我刚刚开始了解Flutter,但我无法弄清楚如何设置按钮的启用状态。
从文档中,它说要将onPressed
设置为null以禁用按钮,并为其设置一个值以启用它。如果按钮在生命周期中继续处于相同状态,则此功能正常。
我得到的印象是我需要创建一个自定义的有状态窗口小部件,它允许我以某种方式更新按钮的启用状态(或onPressed回调)。
所以我的问题是我该怎么做?这似乎是一个非常简单的要求,但我在文档中找不到任何关于如何做的事情。
感谢。
答案 0 :(得分:48)
我想你可能想要向你的按钮build
引入一些辅助函数,以及一个有状态的小部件以及一些关键属性。
isButtonDisabled
)onPressed
值直接设置为null
或某个功能onPressed: () {}
isButtonDisabled
作为此条件的一部分,并返回null
或某些功能。setState(() => isButtonDisabled = true)
翻转条件变量。build()
方法,该按钮将使用null
按下处理程序进行渲染并被禁用。这里是使用Flutter计数器项目的更多上下文。
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => new _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
bool _isButtonDisabled;
@override
void initState() {
_isButtonDisabled = false;
}
void _incrementCounter() {
setState(() {
_isButtonDisabled = true;
_counter++;
});
}
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("The App"),
),
body: new Center(
child: new Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
new Text(
'You have pushed the button this many times:',
),
new Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
_buildCounterButton(),
],
),
),
);
}
Widget _buildCounterButton() {
return new RaisedButton(
child: new Text(
_isButtonDisabled ? "Hold on..." : "Increment"
),
onPressed: _isButtonDisabled ? null : _incrementCounter,
);
}
}
在这个示例中,我使用内联三元来有条件地设置Text
和onPressed
,但是将它提取到函数中可能更合适(可以使用相同的方法也改变按钮的文字):
Widget _buildCounterButton() {
return new RaisedButton(
child: new Text(
_isButtonDisabled ? "Hold on..." : "Increment"
),
onPressed: _counterButtonPress(),
);
}
Function _counterButtonPress() {
if (_isButtonDisabled) {
return null;
} else {
return () {
// do anything else you may want to here
_incrementCounter();
};
}
}
答案 1 :(得分:26)
根据文档:
“如果onPressed回调为null,则该按钮将被禁用,并且默认情况下将类似于DisabledColor中的平面按钮。”
https://docs.flutter.io/flutter/material/RaisedButton-class.html
因此,您可能会执行以下操作:
RaisedButton(
onPressed: calculateWhetherDisabledReturnsBool() ? null : () => whatToDoOnPressed,
child: Text('Button text')
);
答案 2 :(得分:12)
简单的答案是ie. this exclude filter: "//sourcedir//a//////file2" becomes this: "/sourcedir/a/file2"
diff --git a/exclude.c b/exclude.c
index a0090b29..e3a1b089 100644
--- a/exclude.c
+++ b/exclude.c
@@ -772,7 +772,9 @@ int check_filter(filter_rule_list *listp, enum logcode code,
if (rule_matches(name, ent, name_flags)) {
report_filter_result(code, name, ent, name_flags, listp->debug_type);
return ent->rflags & FILTRULE_INCLUDE ? 1 : -1;
- }
+// }else{
+// report_filter_result(code, name, ent, name_flags, listp->debug_type);
+ }
}
return 0;
@@ -805,7 +807,9 @@ static const uchar *rule_strcmp(const uchar *str, const char *rule, int rule_len
* template rflags and the xflags additionally affect parsing. */
static filter_rule *parse_rule_tok(const char **rulestr_ptr,
const filter_rule *template, int xflags,
- const char **pat_ptr, unsigned int *pat_len_ptr)
+ //const char **pat_ptr,
+ char **pat_ptr,
+ unsigned int *pat_len_ptr)
{
const uchar *s = (const uchar *)*rulestr_ptr;
filter_rule *rule;
@@ -1045,7 +1049,8 @@ static filter_rule *parse_rule_tok(const char **rulestr_ptr,
&& !(rule->rflags & (FILTRULES_SIDES|FILTRULE_MERGE_FILE|FILTRULE_PERDIR_MERGE)))
rule->rflags |= FILTRULE_SENDER_SIDE;
- *pat_ptr = (const char *)s;
+ //*pat_ptr = (const char *)s;
+ *pat_ptr = (char *)s;
*pat_len_ptr = len;
*rulestr_ptr = *pat_ptr + len;
return rule;
@@ -1092,7 +1097,8 @@ void parse_filter_str(filter_rule_list *listp, const char *rulestr,
const filter_rule *template, int xflags)
{
filter_rule *rule;
- const char *pat;
+ //const char *pat;
+ char *pat;
unsigned int pat_len;
if (!rulestr)
@@ -1105,6 +1111,25 @@ void parse_filter_str(filter_rule_list *listp, const char *rulestr,
if (!(rule = parse_rule_tok(&rulestr, template, xflags, &pat, &pat_len)))
break;
+ rprintf(FERROR, "!! got filter(len=%d): %.*s\n", //FIXME: the filter pattern here has the adjacent slashes! but it's a pointer not malloc-ed! so not sure if I should modify it? hmm
+ (int)pat_len,(int)pat_len, pat);
+
+ if (pat_len>1) {
+ unsigned int curpos=1;
+ for (unsigned int i=1; i<pat_len; i++) {
+ if (('/' == pat[i-1]) && ('/' == pat[i])) { //FIXME: is string containing 1 char-wide chars? or is it i dno, utf-8/unicode or whatnot? in other words, is a char 1 byte long? is '/' 1 byte long? because the 1 and ++ assume so!
+ continue;
+ } else {
+ pat[curpos]=pat[i];
+ curpos++;
+ }
+ }
+ if (curpos <pat_len) {
+ pat_len=curpos;//curpos is already +1 btw! due to curpos++ above
+ rprintf(FERROR, "!! fixed filter(len=%d): %.*s\n",
+ (int)pat_len,(int)pat_len, pat);
+ }
+ }
if (pat_len >= MAXPATHLEN) {
rprintf(FERROR, "discarding over-long filter: %.*s\n",
(int)pat_len, pat);
给出了一个禁用的按钮。
答案 3 :(得分:11)
我认为这是最简单的方法:
RaisedButton(
child: Text("PRESS BUTTON"),
onPressed: booleanCondition
? () => myTapCallback()
: null
)
答案 4 :(得分:6)
要禁用颤动中的任何 按钮,例如 FlatButton
、RaisedButton
、MaterialButton
、IconButton
等,您需要做的就是设置onPressed
和 onLongPress
属性为 null。下面是一些按钮的简单示例:
FlatButton(启用)
FlatButton(
onPressed: (){},
onLongPress: null, // Set one as NOT null is enough to enable the button
textColor: Colors.black,
disabledColor: Colors.orange,
disabledTextColor: Colors.white,
child: Text('Flat Button'),
),
FlatButton(禁用)
FlatButton(
onPressed: null,
onLongPress: null,
textColor: Colors.black,
disabledColor: Colors.orange,
disabledTextColor: Colors.white,
child: Text('Flat Button'),
),
凸起按钮(启用)
RaisedButton(
onPressed: (){},
onLongPress: null, // Set one as NOT null is enough to enable the button
// For when the button is enabled
color: Colors.lightBlueAccent,
textColor: Colors.black,
splashColor: Colors.blue,
elevation: 8.0,
// For when the button is disabled
disabledTextColor: Colors.white,
disabledColor: Colors.orange,
disabledElevation: 0.0,
child: Text('Raised Button'),
),
凸起按钮(禁用)
RaisedButton(
onPressed: null,
onLongPress: null,
// For when the button is enabled
color: Colors.lightBlueAccent,
textColor: Colors.black,
splashColor: Colors.blue,
elevation: 8.0,
// For when the button is disabled
disabledTextColor: Colors.white,
disabledColor: Colors.orange,
disabledElevation: 0.0,
child: Text('Raised Button'),
),
图标按钮(已启用)
IconButton(
onPressed: () {},
icon: Icon(Icons.card_giftcard_rounded),
color: Colors.lightBlueAccent,
disabledColor: Colors.orange,
),
图标按钮(已禁用)
IconButton(
onPressed: null,
icon: Icon(Icons.card_giftcard_rounded),
color: Colors.lightBlueAccent,
disabledColor: Colors.orange,
),
注意:某些按钮(例如 IconButton
)只有 onPressed
属性。
答案 5 :(得分:6)
此答案基于 TextButton/ElevatedButtonOutlinedButton
的更新按钮 Flutter 2.x
仍然根据 onPressed
属性启用或禁用按钮。如果该属性为空,则按钮将被禁用。如果您将功能分配给 onPressed
,则按钮将被启用。
在下面的片段中,我展示了如何启用/禁用按钮并相应地更新其样式。
这篇文章还说明了如何将不同的样式应用到新的 Flutter 2.x 按钮。
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
bool textBtnswitchState = true;
bool elevatedBtnSwitchState = true;
bool outlinedBtnState = true;
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Padding(
padding: const EdgeInsets.all(16.0),
child: Column(
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
TextButton(
child: Text('Text Button'),
onPressed: textBtnswitchState ? () {} : null,
style: ButtonStyle(
foregroundColor: MaterialStateProperty.resolveWith(
(states) {
if (states.contains(MaterialState.disabled)) {
return Colors.grey;
} else {
return Colors.red;
}
},
),
),
),
Column(
children: [
Text('Change State'),
Switch(
value: textBtnswitchState,
onChanged: (newState) {
setState(() {
textBtnswitchState = !textBtnswitchState;
});
},
),
],
)
],
),
Divider(),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
ElevatedButton(
child: Text('Text Button'),
onPressed: elevatedBtnSwitchState ? () {} : null,
style: ButtonStyle(
foregroundColor: MaterialStateProperty.resolveWith(
(states) {
if (states.contains(MaterialState.disabled)) {
return Colors.grey;
} else {
return Colors.white;
}
},
),
),
),
Column(
children: [
Text('Change State'),
Switch(
value: elevatedBtnSwitchState,
onChanged: (newState) {
setState(() {
elevatedBtnSwitchState = !elevatedBtnSwitchState;
});
},
),
],
)
],
),
Divider(),
Row(
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: [
OutlinedButton(
child: Text('Outlined Button'),
onPressed: outlinedBtnState ? () {} : null,
style: ButtonStyle(
foregroundColor: MaterialStateProperty.resolveWith(
(states) {
if (states.contains(MaterialState.disabled)) {
return Colors.grey;
} else {
return Colors.red;
}
},
), side: MaterialStateProperty.resolveWith((states) {
if (states.contains(MaterialState.disabled)) {
return BorderSide(color: Colors.grey);
} else {
return BorderSide(color: Colors.red);
}
})),
),
Column(
children: [
Text('Change State'),
Switch(
value: outlinedBtnState,
onChanged: (newState) {
setState(() {
outlinedBtnState = !outlinedBtnState;
});
},
),
],
)
],
),
],
),
),
);
}
}
答案 6 :(得分:5)
对于特定数量和数量有限的小部件,将它们包装在小部件IgnorePointer中可以做到这一点:当其ignoring
属性设置为true时,子小部件(实际上是整个子树)是不可点击的。
IgnorePointer(
ignoring: true, // or false
child: RaisedButton(
onPressed: _logInWithFacebook,
child: Text("Facebook sign-in"),
),
),
否则,如果要禁用整个子树,请查看AbsorbPointer()。
答案 7 :(得分:1)
您可以启用或禁用此类按钮
RaisedButton(onPressed: () => isEnabled ? _handleClick : null)
答案 8 :(得分:1)
您还可以使用AbsorbPointer,并且可以通过以下方式使用它:
AbsorbPointer(
absorbing: true, // by default is true
child: RaisedButton(
onPressed: (){
print('pending to implement onPressed function');
},
child: Text("Button Click!!!"),
),
),
如果您想进一步了解此小部件,可以查看以下链接Flutter Docs
答案 9 :(得分:0)
大多数小部件的启用和禁用功能相同。
Ex,按钮,开关,复选框等
只需设置onPressed
属性,如下所示
onPressed : null
返回已禁用的小部件
onPressed : (){}
或onPressed : _functionName
返回已启用的小部件
答案 10 :(得分:0)
您还可以设置空白条件,代替设置null
var isDisable=true;
RaisedButton(
padding: const EdgeInsets.all(20),
textColor: Colors.white,
color: Colors.green,
onPressed: isDisable
? () => (){} : myClickingData(),
child: Text('Button'),
)
答案 11 :(得分:-1)
如果您正在寻找一种快速的方法,并且不关心让用户实际点击一个按钮一次。您也可以通过以下方式进行操作:
// Constant whether button is clicked
bool isClicked = false;
然后在 onPressed() 函数中检查用户是否已经点击了按钮。
onPressed: () async {
if (!isClicked) {
isClicked = true;
// await Your normal function
} else {
Toast.show(
"You click already on this button", context,
duration: Toast.LENGTH_LONG, gravity: Toast.BOTTOM);
}
}
答案 12 :(得分:-2)
我喜欢为此使用 flutter_mobx 并在状态上工作。
接下来我使用观察者:
Container(child: Observer(builder: (_) {
var method;
if (!controller.isDisabledButton) method = controller.methodController;
return RaiseButton(child: Text('Test') onPressed: method);
}));
在控制器上:
@observable
bool isDisabledButton = true;
然后在控件内部,您可以根据需要操作此变量。
参考:Flutter mobx