1 files changed, 26 insertions, 0 deletions
diff --git a/src/book.vala b/src/book.vala
index d2aa54d..e25eb35 100644
--- a/src/book.vala
+++ b/src/book.vala
@@ -11,6 +11,12 @@
 
 public delegate void ProgressionCallback (double fraction);
 
+// Assumes first page has index 0
+public enum FlipEverySecond {
+    Even = 1,
+    Odd = 0,
+}
+
 public class Book : Object
 {
     private List<Page> pages;
@@ -99,6 +105,26 @@ public class Book : Object
         changed ();
     }
 
+    public void flip_every_second (FlipEverySecond flip)
+    {
+        var new_pages = new List<Page> ();
+        for (var i = 0; i < n_pages; i++)
+        {
+            var page = pages.nth_data (i);
+            if (i % 2 == (int)flip) {
+                page.rotate_left();
+                page.rotate_left();
+                new_pages.append (page);
+            } else {
+                new_pages.append (page);
+            }
+        }
+        pages = (owned) new_pages;
+
+        reordered ();
+        changed ();
+    }
+
     public void combine_sides_reverse ()
     {
         var new_pages = new List<Page> ();