refactor mono CreateGraphics handling

Author: ArthurHub

Source/HtmlRenderer.WinForms/HtmlLabel.cs

@@ -471,17 +471,21 @@ protected override void OnLayout(LayoutEventArgs levent)
         {
             if (_htmlContainer != null)
             {
-                using (Graphics g = CreateGraphics())
-                using (var ig = new GraphicsAdapter(g, _htmlContainer.UseGdiPlusTextRendering))
+                Graphics g = Utils.CreateGraphics(this);
+                if (g != null)
                 {
-                    var newSize = HtmlRendererUtils.Layout(ig,
-                        _htmlContainer.HtmlContainerInt,
-                        new RSize(ClientSize.Width - Padding.Horizontal, ClientSize.Height - Padding.Vertical),
-                        new RSize(MinimumSize.Width - Padding.Horizontal, MinimumSize.Height - Padding.Vertical),
-                        new RSize(MaximumSize.Width - Padding.Horizontal, MaximumSize.Height - Padding.Vertical),
-                        AutoSize,
-                        AutoSizeHeightOnly);
-                    ClientSize = Utils.ConvertRound(new RSize(newSize.Width + Padding.Horizontal, newSize.Height + Padding.Vertical));
+                    using (g)
+                    using (var ig = new GraphicsAdapter(g, _htmlContainer.UseGdiPlusTextRendering))
+                    {
+                        var newSize = HtmlRendererUtils.Layout(ig,
+                            _htmlContainer.HtmlContainerInt,
+                            new RSize(ClientSize.Width - Padding.Horizontal, ClientSize.Height - Padding.Vertical),
+                            new RSize(MinimumSize.Width - Padding.Horizontal, MinimumSize.Height - Padding.Vertical),
+                            new RSize(MaximumSize.Width - Padding.Horizontal, MaximumSize.Height - Padding.Vertical),
+                            AutoSize,
+                            AutoSizeHeightOnly);
+                        ClientSize = Utils.ConvertRound(new RSize(newSize.Width + Padding.Horizontal, newSize.Height + Padding.Vertical));
+                    }
                 }
             }
             base.OnLayout(levent);

Source/HtmlRenderer.WinForms/HtmlPanel.cs

@@ -457,15 +457,15 @@ protected void PerformHtmlLayout()
             {
                 _htmlContainer.MaxSize = new SizeF(ClientSize.Width - Padding.Horizontal, 0);
 
-                try
+                Graphics g = Utils.CreateGraphics(this);
+                if (g != null)
                 {
-                    using (var g = CreateGraphics())
+                    using (g)
                     {
                         _htmlContainer.PerformLayout(g);
                     }
                 }
-                catch
-                { }
+
 
                 AutoScrollMinSize = Size.Round(new SizeF(_htmlContainer.ActualSize.Width + Padding.Horizontal, _htmlContainer.ActualSize.Height));
             }
@@ -683,11 +683,16 @@ protected virtual void InvokeMouseMove()
         {
             try
             {
+                // mono has issue throwing exception for no reason
                 var mp = PointToClient(MousePosition);
                 _htmlContainer.HandleMouseMove(this, new MouseEventArgs(MouseButtons.None, 0, mp.X, mp.Y, 0));
             }
             catch
-            { }
+            {
+#if !MONO
+                throw;
+#endif
+            }
         }
 
         /// <summary>

Source/HtmlRenderer.WinForms/Utilities/Utils.cs

@@ -12,6 +12,7 @@
 
 using System;
 using System.Drawing;
+using System.Windows.Forms;
 using TheArtOfDev.HtmlRenderer.Adapters.Entities;
 
 namespace TheArtOfDev.HtmlRenderer.WinForms.Utilities
@@ -119,5 +120,26 @@ public static Color Convert(RColor c)
         {
             return Color.FromArgb(c.A, c.R, c.G, c.B);
         }
+
+        /// <summary>
+        /// mono has issue throwing exception for no reason.
+        /// </summary>
+        /// <param name="control">the control to create graphics object from</param>
+        /// <returns>new graphics object or null in mono if failed</returns>
+        public static Graphics CreateGraphics(Control control)
+        {
+#if MONO
+            try
+            {
+                return control.CreateGraphics();
+            }
+            catch
+            {
+                return null;
+            }
+#else
+            return control.CreateGraphics();
+#endif
+        }
     }
 }