Introduce OmitBackground option on PrintToPdf (#1812)

Author: kblok

lib/PuppeteerSharp/Page.cs

@@ -986,6 +986,11 @@ internal async Task<byte[]> PdfInternalAsync(string file, PdfOptions options)
             var marginBottom = ConvertPrintParameterToInches(options.MarginOptions.Bottom);
             var marginRight = ConvertPrintParameterToInches(options.MarginOptions.Right);
 
+            if (options.OmitBackground)
+            {
+                await SetTransparentBackgroundColorAsync().ConfigureAwait(false);
+            }
+
             var result = await Client.SendAsync<PagePrintToPDFResponse>("Page.printToPDF", new PagePrintToPDFRequest
             {
                 TransferMode = "ReturnAsStream",
@@ -1005,6 +1010,11 @@ internal async Task<byte[]> PdfInternalAsync(string file, PdfOptions options)
                 PreferCSSPageSize = options.PreferCSSPageSize
             }).ConfigureAwait(false);
 
+            if (options.OmitBackground)
+            {
+                await ResetDefaultBackgroundColorAsync().ConfigureAwait(false);
+            }
+
             return await ProtocolStreamReader.ReadProtocolStreamByteAsync(Client, result.Stream, file).ConfigureAwait(false);
         }
 
@@ -1976,16 +1986,7 @@ private async Task<string> PerformScreenshot(ScreenshotType type, ScreenshotOpti
 
                 if (options?.OmitBackground == true && type == ScreenshotType.Png)
                 {
-                    await Client.SendAsync("Emulation.setDefaultBackgroundColorOverride", new EmulationSetDefaultBackgroundColorOverrideRequest
-                    {
-                        Color = new EmulationSetDefaultBackgroundColorOverrideColor
-                        {
-                            R = 0,
-                            G = 0,
-                            B = 0,
-                            A = 0
-                        }
-                    }).ConfigureAwait(false);
+                    await SetTransparentBackgroundColorAsync().ConfigureAwait(false);
                 }
             }
 
@@ -2036,12 +2037,27 @@ private Clip ProcessClip(Clip clip)
         private Task ResetBackgroundColorAndViewportAsync(ScreenshotOptions options)
         {
             var omitBackgroundTask = options?.OmitBackground == true && options.Type == ScreenshotType.Png ?
-                Client.SendAsync("Emulation.setDefaultBackgroundColorOverride") : Task.CompletedTask;
+                ResetDefaultBackgroundColorAsync() : Task.CompletedTask;
             var setViewPortTask = (options?.FullPage == true && Viewport != null) ?
                 SetViewportAsync(Viewport) : Task.CompletedTask;
             return Task.WhenAll(omitBackgroundTask, setViewPortTask);
         }
 
+        private Task ResetDefaultBackgroundColorAsync()
+            => Client.SendAsync("Emulation.setDefaultBackgroundColorOverride");
+
+        private Task SetTransparentBackgroundColorAsync()
+            => Client.SendAsync("Emulation.setDefaultBackgroundColorOverride", new EmulationSetDefaultBackgroundColorOverrideRequest
+            {
+                Color = new EmulationSetDefaultBackgroundColorOverrideColor
+                {
+                    R = 0,
+                    G = 0,
+                    B = 0,
+                    A = 0
+                }
+            });
+
         private decimal ConvertPrintParameterToInches(object parameter)
         {
             if (parameter == null)

lib/PuppeteerSharp/PdfOptions.cs

@@ -87,6 +87,11 @@ public PdfOptions()
         /// </summary>
         public bool PreferCSSPageSize { get; set; }
 
+        /// <summary>
+        /// Hides default white background and allows generating pdfs with transparency.
+        /// </summary>
+        public bool OmitBackground { get; set; }
+
         /// <inheritdoc/>
         public override bool Equals(object obj)
         {
@@ -112,7 +117,8 @@ public bool Equals(PdfOptions options)
                    EqualityComparer<object>.Default.Equals(Width, options.Width) &&
                    EqualityComparer<object>.Default.Equals(Height, options.Height) &&
                    EqualityComparer<MarginOptions>.Default.Equals(MarginOptions, options.MarginOptions) &&
-                   PreferCSSPageSize == options.PreferCSSPageSize;
+                   PreferCSSPageSize == options.PreferCSSPageSize &&
+                   OmitBackground == options.OmitBackground;
 
         /// <inheritdoc/>
         public override int GetHashCode()
@@ -122,6 +128,7 @@ public override int GetHashCode()
                 ^ EqualityComparer<string>.Default.GetHashCode(HeaderTemplate)
                 ^ EqualityComparer<string>.Default.GetHashCode(FooterTemplate)
                 ^ PrintBackground.GetHashCode()
+                ^ OmitBackground.GetHashCode()
                 ^ Landscape.GetHashCode()
                 ^ EqualityComparer<string>.Default.GetHashCode(PageRanges)
                 ^ EqualityComparer<PaperFormat>.Default.GetHashCode(Format)