Merge pull request #36 from jsuarezruiz/implement-opacity

Implement Opacity property

src/AlohaKit.UI.Gallery/AlohaKit.UI.Gallery.csproj

@@ -56,13 +56,4 @@
 	  <ProjectReference Include="..\AlohaKit.UI\AlohaKit.UI.csproj" />
 	</ItemGroup>
 
-	<ItemGroup>
-	  <MauiXaml Update="Views\MainPage.xaml">
-	    <Generator>MSBuild:Compile</Generator>
-	  </MauiXaml>
-	  <MauiXaml Update="Views\XAML\MainPage.xaml">
-	    <Generator>MSBuild:Compile</Generator>
-	  </MauiXaml>
-	</ItemGroup>
-
 </Project>

src/AlohaKit.UI.Gallery/Views/XAML/MainPage.xaml

@@ -10,6 +10,7 @@
             WidthRequest="50" HeightRequest="50" 
             X="30" Y="30" 
             ScaleX="0.5" ScaleY="0.5"
+            Opacity="0.25"
             Fill="Green" />
         <alohakit:RoundRectangle
             WidthRequest="50" HeightRequest="50" 

src/AlohaKit.UI/Controls/CanvasView.cs

@@ -40,7 +40,10 @@
         {
             foreach (var child in Children)
             {
-                child.Draw(canvas, bounds);
+                if (child.IsVisible)
+                {
+                    child.Draw(canvas, bounds);
+                }
             }
         }
     }

src/AlohaKit.UI/Controls/View.cs

@@ -43,6 +43,7 @@ namespace AlohaKit.UI
                     canvas.FillRectangle(bounds);
                 }
 
+                canvas.Alpha = (float)Opacity;
                 canvas.Transform(TranslationX, TranslationY, ScaleX, ScaleY);
 
                 base.Draw(canvas, bounds);

src/AlohaKit.UI/Controls/VisualElement.cs

@@ -3,6 +3,7 @@
     public interface IVisualElement
     {
         bool IsVisible { get; set; }
+        double Opacity { get; set; }
 
         float X { get; set; }
         float Y { get; set; }
@@ -25,6 +26,10 @@
             BindableProperty.Create(nameof(IsVisible), typeof(bool), typeof(VisualElement), true,
                 propertyChanged: InvalidatePropertyChanged);
 
+        public static readonly BindableProperty OpacityProperty = 
+            BindableProperty.Create(nameof(Opacity), typeof(double), typeof(VisualElement), 1d,
+                propertyChanged: InvalidatePropertyChanged);
+
         public static readonly BindableProperty XProperty =
             BindableProperty.Create(nameof(X), typeof(float), typeof(VisualElement), 0.0f,
                 propertyChanged: InvalidatePropertyChanged);
@@ -66,6 +71,12 @@
             set => SetValue(IsVisibleProperty, value);
         }
 
+        public double Opacity
+        {
+            get { return (double)GetValue(OpacityProperty); }
+            set { SetValue(OpacityProperty, value); }
+        }
+
         public float X
         {
             get => (float)GetValue(XProperty);