summaryrefslogtreecommitdiff
path: root/layout/generic/nsFloatManager.h
blob: 32c1387e9b2bc48aeb65be2e17da9830f9fa098d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
// vim:cindent:ts=2:et:sw=2:
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* class that manages rules for positioning floats */

#ifndef nsFloatManager_h_
#define nsFloatManager_h_

#include "mozilla/Attributes.h"
#include "mozilla/WritingModes.h"
#include "nsCoord.h"
#include "nsFrameList.h" // for DEBUG_FRAME_DUMP
#include "nsIntervalSet.h"
#include "nsTArray.h"

class nsIPresShell;
class nsIFrame;
class nsPresContext;
namespace mozilla {
struct ReflowInput;
} // namespace mozilla

/**
 * The available space for content not occupied by floats is divided
 * into a sequence of rectangles in the block direction.  However, we
 * need to know not only the rectangle, but also whether it was reduced
 * (from the content rectangle) by floats that actually intruded into
 * the content rectangle.
 */
struct nsFlowAreaRect {
  mozilla::LogicalRect mRect;
  bool mHasFloats;

  nsFlowAreaRect(mozilla::WritingMode aWritingMode,
                 nscoord aICoord, nscoord aBCoord,
                 nscoord aISize, nscoord aBSize,
                 bool aHasFloats)
    : mRect(aWritingMode, aICoord, aBCoord, aISize, aBSize)
    , mHasFloats(aHasFloats) {}
};

#define NS_FLOAT_MANAGER_CACHE_SIZE 4

class nsFloatManager {
public:
  explicit nsFloatManager(nsIPresShell* aPresShell, mozilla::WritingMode aWM);
  ~nsFloatManager();

  void* operator new(size_t aSize) CPP_THROW_NEW;
  void operator delete(void* aPtr, size_t aSize);

  static void Shutdown();

  /**
   * Get float region stored on the frame. (Defaults to mRect if it's
   * not there.) The float region is the area impacted by this float;
   * the coordinates are relative to the containing block frame.
   */
  static mozilla::LogicalRect GetRegionFor(mozilla::WritingMode aWM,
                                           nsIFrame* aFloatFrame,
                                           const nsSize& aContainerSize);
  /**
   * Calculate the float region for this frame using aMargin and the
   * frame's mRect. The region includes the margins around the float,
   * but doesn't include the relative offsets.
   * Note that if the frame is or has a continuation, aMargin's top
   * and/or bottom must be zeroed by the caller.
   */
  static mozilla::LogicalRect CalculateRegionFor(
                                mozilla::WritingMode aWM,
                                nsIFrame* aFloatFrame,
                                const mozilla::LogicalMargin& aMargin,
                                const nsSize& aContainerSize);
  /**
   * Store the float region on the frame. The region is stored
   * as a delta against the mRect, so repositioning the frame will
   * also reposition the float region.
   */
  static void StoreRegionFor(mozilla::WritingMode aWM,
                             nsIFrame* aFloat,
                             const mozilla::LogicalRect& aRegion,
                             const nsSize& aContainerSize);

  // Structure that stores the current state of a frame manager for
  // Save/Restore purposes.
  struct SavedState {
    explicit SavedState() {}
  private:
    uint32_t mFloatInfoCount;
    nscoord mLineLeft, mBlockStart;
    bool mPushedLeftFloatPastBreak;
    bool mPushedRightFloatPastBreak;
    bool mSplitLeftFloatAcrossBreak;
    bool mSplitRightFloatAcrossBreak;

    friend class nsFloatManager;
  };

  /**
   * Translate the current origin by the specified offsets. This
   * creates a new local coordinate space relative to the current
   * coordinate space.
   */
  void Translate(nscoord aLineLeft, nscoord aBlockStart)
  {
    mLineLeft += aLineLeft;
    mBlockStart += aBlockStart;
  }

  /**
   * Returns the current translation from local coordinate space to
   * world coordinate space. This represents the accumulated calls to
   * Translate().
   */
  void GetTranslation(nscoord& aLineLeft, nscoord& aBlockStart) const
  {
    aLineLeft = mLineLeft;
    aBlockStart = mBlockStart;
  }

  /**
   * Get information about the area available to content that flows
   * around floats.  Two different types of space can be requested:
   *   BAND_FROM_POINT: returns the band containing block-dir coordinate
   *     |aBCoord| (though actually with the top truncated to begin at
   *     aBCoord), but up to at most |aBSize| (which may be nscoord_MAX).
   *     This will return the tallest rectangle whose block start is
   *     |aBCoord| and in which there are no changes in what floats are
   *     on the sides of that rectangle, but will limit the block size
   *     of the rectangle to |aBSize|.  The inline start and end edges
   *     of the rectangle give the area available for line boxes in that
   *     space. The inline size of this resulting rectangle will not be
   *     negative.
   *   WIDTH_WITHIN_HEIGHT: This returns a rectangle whose block start
   *     is aBCoord and whose block size is exactly aBSize.  Its inline
   *     start and end edges give the corresponding edges of the space
   *     that can be used for line boxes *throughout* that space.  (It
   *     is possible that more inline space could be used in part of the
   *     space if a float begins or ends in it.)  The inline size of the
   *     resulting rectangle can be negative.
   *
   * @param aBCoord [in] block-dir coordinate for block start of
   *           available space desired
   * @param aBSize [in] see above
   * @param aContentArea [in] an nsRect representing the content area
   * @param aState [in] If null, use the current state, otherwise, do
   *                    computation based only on floats present in the given
   *                    saved state.
   * @return An nsFlowAreaRect whose:
   *           mRect is the resulting rectangle for line boxes.  It will not
   *             extend beyond aContentArea's inline bounds, but may be
   *             narrower when floats are present.
   *          mBandHasFloats is whether there are floats at the sides of the
   *            return value including those that do not reduce the line box
   *            inline size at all (because they are entirely in the margins)
   *
   * aBCoord and aAvailSpace are positioned relative to the current translation
   */
  enum BandInfoType { BAND_FROM_POINT, WIDTH_WITHIN_HEIGHT };
  nsFlowAreaRect GetFlowArea(mozilla::WritingMode aWM,
                             nscoord aBCoord, BandInfoType aInfoType,
                             nscoord aBSize, mozilla::LogicalRect aContentArea,
                             SavedState* aState,
                             const nsSize& aContainerSize) const;

  /**
   * Add a float that comes after all floats previously added.  Its
   * block start must be even with or below the top of all previous
   * floats.
   *
   * aMarginRect is relative to the current translation.  The caller
   * must ensure aMarginRect.height >= 0 and aMarginRect.width >= 0.
   */
  nsresult AddFloat(nsIFrame* aFloatFrame,
                    const mozilla::LogicalRect& aMarginRect,
                    mozilla::WritingMode aWM, const nsSize& aContainerSize);

  /**
   * Notify that we tried to place a float that could not fit at all and
   * had to be pushed to the next page/column?  (If so, we can't place
   * any more floats in this page/column because of the rule that the
   * top of a float cannot be above the top of an earlier float.  It
   * also means that any clear needs to continue to the next column.)
   */
  void SetPushedLeftFloatPastBreak()
    { mPushedLeftFloatPastBreak = true; }
  void SetPushedRightFloatPastBreak()
    { mPushedRightFloatPastBreak = true; }

  /**
   * Notify that we split a float, with part of it needing to be pushed
   * to the next page/column.  (This means that any 'clear' needs to
   * continue to the next page/column.)
   */
  void SetSplitLeftFloatAcrossBreak()
    { mSplitLeftFloatAcrossBreak = true; }
  void SetSplitRightFloatAcrossBreak()
    { mSplitRightFloatAcrossBreak = true; }

  /**
   * Remove the regions associated with this floating frame and its
   * next-sibling list.  Some of the frames may never have been added;
   * we just skip those. This is not fully general; it only works as
   * long as the N frames to be removed are the last N frames to have
   * been added; if there's a frame in the middle of them that should
   * not be removed, YOU LOSE.
   */
  nsresult RemoveTrailingRegions(nsIFrame* aFrameList);

  bool HasAnyFloats() const { return !mFloats.IsEmpty(); }

  /**
   * Methods for dealing with the propagation of float damage during
   * reflow.
   */
  bool HasFloatDamage() const
  {
    return !mFloatDamage.IsEmpty();
  }

  void IncludeInDamage(nscoord aIntervalBegin, nscoord aIntervalEnd)
  {
    mFloatDamage.IncludeInterval(aIntervalBegin + mBlockStart,
                                 aIntervalEnd + mBlockStart);
  }

  bool IntersectsDamage(nscoord aIntervalBegin, nscoord aIntervalEnd) const
  {
    return mFloatDamage.Intersects(aIntervalBegin + mBlockStart,
                                   aIntervalEnd + mBlockStart);
  }

  /**
   * Saves the current state of the float manager into aState.
   */
  void PushState(SavedState* aState);

  /**
   * Restores the float manager to the saved state.
   *
   * These states must be managed using stack discipline. PopState can only
   * be used after PushState has been used to save the state, and it can only
   * be used once --- although it can be omitted; saved states can be ignored.
   * States must be popped in the reverse order they were pushed.  A
   * call to PopState invalidates any saved states Pushed after the
   * state passed to PopState was pushed.
   */
  void PopState(SavedState* aState);

  /**
   * Get the block start of the last float placed into the float
   * manager, to enforce the rule that a float can't be above an earlier
   * float. Returns the minimum nscoord value if there are no floats.
   *
   * The result is relative to the current translation.
   */
  nscoord GetLowestFloatTop() const;

  /**
   * Return the coordinate of the lowest float matching aBreakType in
   * this float manager. Returns aBCoord if there are no matching
   * floats.
   *
   * Both aBCoord and the result are relative to the current translation.
   */
  enum {
    // Tell ClearFloats not to push to nscoord_MAX when floats have been
    // pushed to the next page/column.
    DONT_CLEAR_PUSHED_FLOATS = (1<<0)
  };
  nscoord ClearFloats(nscoord aBCoord, mozilla::StyleClear aBreakType,
                      uint32_t aFlags = 0) const;

  /**
   * Checks if clear would pass into the floats' BFC's next-in-flow,
   * i.e. whether floats affecting this clear have continuations.
   */
  bool ClearContinues(mozilla::StyleClear aBreakType) const;

  void AssertStateMatches(SavedState *aState) const
  {
    NS_ASSERTION(aState->mLineLeft == mLineLeft &&
                 aState->mBlockStart == mBlockStart &&
                 aState->mPushedLeftFloatPastBreak ==
                   mPushedLeftFloatPastBreak &&
                 aState->mPushedRightFloatPastBreak ==
                   mPushedRightFloatPastBreak &&
                 aState->mSplitLeftFloatAcrossBreak ==
                   mSplitLeftFloatAcrossBreak &&
                 aState->mSplitRightFloatAcrossBreak ==
                   mSplitRightFloatAcrossBreak &&
                 aState->mFloatInfoCount == mFloats.Length(),
                 "float manager state should match saved state");
  }

#ifdef DEBUG_FRAME_DUMP
  /**
   * Dump the state of the float manager out to a file.
   */
  nsresult List(FILE* out) const;
#endif

private:

  struct FloatInfo {
    nsIFrame *const mFrame;
    // The lowest block-ends of left/right floats up to and including
    // this one.
    nscoord mLeftBEnd, mRightBEnd;

    FloatInfo(nsIFrame* aFrame, nscoord aLineLeft, nscoord aBStart,
              nscoord aISize, nscoord aBSize);

    nscoord LineLeft() const { return mRect.x; }
    nscoord LineRight() const { return mRect.XMost(); }
    nscoord ISize() const { return mRect.width; }
    nscoord BStart() const { return mRect.y; }
    nscoord BEnd() const { return mRect.YMost(); }
    nscoord BSize() const { return mRect.height; }
    bool IsEmpty() const { return mRect.IsEmpty(); }

#ifdef NS_BUILD_REFCNT_LOGGING
    FloatInfo(const FloatInfo& aOther);
    ~FloatInfo();
#endif

    // NB! This is really a logical rect in a writing mode suitable for
    // placing floats, which is not necessarily the actual writing mode
    // either of the block which created the frame manager or the block
    // that is calling the frame manager. The inline coordinates are in
    // the line-relative axis of the frame manager and its block
    // coordinates are in the frame manager's real block direction.
    nsRect mRect;
  };

#ifdef DEBUG
  mozilla::WritingMode mWritingMode;
#endif

  // Translation from local to global coordinate space.
  nscoord mLineLeft, mBlockStart;
  nsTArray<FloatInfo> mFloats;
  nsIntervalSet   mFloatDamage;

  // Did we try to place a float that could not fit at all and had to be
  // pushed to the next page/column?  If so, we can't place any more
  // floats in this page/column because of the rule that the top of a
  // float cannot be above the top of an earlier float.  And we also
  // need to apply this information to 'clear', and thus need to
  // separate left and right floats.
  bool mPushedLeftFloatPastBreak;
  bool mPushedRightFloatPastBreak;

  // Did we split a float, with part of it needing to be pushed to the
  // next page/column.  This means that any 'clear' needs to continue to
  // the next page/column.
  bool mSplitLeftFloatAcrossBreak;
  bool mSplitRightFloatAcrossBreak;

  static int32_t sCachedFloatManagerCount;
  static void* sCachedFloatManagers[NS_FLOAT_MANAGER_CACHE_SIZE];

  nsFloatManager(const nsFloatManager&) = delete;
  void operator=(const nsFloatManager&) = delete;
};

/**
 * A helper class to manage maintenance of the float manager during
 * nsBlockFrame::Reflow. It automatically restores the old float
 * manager in the reflow input when the object goes out of scope.
 */
class nsAutoFloatManager {
  using ReflowInput = mozilla::ReflowInput;

public:
  explicit nsAutoFloatManager(ReflowInput& aReflowInput)
    : mReflowInput(aReflowInput),
      mNew(nullptr),
      mOld(nullptr) {}

  ~nsAutoFloatManager();

  /**
   * Create a new float manager for the specified frame. This will
   * `remember' the old float manager, and install the new float
   * manager in the reflow input.
   */
  void
  CreateFloatManager(nsPresContext *aPresContext);

protected:
  ReflowInput &mReflowInput;
  nsFloatManager *mNew;
  nsFloatManager *mOld;
};

#endif /* !defined(nsFloatManager_h_) */