butter smooth resizing.

src/Avalonia.Visuals/Properties/AssemblyInfo.cs

@@ -11,4 +11,5 @@ using Avalonia.Metadata;
 [assembly: InternalsVisibleTo("Avalonia.Direct2D1.RenderTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
 [assembly: InternalsVisibleTo("Avalonia.Skia.RenderTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
 [assembly: InternalsVisibleTo("Avalonia.Skia.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
+[assembly: InternalsVisibleTo("Avalonia.Web.Blazor,  PublicKey=0024000004800000940000000602000000240000525341310004000001000100c1bba1142285fe0419326fb25866ba62c47e6c2b5c1ab0c95b46413fad375471232cb81706932e1cef38781b9ebd39d5100401bacb651c6c5bbf59e571e81b3bc08d2a622004e08b1a6ece82a7e0b9857525c86d2b95fab4bc3dce148558d7f3ae61aa3a234086902aeface87d9dfdd32b9d2fe3c6dd4055b5ab4b104998bd87")]
 

src/Avalonia.Visuals/Rendering/DeferredRenderer.cs

@@ -304,7 +304,7 @@ namespace Avalonia.Rendering
             }
         }
 
-        private void Render(bool forceComposite)
+        internal void Render(bool forceComposite)
         {
             using (var l = _lock.TryLock())
             {

src/Web/Avalonia.Web.Blazor/AvaloniaView.razor.cs

@@ -3,6 +3,7 @@ using Avalonia.Controls.Embedding;
 using Avalonia.Input;
 using Avalonia.Input.Raw;
 using Avalonia.Input.TextInput;
+using Avalonia.Rendering;
 using Avalonia.Web.Blazor.Interop;
 using Microsoft.AspNetCore.Components;
 using Microsoft.AspNetCore.Components.Web;
@@ -327,6 +328,11 @@ namespace Avalonia.Web.Blazor
             _dpi = newDpi;
 
             _topLevelImpl.SetClientSize(_canvasSize, _dpi);
+            
+            if (_topLevel.Renderer is DeferredRenderer dr)
+            {
+                dr.Render(true);
+            }
 
             Invalidate();
         }
@@ -334,9 +340,16 @@ namespace Avalonia.Web.Blazor
         private void OnSizeChanged(SKSize newSize)
         {
             _canvasSize = newSize;
+            
+            _interop.SetCanvasSize((int)(_canvasSize.Width * _dpi), (int)(_canvasSize.Height * _dpi));
 
             _topLevelImpl.SetClientSize(_canvasSize, _dpi);
 
+            if (_topLevel.Renderer is DeferredRenderer dr)
+            {
+                dr.Render(true);
+            }
+
             Invalidate();
         }
 
@@ -348,7 +361,7 @@ namespace Avalonia.Web.Blazor
                 return;
             }
 
-            _interop.RequestAnimationFrame(true, (int)(_canvasSize.Width * _dpi), (int)(_canvasSize.Height * _dpi));
+            _interop.RequestAnimationFrame(true);
         }
 
         public void SetActive(bool active)

src/Web/Avalonia.Web.Blazor/Interop/Typescript/SKHtmlCanvas.ts

@@ -144,6 +144,21 @@ export class SKHtmlCanvas {
     {
         this.newWidth = width;
         this.newHeight = height;
+
+        if(this.htmlCanvas.width != this.newWidth)
+        {
+            this.htmlCanvas.width = this.newWidth;
+        }
+
+        if(this.htmlCanvas.height != this.newHeight)
+        {
+            this.htmlCanvas.height = this.newHeight;
+        }
+
+        if (this.glInfo) {
+            // make current
+            GL.makeContextCurrent(this.glInfo.context);
+        }
     }
 
 	public requestAnimationFrame(renderLoop?: boolean) {
@@ -162,9 +177,13 @@ export class SKHtmlCanvas {
                 GL.makeContextCurrent(this.glInfo.context);
             }
             
-            if(this.htmlCanvas.width != this.newWidth || this.htmlCanvas.height != this.newHeight)
+            if(this.htmlCanvas.width != this.newWidth)
             {
                 this.htmlCanvas.width = this.newWidth;
+            }
+
+            if(this.htmlCanvas.height != this.newHeight)
+            {
                 this.htmlCanvas.height = this.newHeight;
             }