OffScreen - Add IRenderHandler and DefaultRenderHandler basic implementation

Only supports OnPaint, will expand to support the other methods

Author: amaitland

CefSharp.OffScreen/CefSharp.OffScreen.csproj

@@ -74,6 +74,7 @@
   <ItemGroup>
     <Compile Include="BitmapBuffer.cs" />
     <Compile Include="ChromiumWebBrowser.cs" />
+    <Compile Include="DefaultRenderHandler.cs" />
     <Compile Include="IRenderHandler.cs" />
     <Compile Include="OnPaintEventArgs.cs" />
     <Compile Include="PopupBlending.cs" />

CefSharp.OffScreen/ChromiumWebBrowser.cs

@@ -27,20 +27,6 @@ public class ChromiumWebBrowser : IRenderWebBrowser
         /// </summary>
         private ManagedCefBrowserAdapter managedCefBrowserAdapter;
 
-        /// <summary>
-        /// Contains the last bitmap buffer. Direct access
-        /// to the underlying buffer - there is no locking when trying
-        /// to access directly, use <see cref="BitmapBuffer.BitmapLock" /> where appropriate.
-        /// </summary>
-        /// <value>The bitmap.</value>
-        public BitmapBuffer BitmapBuffer { get; protected set; }
-
-        /// <summary>
-        /// Need a lock because the caller may be asking for the bitmap
-        /// while Chromium async rendering has returned on another thread.
-        /// </summary>
-        public readonly object BitmapLock = new object();
-
         /// <summary>
         /// Size of the Chromium viewport.
         /// This must be set to something other than 0x0 otherwise Chromium will not render,
@@ -168,6 +154,11 @@ public class ChromiumWebBrowser : IRenderWebBrowser
         /// <value>The request handler.</value>
         public IRequestHandler RequestHandler { get; set; }
         /// <summary>
+        /// Implement <see cref="IRenderHandler" /> and assign to handle events related to browser rendering.
+        /// </summary>
+        /// <value>The render handler.</value>
+        public IRenderHandler RenderHandler { get; set; }
+        /// <summary>
         /// Implement <see cref="IDragHandler" /> and assign to handle events related to dragging.
         /// </summary>
         /// <value>The drag handler.</value>
@@ -294,11 +285,6 @@ public class ChromiumWebBrowser : IRenderWebBrowser
         /// </summary>
         private Size popupSize;
 
-        /// <summary>
-        /// The popup Bitmap.
-        /// </summary>
-        public BitmapBuffer PopupBuffer { get; protected set; }
-
         /// <summary>
         /// Create a new OffScreen Chromium Browser
         /// </summary>
@@ -329,10 +315,10 @@ public ChromiumWebBrowser(string address = "", BrowserSettings browserSettings =
                 CreateBrowser(IntPtr.Zero);
             }
 
-            BitmapBuffer = new BitmapBuffer(BitmapLock);
-            PopupBuffer = new BitmapBuffer(BitmapLock);
             popupPosition = new Point();
             popupSize = new Size();
+
+            RenderHandler = new DefaultRenderHandler(this);
         }
 
         /// <summary>
@@ -468,24 +454,36 @@ public Size Size
         /// <returns>Bitmap.</returns>
         public Bitmap ScreenshotOrNull(PopupBlending blend = PopupBlending.Main)
         {
-            lock (BitmapLock)
+            if(RenderHandler == null)
+            {
+                throw new NullReferenceException("RenderHandler cannot be null. Use DefaultRenderHandler unless implementing your own");
+            }
+
+            var renderHandler = RenderHandler as DefaultRenderHandler;
+
+            if(renderHandler == null)
+            {
+                throw new Exception("ScreenshotOrNull and ScreenshotAsync can only be used in combination with the DefaultRenderHandler");
+            }
+
+            lock (renderHandler.BitmapLock)
             {
                 if (blend == PopupBlending.Main)
                 {
-                    return BitmapBuffer.CreateBitmap();
+                    return renderHandler.BitmapBuffer.CreateBitmap();
                 }
 
                 if (blend == PopupBlending.Popup)
                 {
-                    return PopupOpen ? PopupBuffer.CreateBitmap() : null;
+                    return PopupOpen ? renderHandler.PopupBuffer.CreateBitmap() : null;
                 }
 
 
-                var bitmap = BitmapBuffer.CreateBitmap();
+                var bitmap = renderHandler.BitmapBuffer.CreateBitmap();
 
                 if (PopupOpen && bitmap != null)
                 {
-                    var popup = PopupBuffer.CreateBitmap();
+                    var popup = renderHandler.PopupBuffer.CreateBitmap();
                     if (popup == null)
                     {
                         return bitmap;
@@ -761,9 +759,7 @@ protected virtual void OnPaint(PaintElementType type, Rect dirtyRect, IntPtr buf
         {
             var isPopup = type == PaintElementType.Popup;
 
-            var bitmapBuffer = isPopup ? PopupBuffer : BitmapBuffer;
-
-            bitmapBuffer.UpdateBuffer(width, height, buffer, dirtyRect);
+            RenderHandler?.OnPaint(isPopup, dirtyRect, buffer, width, height);
         }
 
         /// <summary>

CefSharp.OffScreen/DefaultRenderHandler.cs

@@ -0,0 +1,54 @@
+// Copyright © 2010-2017 The CefSharp Authors. All rights reserved.
+//
+// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
+
+using System;
+using CefSharp.Structs;
+
+namespace CefSharp.OffScreen
+{
+	public class DefaultRenderHandler : IRenderHandler
+	{
+		private ChromiumWebBrowser browser;
+
+		/// <summary>
+		/// Contains the last bitmap buffer. Direct access
+		/// to the underlying buffer - there is no locking when trying
+		/// to access directly, use <see cref="BitmapBuffer.BitmapLock" /> where appropriate.
+		/// </summary>
+		/// <value>The bitmap.</value>
+		public BitmapBuffer BitmapBuffer { get; private set; }
+
+		/// <summary>
+		/// The popup Bitmap.
+		/// </summary>
+		public BitmapBuffer PopupBuffer { get; private set; }
+
+		/// <summary>
+		/// Need a lock because the caller may be asking for the bitmap
+		/// while Chromium async rendering has returned on another thread.
+		/// </summary>
+		public readonly object BitmapLock = new object();
+
+		public DefaultRenderHandler(ChromiumWebBrowser browser)
+		{
+			this.browser = browser;
+
+			BitmapBuffer = new BitmapBuffer(BitmapLock);
+			PopupBuffer = new BitmapBuffer(BitmapLock);
+
+		}
+
+		public void Dispose()
+		{
+			browser = null;
+		}
+
+		public virtual void OnPaint(bool isPopup, Rect dirtyRect, IntPtr buffer, int width, int height)
+		{
+			var bitmapBuffer = isPopup ? PopupBuffer : BitmapBuffer;
+
+			bitmapBuffer.UpdateBuffer(width, height, buffer, dirtyRect);
+		}
+	}
+}

CefSharp.OffScreen/IRenderHandler.cs

@@ -3,96 +3,17 @@
 // Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
 
 using System;
-using CefSharp.Enums;
 using CefSharp.Structs;
 
 namespace CefSharp.OffScreen
 {
-	public interface IRenderHandler
+	/// <summary>
+	/// Implement this interface to handle Offscreen Rendering (OSR).
+	/// NOTE: Currently only OnPaint is implemented, at some point expand the API to include all
+	/// of CefRenderHandler methods http://magpcss.org/ceforum/apidocs3/projects/(default)/CefRenderHandler.html
+	/// </summary>
+	public interface IRenderHandler : IDisposable
 	{
-		/// <summary>
-		/// Called to allow the client to return a ScreenInfo object with appropriate values.
-		/// If null is returned then the rectangle from GetViewRect will be used.
-		/// If the rectangle is still empty or invalid popups may not be drawn correctly. 
-		/// </summary>
-		/// <returns>Return null if no screenInfo structure is provided.</returns>	
-		ScreenInfo? GetScreenInfo();
-
-		/// <summary>
-		/// Called to retrieve the view rectangle which is relative to screen coordinates. 
-		/// </summary>
-		/// <returns>Return a ViewRect strict containing the rectangle or null. If the rectangle is
-		/// still empty or invalid popups may not be drawn correctly. </returns>
-		ViewRect? GetViewRect();
-
-		/// <summary>
-		/// Called to retrieve the translation from view coordinates to actual screen coordinates. 
-		/// </summary>
-		/// <param name="viewX">x</param>
-		/// <param name="viewY">y</param>
-		/// <param name="screenX">screen x</param>
-		/// <param name="screenY">screen y</param>
-		/// <returns>Return true if the screen coordinates were provided.</returns>
-		bool GetScreenPoint(int viewX, int viewY, out int screenX, out int screenY);
-
-		/// <summary>
-		/// Called when an element should be painted. Pixel values passed to this method are scaled relative to view coordinates based on the
-		/// value of <see cref="ScreenInfo.ScaleFactor"/> returned from <see cref="GetScreenInfo"/>.
-		/// Called on the CEF UI Thread
-		/// </summary>
-		/// <param name="type">indicates whether the element is the view or the popup widget.</param>
-		/// <param name="dirtyRect">contains the set of rectangles in pixel coordinates that need to be repainted</param>
-		/// <param name="buffer">The bitmap will be will be  width * height *4 bytes in size and represents a BGRA image with an upper-left origin</param>
-		/// <param name="width">width</param>
-		/// <param name="height">height</param>
-		void OnPaint(PaintElementType type, Rect dirtyRect, IntPtr buffer, int width, int height);
-
-		/// <summary>
-		/// Called when the browser's cursor has changed. . 
-		/// </summary>
-		/// <param name="cursor">If type is Custom then customCursorInfo will be populated with the custom cursor information</param>
-		/// <param name="type">cursor type</param>
-		/// <param name="customCursorInfo">custom cursor Information</param>
-		void OnCursorChange(IntPtr cursor, CursorType type, CursorInfo customCursorInfo);
-
-		/// <summary>
-		/// Called when the user starts dragging content in the web view. Contextual information about the dragged content is
-		/// supplied by dragData. (|x|, |y|) is the drag start location in screen coordinates. OS APIs that run a system message
-		/// loop may be used within the StartDragging call. Return false to abort the drag operation. Don't call any of
-		/// CefBrowserHost::DragSource*Ended* methods after returning false. Return true to handle the drag operation.
-		/// Call IBrowserHost::DragSourceEndedAt and DragSourceSystemDragEnded either synchronously or asynchronously to inform
-		/// the web view that the drag operation has ended. 
-		/// </summary>
-		/// <param name="dragData">drag data</param>
-		/// <param name="mask">operation mask</param>
-		/// <param name="x">x coordinate</param>
-		/// <param name="y">y coordinate</param>
-		/// <returns>Return false to abort the drag operation.</returns>
-		bool StartDragging(IDragData dragData, DragOperationsMask mask, int x, int y);
-
-		/// <summary>
-		/// Called when the web view wants to update the mouse cursor during a drag & drop operation.
-		/// </summary>
-		/// <param name="operation">describes the allowed operation (none, move, copy, link). </param>
-		void UpdateDragCursor(DragOperationsMask operation);
-
-		/// <summary>
-		/// Called when the browser wants to show or hide the popup widget.  
-		/// </summary>
-		/// <param name="show">The popup should be shown if show is true and hidden if show is false.</param>
-		void OnPopupShow(bool show);
-
-		/// <summary>
-		/// Called when the browser wants to move or resize the popup widget. 
-		/// </summary>
-		/// <param name="rect">|rect| contains the new location and size in view coordinates. </param>
-		void OnPopupSize(Rect rect);
-
-		/// <summary>
-		/// Called when the IME composition range has changed.
-		/// </summary>
-		/// <param name="selectedRange">is the range of characters that have been selected</param>
-		/// <param name="characterBounds">is the bounds of each character in view coordinates.</param>
-		void OnImeCompositionRangeChanged(Range selectedRange, Rect[] characterBounds);
+		void OnPaint(bool isPopup, Rect dirtyRect, IntPtr buffer, int width, int height);
 	}
-}
+}