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
401
|
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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/. */
/**
* compute sticky positioning, both during reflow and when the scrolling
* container scrolls
*/
#include "StickyScrollContainer.h"
#include "mozilla/OverflowChangedTracker.h"
#include "mozilla/ScrollContainerFrame.h"
#include "nsIFrame.h"
#include "nsIFrameInlines.h"
#include "nsLayoutUtils.h"
#include "PresShell.h"
namespace mozilla {
NS_DECLARE_FRAME_PROPERTY_DELETABLE(StickyScrollContainerProperty,
StickyScrollContainer)
StickyScrollContainer::StickyScrollContainer(
ScrollContainerFrame* aScrollContainerFrame)
: mScrollContainerFrame(aScrollContainerFrame) {
mScrollContainerFrame->AddScrollPositionListener(this);
}
StickyScrollContainer::~StickyScrollContainer() {
mScrollContainerFrame->RemoveScrollPositionListener(this);
}
// static
StickyScrollContainer* StickyScrollContainer::GetStickyScrollContainerForFrame(
nsIFrame* aFrame) {
ScrollContainerFrame* scrollContainerFrame =
nsLayoutUtils::GetNearestScrollContainerFrame(
aFrame->GetParent(), nsLayoutUtils::SCROLLABLE_SAME_DOC |
nsLayoutUtils::SCROLLABLE_STOP_AT_PAGE |
nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
if (!scrollContainerFrame) {
// We might not find any, for instance in the case of
// <html style="position: fixed">
return nullptr;
}
StickyScrollContainer* s =
scrollContainerFrame->GetProperty(StickyScrollContainerProperty());
if (!s) {
s = new StickyScrollContainer(scrollContainerFrame);
scrollContainerFrame->SetProperty(StickyScrollContainerProperty(), s);
}
return s;
}
// static
StickyScrollContainer*
StickyScrollContainer::GetStickyScrollContainerForScrollFrame(
nsIFrame* aFrame) {
return aFrame->GetProperty(StickyScrollContainerProperty());
}
static nscoord ComputeStickySideOffset(Side aSide,
const nsStylePosition& aPosition,
nscoord aPercentBasis) {
// Guaranteed to resolve any use of anchor function as invalid.
const auto& side = aPosition.GetAnchorResolvedInset(
aSide, AnchorPosOffsetResolutionParams::UseCBFrameSize(
{nullptr, StylePositionProperty::Sticky}));
if (side->IsAuto()) {
return NS_AUTOOFFSET;
}
return nsLayoutUtils::ComputeCBDependentValue(aPercentBasis,
side->AsLengthPercentage());
}
// static
void StickyScrollContainer::ComputeStickyOffsets(nsIFrame* aFrame) {
ScrollContainerFrame* scrollContainerFrame =
nsLayoutUtils::GetNearestScrollContainerFrame(
aFrame->GetParent(), nsLayoutUtils::SCROLLABLE_SAME_DOC |
nsLayoutUtils::SCROLLABLE_INCLUDE_HIDDEN);
if (!scrollContainerFrame) {
// Bail.
return;
}
nsSize scrollContainerSize =
scrollContainerFrame->GetScrolledFrameSizeAccountingForDynamicToolbar();
nsMargin computedOffsets;
const nsStylePosition* position = aFrame->StylePosition();
computedOffsets.left =
ComputeStickySideOffset(eSideLeft, *position, scrollContainerSize.width);
computedOffsets.right =
ComputeStickySideOffset(eSideRight, *position, scrollContainerSize.width);
computedOffsets.top =
ComputeStickySideOffset(eSideTop, *position, scrollContainerSize.height);
computedOffsets.bottom = ComputeStickySideOffset(eSideBottom, *position,
scrollContainerSize.height);
// Store the offset
nsMargin* offsets = aFrame->GetProperty(nsIFrame::ComputedOffsetProperty());
if (offsets) {
*offsets = computedOffsets;
} else {
aFrame->SetProperty(nsIFrame::ComputedOffsetProperty(),
new nsMargin(computedOffsets));
}
}
static constexpr nscoord gUnboundedNegative = nscoord_MIN / 2;
static constexpr nscoord gUnboundedExtent = nscoord_MAX;
static constexpr nscoord gUnboundedPositive =
gUnboundedNegative + gUnboundedExtent;
void StickyScrollContainer::ComputeStickyLimits(nsIFrame* aFrame,
nsRect* aStick,
nsRect* aContain) const {
NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aFrame),
"Can't sticky position individual continuations");
aStick->SetRect(gUnboundedNegative, gUnboundedNegative, gUnboundedExtent,
gUnboundedExtent);
aContain->SetRect(gUnboundedNegative, gUnboundedNegative, gUnboundedExtent,
gUnboundedExtent);
const nsMargin* computedOffsets =
aFrame->GetProperty(nsIFrame::ComputedOffsetProperty());
if (!computedOffsets) {
// We haven't reflowed the scroll frame yet, so offsets haven't been
// computed. Bail.
return;
}
nsIFrame* scrolledFrame = mScrollContainerFrame->GetScrolledFrame();
nsIFrame* cbFrame = aFrame->GetContainingBlock();
NS_ASSERTION(cbFrame == scrolledFrame ||
nsLayoutUtils::IsProperAncestorFrame(scrolledFrame, cbFrame),
"Scroll frame should be an ancestor of the containing block");
nsRect rect =
nsLayoutUtils::GetAllInFlowRectsUnion(aFrame, aFrame->GetParent());
// FIXME(bug 1421660): Table row groups aren't supposed to be containing
// blocks, but we treat them as such (maybe it's the right thing to do!).
// Anyway, not having this basically disables position: sticky on table cells,
// which would be really unfortunate, and doesn't match what other browsers
// do.
if (cbFrame != scrolledFrame && cbFrame->IsTableRowGroupFrame()) {
cbFrame = cbFrame->GetContainingBlock();
}
// Containing block limits for the position of aFrame relative to its parent.
// The margin box of the sticky element stays within the content box of the
// containing-block element.
if (cbFrame == scrolledFrame) {
// cbFrame is the scrolledFrame, and it won't have continuations. Unlike the
// else clause, we consider scrollable overflow rect because the union of
// its in-flow rects doesn't include the scrollable overflow area. We need
// to subtract the padding however, which _is_ included in the scrollable
// area, since we want the content box.
MOZ_ASSERT(cbFrame->GetUsedBorder() == nsMargin(),
"How did the ::-moz-scrolled-frame end up with border?");
*aContain = cbFrame->ScrollableOverflowRectRelativeToSelf();
aContain->Deflate(cbFrame->GetUsedPadding());
nsLayoutUtils::TransformRect(cbFrame, aFrame->GetParent(), *aContain);
} else {
*aContain = nsLayoutUtils::GetAllInFlowRectsUnion(
cbFrame, aFrame->GetParent(),
nsLayoutUtils::GetAllInFlowRectsFlag::UseContentBox);
}
nsRect marginRect = nsLayoutUtils::GetAllInFlowRectsUnion(
aFrame, aFrame->GetParent(),
nsLayoutUtils::GetAllInFlowRectsFlag::UseMarginBoxWithAutoResolvedAsZero);
// Deflate aContain by the difference between the union of aFrame's
// continuations' margin boxes and the union of their border boxes, so that
// by keeping aFrame within aContain, we keep the union of the margin boxes
// within the containing block's content box.
aContain->Deflate(marginRect - rect);
// Deflate aContain by the border-box size, to form a constraint on the
// upper-left corner of aFrame and continuations.
aContain->Deflate(nsMargin(0, rect.width, rect.height, 0));
nsMargin sfPadding = scrolledFrame->GetUsedPadding();
nsPoint sfOffset = aFrame->GetParent()->GetOffsetTo(scrolledFrame);
// Top
if (computedOffsets->top != NS_AUTOOFFSET) {
aStick->SetTopEdge(mScrollPosition.y + sfPadding.top +
computedOffsets->top - sfOffset.y);
}
nsSize sfSize =
mScrollContainerFrame->GetScrolledFrameSizeAccountingForDynamicToolbar();
// Bottom
if (computedOffsets->bottom != NS_AUTOOFFSET &&
(computedOffsets->top == NS_AUTOOFFSET ||
rect.height <= sfSize.height - computedOffsets->TopBottom())) {
aStick->SetBottomEdge(mScrollPosition.y + sfPadding.top + sfSize.height -
computedOffsets->bottom - rect.height - sfOffset.y);
}
StyleDirection direction = cbFrame->StyleVisibility()->mDirection;
// Left
if (computedOffsets->left != NS_AUTOOFFSET &&
(computedOffsets->right == NS_AUTOOFFSET ||
direction == StyleDirection::Ltr ||
rect.width <= sfSize.width - computedOffsets->LeftRight())) {
aStick->SetLeftEdge(mScrollPosition.x + sfPadding.left +
computedOffsets->left - sfOffset.x);
}
// Right
if (computedOffsets->right != NS_AUTOOFFSET &&
(computedOffsets->left == NS_AUTOOFFSET ||
direction == StyleDirection::Rtl ||
rect.width <= sfSize.width - computedOffsets->LeftRight())) {
aStick->SetRightEdge(mScrollPosition.x + sfPadding.left + sfSize.width -
computedOffsets->right - rect.width - sfOffset.x);
}
// These limits are for the bounding box of aFrame's continuations. Convert
// to limits for aFrame itself.
nsPoint frameOffset = aFrame->GetPosition() - rect.TopLeft();
aStick->MoveBy(frameOffset);
aContain->MoveBy(frameOffset);
}
nsPoint StickyScrollContainer::ComputePosition(nsIFrame* aFrame) const {
nsRect stick;
nsRect contain;
ComputeStickyLimits(aFrame, &stick, &contain);
nsPoint position = aFrame->GetNormalPosition();
// For each sticky direction (top, bottom, left, right), move the frame along
// the appropriate axis, based on the scroll position, but limit this to keep
// the element's margin box within the containing block.
position.y = std::max(position.y, std::min(stick.y, contain.YMost()));
position.y = std::min(position.y, std::max(stick.YMost(), contain.y));
position.x = std::max(position.x, std::min(stick.x, contain.XMost()));
position.x = std::min(position.x, std::max(stick.XMost(), contain.x));
return position;
}
bool StickyScrollContainer::IsStuckInYDirection(nsIFrame* aFrame) const {
nsPoint position = ComputePosition(aFrame);
return position.y != aFrame->GetNormalPosition().y;
}
void StickyScrollContainer::GetScrollRanges(nsIFrame* aFrame,
nsRectAbsolute* aOuter,
nsRectAbsolute* aInner) const {
// We need to use the first in flow; continuation frames should not move
// relative to each other and should get identical scroll ranges.
// Also, ComputeStickyLimits requires this.
nsIFrame* firstCont =
nsLayoutUtils::FirstContinuationOrIBSplitSibling(aFrame);
nsRect stickRect;
nsRect containRect;
ComputeStickyLimits(firstCont, &stickRect, &containRect);
nsRectAbsolute stick = nsRectAbsolute::FromRect(stickRect);
nsRectAbsolute contain = nsRectAbsolute::FromRect(containRect);
aOuter->SetBox(gUnboundedNegative, gUnboundedNegative, gUnboundedPositive,
gUnboundedPositive);
aInner->SetBox(gUnboundedNegative, gUnboundedNegative, gUnboundedPositive,
gUnboundedPositive);
const nsPoint normalPosition = firstCont->GetNormalPosition();
// Bottom and top
if (stick.YMost() != gUnboundedPositive) {
aOuter->SetTopEdge(contain.Y() - stick.YMost());
aInner->SetTopEdge(normalPosition.y - stick.YMost());
}
if (stick.Y() != gUnboundedNegative) {
aInner->SetBottomEdge(normalPosition.y - stick.Y());
aOuter->SetBottomEdge(contain.YMost() - stick.Y());
}
// Right and left
if (stick.XMost() != gUnboundedPositive) {
aOuter->SetLeftEdge(contain.X() - stick.XMost());
aInner->SetLeftEdge(normalPosition.x - stick.XMost());
}
if (stick.X() != gUnboundedNegative) {
aInner->SetRightEdge(normalPosition.x - stick.X());
aOuter->SetRightEdge(contain.XMost() - stick.X());
}
// Make sure |inner| does not extend outside of |outer|. (The consumers of
// the Layers API, to which this information is propagated, expect this
// invariant to hold.) The calculated value of |inner| can sometimes extend
// outside of |outer|, for example due to margin collapsing, since
// GetNormalPosition() returns the actual position after margin collapsing,
// while |contain| is calculated based on the frame's GetUsedMargin() which
// is pre-collapsing.
// Note that this doesn't necessarily solve all problems stemming from
// comparing pre- and post-collapsing margins (TODO: find a proper solution).
*aInner = aInner->Intersect(*aOuter);
if (aInner->IsEmpty()) {
// This might happen if aInner didn't intersect aOuter at all initially,
// in which case aInner is empty and outside aOuter. Make sure it doesn't
// extend outside aOuter.
*aInner = aInner->MoveInsideAndClamp(*aOuter);
}
}
void StickyScrollContainer::PositionContinuations(nsIFrame* aFrame) {
NS_ASSERTION(nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(aFrame),
"Should be starting from the first continuation");
bool hadProperty;
nsPoint translation =
ComputePosition(aFrame) - aFrame->GetNormalPosition(&hadProperty);
if (NS_WARN_IF(!hadProperty)) {
// If the frame was never relatively positioned, don't move its position
// dynamically. There are a variety of frames for which `position` doesn't
// really apply like frames inside svg which would get here and be sticky
// only in one direction.
return;
}
// Move all continuation frames by the same amount.
for (nsIFrame* cont = aFrame; cont;
cont = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(cont)) {
cont->SetPosition(cont->GetNormalPosition() + translation);
}
}
void StickyScrollContainer::UpdatePositions(nsPoint aScrollPosition,
nsIFrame* aSubtreeRoot) {
#ifdef DEBUG
{
nsIFrame* scrollFrameAsFrame = do_QueryFrame(mScrollContainerFrame);
NS_ASSERTION(!aSubtreeRoot || aSubtreeRoot == scrollFrameAsFrame,
"If reflowing, should be reflowing the scroll frame");
}
#endif
mScrollPosition = aScrollPosition;
OverflowChangedTracker oct;
oct.SetSubtreeRoot(aSubtreeRoot);
// We need to position ancestors before children, so iter from shallowest. We
// don't use mFrames.IterFromShallowest() because we want to handle removal of
// non-first continuations while we iterate.
for (size_t i = mFrames.Length(); i--;) {
nsIFrame* f = mFrames.ElementAt(i);
if (!nsLayoutUtils::IsFirstContinuationOrIBSplitSibling(f)) {
// This frame was added in nsIFrame::DidSetComputedStyle before we knew it
// wasn't the first ib-split-sibling.
mFrames.RemoveElementAt(i);
continue;
}
if (aSubtreeRoot) {
// Reflowing the scroll frame, so recompute offsets.
ComputeStickyOffsets(f);
}
// mFrames will only contain first continuations, because we filter in
// nsIFrame::DidSetComputedStyle.
PositionContinuations(f);
f = f->GetParent();
if (f != aSubtreeRoot) {
for (nsIFrame* cont = f; cont;
cont = nsLayoutUtils::GetNextContinuationOrIBSplitSibling(cont)) {
oct.AddFrame(cont, OverflowChangedTracker::CHILDREN_CHANGED);
}
}
}
oct.Flush();
}
void StickyScrollContainer::ScrollPositionWillChange(nscoord aX, nscoord aY) {}
void StickyScrollContainer::ScrollPositionDidChange(nscoord aX, nscoord aY) {
UpdatePositions(nsPoint(aX, aY), nullptr);
}
void StickyScrollContainer::MarkFramesForReflow() {
PresShell* ps = mScrollContainerFrame->PresShell();
for (nsIFrame* frame : mFrames.IterFromShallowest()) {
ps->FrameNeedsReflow(frame, IntrinsicDirty::None, NS_FRAME_IS_DIRTY);
}
}
} // namespace mozilla
|
