From 24be76616058f259104a67ebc01fcabe1ff7255b Mon Sep 17 00:00:00 2001
From: Vikram Reddy <gvreddy04@gmail.com>
Date: Mon, 22 Jun 2026 20:46:27 +0530
Subject: [PATCH] Enhance PdfViewer download functionality

Refactored the `DownloadPdf` implementation in `PdfViewer.razor.cs` and `PdfViewerJsInterop.cs` to support downloading PDFs from both base64 data and validated URLs. Added error handling for empty URLs and introduced unique filename generation for downloads. Updated JavaScript functions in `blazor.bootstrap.pdf.js` to align with the new interop methods and improve maintainability.
---
 .../Components/PdfViewer/PdfViewer.razor.cs   |  9 +--
 .../PdfViewer/PdfViewerJsInterop.cs           | 16 ++---
 .../wwwroot/blazor.bootstrap.pdf.js           | 62 ++++++++++++++++---
 3 files changed, 68 insertions(+), 19 deletions(-)

diff --git a/blazorbootstrap/Components/PdfViewer/PdfViewer.razor.cs b/blazorbootstrap/Components/PdfViewer/PdfViewer.razor.cs
index 8d59fe9e4..c1d1b82cb 100644
--- a/blazorbootstrap/Components/PdfViewer/PdfViewer.razor.cs
+++ b/blazorbootstrap/Components/PdfViewer/PdfViewer.razor.cs
@@ -113,6 +113,11 @@ public void SetPdfViewerMetaData(PdfViewerModel pdfViewerModel)
             OnPageChanged.InvokeAsync(new PdfViewerEventArgs(pageNumber, pagesCount));
     }
 
+    private async Task DownloadPdf()
+    {
+        await PdfViewerJsInterop!.DownloadPdfAsync(objRef!, Id!, Url!);
+    }
+
     private async Task FirstPageAsync() => await PdfViewerJsInterop!.FirstPageAsync(objRef!, Id!);
 
     private int GetZoomPercentage(int zoomLevel) =>
@@ -225,10 +230,6 @@ private async Task ZoomOutAsync()
         await PdfViewerJsInterop!.ZoomInOutAsync(objRef!, Id!, scale);
     }
 
-    private async Task DownloadPdf()
-    {
-        await PdfViewerJsInterop!.DownloadPdfAsync(Url);
-    }
     #endregion
 
     #region Properties, Indexers
diff --git a/blazorbootstrap/Components/PdfViewer/PdfViewerJsInterop.cs b/blazorbootstrap/Components/PdfViewer/PdfViewerJsInterop.cs
index 15ba1b6d9..6add82a0f 100644
--- a/blazorbootstrap/Components/PdfViewer/PdfViewerJsInterop.cs
+++ b/blazorbootstrap/Components/PdfViewer/PdfViewerJsInterop.cs
@@ -1,5 +1,4 @@
-
-namespace BlazorBootstrap;
+namespace BlazorBootstrap;
 
 public class PdfViewerJsInterop : JsInteropBase
 {
@@ -14,6 +13,14 @@ public PdfViewerJsInterop(IJSRuntime jsRuntime)
 
     #region Methods
 
+    public async Task DownloadPdfAsync(object objRef, string elementId, string url)
+    {
+        if (string.IsNullOrWhiteSpace(url))
+            throw new ArgumentException("URL cannot be null or empty.", nameof(url));
+
+        await SafeInvokeVoidAsync("downloadPdf", objRef, elementId, url);
+    }
+
     public async Task FirstPageAsync(object objRef, string elementId)
     {
         await SafeInvokeVoidAsync("firstPage", objRef, elementId);
@@ -58,10 +65,5 @@ public async Task ZoomInOutAsync(object objRef, string elementId, double scale)
     {
         await SafeInvokeVoidAsync("zoomInOut", objRef, elementId, scale);
     }
-
-    public async Task DownloadPdfAsync(string fileUrl)
-    {
-        await SafeInvokeVoidAsync("downloadPdf", fileUrl);
-    }
     #endregion
 }
diff --git a/blazorbootstrap/wwwroot/blazor.bootstrap.pdf.js b/blazorbootstrap/wwwroot/blazor.bootstrap.pdf.js
index 2f6cd2efd..536eb3bb3 100644
--- a/blazorbootstrap/wwwroot/blazor.bootstrap.pdf.js
+++ b/blazorbootstrap/wwwroot/blazor.bootstrap.pdf.js
@@ -51,6 +51,24 @@ class Pdf {
     }
 }
 
+export function downloadPdf(dotNetHelper, elementId, url) {
+    if (url) {
+        if (url.indexOf('data:') === 0) {
+            const split = url.split(',');
+            const base64Data = split.length > 1 ? split[1] : '';
+            try {
+                saveAsFileFromBase64Data(base64Data);
+            } catch (e) {
+                console.error('Failed to trigger PDF download:', e);
+            }
+        } else {
+            saveAsFileFromUrl(url);
+        }
+    } else {
+        console.error('Pdf Url empty');
+    }
+}
+
 export function firstPage(dotNetHelper, elementId) {
     const pdf = getPdf(elementId);
 
@@ -65,6 +83,11 @@ export function firstPage(dotNetHelper, elementId) {
     setPdfViewerMetaData(dotNetHelper, pdf);
 }
 
+function getUUIDPDFName(prefix = 'document') {
+    const uuid = self.crypto.randomUUID(); // Built-in browser API
+    return `${prefix}-${uuid}.pdf`;
+}
+
 export function gotoPage(dotNetHelper, elementId, gotoPageNum) {
     const pdf = getPdf(elementId);
 
@@ -170,6 +193,37 @@ export function rotate(dotNetHelper, elementId, rotation) {
     queueRenderPage(pdf, pdf.pageNum);
 }
 
+function saveAsFileFromBase64Data(base64Data) {
+    const link = document.createElement('a');
+    link.download = getUUIDPDFName();
+    link.href = "data:application/pdf;base64," + base64Data;
+    link.style.display = 'none'; // Avoid potential layout/scroll quirks
+    document.body.appendChild(link);
+    link.click();
+    document.body.removeChild(link);
+}
+
+function saveAsFileFromUrl(url) {
+    // Validate the URL to ensure it uses an allowed scheme
+    const allowedSchemes = ['http:', 'https:', 'blob:'];
+    try {
+        const parsedUrl = new URL(url, window.location.origin);
+        if (!allowedSchemes.includes(parsedUrl.protocol)) {
+            console.error('Invalid URL scheme:', parsedUrl.protocol);
+            return;
+        }
+    } catch (e) {
+        console.error('Invalid URL:', e);
+        return;
+    }
+
+    var link = document.createElement('a');
+    link.href = url;
+    document.body.appendChild(link);
+    link.click();
+    document.body.removeChild(link);
+}
+
 export function zoomInOut(dotNetHelper, elementId, scale) {
     const pdf = getPdf(elementId);
 
@@ -182,14 +236,6 @@ export function zoomInOut(dotNetHelper, elementId, scale) {
     queueRenderPage(pdf, pdf.pageNum);
 }
 
-export function downloadPdf(fileUrl) {
-    const link = document.createElement('a');
-    link.href = fileUrl;
-    document.body.appendChild(link);
-    link.click();
-    document.body.removeChild(link);
-}
-
 // resize
 // print
 // download