add layout constraints and abs/rel units

1 files changed, 16 insertions, 0 deletions

diff --git a/len_test.go b/len_test.go
new file mode 100644
index 0000000..91b0886
--- /dev/null
+++ b/len_test.go
@@ -0,0 +1,16 @@
+package gui_test
+
+import (
+	"fmt"
+	"image"
+
+	"github.com/faiface/gui"
+)
+
+func ExampleRelative() {
+	var l Length = Relative(0.10)   // 10%
+	r := image.Rect(0, 0, 100, 100) // 100x100 rectangle
+	fmt.Println(l.Px(r))
+	// Output:
+	// 10
+}