layout/generic/nsIAnonymousContentCreator.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 /*
   7  * interface for rendering objects that manually create subtrees of
   8  * anonymous content
   9  */
  10
  11 #ifndef nsIAnonymousContentCreator_h___
  12 #define nsIAnonymousContentCreator_h___
  13
  14 #include "nsQueryFrame.h"
  15 #include "nsIContent.h"
  16 #include "nsStyleContext.h"
  17 #include "nsTArrayForwardDeclare.h"
  18
  19 class nsBaseContentList;
  20 class nsIFrame;
  21
  22 /**
  23  * Any source for anonymous content can implement this interface to provide it.
  24  * HTML frames like nsFileControlFrame currently use this.
  25  *
  26  * @see nsCSSFrameConstructor
  27  */
  28 class nsIAnonymousContentCreator
  29 {
  30 public:
  31   NS_DECL_QUERYFRAME_TARGET(nsIAnonymousContentCreator)
  32
  33   struct ContentInfo {
  34     ContentInfo(nsIContent* aContent) :
  35       mContent(aContent)
  36     {}
  37
  38     ContentInfo(nsIContent* aContent, nsStyleContext* aStyleContext) :
  39       mContent(aContent), mStyleContext(aStyleContext)
  40     {}
  41
  42     nsIContent* mContent;
  43     nsRefPtr<nsStyleContext> mStyleContext;
  44     nsTArray<ContentInfo> mChildren;
  45   };
  46
  47   /**
  48    * Creates "native" anonymous content and adds the created content to
  49    * the aElements array. None of the returned elements can be nullptr.
  50    *
  51    * If the anonymous content creator sets the editable flag on some
  52    * of the elements that it creates, the flag will be applied to the node
  53    * upon being bound to the document.
  54    *
  55    * @note The returned elements are owned by this object. This object is
  56    *       responsible for calling UnbindFromTree on the elements it returned
  57    *       from CreateAnonymousContent when appropriate (i.e. before releasing
  58    *       them).
  59    *
  60    * @note Implementations of this method that add items to mChildren must not
  61    *       hook them up to any parent since frame construction takes care of
  62    *       that.
  63    */
  64   virtual nsresult CreateAnonymousContent(nsTArray<ContentInfo>& aElements)=0;
  65
  66   /**
  67    * Appends "native" anonymous children created by CreateAnonymousContent()
  68    * to the given content list depending on the filter.
  69    *
  70    * @see nsIContent::GetChildren for set of values used for filter.
  71    */
  72   virtual void AppendAnonymousContentTo(nsBaseContentList& aElements,
  73                                         uint32_t aFilter) = 0;
  74
  75   /**
  76    * Implementations can override this method to create special frames for the
  77    * anonymous content returned from CreateAnonymousContent.
  78    * By default this method returns nullptr, which means the default frame
  79    * is created.
  80    */
  81   virtual nsIFrame* CreateFrameFor(nsIContent* aContent) { return nullptr; }
  82 };
  83
  84 #endif
  85