Write auto column width

[Discolai]

Closes #682
Closes #379
Closes #268

This PR implements writing excel documents with auto column width. The required width is an estimate based on the string length and an average factor based on the Calibri font with size 11pt.

[shps951023]

❤ Reviewed & Merged, please feel free to feedback

[stian-bay]

Could this also check the header column width? The header can be longer than the data. Im setting the header name in the data model like this [ExcelColumn(Name = "My longer column header", Index = 0)]

[Narendin]

@stian-bay try this

List<Dictionary<string, object>> data; // data to export

var headers = data.SelectMany(x => x.Keys).Distinct().Select(x => new DynamicExcelColumn(x)
{
    Width = ExcelWidthCollection.GetApproximateRequiredCalibriWidth(x.Length)
}).ToArray();

var config = new OpenXmlConfiguration
{
    EnableAutoWidth = true,
    FastMode = true,
    DynamicColumns = headers
};

MiniExcel.SaveAs(path, data, configuration: config);

[stian-bay]

@stian-bay try this

List<Dictionary<string, object>> data; // data to export



var headers = data.SelectMany(x => x.Keys).Distinct().Select(x => new DynamicExcelColumn(x)

{

    Width = ExcelWidthCollection.GetApproximateRequiredCalibriWidth(x.Length)

}).ToArray();



var config = new OpenXmlConfiguration

{

    EnableAutoWidth = true,

    FastMode = true,

    DynamicColumns = headers

};



MiniExcel.SaveAs(path, data, configuration: config);

Ah cool, I will try this. Thanks

[stian-bay]

Got it working in my dynamic method like this. Maybe a little more complex, but this seems to be working great 🎉

public static MemoryStream Export<T>(IEnumerable<T> data)
{
    var columns = typeof(T)
        .GetProperties()
        .Select(p => new { Property = p, Attribute = p.GetCustomAttribute<ExcelColumnAttribute>() })
        .Select(x => new DynamicExcelColumn(x.Property.Name)
        {
            Name = x.Attribute?.Name,
            Width = ExcelWidthCollection.GetApproximateTextWidth(x.Attribute?.Name?.Length ?? x.Property.Name.Length) + 1
        })
        .ToArray();

    var config = ExportSettings.DefaultConfiguration;

    config.DynamicColumns = columns;

    var memoryStream = new MemoryStream();
    memoryStream.SaveAs(data, configuration: config);
    memoryStream.Seek(0, SeekOrigin.Begin);

    return memoryStream;
}