我制作了一個小應用程式來向用戶顯示影像串列我從api獲取這些影像并使用這些影像串列我嘗試使用smooth_page_indicator 1.0.0 2來自flutter的Package with image list但我發現錯誤為：
Unsupported operation: Infinity or NaN toInt
完整代碼：
class _WidgetImageState extends State<WidgetImage> {
List<ImageTopicModel> _ListData = [];
List<ImageTopicModel> _ListDataDisplay = [];
@override
void initState() {
Api().then((value) {
if (this.mounted) {
setState(() {
_ListData.addAll(value);
_ListDataDisplay = _ListData;
});
}
});
super.initState();
}
PageController _pageController = PageController();
int page = 0;
void onPageViewChange(int _page) {
page = _page;
// setState(() {});
}
@override
Widget build(BuildContext context) {
return Container(
width: double.infinity,
height: 400,
child: Stack(children: <Widget>[
Stack(
children: <Widget>[
Container(
width: double.infinity,
height: 400,
child: PageView.builder(
physics: BouncingScrollPhysics(),
controller: _pageController,
onPageChanged: onPageViewChange,
itemCount: _ListDataDisplay.length,
itemBuilder: (BuildContext context, int index) {
return Container(
child: Column(children: <Widget>[
InkWell(
child: CachedNetworkImage(
imageUrl:
"${_ListDataDisplay[index].image}",
width: double.infinity,
height: 400,
fit: BoxFit.cover,
errorWidget:
(context, url, error) =>
Icon(Icons.error),
),
onTap: () {
Navigator.push(context,
MaterialPageRoute(
builder: (context) {
return ShowImageOfAd(
"${_ListDataDisplay[index].image}");
}));
}),
]),
);
}),
),
Container(
child: Align(
alignment: Alignment.bottomCenter,
child: Container(
height: 40,
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
colors: [
Colors.black.withOpacity(0.0),
Colors.black.withOpacity(0.5)
])),
child: Align(
alignment: Alignment.center,
child: SmoothPageIndicator(
controller: _pageController, // PageController
count: _ListDataDisplay.length,
axisDirection: Axis.horizontal,
effect: WormEffect(
dotWidth: 9.0,
dotHeight: 9.0,
dotColor: Colors.black26,
activeDotColor: Colors.white,
),
onDotClicked: (index) {}),
),
),
)),
],
),
]),
);
}
}
我試圖找到很長一段時間的解決方案，但我找不到任何解決方案。我該如何解決這個問題？有什么想法可以解決這個問題嗎？
======== Exception caught by rendering library =====================================================
The following UnsupportedError was thrown during paint():
Unsupported operation: Infinity or NaN toInt
The relevant error-causing widget was:
SmoothPageIndicator SmoothPageIndicator:file:///C:/Users/**********/widgetImage.dart:96:30
When the exception was thrown, this was the stack:
#0 double.toInt (dart:core-patch/double.dart)
#1 WormPainter.paint (package:smooth_page_indicator/src/painters/worm_painter.dart:21:40)
#2 RenderCustomPaint._paintWithPainter (package:flutter/src/rendering/custom_paint.dart:571:13)
#3 RenderCustomPaint.paint (package:flutter/src/rendering/custom_paint.dart:613:7)
#4 RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:2796:7)
#5 PaintingContext.paintChild (package:flutter/src/rendering/object.dart:239:13)
#6 RenderProxyBoxMixin.paint (package:flutter/src/rendering/proxy_box.dart:144:15)
#7 RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:2796:7)
uj5u.com熱心網友回復：
發生這種情況是因為您有一個async操作，initState并且顫動嘗試繪制所有小部件樹，但WormIndicator有 0 個專案。為了正確處理這個問題，在資料加載時渲染一些占位符。
例如，您可以在以下build方法中正確顯示條件之前添加條件_WidgetImageState：
... code above ...
@override
Widget build(BuildContext context) {
return _ListData.isEmpty
? SizedBox.shrink()
: Container(
width: 500,
height: 400,
child: Stack(children: <Widget>[
... code below ...
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