Reduce PC scroll command distance (#304)

Co-authored-by: Owen McGirr <o.a.mcgirr@gmail.com>

Author: enaboapps

src/SwitchifyPc.Tests/WindowsDesktopInputAdapterTests.cs

@@ -47,9 +47,20 @@ public async Task ScrollsWithNativeDeltaScaling()
         FakeNativeInput native = new();
         WindowsDesktopInputAdapter adapter = new(native);
 
-        await adapter.ScrollMouseAsync(0.1, -3);
+        await adapter.ScrollMouseAsync(0, -5);
 
-        Assert.Equal(new PointerDelta(1, -12), native.Scrolled);
+        Assert.Equal(new PointerDelta(0, -2), native.Scrolled);
+    }
+
+    [Fact]
+    public async Task ScrollsSmallNonZeroDeltaByAtLeastOneDetent()
+    {
+        FakeNativeInput native = new();
+        WindowsDesktopInputAdapter adapter = new(native);
+
+        await adapter.ScrollMouseAsync(0.1, 0);
+
+        Assert.Equal(new PointerDelta(1, 0), native.Scrolled);
     }
 
     [Fact]

src/SwitchifyPc.Tests/WindowsPointerMovementTests.cs

@@ -42,9 +42,10 @@ public void FallsBackToReferenceShortEdgeForInvalidDisplayData()
     [Fact]
     public void CalculatesNativeScrollDelta()
     {
-        Assert.Equal(new PointerDelta(0, -12), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, -3)));
+        Assert.Equal(new PointerDelta(0, -2), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, -5)));
+        Assert.Equal(new PointerDelta(0, 2), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, 5)));
         Assert.Equal(new PointerDelta(1, 0), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0.1, 0)));
         Assert.Equal(new PointerDelta(0, 1), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, 0.1)));
-        Assert.Equal(new PointerDelta(0, -3), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, -3), 0));
+        Assert.Equal(new PointerDelta(0, -5), WindowsPointerMovement.CalculateNativeScrollDelta(new PointerDelta(0, -5), 0));
     }
 }

src/SwitchifyPc.Windows/Input/WindowsPointerMovement.cs

@@ -9,7 +9,7 @@ public sealed record PointerPosition(double X, double Y);
 
 public static class WindowsPointerMovement
 {
-    public const double NativeScrollDeltaMultiplier = 4;
+    public const double NativeScrollDeltaMultiplier = 0.4;
     public const double ReferencePointerShortEdge = 1080;
 
     private static readonly IReadOnlyDictionary<PointerMovementSizeKey, double> BaselinePointerDeltas =