Improved opacity support in Radial Gauge

This change adds support for Opacity in the brushes for the Radial Gauge elements that are drawn with the Composition API: Ticks, ScaleTicks, and Needle.

Author: XamlBrewer

Microsoft.Toolkit.Uwp.UI.Controls.Input/RadialGauge/RadialGauge.cs

@@ -642,6 +642,7 @@ private static void OnFaceChanged(DependencyObject d)
                     tick = radialGauge._compositor.CreateSpriteVisual();
                     tick.Size = new Vector2((float)radialGauge.TickWidth, (float)radialGauge.TickLength);
                     tick.Brush = radialGauge._compositor.CreateColorBrush(radialGauge.TickBrush.Color);
+                    tick.Opacity = (float)radialGauge.TickBrush.Opacity;
                     tick.Offset = new Vector3(100 - ((float)radialGauge.TickWidth / 2), 0.0f, 0);
                     tick.CenterPoint = new Vector3((float)radialGauge.TickWidth / 2, 100.0f, 0);
                     tick.RotationAngleInDegrees = (float)radialGauge.ValueToAngle(i);
@@ -654,6 +655,7 @@ private static void OnFaceChanged(DependencyObject d)
                     tick = radialGauge._compositor.CreateSpriteVisual();
                     tick.Size = new Vector2((float)radialGauge.ScaleTickWidth, (float)radialGauge.ScaleWidth);
                     tick.Brush = radialGauge._compositor.CreateColorBrush(radialGauge.ScaleTickBrush.Color);
+                    tick.Opacity = (float)radialGauge.ScaleTickBrush.Opacity;
                     tick.Offset = new Vector3(100 - ((float)radialGauge.ScaleTickWidth / 2), (float)radialGauge.ScalePadding, 0);
                     tick.CenterPoint = new Vector3((float)radialGauge.ScaleTickWidth / 2, 100 - (float)radialGauge.ScalePadding, 0);
                     tick.RotationAngleInDegrees = (float)radialGauge.ValueToAngle(i);
@@ -665,6 +667,7 @@ private static void OnFaceChanged(DependencyObject d)
             radialGauge._needle = radialGauge._compositor.CreateSpriteVisual();
             radialGauge._needle.Size = new Vector2((float)radialGauge.NeedleWidth, (float)radialGauge.NeedleLength);
             radialGauge._needle.Brush = radialGauge._compositor.CreateColorBrush(radialGauge.NeedleBrush.Color);
+            radialGauge._needle.Opacity = (float)radialGauge.NeedleBrush.Opacity;
             radialGauge._needle.CenterPoint = new Vector3((float)radialGauge.NeedleWidth / 2, (float)radialGauge.NeedleLength, 0);
             radialGauge._needle.Offset = new Vector3(100 - ((float)radialGauge.NeedleWidth / 2), 100 - (float)radialGauge.NeedleLength, 0);
             radialGauge._root.Children.InsertAtTop(radialGauge._needle);