Allow screenshot to return a base64 string (#541)

* Allow screenshot to return a base64 string

* Code Factor

Author: kblok

lib/PuppeteerSharp.Tests/PageTests/ScreenshotTests.cs

@@ -256,6 +256,23 @@ public async Task ShouldWorkWithOddClipSizeOnRetinaDisplays()
             }
         }
 
+        [Fact]
+        public async Task ShouldReturnBase64()
+        {
+            using (var page = await Browser.NewPageAsync())
+            {
+                await page.SetViewportAsync(new ViewPortOptions
+                {
+                    Width = 500,
+                    Height = 500
+                });
+                await page.GoToAsync(TestConstants.ServerUrl + "/grid.html");
+                var screenshot = await page.ScreenshotBase64Async();
+
+                Assert.True(ScreenshotHelper.PixelMatch("screenshot-sanity.png", Convert.FromBase64String(screenshot)));
+            }
+        }
+
         [Fact]
         public void ShouldInferScreenshotTypeFromName()
         {

lib/PuppeteerSharp/ElementHandle.cs

@@ -98,6 +98,22 @@ public async Task<Stream> ScreenshotStreamAsync(ScreenshotOptions options)
         /// <returns>Task which resolves to a <see cref="byte"/>[] containing the image data.</returns>
         /// <param name="options">Screenshot options.</param>
         public async Task<byte[]> ScreenshotDataAsync(ScreenshotOptions options)
+            => Convert.FromBase64String(await ScreenshotBase64Async(options).ConfigureAwait(false));
+
+        /// <summary>
+        /// This method scrolls element into view if needed, and then uses <seealso cref="Page.ScreenshotBase64Async(ScreenshotOptions)"/> to take a screenshot of the element. 
+        /// If the element is detached from DOM, the method throws an error.
+        /// </summary>
+        /// <returns>Task which resolves to a <see cref="string"/> containing the image data as base64.</returns>
+        public Task<string> ScreenshotBase64Async() => ScreenshotBase64Async(new ScreenshotOptions());
+
+        /// <summary>
+        /// This method scrolls element into view if needed, and then uses <seealso cref="Page.ScreenshotBase64Async(ScreenshotOptions)"/> to take a screenshot of the element. 
+        /// If the element is detached from DOM, the method throws an error.
+        /// </summary>
+        /// <returns>Task which resolves to a <see cref="string"/> containing the image data as base64.</returns>
+        /// <param name="options">Screenshot options.</param>
+        public async Task<string> ScreenshotBase64Async(ScreenshotOptions options)
         {
             var needsViewportReset = false;
             var boundingBox = await AssertBoundingBoxAsync().ConfigureAwait(false);
@@ -126,7 +142,7 @@ await ExecutionContext.EvaluateFunctionAsync(@"function(element) {
             clip.Y += getLayoutMetricsResponse.LayoutViewport.PageY;
 
             options.Clip = boundingBox.ToClip();
-            var imageData = await Page.ScreenshotDataAsync(options).ConfigureAwait(false);
+            var imageData = await Page.ScreenshotBase64Async(options).ConfigureAwait(false);
 
             if (needsViewportReset)
             {

lib/PuppeteerSharp/Helpers/TaskQueue.cs

@@ -6,7 +6,7 @@ namespace PuppeteerSharp.Helpers
 {
     internal class TaskQueue
     {
-        private SemaphoreSlim _semaphore;
+        private readonly SemaphoreSlim _semaphore;
 
         internal TaskQueue()
         {

lib/PuppeteerSharp/Page.cs

@@ -78,7 +78,8 @@ private Page(CDPSession client, Target target, FrameTree frameTree, bool ignoreH
             _networkManager.Response += (sender, e) => Response?.Invoke(this, e);
             _networkManager.RequestFinished += (sender, e) => RequestFinished?.Invoke(this, e);
 
-            target.CloseTask.ContinueWith((arg) => {
+            target.CloseTask.ContinueWith((arg) =>
+            {
                 Close?.Invoke(this, EventArgs.Empty);
                 IsClosed = true;
             });
@@ -955,15 +956,15 @@ public async Task<Stream> ScreenshotStreamAsync(ScreenshotOptions options)
         /// <summary>
         /// Takes a screenshot of the page
         /// </summary>
-        /// <returns>Task which resolves to a <see cref="byte"/>[] containing the image data.</returns>
-        public Task<byte[]> ScreenshotDataAsync() => ScreenshotDataAsync(new ScreenshotOptions());
+        /// <returns>Task which resolves to a <see cref="string"/> containing the image data as base64.</returns>
+        public Task<string> ScreenshotBase64Async() => ScreenshotBase64Async(new ScreenshotOptions());
 
         /// <summary>
         /// Takes a screenshot of the page
         /// </summary>
-        /// <returns>Task which resolves to a <see cref="byte"/>[] containing the image data.</returns>
+        /// <returns>Task which resolves to a <see cref="string"/> containing the image data as base64.</returns>
         /// <param name="options">Screenshot options.</param>
-        public Task<byte[]> ScreenshotDataAsync(ScreenshotOptions options)
+        public Task<string> ScreenshotBase64Async(ScreenshotOptions options)
         {
             var screenshotType = options.Type;
 
@@ -993,6 +994,20 @@ public Task<byte[]> ScreenshotDataAsync(ScreenshotOptions options)
             return _screenshotTaskQueue.Enqueue(() => PerformScreenshot(screenshotType.Value, options));
         }
 
+        /// <summary>
+        /// Takes a screenshot of the page
+        /// </summary>
+        /// <returns>Task which resolves to a <see cref="byte"/>[] containing the image data.</returns>
+        public Task<byte[]> ScreenshotDataAsync() => ScreenshotDataAsync(new ScreenshotOptions());
+
+        /// <summary>
+        /// Takes a screenshot of the page
+        /// </summary>
+        /// <returns>Task which resolves to a <see cref="byte"/>[] containing the image data.</returns>
+        /// <param name="options">Screenshot options.</param>
+        public async Task<byte[]> ScreenshotDataAsync(ScreenshotOptions options)
+            => Convert.FromBase64String(await ScreenshotBase64Async(options).ConfigureAwait(false));
+
         /// <summary>
         /// Returns page's title
         /// </summary>
@@ -1022,10 +1037,8 @@ public Task CloseAsync(PageCloseOptions options = null)
                     }).ContinueWith((task) => Target.CloseTask);
                 }
             }
-            else
-            {
-                _logger.LogWarning("Protocol error: Connection closed. Most likely the page has been closed.");
-            }
+
+            _logger.LogWarning("Protocol error: Connection closed. Most likely the page has been closed.");
             return Task.CompletedTask;
         }
 
@@ -1457,7 +1470,7 @@ private Dictionary<string, decimal> BuildMetricsObject(List<Metric> metrics)
             return result;
         }
 
-        private async Task<byte[]> PerformScreenshot(ScreenshotType type, ScreenshotOptions options)
+        private async Task<string> PerformScreenshot(ScreenshotType type, ScreenshotOptions options)
         {
             await Client.SendAsync("Target.activateTarget", new
             {
@@ -1551,9 +1564,7 @@ private async Task<byte[]> PerformScreenshot(ScreenshotType type, ScreenshotOpti
                 await SetViewportAsync(Viewport).ConfigureAwait(false);
             }
 
-            var buffer = Convert.FromBase64String(result.GetValue("data").Value<string>());
-
-            return buffer;
+            return result.GetValue("data").Value<string>();
         }
 
         private decimal ConvertPrintParameterToInches(object parameter)