[WPF] Widget allocation optimization

Box: Only measure the child widget when it is first added to the box.

1 files changed, 9 insertions, 5 deletions

diff --git a/Xwt.WPF/Xwt.WPFBackend/BoxBackend.cs b/Xwt.WPF/Xwt.WPFBackend/BoxBackend.cs
index 688a01d0..a31a3e1a 100644
--- a/Xwt.WPF/Xwt.WPFBackend/BoxBackend.cs
+++ b/Xwt.WPF/Xwt.WPFBackend/BoxBackend.cs
@@ -120,11 +120,15 @@ namespace Xwt.WPFBackend
 					// because WPF widgets my cache some measurement information based on the

 					// constraints provided in the last Measure call (which when calculating the

 					// preferred size is normally set to infinite.

-					element.InvalidateMeasure ();

-					element.Measure (new SW.Size (rects[i].Width, rects[i].Height));

-

-					element.Arrange (rects[i].ToWpfRect ());

-					element.UpdateLayout ();

+					var r = rects[i].WithPositiveSize ();

+					if (force) {

+						// Don't recalculate the size unless a relayout is being forced

+						element.InvalidateMeasure ();

+						element.Measure (new SW.Size (r.Width, r.Height));

+					}

+					

+					element.Arrange (r.ToWpfRect ());

+				//	element.UpdateLayout ();

 				}

 			}

 		}