implement down arrow to move cursor

diff --git a/editor.coffee b/editor.coffee
index a932f16..44b5fb6 100644 (file)
--- a/editor.coffee
+++ b/editor.coffee
@@ -806,6 +806,44 @@ class PeachHTML5Editor
                                                @move_cursor new_cursor
                                return false
                        when KEY_DOWN
+                               if @cursor?
+                                       new_cursor = @cursor
+                                       # go next until we move on the y axis
+                                       while new_cursor.y <= @cursor.y
+                                               new_cursor = find_next_cursor_position @tree, new_cursor
+                                               return false unless new_cursor?
+                                       # done early if we're already right of old cursor position
+                                       if new_cursor.x >= @cursor.x
+                                               # this would be strange, but could happen due to runaround
+                                               @move_cursor new_cursor
+                                               return false
+                                       target_y = new_cursor.y
+                                       # search rightward, until we find the closest position
+                                       # new_cursor is the next-most position we've checked
+                                       # prev_cursor is the older value, so it's not as next as new_cursor
+                                       while new_cursor.x < @cursor.x and new_cursor.y is target_y
+                                               prev_cursor = new_cursor
+                                               new_cursor = find_next_cursor_position @tree, new_cursor
+                                               break unless new_cursor?
+                                       # move cursor to prev_cursor or new_cursor
+                                       if new_cursor?
+                                               if new_cursor.y is target_y
+                                                       # both valid, and on the same line, use closest
+                                                       if (new_cursor.x - @cursor.x) < (@cursor.x - prev_cursor.x)
+                                                               @move_cursor new_cursor
+                                                       else
+                                                               @move_cursor prev_cursor
+                                               else
+                                                       # new_cursor on wrong line, use prev_cursor
+                                                       @move_cursor prev_cursor
+                                       else
+                                               # can't go any further prev, use prev_cursor
+                                               @move_cursor prev_cursor
+                               else
+                                       # move cursor to first position in document
+                                       new_cursor = last_cursor_position @tree
+                                       if new_cursor?
+                                               @move_cursor new_cursor
                                return false
                        when KEY_END
                                return false