3.5 图片组件封装

3.5 图片组件封装

实现步骤：

第 1 步：安装插件 extended_image

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flutter pub add extended_image

第 2 步：ImageWidget 封装

定义如下

name 说明 参数
url 图片来自于网络 url 图片网址
asset 图片来自于 asset assetName 文件路径
file 图片来自于本地文件 file path 绝对路径

图片可以来自 url asset

lib/common/widgets/image.dart

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import 'dart:io';

import 'package:extended_image/extended_image.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

import '../index.dart';

enum ImageWidgetType { asset, network, file }

/// 图片组件
class ImageWidget extends StatelessWidget {
  /// 网址
  final String url;

  /// 类型
  final ImageWidgetType type;

  /// 圆角
  final double? radius;

  /// 宽度
  final double? width;

  /// 高度
  final double? height;

  /// 自适应方式
  final BoxFit? fit;

  /// 占位图
  final Widget? placeholder;

  /// 背景颜色
  final Color? backgroundColor;

  /// builder 函数
  final Widget Function(
    BuildContext context,
    ImageProvider provider,
    Widget completed,
    Size? size,
  )? builder;

  const ImageWidget({
    Key? key,
    required this.type,
    required this.url,
    this.radius,
    this.width,
    this.height,
    this.fit,
    this.placeholder,
    this.backgroundColor,
    this.builder,
  }) : super(key: key);

  const ImageWidget.url(
    this.url, {
    Key? key,
    this.radius,
    this.width,
    this.height,
    this.fit,
    this.placeholder,
    this.backgroundColor,
    this.builder,
  })  : type = ImageWidgetType.network,
        super(key: key);

  const ImageWidget.asset(
    this.url, {
    Key? key,
    this.radius,
    this.width,
    this.height,
    this.fit,
    this.placeholder,
    this.backgroundColor,
    this.builder,
  })  : type = ImageWidgetType.asset,
        super(key: key);

  const ImageWidget.file(
    this.url, {
    Key? key,
    this.radius,
    this.width,
    this.height,
    this.fit,
    this.placeholder,
    this.backgroundColor,
    this.builder,
  })  : type = ImageWidgetType.file,
        super(key: key);

  Widget get _placeholder =>
      placeholder ??
      IconWidget.image(
        'assets/images/default.png',
        size: 36,
      );

  @override
  Widget build(BuildContext context) {
    final borderRadius = BorderRadius.all(
      Radius.circular(radius ?? AppRadius.image),
    );
    Widget? image;
    switch (type) {
      case ImageWidgetType.asset:
        image = ExtendedImage.asset(
          url,
          width: width,
          height: height,
          fit: fit,
          shape: BoxShape.rectangle,
          borderRadius: borderRadius,
          loadStateChanged: (state) => _buildLoadState(context, state),
        );
        break;
      case ImageWidgetType.network:
        if (!url.contains('http')) break;
        image = ExtendedImage.network(
          url,
          width: width,
          height: height,
          fit: fit,
          shape: BoxShape.rectangle,
          borderRadius: borderRadius,
          loadStateChanged: (state) => _buildLoadState(context, state),
        );
        break;
      case ImageWidgetType.file:
        image = ExtendedImage.file(
          File(url),
          width: width,
          height: height,
          fit: fit,
          shape: BoxShape.rectangle,
          borderRadius: borderRadius,
          loadStateChanged: (state) => _buildLoadState(context, state),
        );
    }

    return Container(
      clipBehavior: Clip.antiAlias,
      width: width,
      height: height,
      child: image ?? _placeholder,
      decoration: BoxDecoration(
        color: backgroundColor,
        borderRadius: borderRadius,
      ),
    );
  }

  Widget _buildLoadState(BuildContext context, ExtendedImageState state) {
    switch (state.extendedImageLoadState) {
      // 正在读取
      case LoadState.loading:
        return _placeholder;
      // 读取成功
      case LoadState.completed:
        Size? size;
        if (state.extendedImageInfo != null) {
          size = Size(
            state.extendedImageInfo!.image.width.toDouble(),
            state.extendedImageInfo!.image.height.toDouble(),
          );
        }
        final provider = state.imageProvider;
        final completed = state.completedWidget;
        return builder?.call(context, provider, completed, size) ?? completed;
      // 读取失败
      case LoadState.failed:
        return const Center(
          child: Icon(
            CupertinoIcons.info_circle,
            size: 20,
            color: Colors.grey,
          ),
        );
    }
  }
}

第 3 步：Image 调试界面

lib/pages/styles/styles_index/view.dart

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// Image 图片
ListTile(
  onTap: () => Get.toNamed(RouteNames.stylesImage),
  title: const TextWidget.body1("Image 图片"),
),

lib/pages/styles/image/view.dart

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Widget _buildView() {
  return ListView(
    children: [
      const ListTile(
        leading: ImageWidget.url(
            "https://ducafecat.oss-cn-beijing.aliyuncs.com/wp-content/uploads/2022/02/90bb74497f090c48e1df1ec1ca31fb11-450x450.jpg"),
        title: TextWidget.body1("ImageWidget.url"),
      ),
      ListTile(
        leading: ImageWidget.asset(AssetsImages.pPaypalPng),
        title: const TextWidget.body1("ImageWidget.asset"),
      ),
    ],
  );
}

最后：运行

img

提交代码到 git