layout/base/nsIPercentHeightObserver.h

   1 /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #ifndef nsIPercentHeightObserver_h___
   7 #define nsIPercentHeightObserver_h___
   8
   9 #include "nsQueryFrame.h"
  10
  11 struct nsHTMLReflowState;
  12
  13 /**
  14  * This interface is supported by frames that need to provide computed height
  15  * values to children during reflow which would otherwise not happen. Currently only
  16  * table cells support this.
  17  */
  18 class nsIPercentHeightObserver
  19 {
  20 public:
  21   NS_DECL_QUERYFRAME_TARGET(nsIPercentHeightObserver)
  22
  23   // Notify the observer that aReflowState has no computed height, but it has a percent height
  24   virtual void NotifyPercentHeight(const nsHTMLReflowState& aReflowState) = 0;
  25
  26   // Ask the observer if it should observe aReflowState.frame
  27   virtual bool NeedsToObserve(const nsHTMLReflowState& aReflowState) = 0;
  28 };
  29
  30 #endif // nsIPercentHeightObserver_h___