new feature: save scroll position

README.md

@@ -18,6 +18,16 @@ And use the `HtmlViewer` control
 <darkhtmlviewer:HtmlViewer x:Name="htmlViewer" />
 ```
 
+### Commands & methods
+`LoadCommand` => `void Load(string html)`\
+`ScrollCommand` => `Task ScrollAsync(string elementId)`\
+`ScrollOnNextLoadCommand` => `void ScrollOnNextLoad(string elementId)`\
+`SearchCommand` => `Task SearchAsync(string text)`\
+`SearchOnNextLoadCommand` => `void SearchOnNextLoad(string text)`\
+`SaveScrollPositionForNextLoadCommand` => `SaveScrollPositionForNextLoadAsync()`\
+`PrintCommand` => `Task PrintAsync()`\
+`ZoomCommand` => `void Zoom(double zoom)`
+
 ### Loading HTML content
 To load content into the viewer, bind an HTML string to it's `HtmlContent` property
 ```XAML
@@ -70,6 +80,16 @@ To scroll to a specific element id, you have several options.
     Content="Scroll to elementId on next load" />
 ```
 
+### Save scroll position
+Saves the current scroll position and tries to restore it next time HTML content is loaded. If `ScrollOnNextLoad` is used as well, this will be ignored
+
+`SaveScrollPositionForNextLoadCommand`: will try to scroll to a specific element in the next loaded HTML file
+```XAML
+<Button
+    Command="{Binding ElementName=htmlViewer, Path=SaveScrollPositionForNextLoadCommand}"
+    Content="Save scroll position for next load" />
+```
+
 ### Search
 
 `SearchCommand`: finds a search term on the current page

demos/DarkHtmlViewerBasicDemo/DemoView.xaml

@@ -48,6 +48,11 @@
                     Command="{Binding ElementName=htmlViewer, Path=SearchOnNextLoadCommand}"
                     CommandParameter="{Binding ElementName=txtSearch, Path=Text}"
                     Content="Search on next load" />
+                <Button
+                    Margin="5"
+                    Padding="10,5,10,5"
+                    Command="{Binding ElementName=htmlViewer, Path=SaveScrollPositionForNextLoadCommand}"
+                    Content="Save scroll position for next load" />
                 <Button
                     Margin="5"
                     Padding="10,5,10,5"

src/DarkHtmlViewer/HtmlViewer.xaml.cs

@@ -57,6 +57,7 @@ public ICommand LinkClickedCommand
         public ICommand LoadCommand => new DarkCommand<string>(Load);
         public ICommand ScrollCommand => new DarkAsyncCommand<string>(ScrollAsync);
         public ICommand ScrollOnNextLoadCommand => new DarkCommand<string>(ScrollOnNextLoad);
+        public ICommand SaveScrollPositionForNextLoadCommand => new DarkAsyncCommand(SaveScrollPositionForNextLoadAsync);
         public ICommand SearchCommand => new DarkAsyncCommand<string>(SearchAsync);
         public ICommand SearchOnNextLoadCommand => new DarkCommand<string>(SearchOnNextLoad);
         public ICommand PrintCommand => new DarkAsyncCommand(PrintAsync);
@@ -191,6 +192,12 @@ private async void WebView2_NavigationCompleted(object sender, CoreWebView2Navig
                 await ScrollAsync(_scrollToNext);
                 _scrollToNext = null;
             }
+            else if(_scrollPositionXNext is not null)
+            {
+                await ScrollAsync(_scrollPositionXNext, _scrollPositionYNext);
+                _scrollPositionXNext = null;
+                _scrollPositionYNext = null;
+            }
 
             if (_textToFind is not null)
             {
@@ -214,6 +221,15 @@ public async Task ScrollAsync(string elementId)
             await webView2.ExecuteScriptAsync(script);
         }
 
+        /// <summary>
+        /// Tries to scroll to a position
+        /// </summary>
+        private async Task ScrollAsync(string x, string y)
+        {
+            var script = $"window.scrollTo({x}, {y});";
+            await webView2.ExecuteScriptAsync(script);
+        }
+
         /// <summary>
         /// Sets the elementId to be scrolled to next time HTML content is loaded
         /// </summary>
@@ -224,6 +240,23 @@ public void ScrollOnNextLoad(string elementId)
 
         #endregion
 
+        #region Save scroll position
+
+        private string _scrollPositionXNext = null;
+        private string _scrollPositionYNext = null;
+
+        /// <summary>
+        /// Saves the current scroll position and tries to restore it next time HTML content is loaded
+        /// <para>If <see cref="ScrollOnNextLoad"/> is used as well, this will be ignored</para>
+        /// </summary>
+        public async Task SaveScrollPositionForNextLoadAsync()
+        {
+            _scrollPositionXNext = await webView2.ExecuteScriptAsync("window.scrollX");
+            _scrollPositionYNext = await webView2.ExecuteScriptAsync("window.scrollY");
+        }
+
+        #endregion
+
         #region Search
 
         private string _textToFind = null;