Merge branch 'master' into fixes/1436-border-layout-issues

src/Avalonia.Controls/Border.cs

@@ -115,7 +115,7 @@ namespace Avalonia.Controls
                 Child.Arrange(new Rect(finalSize).Deflate(padding));
             }
 
-            _borderRenderHelper.Update(finalSize, BorderThickness, CornerRadius);           
+            _borderRenderHelper.Update(finalSize, BorderThickness, CornerRadius);
 
             return finalSize;
         }

src/Avalonia.Controls/Presenters/ContentPresenter.cs

@@ -385,7 +385,7 @@ namespace Avalonia.Controls.Presenters
             {
                 size = size.WithWidth(Math.Min(size.Width, DesiredSize.Width - padding.Left - padding.Right));
             }
-            
+
             if (verticalContentAlignment != VerticalAlignment.Stretch)
             {
                 size = size.WithHeight(Math.Min(size.Height, DesiredSize.Height - padding.Top - padding.Bottom));
@@ -427,7 +427,7 @@ namespace Avalonia.Controls.Presenters
                 originY = Math.Floor(originY * scale) / scale;
             }
 
-            Child.Arrange(new Rect(originX, originY, size.Width, size.Height));
+            Child.Arrange(new Rect(originX, originY, Math.Max(0, size.Width), Math.Max(0, size.Height)));
 
             return finalSize;
         }

tests/Avalonia.Controls.UnitTests/BorderTests.cs

@@ -20,5 +20,27 @@ namespace Avalonia.Controls.UnitTests
 
             Assert.Equal(new Size(20, 20), target.DesiredSize);
         }
+
+        [Fact]
+        public void Child_Should_Arrange_With_Zero_Height_Width_If_Padding_Greater_Than_Child_Size()
+        {
+            Border content;
+
+            var target = new Border
+            {
+                Padding = new Thickness(6),
+                MaxHeight = 12,
+                MaxWidth = 12,
+                Child = content = new Border
+                {
+                    Height = 0,
+                    Width = 0
+                }
+            };
+
+            target.Arrange(new Rect(0, 0, 100, 100));
+
+            Assert.Equal(new Rect(6, 6, 0, 0), content.Bounds);
+        }
     }
 }

tests/Avalonia.Controls.UnitTests/Presenters/ContentPresenterTests_Layout.cs

@@ -210,5 +210,30 @@ namespace Avalonia.Controls.UnitTests.Presenters
 
             Assert.Equal(new Rect(84, 0, 16, 16), content.Bounds);
         }
+
+        [Fact]
+        public void Child_Arrange_With_Zero_Height_When_Padding_Height_Greater_Than_Child_Height()
+        {
+            Border content;
+            var target = new ContentPresenter
+            {
+                Padding = new Thickness(32),
+                MaxHeight = 32,
+                MaxWidth = 32,
+                HorizontalContentAlignment = HorizontalAlignment.Center,
+                VerticalContentAlignment = VerticalAlignment.Center,
+                Content = content = new Border
+                {
+                    Height = 0,
+                    Width = 0,
+                },
+            };
+
+            target.UpdateChild();
+
+            target.Arrange(new Rect(0, 0, 100, 100));
+
+            Assert.Equal(new Rect(48, 48, 0, 0), content.Bounds);
+        }
     }
 }