Add Width and Height to Canvas

Ooui/Canvas.cs

@@ -7,6 +7,18 @@ namespace Ooui
         Context2d context2d = new Context2d ();
         int gotContext2d = 0;
 
+        int width = 150;
+        public int Width {
+            get => width;
+            set => SetProperty (ref width, value <= 0 ? 150 : value, "width");
+        }
+
+        int height = 150;
+        public int Height {
+            get => height;
+            set => SetProperty (ref height, value <= 0 ? 150 : value, "height");
+        }
+
         public Canvas ()
             : base ("canvas")
         {

Tests/CanvasTests.cs

@@ -19,5 +19,39 @@ namespace Tests
             Assert.AreEqual (2, c.StateMessages.Count);
             Assert.AreEqual (c2d, c2d2);
         }
+
+        [TestMethod]
+        public void DefaultWidthAndHeight ()
+        {
+            var c = new Canvas ();
+            Assert.AreEqual (150, c.Width);
+            Assert.AreEqual (150, c.Height);
+        }
+
+        [TestMethod]
+        public void WidthAndHeight ()
+        {
+            var c = new Canvas {
+                Width = 640,
+                Height = 480,
+            };
+            Assert.AreEqual (640, c.Width);
+            Assert.AreEqual (480, c.Height);
+        }
+
+        [TestMethod]
+        public void CantBeNegativeOrZero ()
+        {
+            var c = new Canvas {
+                Width = 640,
+                Height = 480,
+            };
+            Assert.AreEqual (640, c.Width);
+            Assert.AreEqual (480, c.Height);
+            c.Width = 0;
+            c.Height = 0;
+            Assert.AreEqual (150, c.Width);
+            Assert.AreEqual (150, c.Height);
+        }
     }
 }