gpt4 book ai didi

text - 如何在给定宽度的小部件中移动文本

转载 作者:行者123 更新时间:2023-12-03 22:53:25 26 4
gpt4 key购买 nike

我正在构建一个广播应用程序。就像在 Spotify 中一样,有一个带有当前标题和艺术家的栏,文本应该在一行中并具有给定的宽度。如何让文本从右向左和向后移动?

使用自制动画时,我希望移动文本的速度是固定的,因此需要文本小部件的时间和宽度。

是否有一个包/内置选项来做到这一点?
还是我必须使用自制的动画?如果是这样,我怎样才能获得文本小部件的宽度?

Controller 和动画:

    AnimationController(duration: Duration(seconds: 10), vsync: this);
animation = Tween<double>(begin: 0, end: 1)
.animate(CurvedAnimation(parent: _controller, curve: Curves.linear));
animation.addListener(() {
setState(() {});
});
_controller.repeat();

构建方法
    double value =
-300 * (animation.value <= 0.5 ? animation.value : 1 - animation.value);
return Container(
child: SizedBox(
width: widget.width,
height: 24,
child: Transform.translate(
offset: Offset(value, 0),
child: widget.text,
),
),
);

最佳答案

你可以这样做:

import 'dart:async';

import 'package:flutter/material.dart';

class ScrollingText extends StatefulWidget {
final String text;
final TextStyle textStyle;
final Axis scrollAxis;
final double ratioOfBlankToScreen;

ScrollingText({
@required this.text,
this.textStyle,
this.scrollAxis: Axis.horizontal,
this.ratioOfBlankToScreen: 0.25,
}) : assert(text != null,);

@override
State<StatefulWidget> createState() {
return ScrollingTextState();
}
}

class ScrollingTextState extends State<ScrollingText>
with SingleTickerProviderStateMixin {
ScrollController scrollController;
double screenWidth;
double screenHeight;
double position = 0.0;
Timer timer;
final double _moveDistance = 3.0;
final int _timerRest = 100;
GlobalKey _key = GlobalKey();

@override
void initState() {
super.initState();
scrollController = ScrollController();
WidgetsBinding.instance.addPostFrameCallback((callback) {
startTimer();
});
}

void startTimer() {
if (_key.currentContext != null) {
double widgetWidth =
_key.currentContext.findRenderObject().paintBounds.size.width;
double widgetHeight =
_key.currentContext.findRenderObject().paintBounds.size.height;

timer = Timer.periodic(Duration(milliseconds: _timerRest), (timer) {
double maxScrollExtent = scrollController.position.maxScrollExtent;
double pixels = scrollController.position.pixels;
if (pixels + _moveDistance >= maxScrollExtent) {
if (widget.scrollAxis == Axis.horizontal) {
position = (maxScrollExtent -
screenWidth * widget.ratioOfBlankToScreen +
widgetWidth) /
2 -
widgetWidth +
pixels -
maxScrollExtent;
} else {
position = (maxScrollExtent -
screenHeight * widget.ratioOfBlankToScreen +
widgetHeight) /
2 -
widgetHeight +
pixels -
maxScrollExtent;
}
scrollController.jumpTo(position);
}
position += _moveDistance;
scrollController.animateTo(position,
duration: Duration(milliseconds: _timerRest), curve: Curves.linear);
});
}
}

@override
void didChangeDependencies() {
super.didChangeDependencies();
screenWidth = MediaQuery.of(context).size.width;
screenHeight = MediaQuery.of(context).size.height;
}

Widget getBothEndsChild() {
if (widget.scrollAxis == Axis.vertical) {
String newString = widget.text.split("").join("\n");
return Center(
child: Text(
newString,
style: widget.textStyle,
textAlign: TextAlign.center,
),
);
}
return Center(
child: Text(
widget.text,
style: widget.textStyle,
));
}

Widget getCenterChild() {
if (widget.scrollAxis == Axis.horizontal) {
return Container(width: screenWidth * widget.ratioOfBlankToScreen);
} else {
return Container(height: screenHeight * widget.ratioOfBlankToScreen);
}
}

@override
void dispose() {
super.dispose();
if (timer != null) {
timer.cancel();
}
}

@override
Widget build(BuildContext context) {
return ListView(
key: _key,
scrollDirection: widget.scrollAxis,
controller: scrollController,
physics: NeverScrollableScrollPhysics(),
children: <Widget>[
getBothEndsChild(),
getCenterChild(),
getBothEndsChild(),
],
);
}
}

并像这样使用小部件:
ScrollingText(
text: text,
textStyle: TextStyle(fontSize: 12),
)


enter image description here

关于text - 如何在给定宽度的小部件中移动文本,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/55716719/

26 4 0
Copyright 2021 - 2024 cfsdn All Rights Reserved 蜀ICP备2022000587号
广告合作:1813099741@qq.com 6ren.com