Intro#

我維護了一個 NPOI 的擴充套件(WeihanLi.Npoi)，主要用來匯入匯出 Excel 資料，最近有網友提出了匯入 Excel 的時候解析圖片的需求，於是就有了本文的探索

匯入Excel 時解析圖片#

xls 和 xlsx 的 API 稍有不同，詳細可以直接參考以下程式碼，實現程式碼如下：

public static Dictionary<CellPosition, IPictureData> GetPicturesAndPosition(this ISheet sheet){    var dictionary = new Dictionary<CellPosition, IPictureData>();    if (sheet.Workbook is HSSFWorkbook)    {        foreach (var shape in ((HSSFPatriarch)sheet.DrawingPatriarch).Children)        {            if (shape is HSSFPicture picture)            {                var position = new CellPosition(picture.ClientAnchor.Row1, picture.ClientAnchor.Col1);                dictionary[position] = picture.PictureData;            }        }    }    else if (sheet.Workbook is XSSFWorkbook)    {        foreach (var shape in ((XSSFDrawing)sheet.DrawingPatriarch).GetShapes())        {            if (shape is XSSFPicture picture)            {                var position = new CellPosition(picture.ClientAnchor.Row1, picture.ClientAnchor.Col1);                dictionary[position] = picture.PictureData;            }        }    }    return dictionary;}

CellPosition 是一個自定義的結構體，表示當前單元格的位置，原始碼如下：

public readonly struct CellPosition : IEquatable<CellPosition>{    public CellPosition(int row, int col)    {        Row = row;        Column = col;    }    public int Row { get; }    public int Column { get; }    public bool Equals(CellPosition other)    {        return Row == other.Row && Column == other.Column;    }    public override bool Equals(object? obj) => obj is CellPosition other && Equals(other);    public override int GetHashCode() => $"{Row}_{Column}".GetHashCode();}

根據上面的程式碼，我們就可以獲取到獲取到所有的圖片以及圖片的所在位置，這樣根據單元格位置去找圖片資訊的時候就會很方便了

匯出 Excel 時設定圖片#

實現程式碼如下：

public static bool TryAddPicture(this ISheet sheet, int row, int col, byte[] pictureBytes, PictureType pictureType = PictureType.PNG){    if (sheet is null)    {        throw new ArgumentNullException(nameof(sheet));    }    try    {        var pictureIndex = sheet.Workbook.AddPicture(pictureBytes, pictureType);        var clientAnchor = sheet.Workbook.GetCreationHelper().CreateClientAnchor();        clientAnchor.Row1 = row;        clientAnchor.Col1 = col;        var picture = (sheet.DrawingPatriarch ?? sheet.CreateDrawingPatriarch())            .CreatePicture(clientAnchor, pictureIndex);        picture.Resize();        return true;    }    catch (Exception e)    {        Debug.WriteLine(e);    }    return false;}

透過上面的程式碼我們就可以在指定的單元格設定圖片，目前沒有支援單元格合併操作，有需要自己進行修改

WeihanLi.Npoi#

WeihanLi.Npoi 在 1.15.0 版本中增加了圖片匯入匯出的支援，使用示例可以參考下面的單元測試：

[Theory][ExcelFormatData]public async Task ImageImportExportTest(ExcelFormat excelFormat){    using var httpClient = new HttpClient();    var imageBytes = await httpClient.GetByteArrayAsync("https://weihanli.xyz/assets/avator.jpg");    var list = Enumerable.Range(1, 5)        .Select(x => new ImageTest() { Id = x, Image = imageBytes })        .ToList();    var excelBytes = list.ToExcelBytes(excelFormat);    var importResult = ExcelHelper.ToEntityList<ImageTest>(excelBytes, excelFormat);    Assert.NotNull(importResult);    Assert.Equal(list.Count, importResult.Count);    for (var i = 0; i < list.Count; i++)    {        Assert.NotNull(importResult[i]);        var result = importResult[i]!;        Assert.Equal(list[i].Id, result.Id);        Assert.NotNull(result.Image);        Assert.True(list[i].Image.SequenceEqual(result.Image));    }}private class ImageTest{    public int Id { get; set; }    public byte[] Image { get; set; } = null!;}

匯入時會自動將 byte[] 型別的屬性嘗試獲取對應的單元格位置的圖片，如果在對應的位置找到了圖片就能夠讀取到圖片的位元組陣列資訊對映到 model 裡的位元組陣列屬性

除此之外，還支援直接匯入的時候將圖片資訊 Map 到 IPictureData 屬性上，但是覺得還是位元組陣列更通用一些，如果對此感興趣可以參考專案原始碼以及單元測試

More#

感謝 @ZeguangZhang94 童鞋提出的需求和幫忙測試~

References#https://github.com/WeihanLi/WeihanLi.Npoihttps://github.com/WeihanLi/WeihanLi.Npoi/blob/dev/src/WeihanLi.Npoi/NpoiExtensions.cs#L1143https://stackoverflow.com/questions/24084129/read-image-from-excel-file-using-npoihttps://stackoverflow.com/questions/41138848/add-image-to-excel-xlsx-using-npoi-c-sharphttps://github.com/WeihanLi/WeihanLi.Npoi/issues/99

作者：WeihanLi

出處：https://www.cnblogs.com/weihanli/p/14471773.html