blazor-grid-conditional-formatting/CS/GridConditionalFormatting/Pages/Index.razor at 25.1.4+ · DevExpress-Examples/blazor-grid-conditional-formatting · GitHub

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@page "/"

@using GridConditionalFormatting.Northwind
@using Microsoft.EntityFrameworkCore
@using System.Drawing;
@inject IDbContextFactory<NorthwindContext> NorthwindContextFactory
@implements IDisposable

<div>
    <DxGrid Data="GridDataSource"
            CustomizeElement="OnCustomizeElement">
        <Columns>
            <DxGridDataColumn FieldName="CustomerName" />
            <DxGridDataColumn FieldName="UnitPrice" DisplayFormat="c" />
            <DxGridDataColumn FieldName="Discount" DisplayFormat="P" />
            <DxGridDataColumn FieldName="Quantity" />
            <DxGridDataColumn FieldName="Total" UnboundType="GridUnboundColumnType.Decimal" UnboundExpression="UnitPrice * Quantity" DisplayFormat="c" />
        </Columns>
        <TotalSummary>
            <DxGridSummaryItem SummaryType="GridSummaryItemType.Avg" FieldName="UnitPrice" Name="AvgUnitPrice" />
            <DxGridSummaryItem SummaryType="GridSummaryItemType.Min" FieldName="Quantity" Name="MinQuantity" Visible=false />
            <DxGridSummaryItem SummaryType="GridSummaryItemType.Max" FieldName="Quantity" Name="MaxQuantity" Visible=false />
            <DxGridSummaryItem SummaryType="GridSummaryItemType.Min" FieldName="Total" Name="MinTotal" Visible=false />
            <DxGridSummaryItem SummaryType="GridSummaryItemType.Max" FieldName="Total" Name="MaxTotal" />
        </TotalSummary>
    </DxGrid>
</div>

@code {
    IEnumerable<Invoice> GridDataSource { get; set; }
    NorthwindContext Northwind { get; set; }

    protected override async Task OnInitializedAsync() {
        Northwind = NorthwindContextFactory.CreateDbContext();
        GridDataSource = await Northwind.Invoices.ToListAsync();
    }

    void OnCustomizeElement(GridCustomizeElementEventArgs e) {
        if (e.ElementType == GridElementType.DataCell) {
            var dataColumn = (IGridDataColumn)e.Column;
            switch (dataColumn.FieldName) {
                case "UnitPrice":
                    var averageUnitPrice= Convert.ToDecimal(GetSummaryValue("AvgUnitPrice", e.Grid));
                    var unitPriceValue = Convert.ToDecimal(e.Grid.GetRowValue(e.VisibleIndex, "UnitPrice"));
                    if (unitPriceValue < averageUnitPrice)
                        e.CssClass = "lowUnitPrice";
                    else
                        e.CssClass = "highUnitPrice";
                    break;
                case "Discount":
                    var discountValue = Convert.ToDouble(e.Grid.GetRowValue(e.VisibleIndex, "Discount"));
                    if (discountValue > 0)
                        e.Style = "background-color: #90ee90";
                    break;
                case "Total":
                    int minTotal = Convert.ToInt32(GetSummaryValue("MinTotal", e.Grid));
                    int maxTotal = Convert.ToInt32(GetSummaryValue("MaxTotal", e.Grid));
                    int totalValue = Convert.ToInt32(e.Grid.GetRowValue(e.VisibleIndex, "Total"));
                    e.CssClass = "arrow " + GetArrowCssClass(totalValue, minTotal, maxTotal);
                    break;
                case "Quantity":
                    int minQuantity = Convert.ToInt32(GetSummaryValue("MinQuantity", e.Grid));
                    int maxQuantity = Convert.ToInt32(GetSummaryValue("MaxQuantity", e.Grid));
                    int quantityValue = Convert.ToInt32(e.Grid.GetRowValue(e.VisibleIndex, "Quantity"));
                    Color color = GetCellColor(quantityValue, minQuantity, maxQuantity);
                    e.Style = "background: " + ColorTranslator.ToHtml(color);
                    break;
            }
        }
    }

    object GetSummaryValue(string summaryName, IGrid grid) {
        var summaryItem = grid.GetTotalSummaryItems().Where(i => i.Name == summaryName).First();
        return grid.GetTotalSummaryValue(summaryItem);
    }

    String GetArrowCssClass(int value, int min, int max) {
        int firstRangeEnd = min + (max - min) / 3;
        int secondRangeEnd = max - (max - min) / 3;
        if (value <= firstRangeEnd)
            return "arrow1";
        if (value <= secondRangeEnd)
            return "arrow2";
        return "arrow3";
    }

    Color GetCellColor(int value, int min, int max) {
        int average = (max + min) / 2;
        int range = max - min;
        double maxBrightness = 0.5;
        double distanceToMean = Math.Abs(average - value) / ((double)range / 2);
        double ratio = 1 - maxBrightness * distanceToMean;
        if (value < average)
            return Color.FromArgb(255, Convert.ToInt32(255 * ratio), Convert.ToInt32(255 * ratio));
        if (value == average)
            return Color.FromArgb(255, 255, 255);
        return Color.FromArgb(Convert.ToInt32(255 * ratio), Convert.ToInt32(255 * ratio), 255);
    }

    public void Dispose() {
        Northwind?.Dispose();
    }
}