Refactor PDF editor with custom rendering

Replaced `DxPdfViewer` with a custom PDF rendering solution in `SenderPdfImageEditor` to improve flexibility and control. Added support for displaying placeholder messages and interactive signature fields. Introduced the `SenderPdfFieldOverlay` record to encapsulate field data.

Updated `SenderEditorPage` logic to manage page counts, image URLs, and field overlays. Added a method to estimate PDF page counts. Refactored field removal logic to use index-based operations.

Enhanced styling in `envelope-viewer.css` for improved layout and responsiveness. Updated localization files with new strings for page labels and placeholders. Adjusted JavaScript selectors in `envelope-editor.js` to support the new rendering approach.

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Components/PdfEditor/SenderPdfFieldOverlay.cs

@@ -0,0 +1,9 @@
+namespace EnvelopeGenerator.Server.Client.Components.PdfEditor;
+
+public sealed record SenderPdfFieldOverlay(
+    int Index,
+    int Page,
+    double XPt,
+    double YPt,
+    string ReceiverName,
+    string Color);

EnvelopeGenerator.Server/EnvelopeGenerator.Server.Client/Components/PdfEditor/SenderPdfImageEditor.razor

@@ -1,31 +1,110 @@
-@using DevExpress.Blazor.PdfViewer
+@using EnvelopeGenerator.Application.Resources
+@using Microsoft.Extensions.Localization
+@inject IStringLocalizer<Resource> UiLocalizer
 
-<div class="pdf-editor-wrapper"
+<div class="pdf-editor-wrapper sender-image-editor sender-editor-pdf-viewer"
      style="cursor: @(IsPlacementMode ? "crosshair" : "default");"
      @onclick="HandleClickAsync">
-    @if (PdfBytes is { Length: > 0 })
+    @if (PageCount <= 0)
     {
-        <DxPdfViewer DocumentContent="@PdfBytes"
-                     CssClass="@ViewerCssClass" />
+        <div class="sender-image-editor__empty">@L("SenderEditor_NoPagesToDisplay", "Keine Seiten zur Anzeige verfügbar.")</div>
+    }
+    else
+    {
+        @if (PageImageDataUrls.Count == 0 && !string.IsNullOrWhiteSpace(PdfDataUrl))
+        {
+            <div class="sender-image-editor__native-preview">
+                <iframe class="sender-image-editor__native-frame"
+                        src="@PdfDataUrl"
+                        title="PDF Preview"></iframe>
+            </div>
+        }
+
+        <div class="sender-image-editor__pages">
+            @for (var pageNumber = 1; pageNumber <= PageCount; pageNumber++)
+            {
+                <div class="sender-image-editor__page-block"
+                     data-editor-page="@pageNumber"
+                     data-page-width-pt="595"
+                     data-page-height-pt="842">
+                    <div class="sender-image-editor__page-canvas">
+                        @if (PageImageDataUrls.TryGetValue(pageNumber, out var imageDataUrl) && !string.IsNullOrWhiteSpace(imageDataUrl))
+                        {
+                            <img class="sender-image-editor__page-image"
+                                 src="@imageDataUrl"
+                                 alt="PDF Page @pageNumber"
+                                 draggable="false" />
+                        }
+                        else
+                        {
+                            <div class="sender-image-editor__page-placeholder">@L("SenderEditor_PageLabel", "Seite") @pageNumber</div>
+                        }
+
+                        @foreach (var field in Fields.Where(f => f.Page == pageNumber))
+                        {
+                            <button type="button"
+                                    class="sender-image-editor__field"
+                                    style="@GetFieldStyle(field)"
+                                    title="@field.ReceiverName"
+                                    @onclick:stopPropagation="true"
+                                    @onclick="() => RemoveField.InvokeAsync(field.Index)">
+                                @field.ReceiverName
+                            </button>
+                        }
+                    </div>
+                </div>
+            }
+        </div>
     }
 </div>
 
 @code {
-    [Parameter]
-    public byte[]? PdfBytes { get; set; }
-
     [Parameter]
     public bool IsPlacementMode { get; set; }
 
     [Parameter]
-    public string ViewerCssClass { get; set; } = "sender-editor-pdf-viewer";
+    public int PageCount { get; set; }
+
+    [Parameter]
+    public IReadOnlyDictionary<int, string> PageImageDataUrls { get; set; } = new Dictionary<int, string>();
+
+    [Parameter]
+    public string? PdfDataUrl { get; set; }
+
+    [Parameter]
+    public IReadOnlyList<SenderPdfFieldOverlay> Fields { get; set; } = Array.Empty<SenderPdfFieldOverlay>();
 
     [Parameter]
     public EventCallback<MouseEventArgs> EditorClick { get; set; }
 
+    [Parameter]
+    public EventCallback<int> RemoveField { get; set; }
+
+    private static string GetFieldStyle(SenderPdfFieldOverlay field)
+    {
+        var leftPercent = (field.XPt / 595.0) * 100.0;
+        var topPercent = (field.YPt / 842.0) * 100.0;
+        var widthPercent = (127.44 / 595.0) * 100.0;
+        var heightPercent = (141.12 / 842.0) * 100.0;
+
+        return string.Join(' ',
+            $"left:{leftPercent:F4}%;",
+            $"top:{topPercent:F4}%;",
+            $"width:{widthPercent:F4}%;",
+            $"height:{heightPercent:F4}%;",
+            $"border-color:{field.Color};",
+            $"background-color:{field.Color}22;");
+    }
+
     private async Task HandleClickAsync(MouseEventArgs args)
     {
         if (EditorClick.HasDelegate)
             await EditorClick.InvokeAsync(args);
     }
+
+    private string L(string key, string fallback)
+    {
+        var value = UiLocalizer[key];
+        return value.ResourceNotFound ? fallback : value.Value;
+    }
 }