layout/base/nsIPercentBSizeObserver.h

   1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* vim: set ts=8 sts=2 et sw=2 tw=80: */
   3 /* This Source Code Form is subject to the terms of the Mozilla Public
   4  * License, v. 2.0. If a copy of the MPL was not distributed with this
   5  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6
   7 #ifndef nsIPercentBSizeObserver_h___
   8 #define nsIPercentBSizeObserver_h___
   9
  10 #include "nsQueryFrame.h"
  11
  12 namespace mozilla {
  13 struct ReflowInput;
  14 }  // namespace mozilla
  15
  16 /**
  17  * This interface is supported by frames that need to provide computed bsize
  18  * values to children during reflow which would otherwise not happen. Currently
  19  * only table cells support this.
  20  */
  21 class nsIPercentBSizeObserver {
  22  public:
  23   NS_DECL_QUERYFRAME_TARGET(nsIPercentBSizeObserver)
  24
  25   // Notify the observer that aReflowInput has no computed bsize,
  26   // but it has a percent bsize
  27   virtual void NotifyPercentBSize(const mozilla::ReflowInput& aReflowInput) = 0;
  28
  29   // Ask the observer if it should observe aReflowInput.frame
  30   virtual bool NeedsToObserve(const mozilla::ReflowInput& aReflowInput) = 0;
  31 };
  32
  33 #endif  // nsIPercentBSizeObserver_h___