EnvelopeGenerator/EnvelopeGenerator.ReceiverUI/Pages/ReportViewer.razor

@page "/reportviewer/"
@using System.Drawing
@using DevExpress.Drawing
@using DevExpress.Utils
@using DevExpress.XtraPrinting
@using DevExpress.XtraPrinting.Drawing
@using DevExpress.XtraReports.UI;
@using EnvelopeGenerator.ReceiverUI.Services;
@inject IJSRuntime JSRuntime
@inject InMemoryReportStorageWebExtension ReportStorage

<link href="_content/DevExpress.Blazor.Themes/blazing-berry.bs5.min.css" rel="stylesheet" />
<link href="_content/DevExpress.Blazor.Reporting.Viewer/css/dx-blazor-reporting-components.bs5.css" rel="stylesheet" />

<div class="card m-3">
    <div class="card-body">
        <h5 class="card-title">Unterschrift</h5>
        <p class="card-text text-muted mb-2">
            @if(SignatureApplied) {
                <span>Die Unterschrift wurde dem Bericht hinzugefuegt. Sie koennen die Unterschrift erneuern oder das signierte PDF exportieren.</span>
            } else {
                <span>Bitte fuegen Sie vor dem PDF-Export Ihre Unterschrift hinzu.</span>
            }
        </p>
        @if(!string.IsNullOrWhiteSpace(SignatureValidationMessage)) {
            <div class="text-danger mb-2">@SignatureValidationMessage</div>
        }
        <div class="d-flex gap-2 flex-wrap">
            <button class="btn btn-primary" @onclick="OpenSignaturePopupAsync">
                @(SignatureApplied ? "Unterschrift erneuern" : "Unterschrift hinzufuegen")
            </button>
            <button class="btn btn-success" disabled="@(!SignatureApplied)" @onclick="ExportSignedPdfAsync">Signiertes PDF exportieren</button>
        </div>
    </div>
</div>

<DxPopup @bind-Visible="SignaturePopupVisible"
         HeaderText="Unterschrift erfassen"
         Width="520px"
         ShowFooter="true"
         CloseOnEscape="true"
         CloseOnOutsideClick="false">
    <BodyContentTemplate>
        <p class="text-muted mb-2">Bitte unterschreiben Sie im folgenden Feld.</p>
        <canvas id="receiver-signature-pad" width="420" height="150" class="border rounded bg-white w-100" style="max-width: 420px; touch-action: none;"></canvas>
        @if(!string.IsNullOrWhiteSpace(PopupValidationMessage)) {
            <div class="text-danger mt-2">@PopupValidationMessage</div>
        }
    </BodyContentTemplate>
    <FooterContentTemplate>
        <div class="d-flex gap-2 flex-wrap justify-content-end w-100">
            <button class="btn btn-outline-secondary" @onclick="RenewSignatureAsync">Unterschrift erneuern</button>
            <button class="btn btn-primary" @onclick="ApplySignatureAsync">Zum Bericht hinzufuegen</button>
            <button class="btn btn-secondary" @onclick="CloseSignaturePopup">Schliessen</button>
        </div>
    </FooterContentTemplate>
</DxPopup>

@if(Report is not null) {
    <DxReportViewer @key="ViewerKey" @ref="reportViewer" Report="Report" RootCssClasses="w-100 h-100" />
}

@code {
    DxReportViewer reportViewer;
    XtraReport? Report;
    bool SignatureApplied;
    bool SignaturePopupVisible;
    string? SignatureValidationMessage;
    string? PopupValidationMessage;
    int ViewerKey;

    protected override async Task OnInitializedAsync() {
        Report = CreateReportInstance();

        await Task.CompletedTask;
    }

    async Task OpenSignaturePopupAsync() {
        SignaturePopupVisible = true;
        SignatureValidationMessage = null;
        PopupValidationMessage = null;
        await InvokeAsync(StateHasChanged);
        await Task.Delay(50);
        await JSRuntime.InvokeVoidAsync("receiverSignature.initialize", "receiver-signature-pad");
    }

    async Task RenewSignatureAsync() {
        PopupValidationMessage = null;
        await JSRuntime.InvokeVoidAsync("receiverSignature.clear", "receiver-signature-pad");
    }

    void CloseSignaturePopup() {
        PopupValidationMessage = null;
        SignaturePopupVisible = false;
    }

    async Task ApplySignatureAsync() {
        var signatureDataUrl = await JSRuntime.InvokeAsync<string?>("receiverSignature.getDataUrl", "receiver-signature-pad");

        if(string.IsNullOrWhiteSpace(signatureDataUrl)) {
            PopupValidationMessage = "Die Unterschrift ist fuer den PDF-Export erforderlich.";
            return;
        }

        PopupValidationMessage = null;
        SignatureValidationMessage = null;
        Report = CreateSignedReportInstance(signatureDataUrl);
        SignatureApplied = true;
        SignaturePopupVisible = false;
        ViewerKey++;
    }

    async Task ExportSignedPdfAsync() {
        if(!SignatureApplied || Report is null) {
            SignatureValidationMessage = "Bitte fuegen Sie die Unterschrift zuerst zum Bericht hinzu.";
            return;
        }

        try {
            SignatureValidationMessage = null;
            await reportViewer.ExportToAsync(ExportFormat.Pdf);
        } catch(Exception) {
            SignatureValidationMessage = "Das signierte PDF konnte nicht exportiert werden. Bitte laden Sie die Seite neu und versuchen Sie es erneut.";
        }
    }

    XtraReport CreateReportInstance() {
        return ReportStorage.TryGetReport("LargeDatasetReport", out var savedReport)
            ? savedReport
            : PredefinedReports.ReportsFactory.GetReport("LargeDatasetReport");
    }

    XtraReport CreateSignedReportInstance(string signatureDataUrl) {
        var report = CreateReportInstance();
        AddSignature(report, signatureDataUrl);
        return report;
    }

    static void AddSignature(XtraReport report, string signatureDataUrl) {
        var imageBytes = Convert.FromBase64String(signatureDataUrl[(signatureDataUrl.IndexOf(',') + 1)..]);
        using var imageStream = new MemoryStream(imageBytes);
        var imageSource = new ImageSource(DXImage.FromStream(imageStream));
        var bottomMargin = report.Bands.OfType<BottomMarginBand>().FirstOrDefault();

        if(bottomMargin is null) {
            bottomMargin = new BottomMarginBand();
            report.Bands.Add(bottomMargin);
        }

        bottomMargin.HeightF = Math.Max(bottomMargin.HeightF, 120F);
        RemoveExistingSignature(bottomMargin);

        var signatureLabel = new XRLabel {
            Name = "receiverSignatureLabel",
            Text = $"Empfaengerunterschrift - {DateTime.Now:g}",
            BoundsF = new RectangleF(390F, 6F, 230F, 18F),
            Font = new DXFont("Open Sans", 8F, DXFontStyle.Bold),
            ForeColor = System.Drawing.Color.FromArgb(73, 80, 87),
            TextAlignment = TextAlignment.MiddleLeft
        };

        var signature = new XRPictureBox {
            Name = "receiverSignatureImage",
            ImageSource = imageSource,
            BoundsF = new RectangleF(390F, 28F, 230F, 70F),
            Sizing = ImageSizeMode.ZoomImage,
            Borders = BorderSide.Bottom,
            BorderColor = System.Drawing.Color.FromArgb(73, 80, 87)
        };

        bottomMargin.Controls.AddRange(new XRControl[] { signatureLabel, signature });
    }

    static void RemoveExistingSignature(BottomMarginBand bottomMargin) {
        var controls = bottomMargin.Controls
            .Cast<XRControl>()
            .Where(control => control.Name is "receiverSignatureLabel" or "receiverSignatureImage")
            .ToArray();

        foreach(var control in controls)
            bottomMargin.Controls.Remove(control);
    }
}