The beginnings of a layout system

tomo.go

@@ -150,6 +150,28 @@ type Window interface {
 	OnClose (func ())
 }
 
+// LayoutEntry associates an element with layout and positioning information so
+// it can be arranged by a Layout.
+type LayoutEntry struct {
+	Element
+	Position image.Point
+	Expand bool
+}
+
+// Layout is capable of arranging elements within a container. It is also able
+// to determine the minimum amount of room it needs to do so.
+type Layout interface {
+	// Arrange takes in a slice of entries and a bounding width and height,
+	// and changes the position of the entiries in the slice so that they
+	// are properly laid out. The given width and height should not be less
+	// than what is returned by MinimumSize.
+	Arrange (entries []LayoutEntry, width, height int)
+
+	// MinimumSize returns the minimum width and height that the layout
+	// needs to properly arrange the given slice of layout entries.
+	MinimumSize (entries []LayoutEntry) (width, height int)
+}
+
 var backend Backend
 
 // Run initializes a backend, calls the callback function, and begins the event