1 : /* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
2 : /* ***** BEGIN LICENSE BLOCK *****
3 : * Version: MPL 1.1/GPL 2.0/LGPL 2.1
4 : *
5 : * The contents of this file are subject to the Mozilla Public License Version
6 : * 1.1 (the "License"); you may not use this file except in compliance with
7 : * the License. You may obtain a copy of the License at
8 : * http://www.mozilla.org/MPL/
9 : *
10 : * Software distributed under the License is distributed on an "AS IS" basis,
11 : * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
12 : * for the specific language governing rights and limitations under the
13 : * License.
14 : *
15 : * The Original Code is mozilla.org code.
16 : *
17 : * The Initial Developer of the Original Code is
18 : * Netscape Communications Corporation.
19 : * Portions created by the Initial Developer are Copyright (C) 1998
20 : * the Initial Developer. All Rights Reserved.
21 : *
22 : * Contributor(s):
23 : *
24 : * Alternatively, the contents of this file may be used under the terms of
25 : * either of the GNU General Public License Version 2 or later (the "GPL"),
26 : * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
27 : * in which case the provisions of the GPL or the LGPL are applicable instead
28 : * of those above. If you wish to allow use of your version of this file only
29 : * under the terms of either the GPL or the LGPL, and not to allow others to
30 : * use your version of this file under the terms of the MPL, indicate your
31 : * decision by deleting the provisions above and replace them with the notice
32 : * and other provisions required by the GPL or the LGPL. If you do not delete
33 : * the provisions above, a recipient may use your version of this file under
34 : * the terms of any one of the MPL, the GPL or the LGPL.
35 : *
36 : * ***** END LICENSE BLOCK ***** */
37 :
38 : /*
39 : * rendering object for the point that anchors out-of-flow rendering
40 : * objects such as floats and absolutely positioned elements
41 : */
42 :
43 : /*
44 : * Destruction of a placeholder and its out-of-flow must observe the
45 : * following constraints:
46 : *
47 : * - The mapping from the out-of-flow to the placeholder must be
48 : * removed from the frame manager before the placeholder is destroyed.
49 : * - The mapping from the out-of-flow to the placeholder must be
50 : * removed from the frame manager before the out-of-flow is destroyed.
51 : * - The placeholder must be removed from the frame tree, or have the
52 : * mapping from it to its out-of-flow cleared, before the out-of-flow
53 : * is destroyed (so that the placeholder will not point to a destroyed
54 : * frame while it's in the frame tree).
55 : *
56 : * Furthermore, some code assumes that placeholders point to something
57 : * useful, so placeholders without an associated out-of-flow should not
58 : * remain in the tree.
59 : *
60 : * The placeholder's Destroy() implementation handles the destruction of
61 : * the placeholder and its out-of-flow. To avoid crashes, frame removal
62 : * and destruction code that works with placeholders must not assume
63 : * that the placeholder points to its out-of-flow.
64 : */
65 :
66 : #ifndef nsPlaceholderFrame_h___
67 : #define nsPlaceholderFrame_h___
68 :
69 : #include "nsFrame.h"
70 : #include "nsGkAtoms.h"
71 :
72 : nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
73 : nsStyleContext* aContext,
74 : nsFrameState aTypeBit);
75 :
76 : // Frame state bits that are used to keep track of what this is a
77 : // placeholder for.
78 : #define PLACEHOLDER_FOR_FLOAT NS_FRAME_STATE_BIT(20)
79 : #define PLACEHOLDER_FOR_ABSPOS NS_FRAME_STATE_BIT(21)
80 : #define PLACEHOLDER_FOR_FIXEDPOS NS_FRAME_STATE_BIT(22)
81 : #define PLACEHOLDER_FOR_POPUP NS_FRAME_STATE_BIT(23)
82 : #define PLACEHOLDER_TYPE_MASK (PLACEHOLDER_FOR_FLOAT | \
83 : PLACEHOLDER_FOR_ABSPOS | \
84 : PLACEHOLDER_FOR_FIXEDPOS | \
85 : PLACEHOLDER_FOR_POPUP)
86 :
87 : /**
88 : * Implementation of a frame that's used as a placeholder for a frame that
89 : * has been moved out of the flow
90 : */
91 : class nsPlaceholderFrame : public nsFrame {
92 : public:
93 : NS_DECL_FRAMEARENA_HELPERS
94 :
95 : /**
96 : * Create a new placeholder frame. aTypeBit must be one of the
97 : * PLACEHOLDER_FOR_* constants above.
98 : */
99 : friend nsIFrame* NS_NewPlaceholderFrame(nsIPresShell* aPresShell,
100 : nsStyleContext* aContext,
101 : nsFrameState aTypeBit);
102 0 : nsPlaceholderFrame(nsStyleContext* aContext, nsFrameState aTypeBit) :
103 0 : nsFrame(aContext)
104 : {
105 0 : NS_PRECONDITION(aTypeBit == PLACEHOLDER_FOR_FLOAT ||
106 : aTypeBit == PLACEHOLDER_FOR_ABSPOS ||
107 : aTypeBit == PLACEHOLDER_FOR_FIXEDPOS ||
108 : aTypeBit == PLACEHOLDER_FOR_POPUP,
109 : "Unexpected type bit");
110 0 : AddStateBits(aTypeBit);
111 0 : }
112 : virtual ~nsPlaceholderFrame();
113 :
114 : // Get/Set the associated out of flow frame
115 0 : nsIFrame* GetOutOfFlowFrame() const {return mOutOfFlowFrame;}
116 0 : void SetOutOfFlowFrame(nsIFrame* aFrame) {
117 0 : NS_ASSERTION(!aFrame || !aFrame->GetPrevContinuation(),
118 : "OOF must be first continuation");
119 0 : mOutOfFlowFrame = aFrame;
120 0 : }
121 :
122 : // nsIHTMLReflow overrides
123 : // We need to override GetMinWidth and GetPrefWidth because XUL uses
124 : // placeholders not within lines.
125 : virtual nscoord GetMinWidth(nsRenderingContext *aRenderingContext);
126 : virtual nscoord GetPrefWidth(nsRenderingContext *aRenderingContext);
127 : virtual void AddInlineMinWidth(nsRenderingContext *aRenderingContext,
128 : InlineMinWidthData *aData);
129 : virtual void AddInlinePrefWidth(nsRenderingContext *aRenderingContext,
130 : InlinePrefWidthData *aData);
131 : virtual nsSize GetMinSize(nsBoxLayoutState& aBoxLayoutState);
132 : virtual nsSize GetPrefSize(nsBoxLayoutState& aBoxLayoutState);
133 : virtual nsSize GetMaxSize(nsBoxLayoutState& aBoxLayoutState);
134 : NS_IMETHOD Reflow(nsPresContext* aPresContext,
135 : nsHTMLReflowMetrics& aDesiredSize,
136 : const nsHTMLReflowState& aReflowState,
137 : nsReflowStatus& aStatus);
138 :
139 : virtual void DestroyFrom(nsIFrame* aDestructRoot);
140 :
141 : // nsIFrame overrides
142 : #if defined(DEBUG) || (defined(MOZ_REFLOW_PERF_DSP) && defined(MOZ_REFLOW_PERF))
143 : NS_IMETHOD BuildDisplayList(nsDisplayListBuilder* aBuilder,
144 : const nsRect& aDirtyRect,
145 : const nsDisplayListSet& aLists);
146 : #endif // DEBUG || (MOZ_REFLOW_PERF_DSP && MOZ_REFLOW_PERF)
147 :
148 : #ifdef DEBUG
149 : NS_IMETHOD List(FILE* out, PRInt32 aIndent) const;
150 : #endif // DEBUG
151 :
152 : /**
153 : * Get the "type" of the frame
154 : *
155 : * @see nsGkAtoms::placeholderFrame
156 : */
157 : virtual nsIAtom* GetType() const;
158 :
159 : #ifdef DEBUG
160 : NS_IMETHOD GetFrameName(nsAString& aResult) const;
161 : #endif
162 :
163 0 : virtual bool IsEmpty() { return true; }
164 0 : virtual bool IsSelfEmpty() { return true; }
165 :
166 : virtual bool CanContinueTextRun() const;
167 :
168 : #ifdef ACCESSIBILITY
169 0 : virtual already_AddRefed<nsAccessible> CreateAccessible()
170 : {
171 0 : nsIFrame* realFrame = GetRealFrameForPlaceholder(this);
172 0 : return realFrame ? realFrame->CreateAccessible() :
173 0 : nsFrame::CreateAccessible();
174 : }
175 : #endif
176 :
177 : virtual nsIFrame* GetParentStyleContextFrame() const;
178 :
179 : /**
180 : * @return the out-of-flow for aFrame if aFrame is a placeholder; otherwise
181 : * aFrame
182 : */
183 0 : static nsIFrame* GetRealFrameFor(nsIFrame* aFrame) {
184 0 : NS_PRECONDITION(aFrame, "Must have a frame to work with");
185 0 : if (aFrame->GetType() == nsGkAtoms::placeholderFrame) {
186 0 : return GetRealFrameForPlaceholder(aFrame);
187 : }
188 0 : return aFrame;
189 : }
190 :
191 : /**
192 : * @return the out-of-flow for aFrame, which is known to be a placeholder
193 : */
194 0 : static nsIFrame* GetRealFrameForPlaceholder(nsIFrame* aFrame) {
195 0 : NS_PRECONDITION(aFrame->GetType() == nsGkAtoms::placeholderFrame,
196 : "Must have placeholder frame as input");
197 : nsIFrame* outOfFlow =
198 0 : static_cast<nsPlaceholderFrame*>(aFrame)->GetOutOfFlowFrame();
199 0 : NS_ASSERTION(outOfFlow, "Null out-of-flow for placeholder?");
200 0 : return outOfFlow;
201 : }
202 :
203 : protected:
204 : nsIFrame* mOutOfFlowFrame;
205 : };
206 :
207 : #endif /* nsPlaceholderFrame_h___ */
|