summaryrefslogtreecommitdiffstats
path: root/dom/svg/DOMSVGLength.h
blob: fa50ba8fe059afe38dc465bc0c9cc55e6787439e (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
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 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/. */

#ifndef MOZILLA_DOMSVGLENGTH_H__
#define MOZILLA_DOMSVGLENGTH_H__

#include "DOMSVGLengthList.h"
#include "nsCycleCollectionParticipant.h"
#include "nsDebug.h"
#include "nsIDOMSVGLength.h"
#include "nsTArray.h"
#include "SVGLength.h"
#include "mozilla/Attributes.h"
#include "nsWrapperCache.h"

class nsSVGElement;

// We make DOMSVGLength a pseudo-interface to allow us to QI to it in order to
// check that the objects that scripts pass to DOMSVGLengthList methods are our
// *native* length objects.
//
// {A8468350-7F7B-4976-9A7E-3765A1DADF9A}
#define MOZILLA_DOMSVGLENGTH_IID \
  { 0xA8468350, 0x7F7B, 0x4976, { 0x9A, 0x7E, 0x37, 0x65, 0xA1, 0xDA, 0xDF, 0x9A } }

#define MOZ_SVG_LIST_INDEX_BIT_COUNT 22 // supports > 4 million list items

namespace mozilla {

class ErrorResult;

/**
 * Class DOMSVGLength
 *
 * This class creates the DOM objects that wrap internal SVGLength objects that
 * are in an SVGLengthList. It is also used to create the objects returned by
 * SVGSVGElement.createSVGLength().
 *
 * For the DOM wrapper classes for non-list SVGLength, see nsSVGLength2.h.
 *
 * See the architecture comment in DOMSVGAnimatedLengthList.h.
 *
 * This class is strongly intertwined with DOMSVGAnimatedLengthList and
 * DOMSVGLengthList. We are a friend of DOMSVGLengthList, and are responsible
 * for nulling out our DOMSVGLengthList's pointer to us when we die, making it
 * a real weak pointer.
 *
 * When objects of this type are in a DOMSVGLengthList they belong to an
 * attribute. While they belong to an attribute, the objects' values come from
 * their corresponding internal SVGLength objects in the internal SVGLengthList
 * objects for the attribute. Getting and setting values of a DOMSVGLength
 * requires reading and writing to its internal SVGLength. However, if the
 * DOMSVGLength is detached from its DOMSVGLengthList then it first makes a
 * copy of its internal SVGLength's value and unit so that it doesn't appear to
 * "lose" its value from script's perspective on being removed from the list.
 * This means that these DOM tearoffs have space to store these values, even
 * though they're not used in the common case.
 *
 * Objects of this type are also used to reflect the baseVal and animVal of
 * a single, non-list SVGLength attribute. Getting and settings values of the
 * DOMSVGLength in this case requires reading and writing to the corresponding
 * nsSVGLength2 object.
 *
 * This class also stores its current list index, attribute enum, and whether
 * it belongs to a baseVal or animVal list. This is so that objects of this
 * type can find their corresponding internal SVGLength.
 *
 * To use these classes for <length> attributes as well as <list-of-length>
 * attributes, we would need to take a bit from mListIndex and use that to
 * indicate whether the object belongs to a list or non-list attribute, then
 * if-else as appropriate. The bug for doing that work is:
 * https://bugzilla.mozilla.org/show_bug.cgi?id=571734
 */
class DOMSVGLength final : public nsIDOMSVGLength,
                           public nsWrapperCache
{
  friend class AutoChangeLengthNotifier;

  /**
   * Ctor for creating the object returned by nsSVGLength2::ToDOMBaseVal/ToDOMAnimVal
   */
  DOMSVGLength(nsSVGLength2* aVal, nsSVGElement* aSVGElement, bool aAnimVal);

  ~DOMSVGLength();

public:
  NS_DECLARE_STATIC_IID_ACCESSOR(MOZILLA_DOMSVGLENGTH_IID)
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(DOMSVGLength)
  NS_DECL_NSIDOMSVGLENGTH

  /**
   * Generic ctor for DOMSVGLength objects that are created for an attribute.
   */
  DOMSVGLength(DOMSVGLengthList *aList,
               uint8_t aAttrEnum,
               uint32_t aListIndex,
               bool aIsAnimValItem);

  /**
   * Ctor for creating the objects returned by SVGSVGElement.createSVGLength(),
   * which do not initially belong to an attribute.
   */
  DOMSVGLength();

  static already_AddRefed<DOMSVGLength> GetTearOff(nsSVGLength2* aVal,
                                                   nsSVGElement* aSVGElement,
                                                   bool aAnimVal);

  /**
   * Create an unowned copy of a length that is owned or is reflecting a single
   * attribute. The caller is responsible for the first AddRef().
   */
  DOMSVGLength* Copy();

  bool IsInList() const {
    return !!mList;
  }

  /**
   * In future, if this class is used for non-list lengths, this will be
   * different to IsInList().
   */
  bool HasOwner() const {
    return !!mList;
  }

  /**
   * Returns whether this length object is reflecting a single SVG element
   * attribute.  This includes the baseVal or animVal of SVGRectElement.x, for
   * example, but not an item in an SVGLengthList, such as those in the
   * baseVal or animVal of SVGTextElement.x.
   */
  bool IsReflectingAttribute() const {
    return mVal;
  }

  /**
   * This method is called to notify this DOM object that it is being inserted
   * into a list, and give it the information it needs as a result.
   *
   * This object MUST NOT already belong to a list when this method is called.
   * That's not to say that script can't move these DOM objects between
   * lists - it can - it's just that the logic to handle that (and send out
   * the necessary notifications) is located elsewhere (in DOMSVGLengthList).)
   */
  void InsertingIntoList(DOMSVGLengthList *aList,
                         uint8_t aAttrEnum,
                         uint32_t aListIndex,
                         bool aIsAnimValItem);

  static uint32_t MaxListIndex() {
    return (1U << MOZ_SVG_LIST_INDEX_BIT_COUNT) - 1;
  }

  /// This method is called to notify this object that its list index changed.
  void UpdateListIndex(uint32_t aListIndex) {
    mListIndex = aListIndex;
  }

  /**
   * This method is called to notify this DOM object that it is about to be
   * removed from its current DOM list so that it can first make a copy of its
   * internal counterpart's values. (If it didn't do this, then it would
   * "lose" its value on being removed.)
   */
  void RemovingFromList();

  SVGLength ToSVGLength();

  // WebIDL
  uint16_t UnitType();
  float GetValue(ErrorResult& aRv);
  void SetValue(float aValue, ErrorResult& aRv);
  float ValueInSpecifiedUnits();
  void SetValueInSpecifiedUnits(float aValue, ErrorResult& aRv);
  // The XPCOM GetValueAsString is good
  void SetValueAsString(const nsAString& aValue, ErrorResult& aRv);
  void NewValueSpecifiedUnits(uint16_t aUnit, float aValue,
                              ErrorResult& aRv);
  void ConvertToSpecifiedUnits(uint16_t aUnit, ErrorResult& aRv);

  nsISupports* GetParentObject() const {
    auto svgElement = mList ? Element() : mSVGElement.get();
    return static_cast<nsIDOMSVGElement*> (svgElement);
  }

  JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;

private:

  nsSVGElement* Element() const {
    return mList->Element();
  }

  uint8_t AttrEnum() const {
    return mAttrEnum;
  }

  /**
   * Get the axis that this length lies along. This method must only be called
   * when this object is associated with an element (HasOwner() returns true).
   */
  uint8_t Axis() const {
    return mList->Axis();
  }

  /**
   * Get a reference to the internal SVGLength list item that this DOM wrapper
   * object currently wraps.
   *
   * To simplify the code we just have this one method for obtaining both
   * baseVal and animVal internal items. This means that animVal items don't
   * get const protection, but then our setter methods guard against changing
   * animVal items.
   */
  SVGLength& InternalItem();

#ifdef DEBUG
  bool IndexIsValid();
#endif

  /**
   * Clears soon-to-be-invalid weak references in external objects that were
   * set up during the creation of this object. This should be called during
   * destruction and during cycle collection.
   */
  void CleanupWeakRefs();

  RefPtr<DOMSVGLengthList> mList;

  // Bounds for the following are checked in the ctor, so be sure to update
  // that if you change the capacity of any of the following.

  uint32_t mListIndex:MOZ_SVG_LIST_INDEX_BIT_COUNT;
  uint32_t mAttrEnum:4; // supports up to 16 attributes
  uint32_t mIsAnimValItem:1;

  // The following members are only used when we're not in a list:
  uint32_t mUnit:5; // can handle 31 units (the 10 SVG 1.1 units + rem, vw, vh, wm, calc + future additions)
  float mValue;

  // The following members are only used when we have an nsSVGLength2
  nsSVGLength2* mVal; // kept alive because it belongs to mSVGElement
  RefPtr<nsSVGElement> mSVGElement;
};

NS_DEFINE_STATIC_IID_ACCESSOR(DOMSVGLength, MOZILLA_DOMSVGLENGTH_IID)

} // namespace mozilla

#undef MOZ_SVG_LIST_INDEX_BIT_COUNT

#endif // MOZILLA_DOMSVGLENGTH_H__