layout/generic/nsIStatefulFrame.h

   1 /*
   2  * interface for rendering objects whose state is saved in
   3  * session-history (back-forward navigation)
   4  */
   5
   6 #ifndef _nsIStatefulFrame_h
   7 #define _nsIStatefulFrame_h
   8
   9 #include "nsISupports.h"
  10
  11 class nsPresContext;
  12 class nsPresState;
  13
  14 #define NS_ISTATEFULFRAME_IID \
  15 { 0x25c232cf, 0x40ba, 0x4394, \
  16  { 0x84, 0xe4, 0x73, 0xa2, 0xf7, 0x4d, 0x8b, 0x64 } }
  17
  18 class nsIStatefulFrame : public nsISupports {
  19  public:
  20   NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISTATEFULFRAME_IID)
  21
  22   // If you create a special type stateful frame (e.g. scroll) that needs
  23   // to be captured outside of the standard pass through the frames, you'll need
  24   // a special ID by which to refer to that type.
  25   enum SpecialStateID {eNoID=0, eDocumentScrollState};
  26
  27   // Save the state for this frame.  Some implementations may choose to return
  28   // different states depending on the value of aStateID.  If this method
  29   // succeeds, the caller is responsible for deleting the resulting state when
  30   // done with it.
  31   NS_IMETHOD SaveState(SpecialStateID aStateID, nsPresState** aState) = 0;
  32
  33   // Restore the state for this frame from aState
  34   NS_IMETHOD RestoreState(nsPresState* aState) = 0;
  35 };
  36
  37 NS_DEFINE_STATIC_IID_ACCESSOR(nsIStatefulFrame, NS_ISTATEFULFRAME_IID)
  38
  39 #endif /* _nsIStatefulFrame_h */