dart

问题 I have some basic code to load some sprite images, I am using Future.wait to wait until both images are loaded. However this still does not what I exactly want to do, Because I want to assign image width and height to members before It exits. SpaceShip(this.x, this.y) { rocket = new ImageElement(src: "nofire.png"); firingRockets = new ImageElement(src: "fire.png"); var futures = [rocket.onLoad.first, firingRockets.onLoad.first]; Future.wait(futures).then((_) { width = rocket.width; height =

问题 I have some basic code to load some sprite images, I am using Future.wait to wait until both images are loaded. However this still does not what I exactly want to do, Because I want to assign image width and height to members before It exits. SpaceShip(this.x, this.y) { rocket = new ImageElement(src: "nofire.png"); firingRockets = new ImageElement(src: "fire.png"); var futures = [rocket.onLoad.first, firingRockets.onLoad.first]; Future.wait(futures).then((_) { width = rocket.width; height =

问题 I have some basic code to load some sprite images, I am using Future.wait to wait until both images are loaded. However this still does not what I exactly want to do, Because I want to assign image width and height to members before It exits. SpaceShip(this.x, this.y) { rocket = new ImageElement(src: "nofire.png"); firingRockets = new ImageElement(src: "fire.png"); var futures = [rocket.onLoad.first, firingRockets.onLoad.first]; Future.wait(futures).then((_) { width = rocket.width; height =

问题 Is there a way to resize an image without having it previously written to storage? I am using a pdf library that for the images needs the bytes of it. What I do is get image with an http.get and I get the bytes to put it in the pdf. The problem is that I need to resize the image BEFORE putting it in the pdf. The only thing I have is the url of the image or the uint8list Response response = await http.get(imageUrl); Uint8List imgBytes = response.bodyBytes; Later: Image( PdfImage.file(pdf

问题 Is there a way to resize an image without having it previously written to storage? I am using a pdf library that for the images needs the bytes of it. What I do is get image with an http.get and I get the bytes to put it in the pdf. The problem is that I need to resize the image BEFORE putting it in the pdf. The only thing I have is the url of the image or the uint8list Response response = await http.get(imageUrl); Uint8List imgBytes = response.bodyBytes; Later: Image( PdfImage.file(pdf

问题 Hey so I haven't really messed around with it too much, but I was wondering if there was actually a way (before I go down a neverending rabbit hole) to read and write to CSV files in Dart/Flutter? I need to write to the files, not necessarily read them, and I'm willing to go to quite extreme lengths to do so. Any library works, built-in functions are even better. Any and all help is appreciated! 回答1: Use this package csv from https://pub.dartlang.org/packages/csv. If you have a List<List

问题 In Dart site they said that the integer size is 64 bit , is this the max size of an integer, or this is the size of any integer even if the integer is a small number such as 12? If every integer size is 64 bit , does this affect the performance of the application? 回答1: The answer is: "It depends". First of all, if you compile Dart to JavaScript, all numbers are JavaScript numbers, which means Dart double s. Even the integers, they just happen to be non-fractional doubles. That means that you

问题 I tried using named routes but it doesn't seem it work giving me an error "could not find a generator for route ("/homepage",null) for _MaterialAppState.I couldn't understand the working of namedRoutes in this case. import 'package:flutter/material.dart'; import './home.dart'; import './auth.dart'; void main() { runApp(new MyApp()); } class MyApp extends StatefulWidget { @override State<StatefulWidget> createState() { return MyAppState(); } } class MyAppState extends State<MyApp> { Widget

问题 I want to make a 3D pie chart in my app but I am finding difficult to find the solution that shows the percentage and name for the area of selected region in the graph. I am using AnimatedCircularChart and for that the package is: import 'package:flutter_circular_chart/flutter_circular_chart.dart'; > AnimatedCircularChart( key: _chartKey, size: _chartSize, initialChartData: _quarterlyProfitPieData[0], chartType: CircularChartType.Pie, I want the label over the selected region. 回答1: Please try

问题 I use Firebase Authentication in my flutter app. I use PIN instead of normal password which is I strictly defined 6-digit number. In the case my user forgot their PIN, my only option (or not?) is by calling the sendPasswordResetEmail method. await firebaseAuth.sendPasswordResetEmail(email: userEmail); The problem is they can type any new password in the Firebase reset password input and breaking the rule for 6-digit numeric only. Is there any way to customize the validation, caption text, etc