Added preferred size code for Mac OS X.

1 files changed, 21 insertions, 0 deletions

diff --git a/prefsize_darwin.go b/prefsize_darwin.go
new file mode 100644
index 0000000..316662e
--- /dev/null
+++ b/prefsize_darwin.go
@@ -0,0 +1,21 @@
+// 1 march 2014
+package ui
+
+// #cgo LDFLAGS: -lobjc -framework Foundation -framework AppKit
+// #include "objc_darwin.h"
+import "C"
+
+// -[NSCell cellSize] is documented as determining the minimum size needed to draw its receiver. This will work for our case; it appears to be what GTK+ does as well.
+// See also: http://stackoverflow.com/questions/1056079/is-there-a-way-to-programmatically-determine-the-proper-sizes-for-apples-built
+// TODO figure out what to do if one of our controls returns the sentinel (10000, 10000) that indicates we can't use -[NSCell cellSize]
+
+var (
+	_cell = sel_getUid("cell")
+	_cellSize = sel_getUid("cellSize")
+)
+
+func (s *sysData) preferredSize() (width int, height int) {
+	cell := C.objc_msgSend_noargs(s.id, _cell)
+	cs := C.objc_msgSend_stret_size_noargs(cell, _cellSize)
+	return int(cs.width), int(cs.height)
+}