功能更新

Melskin/Controls/Toast/WindowHost.cs

@@ -0,0 +1,77 @@
+using System.Windows.Documents;
+
+
+namespace Melskin.Controls;
+#region Internal Implementation
+
+internal class WindowHost : IToastHost
+{
+    private readonly StackPanel toastContainer;
+
+    public WindowHost(Window window)
+    {
+        toastContainer = new StackPanel();
+
+        // Use a style to apply margin between toasts, which is a robust approach.
+        var childStyle = new Style(typeof(ToastControl));
+        childStyle.Setters.Add(new Setter(FrameworkElement.MarginProperty, new Thickness(0, 8, 0, 8)));
+        toastContainer.Resources.Add(typeof(ToastControl), childStyle);
+
+        var adornerLayer = AdornerLayer.GetAdornerLayer(window.Content as Visual);
+        if (adornerLayer == null) throw new InvalidOperationException("在指定的窗口中找不到 AdornerLayer。");
+
+        adornerLayer.Add(new ToastAdorner(window.Content as UIElement, toastContainer));
+    }
+
+    public void AddToast(ToastControl toast) => toastContainer.Children.Add(toast);
+    public void RemoveToast(ToastControl toast) => toastContainer.Children.Remove(toast);
+
+
+    private class ToastAdorner : Adorner
+    {
+        private readonly UIElement child; // This is our StackPanel
+
+        public ToastAdorner(UIElement? adornedElement, UIElement child) : base(adornedElement)
+        {
+            this.child = child;
+            // Add the child to the visual tree. This is essential.
+            AddVisualChild(this.child);
+        }
+
+        protected override int VisualChildrenCount => 1;
+        protected override Visual GetVisualChild(int index) => child;
+
+        // We override Measure to tell our child (StackPanel) how much space it has.
+        protected override Size MeasureOverride(Size constraint)
+        {
+            // Give the child all the space it could possibly want.
+            // It will then measure itself and its children, establishing its DesiredSize.
+            child.Measure(new Size(double.PositiveInfinity, double.PositiveInfinity));
+            // The Adorner itself doesn't need to return a specific size, as it's a transparent overlay.
+            return base.MeasureOverride(constraint);
+        }
+
+        // ArrangeOverride is where we do the actual positioning.
+        protected override Size ArrangeOverride(Size finalSize)
+        {
+            // 'finalSize' is the full size of the element we are adorning (e.g., the window's content area).
+            // '_child.DesiredSize' is the size our StackPanel reported it needs after being measured.
+
+            // Calculate the X coordinate to center the child (StackPanel).
+            var x = (finalSize.Width - child.DesiredSize.Width) / 2;
+
+            // The Y coordinate is 0, placing it at the very top.
+            double y = 0;
+
+            // Create the final rectangle for our child, positioned correctly.
+            var finalRect = new Rect(new Point(x, y), child.DesiredSize);
+
+            // Arrange the child (our StackPanel) in the calculated centered rectangle.
+            child.Arrange(finalRect);
+
+            // The Adorner itself arranges to fill the entire space.
+            return finalSize;
+        }
+    }
+}
+#endregion