flutter多图像选择和插入PDF表仅插入最后一个列表

Question

我是Flutter的新手，我正在使用Image_picker软件包选择多个图像并将其插入PDF表中。我能够根据所需的行数获取图像并列出列表，但是当创建PDF时，行是正确的，但仅反复显示嵌套列表中的最后一个列表。我的代码如下。有什么建议吗？

页面从位置加载的

class imagecollager extends StatefulWidget {
  @override
  _imagecollagerState createState() => _imagecollagerState();
}

class _imagecollagerState extends State<imagecollager> {
  String pdfFile = '';

  final ImagePicker imagePicker = ImagePicker();
  List<XFile>? imageFileList = [];

  int numbofcol = 3;// Number of column in Row
  int numbofpgs =1; // number of pages
 var numboflist = 0; // number of rows
  List imagelist=[];
  List<List> imagedata=[];
  List<XFile>?  selectedImages =[];
  String selimages = "";
  var  imagefilestart=0;
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [

           TextButton(
                onPressed: () async {
                  selectImages();
                },
                child: Text('Load Image')),
            Text(selimages),
            TextButton(
                onPressed: () async {
                 sortImages();
                },
                child: Text('Create a Pdf')),
          ],
        ),
      ),
    );
  }


  void selectImages() async {
    imageFileList!.clear();
  selectedImages = await imagePicker.pickMultiImage();
    if (selectedImages!.isNotEmpty) {

      imageFileList!.addAll(selectedImages!);
    }
    setState(() {
    });

  setState(() {
    selimages =   imageFileList!.length.toString();
    imagefilestart=0;
  });
  }

void sortImages() async {
  imagedata.clear();
  numboflist=(imageFileList!.length/numbofcol).ceil(); //
    for (var row = 0; row < numboflist; row++) {
    imagelist.clear();

    for (var j = 0; j < numbofcol; j++) {

      File imageFile = File(imageFileList![imagefilestart].path);
      Uint8List imageRaw = await imageFile.readAsBytes();
      imagelist.add(imageRaw);
         imagefilestart= imagefilestart+1 ;
     if(imagefilestart==imageFileList!.length) break ;

    }

    imagedata.insert(row, imagelist);
   
  }

 
   final pdfFile = await PdfApi.generateImage(imagedata);
PdfApi.openFile(pdfFile);

}

}

PDF处理代码如下

class PdfApi {
  static Future<File> generateCenteredText(String text) async {
    final pdf = Document();

    pdf.addPage(Page(
      build: (context) => Center(
        child: Text(text, style: const TextStyle(fontSize: 48)),
      ),
    ));

    return saveDocument(name: 'my_example.pdf', pdf: pdf);
  }
  
  static Future<File> generateImage( var imagedata) async {
    final pdf = Document();
  
    final pageTheme = PageTheme(
      pageFormat: PdfPageFormat.a4,
    
    );

    pdf.addPage(
      MultiPage(
        pageTheme: pageTheme,
        build: (context) => [
          for (var i = 0; i < imagedata.length; i++)
            Table(
                border: TableBorder.all(
                  color: PdfColors.black,
                  //style: BorderStyle.solid,
                  width: 0.5,
                ),
                children: [

                  TableRow(children: [
                    //for(var item in imagedata[i] )
                      for (var j = 0; j < imagedata[i].length; j++)
                      Image(MemoryImage(imagedata[i][j]),
                      )
                  ]),
        ],
      ),
                      ]
      )
    );

    return saveDocument(name: 'my_example.pdf', pdf: pdf);
  }


  static Future<File> saveDocument({
    required String name,
    required Document pdf,
  }) async {
    final bytes = await pdf.save();
    final dir = await getApplicationDocumentsDirectory();
    final file = File('${dir.path}/$name');
    await file.writeAsBytes(bytes);
    return file;
  }

  static Future openFile(File file) async {
    final url = file.path;
    await OpenFile.open(url);
  }
}

Answer 1

我认为，当我尝试清除循环清单时，这是一个引用问题。当我将下面更改

imagelist.clear();

为时，

imagelist=[];

它开始根据需要工作。