1 files changed, 41 insertions, 0 deletions
diff --git a/shiny/widget/sizer.go b/shiny/widget/sizer.go
new file mode 100644
index 0000000..69e430a
--- /dev/null
+++ b/shiny/widget/sizer.go
@@ -0,0 +1,41 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package widget
+
+import (
+	"golang.org/x/exp/shiny/unit"
+	"golang.org/x/exp/shiny/widget/node"
+	"golang.org/x/exp/shiny/widget/theme"
+)
+
+// Sizer is a shell widget that overrides its child's measured size.
+type Sizer struct {
+	node.ShellEmbed
+	NaturalWidth  unit.Value
+	NaturalHeight unit.Value
+}
+
+// NewSizer returns a new Sizer widget of the given natural size. Its parent
+// widget may lay it out at a different size than its natural size, such as
+// expanding to fill a panel's width.
+func NewSizer(naturalWidth, naturalHeight unit.Value, inner node.Node) *Sizer {
+	w := &Sizer{
+		NaturalWidth:  naturalWidth,
+		NaturalHeight: naturalHeight,
+	}
+	w.Wrapper = w
+	if inner != nil {
+		w.Insert(inner, nil)
+	}
+	return w
+}
+
+func (w *Sizer) Measure(t *theme.Theme, widthHint, heightHint int) {
+	w.MeasuredSize.X = t.Pixels(w.NaturalWidth).Round()
+	w.MeasuredSize.Y = t.Pixels(w.NaturalHeight).Round()
+	if c := w.FirstChild; c != nil {
+		c.Wrapper.Measure(t, w.MeasuredSize.X, w.MeasuredSize.Y)
+	}
+}