dart

问题 I need to know is it possible to use ternary/if else inside flutter widgets. I'm trying to create a buttonCreator widget which will take few parameters, one of which will be the background. I need to check whether the widget has background enabled or not. What i have is this but i have no idea how to use it in real dart code. Container buildButton(String text, bool bg){ return new Container( decoration: new BoxDecoration( border: new Border.all(color: Colors.white), if (bg != true ? color:

问题 Not sure if the terminology in the title is 100% correct, but what I mean is easily illustrated by this example: class MyClass{ String str = ''; MyClass(this.str); } void main() { MyClass obj1 = MyClass('obj1 initial'); print(obj1.str); doSomething(obj1); print(obj1.str); doSomethingElse(obj1); print(obj1.str); } void doSomething(MyClass obj){ obj.str = 'obj1 new string'; } void doSomethingElse(MyClass obj){ obj = MyClass('obj1 new object'); } This will print obj1 initial obj1 new string obj1

问题 Not sure if the terminology in the title is 100% correct, but what I mean is easily illustrated by this example: class MyClass{ String str = ''; MyClass(this.str); } void main() { MyClass obj1 = MyClass('obj1 initial'); print(obj1.str); doSomething(obj1); print(obj1.str); doSomethingElse(obj1); print(obj1.str); } void doSomething(MyClass obj){ obj.str = 'obj1 new string'; } void doSomethingElse(MyClass obj){ obj = MyClass('obj1 new object'); } This will print obj1 initial obj1 new string obj1

问题 I have to read and write some values to a Bike Smart trainer with BLE (Bluetooth Low Energy) used with Flutter. When I try to read the values from the GATT characteristic org.bluetooth.characteristic.supported_power_range (found on bluetooth.org site https://www.bluetooth.com/specifications/gatt/characteristics/ ) I get the return value of an Int List [0,0,200,0,1,0]. The GATT characteristic sais that there are 3 sint16 fields for Min., Max. and step size Watts (Power). The Byte transmission

问题 I have to read and write some values to a Bike Smart trainer with BLE (Bluetooth Low Energy) used with Flutter. When I try to read the values from the GATT characteristic org.bluetooth.characteristic.supported_power_range (found on bluetooth.org site https://www.bluetooth.com/specifications/gatt/characteristics/ ) I get the return value of an Int List [0,0,200,0,1,0]. The GATT characteristic sais that there are 3 sint16 fields for Min., Max. and step size Watts (Power). The Byte transmission

问题 I have to read and write some values to a Bike Smart trainer with BLE (Bluetooth Low Energy) used with Flutter. When I try to read the values from the GATT characteristic org.bluetooth.characteristic.supported_power_range (found on bluetooth.org site https://www.bluetooth.com/specifications/gatt/characteristics/ ) I get the return value of an Int List [0,0,200,0,1,0]. The GATT characteristic sais that there are 3 sint16 fields for Min., Max. and step size Watts (Power). The Byte transmission

问题 I have to read and write some values to a Bike Smart trainer with BLE (Bluetooth Low Energy) used with Flutter. When I try to read the values from the GATT characteristic org.bluetooth.characteristic.supported_power_range (found on bluetooth.org site https://www.bluetooth.com/specifications/gatt/characteristics/ ) I get the return value of an Int List [0,0,200,0,1,0]. The GATT characteristic sais that there are 3 sint16 fields for Min., Max. and step size Watts (Power). The Byte transmission

问题 I am creating an App and I am new in flutter, dart. I have problem in "context". I want to replace the page/screen onTab(). But I'm having the following error: > ══════ Exception caught by gesture ════════════════════════ The > following NoSuchMethodError was thrown while handling a gesture: The > method 'findAncestorStateOfType' was called on null. Receiver: null > Tried calling: findAncestorStateOfType<NavigatorState>() Here is my code: class Theorytest extends StatelessWidget { Widget

问题 Im making an app that play sounds when you press FlatButtons, and I want to disable the predetermined pop sound that plays every time you touch the screen. Is there a way to do this? 回答1: you cant disable the sound for the flatbutton .you can use InkWell() Widget it offers you the methode enableFeedback . you can set it as false and you should be alright 回答2: Use MaterialButton . All the styling remains the same but you have the added benefit of implementing enableFeedback: false, which will

问题 I'm battling an issue where I'm given the error " Object was given an infinite size during layout " and "This probably means that it is a render object that tries to be as big as possible, but it was put inside another render object that allows its children to pick their own size.". I understand what it means, but not how I can still keep my current widget tree responsive (it renders when running, so for a front-end user there seems to be no problem) while still fixing this issue. Currently I