更新

WPFDark/Controls/Internals/IHasTransform.cs

@@ -0,0 +1,62 @@
+using System.Windows;
+using System.Windows.Media;
+using WPFDark.Internals;
+
+namespace WPFDark.Controls.Internals
+{
+    public interface IHasTransform
+    {
+        ScaleTransform ScaleTransform { get; }
+
+        TranslateTransform TranslateTransform { get; }
+    }
+
+    public static class HasTransformExtensions
+    {
+        public static Point TransformPos(this IHasTransform self, double x, double y)
+        {
+            var s = self.ScaleTransform.ScaleX;
+
+            return new Point(
+                (x - self.TranslateTransform.X) / s,
+                (y - self.TranslateTransform.Y) / s);
+        }
+
+        public static ImmutableRect_double TransformRect(this IHasTransform self, double w, double h)
+        {
+            var s = self.ScaleTransform.ScaleX;
+
+            return new ImmutableRect_double(
+                -self.TranslateTransform.X / s,
+                -self.TranslateTransform.Y / s,
+                w / s,
+                h / s);
+        }
+
+        public static ImmutableRect_double TransformRect(this IHasTransform self, in ImmutableRect_double rect)
+        {
+            var s = self.ScaleTransform.ScaleX;
+
+            return new ImmutableRect_double(
+                (rect.X - self.TranslateTransform.X) / s,
+                (rect.Y - self.TranslateTransform.Y) / s,
+                rect.Width / s,
+                rect.Height / s);
+        }
+
+        public static void SetTransform(this IHasTransform self, double scale, double centerX, double centerY)
+        {
+            var d0 = self.TransformPos(centerX, centerY);
+
+            self.ScaleTransform.ScaleX = scale;
+            self.ScaleTransform.ScaleY = scale;
+
+            var d1 = self.TransformPos(centerX, centerY);
+
+            var diff = d1 - d0;
+
+            self.TranslateTransform.X += diff.X * scale;
+            self.TranslateTransform.Y += diff.Y * scale;
+        }
+    }
+}