Merge pull request #769 from telerik/new-kb-syntaxeditor-mouse-wheel-step-35d260d42d5c47588b7f8425a220aa30

Added new kb article syntaxeditor-mouse-wheel-step

Author: nade7o

knowledge-base/syntaxeditor-mouse-wheel-step.md

@@ -0,0 +1,77 @@
+---
+title: Adjusting Mouse Wheel Scroll Step in SyntaxEditor for UI for WinForms
+description: Learn how to customize the mouse wheel scroll step in the RadSyntaxEditor control.
+type: how-to
+page_title: Customize Mouse Wheel Scrolling Speed/Step in RadSyntaxEditor
+meta_title: Customize Mouse Wheel Scrolling Speed/Step in RadSyntaxEditor
+slug: syntaxeditor-mouse-wheel-step
+tags: syntaxeditor, scrolling, mouse-wheel, customization
+res_type: kb
+ticketid: 1561729
+---
+
+## Environment
+
+|Product Version|Product|Author|
+|----|----|----|
+|2025.2.520|RadSyntaxEditor for WinForms|[Dinko Krastev](https://www.telerik.com/blogs/author/dinko-krastev)|
+
+## Description
+
+There could be a scenario in which the mouse wheel speed needs to be per user preferences. However, the control does not provide a way to manipulate the scroll step. In this KB article, we will demonstrate how, using custom code, we could manipulate the scroll speed.
+
+## Solution
+
+To adjust the mouse wheel scroll step, create a custom class that inherits from RadSyntaxEditor and override the `OnMouseWheel` method. Modify the `Value` property of the `VerticalScrollBarElement` and the `VerticalScrollOffset` of the `SyntaxEditorPresenter`. The last step is to set the `VerticalScrollOffset` property. This property is not public and we will need to use reflection to set it. Below is a sample implementation:
+
+````C#
+
+public class MySyntax : RadSyntaxEditor
+{
+    protected override void CreateChildItems(RadElement parent)
+    {
+        base.CreateChildItems(parent);
+    }
+
+    protected override void OnMouseWheel(MouseEventArgs e)
+    {
+        // Access and update scrolling properties
+        System.Reflection.PropertyInfo pi = typeof(SyntaxEditorPresenter).GetProperty(
+            "VerticalScrollOffset", 
+            System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.Public
+        );
+
+        if (e.Delta < 0) // Scroll down
+        {
+            this.SyntaxEditorElement.VerticalScrollBar.Value += this.SyntaxEditorElement.VerticalScrollBar.SmallChange;
+            pi.SetValue(this.SyntaxEditorElement.EditorPresenter, this.SyntaxEditorElement.VerticalScrollBar.Value);
+        }
+        else // Scroll up
+        {
+            this.SyntaxEditorElement.VerticalScrollBar.Value -= this.SyntaxEditorElement.VerticalScrollBar.SmallChange;
+            pi.SetValue(this.SyntaxEditorElement.EditorPresenter, this.SyntaxEditorElement.VerticalScrollBar.Value);
+        }
+
+        this.SyntaxEditorElement.EditorPresenter.InvalidateLayout(false);
+    }
+    public override string ThemeClassName
+    {
+        get
+        {
+            return typeof(RadSyntaxEditor).FullName;
+        }
+    }
+}
+
+````
+
+### Steps:
+
+1. Create a new class that inherits `RadSyntaxEditor`.  
+2. Override the `OnMouseWheel` method.  
+3. Use reflection to access and modify the `VerticalScrollOffset` property of `SyntaxEditorPresenter`.  
+4. Update the `Value` property of `VerticalScrollBarElement` based on the mouse wheel scroll direction.  
+5. Test the custom implementation by adding it to your application.
+
+## See Also
+* [RadSyntaxEditor Documentation](https://docs.telerik.com/devtools/winforms/controls/syntaxeditor/overview)