use Future.wait to wait for a list of futures: import ‘dart:async’; Future main() async { var data = []; var futures = <Future>[]; for (var d in data) { futures.add(d.loadData()); } await Future.wait(futures); } DartPad example