Svg thumbnail failed rendering (#32936)

* [SVGThumbnail] Check fill-rule in SVG file and apply it.

* [SVGThumbnail] Comment added

* [SVGThumbnail] SvgContents is used instead of all html content.

* [SVGThumbnail] - Use SvgContents to extract and modify SVG styles efficiently
- Add retry logic and error handling for WebView2 initialization

* use Linq

---------

Co-authored-by: Jaime Bernardo <jaime@janeasystems.com>
Co-authored-by: Leilei Zhang <leilzh@microsoft.com>

src/modules/previewpane/SvgThumbnailProvider/SvgThumbnailProvider.cs

@@ -5,8 +5,7 @@ using System.Drawing.Drawing2D;
 using System.Globalization;
 using System.Reflection;
 using System.Runtime.CompilerServices;
-using System.Threading;
+using System.Xml.Linq;
-
 using Common.Utilities;
 using ManagedCommon;
 using Microsoft.Web.WebView2.Core;
@@ -118,10 +117,51 @@ namespace Microsoft.PowerToys.ThumbnailHandler.Svg
             _browser.Height = (int)cx;
             _browser.NavigationCompleted += async (object sender, CoreWebView2NavigationCompletedEventArgs args) =>
             {
+                try
+                {
+                    // Check if the SVG element is present
                     var a = await _browser.ExecuteScriptAsync($"document.getElementsByTagName('svg')[0].viewBox;");
                     if (a != null)
                     {
-                    await _browser.ExecuteScriptAsync($"document.getElementsByTagName('svg')[0].style = 'width:100%;height:100%';");
+                        var svgContent = SvgContents.Substring(SvgContents.IndexOf("<svg", StringComparison.OrdinalIgnoreCase), SvgContents.IndexOf("</svg>", StringComparison.OrdinalIgnoreCase) - SvgContents.IndexOf("<svg", StringComparison.OrdinalIgnoreCase) + "</svg>".Length);
+
+                        Dictionary<string, string> styleDict = new Dictionary<string, string>();
+
+                        // Try to parse the SVG content
+                        try
+                        {
+                            // Attempt to parse the svgContent
+                            var svgDocument = XDocument.Parse(svgContent);
+                            var svgElement = svgDocument.Root;
+                            var currentStyle = svgElement?.Attribute("style")?.Value;
+
+                            // If style attribute exists, preserve existing styles
+                            if (!string.IsNullOrEmpty(currentStyle) && currentStyle != "null")
+                            {
+                                styleDict = currentStyle
+                                    .Split(';', StringSplitOptions.RemoveEmptyEntries)
+                                    .Select(stylePart => stylePart.Split(':', 2, StringSplitOptions.TrimEntries))
+                                    .Where(styleKeyValue => styleKeyValue.Length == 2 && !string.IsNullOrEmpty(styleKeyValue[0]))
+                                    .ToDictionary(
+                                        styleKeyValue => styleKeyValue[0],
+                                        styleKeyValue => styleKeyValue[1]);
+                            }
+                        }
+                        catch (Exception ex)
+                        {
+                            // Log the error if the SVG content is not valid or parsing fails
+                            Logger.LogError($"Failed to parse SVG content: {ex.Message}");
+                        }
+
+                        // Add or replace width and height in the existing style
+                        styleDict["width"] = "100%";
+                        styleDict["height"] = "100%";
+
+                        // Construct a single JavaScript string to set all properties
+                        var styleScript = string.Join(";", styleDict.Select(kv => $"document.getElementsByTagName('svg')[0].style.setProperty('{kv.Key}', '{kv.Value}');"));
+
+                        // Apply the new style attributes using the constructed script
+                        await _browser.ExecuteScriptAsync(styleScript);
                     }
 
                     // Hide scrollbar - fixes #18286
@@ -142,6 +182,12 @@ namespace Microsoft.PowerToys.ThumbnailHandler.Svg
                     }
 
                     thumbnailDone.Set();
+                }
+                catch (Exception ex)
+                {
+                    Logger.LogError("Error during NavigationCompleted: ", ex);
+                    thumbnailDone.Set();
+                }
             };
 
             var webView2Options = new CoreWebView2EnvironmentOptions("--block-new-web-contents");
@@ -151,6 +197,8 @@ namespace Microsoft.PowerToys.ThumbnailHandler.Svg
                     .ConfigureAwait(true).GetAwaiter();
 
             webView2EnvironmentAwaiter.OnCompleted(async () =>
+            {
+                for (int attempt = 0; attempt < 3; attempt++)
                 {
                     try
                     {
@@ -198,11 +246,21 @@ namespace Microsoft.PowerToys.ThumbnailHandler.Svg
                         {
                             _browser.NavigateToString(SvgContents);
                         }
+
+                        break; // Exit the retry loop if initialization succeeds
                     }
                     catch (Exception ex)
+                    {
+                        Logger.LogError($"Initialization attempt {attempt} failed: {ex.Message}");
+                        if (attempt == 2)
                         {
                             Logger.LogError($"Failed running webView2Environment completed for {FilePath} : ", ex);
                             thumbnailDone.Set();
+                            return;
+                        }
+
+                        await Task.Delay(1000); // Delay before retrying
+                    }
                 }
             });