WinForms - Add CaptureScreenshotAsync

- Simplification of calling the DevTools method
- Moved GetContentSizeAsync from OffScreen into partial class (now accessible from WinForms/WPF/OffScreen).
- Added menu option

Resolves #4081

Author: amaitland

CefSharp.OffScreen/ChromiumWebBrowser.cs

@@ -643,24 +643,6 @@ public Task ResizeAsync(int width, int height, float? deviceScaleFactor = null)
             return tcs.Task;
         }
 
-        /// <summary>
-        /// Size of scrollable area in CSS pixels
-        /// </summary>
-        /// <returns>A task that can be awaited to get the size of the scrollable area in CSS pixels.</returns>
-        public async Task<DevTools.DOM.Rect> GetContentSizeAsync()
-        {
-            ThrowExceptionIfDisposed();
-            ThrowExceptionIfBrowserNotInitialized();
-
-            using (var devToolsClient = browser.GetDevToolsClient())
-            {
-                //Get the content size
-                var layoutMetricsResponse = await devToolsClient.Page.GetLayoutMetricsAsync().ConfigureAwait(continueOnCapturedContext:false);
-
-                return layoutMetricsResponse.CssContentSize;
-            }
-        }
-
         /// <inheritdoc/>
         public void Load(string url)
         {

CefSharp.WinForms.Example/BrowserForm.Designer.cs

@@ -5,6 +5,7 @@
 using System;
 using System.Collections.Generic;
 using System.ComponentModel;
+using System.Diagnostics;
 using System.IO;
 using System.Runtime.InteropServices;
 using System.Threading.Tasks;
@@ -649,5 +650,41 @@ private void HideScrollbarsToolStripMenuItemClick(object sender, EventArgs e)
 
             _ = control?.HideScrollbarsAsync();
         }
+
+        private async void TakeScreenShotMenuItemClick(object sender, EventArgs e)
+        {
+            var control = GetCurrentTabControl();
+
+            if(control == null)
+            {
+                return;
+            }
+
+            var chromiumWebBrowser = (ChromiumWebBrowser)control.Browser;
+
+            var contentSize = await chromiumWebBrowser.GetContentSizeAsync();
+
+            //Capture current scrollable area
+            var viewPort = new DevTools.Page.Viewport
+            {
+                Width = contentSize.Width,
+                Height = contentSize.Height,
+                Scale = 1.0
+            };
+
+            var data = await chromiumWebBrowser.CaptureScreenshotAsync(viewPort: viewPort, captureBeyondViewport: true);
+
+            // Make a file to save it to (e.g. C:\Users\[user]\Desktop\CefSharp screenshot.png)
+            var screenshotPath = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "CefSharp screenshot" + DateTime.Now.Ticks + ".png");
+
+            File.WriteAllBytes(screenshotPath, data);
+
+            // Tell Windows to launch the saved image.
+            Process.Start(new ProcessStartInfo(screenshotPath)
+            {
+                // UseShellExecute is false by default on .NET Core.
+                UseShellExecute = true
+            });
+        }
     }
 }

CefSharp.WinForms.Example/BrowserForm.cs

@@ -12,6 +12,8 @@
 using CefSharp.Web;
 using CefSharp.WinForms.Internals;
 using CefSharp.WinForms.Host;
+using CefSharp.DevTools.Page;
+using System.Threading.Tasks;
 
 namespace CefSharp.WinForms
 {
@@ -477,6 +479,28 @@ public void Load(string url)
             }
         }
 
+        /// <summary>
+        /// Capture page screenshot.
+        /// </summary>
+        /// <param name="format">Image compression format (defaults to png).</param>
+        /// <param name="quality">Compression quality from range [0..100] (jpeg only).</param>
+        /// <param name="viewPort">Capture the screenshot of a given region only.</param>
+        /// <param name="fromSurface">Capture the screenshot from the surface, rather than the view. Defaults to true.</param>
+        /// <param name="captureBeyondViewport">Capture the screenshot beyond the viewport. Defaults to false.</param>
+        /// <returns>A task that can be awaited to obtain the screenshot as a byte[].</returns>
+        public async Task<byte[]> CaptureScreenshotAsync(CaptureScreenshotFormat format = CaptureScreenshotFormat.Png, int? quality = null, Viewport viewPort = null, bool fromSurface = true, bool captureBeyondViewport = false)
+        {
+            ThrowExceptionIfDisposed();
+            ThrowExceptionIfBrowserNotInitialized();
+
+            using (var devToolsClient = browser.GetDevToolsClient())
+            {
+                var screenShot = await devToolsClient.Page.CaptureScreenshotAsync(format, quality, viewPort, fromSurface, captureBeyondViewport).ConfigureAwait(continueOnCapturedContext: false);
+
+                return screenShot.Data;
+            }
+        }
+
         /// <summary>
         /// The javascript object repository, one repository per ChromiumWebBrowser instance.
         /// </summary>

CefSharp.WinForms/ChromiumWebBrowser.cs

@@ -169,5 +169,11 @@ public interface IWebBrowser : IChromiumWebBrowserBase
         /// <param name="browser">When this method returns, contains the <see cref="IBrowser"/> object reference that matches the specified <paramref name="browserId"/>, or null if no matching instance found.</param>
         /// <returns>true if a <see cref="IBrowser"/> instance was found matching <paramref name="browserId"/>; otherwise, false.</returns>
         bool TryGetBrowserCoreById(int browserId, out IBrowser browser);
+
+        /// <summary>
+        /// Size of scrollable area in CSS pixels
+        /// </summary>
+        /// <returns>A task that can be awaited to get the size of the scrollable area in CSS pixels.</returns>
+        Task<DevTools.DOM.Rect> GetContentSizeAsync();
     }
 }

CefSharp/IWebBrowser.cs

@@ -399,6 +399,21 @@ public bool TryGetBrowserCoreById(int browserId, out IBrowser browser)
             return browser != null;
         }
 
+        /// <inheritdoc/>
+        public async Task<DevTools.DOM.Rect> GetContentSizeAsync()
+        {
+            ThrowExceptionIfDisposed();
+            ThrowExceptionIfBrowserNotInitialized();
+
+            using (var devToolsClient = browser.GetDevToolsClient())
+            {
+                //Get the content size
+                var layoutMetricsResponse = await devToolsClient.Page.GetLayoutMetricsAsync().ConfigureAwait(continueOnCapturedContext: false);
+
+                return layoutMetricsResponse.CssContentSize;
+            }
+        }
+
         private void InitialLoad(bool? isLoading, CefErrorCode? errorCode)
         {
             if(IsDisposed)