Flutter 图片选择器 SelectPhotoWidget

快来打我* 2023-10-07 16:47 108阅读 0赞

> 在码农的世界里，优美的应用体验，来源于程序员对细节的处理以及自我要求的境界，年轻人也是忙忙碌碌的码农中一员，每天、每周，都会留下一些脚印，就是这些创作的内容，有一种执着，就是不知为什么，如果你迷茫，不妨来瞅瞅码农的轨迹。

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*  [Flutter 从入门 到精通系列文章在这里][Flutter _]
 *  [当然也必需是要有源码的 在这里了][Link 1]
 *  [github 有点慢 不妨来看看码云的源码吧][github _]
 *  [系列学习教程在这里][Link 2]

--------------------

先来看看本文章实现的效果

![在这里插入图片描述][20210704222726294.gif_pic_center]

直接来看代码吧

首先是启动函数

main() {
        
      runApp(MaterialApp(
        //不显示 debug标签
        debugShowCheckedModeBanner: false,
        //显示的首页面
        home: DemoSelectImageWidgetPage(),
      ));
    }

然后是这个首页面，核心代码就是 SelectPhotoWidget 这个组件

///代码清单
    class DemoSelectImageWidgetPage extends StatefulWidget {
        
      @override
      _DemoSelectImageWidgetPageState createState() =>
          _DemoSelectImageWidgetPageState();
    }
    
    class _DemoSelectImageWidgetPageState extends State<DemoSelectImageWidgetPage> {
        
      @override
      Widget build(BuildContext context) {
        
        //
        return Scaffold(
          backgroundColor: Colors.grey,
          appBar: AppBar(title: Text("图片选择组件")),
          body: Center(
            child: Container(
              padding: EdgeInsets.all(12),
              //图片选择组件
              child: SelectPhotoWidget(
                header: Text(
                  "请选择照片",
                  style: TextStyle(fontWeight: FontWeight.w600, fontSize: 18),
                ),
                //标题下的红色提醒文本
                tips: "请注意 最多选择5张图片",
                //图片选择回调
                imageSelectAction: (List<String> list) {
        
                  print("实时选择回调${list.toString()}");
                },
                //最大选择图片数据
                maxSelect: 6,
                //预设图片
                imageList: [],
              ),
            ),
          ),
        );
      }
    }

将核心功能封装在了 SelectPhotoWidget 组件中，大家可以直接复制使用

///
    class SelectPhotoWidget extends StatefulWidget {
        
      ///每次点击选择图片后的回调
      final Function(List<String>) imageSelectAction;
    
      ///自定义标题
      final Widget header;
    
      ///标题下的小捍
      final String tips;
    
      ///预显示使用的图片
      final List<String> imageList;
    
      ///最多可选择的图片数量
      final int maxSelect;
    
      ///为true 时显示使用网络图片
      final ImageType imageType;
    
      const SelectPhotoWidget(
          {
        Key key,
          this.header,
          this.tips,
          this.imageList,
          this.imageType = ImageType.asset,
          this.imageSelectAction,
          this.maxSelect = 5})
          : super(key: key);
    
      @override
      State<StatefulWidget> createState() {
        
        return _SelectPhotoWidgetState();
      }
    }

这里也有视频 了，大家可以来瞅瞅

class _SelectPhotoWidgetState extends State<SelectPhotoWidget>
        with WidgetsBindingObserver {
        
      ///当前是否正在选择图片
      bool _isSelect = false;
    
      @override
      void initState() {
        
        super.initState();
        if (widget.imageList != null) {
        
          //判断一下最大选择图片数据
          if (widget.imageList.length <= widget.maxSelect) {
        
            _imageList = widget.imageList;
          } else {
        
            //截取图片
            _imageList = widget.imageList.sublist(0, widget.maxSelect);
          }
        }
        //绑定视图监听
        WidgetsBinding.instance.addObserver(this);
      }
    
      @override
      void didChangeAppLifecycleState(AppLifecycleState state) {
        
        switch (state) {
        
          case AppLifecycleState.inactive:
            // 处于这种状态的应用程序应该假设它们可能在任何时候暂停。
            break;
          case AppLifecycleState.resumed:
            //从后台切换前台，界面可见
            break;
          case AppLifecycleState.paused:
            // 界面不可见，后台
            break;
          case AppLifecycleState.detached:
            // APP结束时调用
            break;
        }
      }
    
      @override
      void dispose() {
        
        //解绑视图监听
        WidgetsBinding.instance.removeObserver(this);
        super.dispose();
      }
    
      @override
      Widget build(BuildContext context) {
        
        //圆角矩形剪裁
        return ClipRRect(
          //圆角
          borderRadius: BorderRadius.all(Radius.circular(12)),
          child: Container(
            color: Color(0xffFFFFFF),
            //宽度填充
            width: double.infinity,
            //统一内边距
            padding: EdgeInsets.all(10),
            //垂直方向的线性排列
            child: Column(
              //水平方向
              crossAxisAlignment: CrossAxisAlignment.start,
              //包裹
              mainAxisSize: MainAxisSize.min,
              children: [
                //标题
                buildHeaderWidget(),
                //第二行的小提示
                buildTipsWidget(),
                //显示的图片
                buildGridView(),
                SizedBox(
                  height: 10,
                ),
              ],
            ),
          ),
        );
      }
    
      buildHeaderWidget() {
        
        return widget.header != null ? widget.header : Container();
      }
    
      buildTipsWidget() {
        
        if (widget.tips == null || widget.tips.length == 0) {
        
          return Container();
        }
        return Container(
          padding: EdgeInsets.only(top: 10, bottom: 16),
          //圆角矩形裁剪
          child: ClipRRect(
            //圆角
            borderRadius: BorderRadius.all(Radius.circular(12)),
            child: Container(
              padding: EdgeInsets.only(left: 10, right: 10, top: 6, bottom: 6),
              color: Color(0xffFFF1F1),
              child: Text(
                "${widget.tips}",
                style: TextStyle(
                  color: Color(0xffBD2F2F),
                  fontSize: 14,
                ),
              ),
            ),
          ),
        );
      }
    
      List<String> _imageList = [];
    
      buildGridView() {
        
        return Container(
          child: GridView.builder(
            padding: EdgeInsets.only(top: 8, bottom: 8),
            //包裹
            shrinkWrap: true,
            //不可滑动
            physics: NeverScrollableScrollPhysics(),
            //图片个数
            itemCount: getSelectCount(),
            //SliverGridDelegateWithFixedCrossAxisCount 构建一个横轴固定数量Widget
            gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
                //横轴元素个数
                crossAxisCount: 4,
                //主轴间距
                mainAxisSpacing: 1.0,
                //从轴间距
                crossAxisSpacing: 1.0,
                //子组件宽高长度比例
                childAspectRatio: 1.0),
            itemBuilder: (BuildContext context, int index) {
        
              //Widget Function(BuildContext context, int index)
              if (index == _imageList.length) {
        
                if (_isSelect) {
        
                  return Center(child: Text("..."));
                }
                return Container(
                  margin: EdgeInsets.only(top: 10),
                  child: IconButton(
                    icon: Icon(Icons.add),
                    onPressed: () {
        
                      onSelectImageFunction();
                    },
                  ),
                  color: Color(0xFFF1F1F2),
                );
              }
              //显示当前的图片
              String imageUrl = _imageList[index];
              return Container(
                //层叠布局
                child: Stack(
                  children: [
                    //向左下偏移一点
                    Positioned.fill(
                      top: 10,
                      right: 10,
                      child: GestureDetector(
                        onTap: () {
        
                          //查看大图
                        },
                        child: Container(
                          padding: EdgeInsets.all(1),
                          child: buildImageWidget(imageUrl),
                          color: Colors.grey[200],
                        ),
                      ),
                    ),
                    Positioned(
                      top: 0,
                      right: 0,
                      child: GestureDetector(
                        onTap: () {
        
                          onDeleteImageFunction(index);
                        },
                        child: ClipOval(
                          child: Container(
                            padding: EdgeInsets.all(2),
                            color: Colors.red,
                            child: Icon(
                              Icons.close,
                              color: Colors.white,
                              size: 14,
                            ),
                          ),
                        ),
                      ),
                    ),
                  ],
                ),
              );
            },
          ),
        );
      }
    
      Widget buildImageWidget(String image) {
        
        if (widget.imageType == ImageType.net) {
        
          return Image.network(
            image,
            fit: BoxFit.fitWidth,
          );
        } else if (widget.imageType == ImageType.asset) {
        
          return Image.asset(
            image,
            fit: BoxFit.fitWidth,
          );
        }
        return Image.file(
          File(image),
          fit: BoxFit.fitWidth,
        );
      }
    
      ///最大选择图片数据限制
      getSelectCount() {
        
        if (_imageList.length >= widget.maxSelect) {
        
          return widget.maxSelect;
        }
        return _imageList.length + 1;
      }
    
      //删除照片
      void onDeleteImageFunction(int index) {
        
        _imageList.removeAt(index);
        setState(() {
        });
        widget.imageSelectAction(_imageList);
      }
    
      void onSelectImageFunction() async {
        
        _isSelect = true;
        setState(() {
        });
        String localImageUrl = "assets/images/sp03.png";
        await Future.delayed(Duration(milliseconds: 1000));
        _isSelect = false;
        if (localImageUrl.length > 0) {
        
          _imageList.add(localImageUrl);
          setState(() {
        });
          widget.imageSelectAction(_imageList);
        }
      }
    }

[Flutter _]: https://blog.csdn.net/zl18603543572/article/details/93532582
[Link 1]: https://gitee.com/android.long/flutter-ho/blob/279b5185f50a3379c71a74fc6c51b421f59c0354/lib/src/pages/demo/demo18/demo_DateRangPage.dart
[github _]: https://github.com/zhaolongs
[Link 2]: https://study.163.com/instructor/1021406098.htm?_trace_c_p_k2_=09d88ef1f37645abadcc2b58620d4b00
[20210704222726294.gif_pic_center]: https://img-blog.csdnimg.cn/20210704222726294.gif#pic_center