Add a new option to preserve transparency

readme.md

@@ -33,7 +33,7 @@ public static class ModuleInitializer
     public static void Initialize()
     {
         VerifyDocNet.Initialize();
-        VerifyImageMagick.RegisterComparers(threshold: 0.05, ImageMagick.ErrorMetric.PerceptualHash);
+        VerifyImageMagick.RegisterComparers(threshold: 0.13, ImageMagick.ErrorMetric.PerceptualHash);
     }
 }
 ```
@@ -50,10 +50,11 @@ public static class ModuleInitializer
 public Task VerifyPdf()
 {
     return Verifier.VerifyFile("sample.pdf")
+        .PreserveTransparency()
         .PageDimensions(new(1080, 1920));
 }
 ```
-<sup><a href='/src/Tests/Samples.cs#L10-L19' title='Snippet source file'>snippet source</a> | <a href='#snippet-verifypdf' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Tests/Samples.cs#L10-L20' title='Snippet source file'>snippet source</a> | <a href='#snippet-verifypdf' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 
@@ -70,7 +71,7 @@ public Task VerifyPdfStream()
         .PageDimensions(new(1080, 1920));
 }
 ```
-<sup><a href='/src/Tests/Samples.cs#L21-L31' title='Snippet source file'>snippet source</a> | <a href='#snippet-verifypdfstream' title='Start of snippet'>anchor</a></sup>
+<sup><a href='/src/Tests/Samples.cs#L22-L32' title='Snippet source file'>snippet source</a> | <a href='#snippet-verifypdfstream' title='Start of snippet'>anchor</a></sup>
 <!-- endSnippet -->
 
 

src/Tests/ModuleInitializer.cs

@@ -7,6 +7,6 @@ public static class ModuleInitializer
     public static void Initialize()
     {
         VerifyDocNet.Initialize();
-        VerifyImageMagick.RegisterComparers(threshold: 0.05, ImageMagick.ErrorMetric.PerceptualHash);
+        VerifyImageMagick.RegisterComparers(threshold: 0.13, ImageMagick.ErrorMetric.PerceptualHash);
     }
 }

src/Tests/Samples.cs

@@ -13,6 +13,7 @@ public class Samples
     public Task VerifyPdf()
     {
         return Verifier.VerifyFile("sample.pdf")
+            .PreserveTransparency()
             .PageDimensions(new(1080, 1920));
     }
 

src/Verify.DocNet/VerifyDocNet.cs

@@ -54,5 +54,26 @@ static PageDimensions GetPageDimensions(this IReadOnlyDictionary<string, object>
 
             return pageDimensions;
         }
+
+        public static void PreserveTransparency(this VerifySettings settings)
+        {
+            settings.Context["VerifyDocNetPreserveTransparency"] = true;
+        }
+
+        public static SettingsTask PreserveTransparency(this SettingsTask settings)
+        {
+            settings.CurrentSettings.PreserveTransparency();
+            return settings;
+        }
+
+        static bool GetPreserveTransparency(this IReadOnlyDictionary<string, object> settings, bool preserveTransparency)
+        {
+            if (settings.TryGetValue("VerifyDocNetPreserveTransparency", out var value))
+            {
+                return (bool)value;
+            }
+
+            return preserveTransparency;
+        }
     }
 }

src/Verify.DocNet/VerifyDocNet_Pdf.cs

@@ -26,16 +26,17 @@ static ConversionResult Convert(IDocReader document, IReadOnlyDictionary<string,
             return new(null, targets);
         }
 
-        static NaiveTransparencyRemover transparencyRemover = new();
+        static readonly NaiveTransparencyRemover TransparencyRemover = new();
 
         static IEnumerable<Target> GetStreams(IDocReader document, IReadOnlyDictionary<string, object> settings)
         {
             var pagesToInclude = settings.GetPagesToInclude(document.GetPageCount());
+            var preserveTransparency = settings.GetPreserveTransparency(false);
             for (var index = 0; index < pagesToInclude; index++)
             {
                 using var reader = document.GetPageReader(index);
 
-                var rawBytes = reader.GetImage(transparencyRemover);
+                var rawBytes = preserveTransparency ? reader.GetImage() : reader.GetImage(TransparencyRemover);
 
                 var width = reader.GetPageWidth();
                 var height = reader.GetPageHeight();