Android|Android Flutter自适应瀑布流案例详解 AndroidFlutter自适应瀑布流案例详

Flutter自适应瀑布流
根据效果图可以分为四步：

1.图片自适应：
2.自适应标签：
3.上拉刷新和下拉加载
4.底部的点赞按钮

Flutter自适应瀑布流前言：在电商app经常会看到首页商品推荐的瀑布流，或者类似短视频app首页也是瀑布流，这些都是需要自适应的，才能给用户带来好的体验
（具体代码请联系我，当天会回复）
话不多说先上效果图:

文章图片

文章图片

根据效果图可以分为四步：

图片自适应
自适应标签
上拉刷新和下拉加载
底部的点赞按钮可以去掉或者自己修改样式，我这里使用的like_button库

注：本文使用的库：为啥这么多呢，因为我把图片缓存这样东西都加上了，单纯的瀑布流就用waterfall_flow

waterfall_flow: ^3.0.1extended_image: anyextended_sliver: anyff_annotation_route_library: anyhttp_client_helper: anyintl: anylike_button: anyloading_more_list: anypull_to_refresh_notification: anyurl_launcher: any

1.图片自适应：

Widget image = Stack(children: [ExtendedImage.network(item.imageUrl,shape: BoxShape.rectangle,//clearMemoryCacheWhenDispose: true,border: Border.all(color: Colors.grey.withOpacity(0.4), width: 1.0),borderRadius: const BorderRadius.all(Radius.circular(10.0),),loadStateChanged: (ExtendedImageState value) {if (value.extendedImageLoadState == LoadState.loading) {Widget loadingWidget = Container(alignment: Alignment.center,color: Colors.grey.withOpacity(0.8),child: CircularProgressIndicator(strokeWidth: 2.0,valueColor:AlwaysStoppedAnimation(Theme.of(c).primaryColor),),); if (!konwSized) {//todo: not work in webloadingWidget = AspectRatio(aspectRatio: 1.0,child: loadingWidget,); }return loadingWidget; } else if (value.extendedImageLoadState == LoadState.completed) {item.imageRawSize = Size(value.extendedImageInfo.image.width.toDouble(),value.extendedImageInfo.image.height.toDouble()); }return null; },),Positioned(top: 5.0,right: 5.0,child: Container(padding: const EdgeInsets.all(3.0),decoration: BoxDecoration(color: Colors.grey.withOpacity(0.6),border: Border.all(color: Colors.grey.withOpacity(0.4), width: 1.0),borderRadius: const BorderRadius.all(Radius.circular(5.0),),),child: Text('${index + 1}',textAlign: TextAlign.center,style: const TextStyle(fontSize: fontSize, color: Colors.white),),),)],); if (konwSized) {image = AspectRatio(aspectRatio: item.imageSize.width / item.imageSize.height,child: image,); } else if (item.imageRawSize != null) {image = AspectRatio(aspectRatio: item.imageRawSize.width / item.imageRawSize.height,child: image,); } return Column(crossAxisAlignment: CrossAxisAlignment.start,children: [image,const SizedBox(height: 5.0,),buildTagsWidget(item),const SizedBox(height: 5.0,),buildBottomWidget(item),],); }

2.自适应标签：

Widget buildTagsWidget(TuChongItem item, {int maxNum = 6,}) {const double fontSize = 12.0; return Wrap(runSpacing: 5.0,spacing: 5.0,children: item.tags.take(maxNum).map((String tag) {final Color color = item.tagColors[item.tags.indexOf(tag)]; return Container(padding: const EdgeInsets.all(3.0),decoration: BoxDecoration(color: color,border: Border.all(color: Colors.grey.withOpacity(0.4), width: 1.0),borderRadius: const BorderRadius.all(Radius.circular(5.0),),),child: Text(tag,textAlign: TextAlign.start,style: TextStyle(fontSize: fontSize,color: color.computeLuminance() < 0.5? Colors.white: Colors.black),),); }).toList()); }

3.上拉刷新和下拉加载

class PullToRefreshHeader extends StatelessWidget {const PullToRefreshHeader(this.info, this.lastRefreshTime, {this.color}); final PullToRefreshScrollNotificationInfo info; final DateTime lastRefreshTime; final Color color; @overrideWidget build(BuildContext context) {if (info == null) {return Container(); }String text = ''; if (info.mode == RefreshIndicatorMode.armed) {text = 'Release to refresh'; } else if (info.mode == RefreshIndicatorMode.refresh ||info.mode == RefreshIndicatorMode.snap) {text = 'Loading...'; } else if (info.mode == RefreshIndicatorMode.done) {text = 'Refresh completed.'; } else if (info.mode == RefreshIndicatorMode.drag) {text = 'Pull to refresh'; } else if (info.mode == RefreshIndicatorMode.canceled) {text = 'Cancel refresh'; }final TextStyle ts = const TextStyle(color: Colors.grey,).copyWith(fontSize: 13); final double dragOffset = info?.dragOffset ?? 0.0; final DateTime time = lastRefreshTime ?? DateTime.now(); final double top = -hideHeight + dragOffset; return Container(height: dragOffset,color: color ?? Colors.transparent,//padding: EdgeInsets.only(top: dragOffset / 3),//padding: EdgeInsets.only(bottom: 5.0),child: Stack(children: [Positioned(left: 0.0,right: 0.0,top: top,child: Row(mainAxisAlignment: MainAxisAlignment.center,crossAxisAlignment: CrossAxisAlignment.center,children: [Expanded(child: Container(alignment: Alignment.centerRight,child: RefreshImage(top),margin: const EdgeInsets.only(right: 12.0),),),Column(children: [Text(text,style: ts,),Text('Last updated:' +DateFormat('yyyy-MM-dd hh:mm').format(time),style: ts.copyWith(fontSize: 12),)],),Expanded(child: Container(),),],),)],),); }}class RefreshImage extends StatelessWidget {const RefreshImage(this.top); final double top; @overrideWidget build(BuildContext context) {const double imageSize = 40; return ExtendedImage.asset(Assets.assets_fluttercandies_grey_png,width: imageSize,height: imageSize,afterPaintImage: (Canvas canvas, Rect rect, ui.Image image, Paint paint) {final double imageHeight = image.height.toDouble(); final double imageWidth = image.width.toDouble(); final Size size = rect.size; final double y = (1 - min(top / (refreshHeight - hideHeight), 1)) *imageHeight; canvas.drawImageRect(image,Rect.fromLTWH(0.0, y, imageWidth, imageHeight - y),Rect.fromLTWH(rect.left, rect.top + y / imageHeight * size.height,size.width, (imageHeight - y) / imageHeight * size.height),Paint()..colorFilter =const ColorFilter.mode(Color(0xFFea5504), BlendMode.srcIn)..isAntiAlias = false..filterQuality = FilterQuality.low); //canvas.restore(); },); }}

4.底部的点赞按钮

LikeButton(size: 18.0,isLiked: item.isFavorite,likeCount: item.favorites,countBuilder: (int count, bool isLiked, String text) {final ColorSwatch color =isLiked ? Colors.pinkAccent : Colors.grey; Widget result; if (count == 0) {result = Text('love',style: TextStyle(color: color, fontSize: fontSize),); } else {result = Text(count >= 1000 ? (count / 1000.0).toStringAsFixed(1) + 'k' : text,style: TextStyle(color: color, fontSize: fontSize),); }return result; },likeCountAnimationType: item.favorites < 1000? LikeCountAnimationType.part: LikeCountAnimationType.none,onTap: (bool isLiked) {return onLikeButtonTap(isLiked, item); },)

这样自适应的瀑布流就完成了。
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