summaryrefslogtreecommitdiffstats
path: root/pdf/paint_aggregator.cc
blob: 549cab6d091646a783f52ccafeae94c4cbf12cff (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
// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "pdf/paint_aggregator.h"

#include <algorithm>

#include "base/logging.h"

// ----------------------------------------------------------------------------
// ALGORITHM NOTES
//
// We attempt to maintain a scroll rect in the presence of invalidations that
// are contained within the scroll rect.  If an invalidation crosses a scroll
// rect, then we just treat the scroll rect as an invalidation rect.
//
// For invalidations performed prior to scrolling and contained within the
// scroll rect, we offset the invalidation rects to account for the fact that
// the consumer will perform scrolling before painting.
//
// We only support scrolling along one axis at a time.  A diagonal scroll will
// therefore be treated as an invalidation.
// ----------------------------------------------------------------------------

PaintAggregator::PaintUpdate::PaintUpdate() {
}

PaintAggregator::PaintUpdate::~PaintUpdate() {
}

PaintAggregator::InternalPaintUpdate::InternalPaintUpdate() :
    synthesized_scroll_damage_rect_(false) {
}

PaintAggregator::InternalPaintUpdate::~InternalPaintUpdate() {
}

pp::Rect PaintAggregator::InternalPaintUpdate::GetScrollDamage() const {
  // Should only be scrolling in one direction at a time.
  DCHECK(!(scroll_delta.x() && scroll_delta.y()));

  pp::Rect damaged_rect;

  // Compute the region we will expose by scrolling, and paint that into a
  // shared memory section.
  if (scroll_delta.x()) {
    int32_t dx = scroll_delta.x();
    damaged_rect.set_y(scroll_rect.y());
    damaged_rect.set_height(scroll_rect.height());
    if (dx > 0) {
      damaged_rect.set_x(scroll_rect.x());
      damaged_rect.set_width(dx);
    } else {
      damaged_rect.set_x(scroll_rect.right() + dx);
      damaged_rect.set_width(-dx);
    }
  } else {
    int32_t dy = scroll_delta.y();
    damaged_rect.set_x(scroll_rect.x());
    damaged_rect.set_width(scroll_rect.width());
    if (dy > 0) {
      damaged_rect.set_y(scroll_rect.y());
      damaged_rect.set_height(dy);
    } else {
      damaged_rect.set_y(scroll_rect.bottom() + dy);
      damaged_rect.set_height(-dy);
    }
  }

  // In case the scroll offset exceeds the width/height of the scroll rect
  return scroll_rect.Intersect(damaged_rect);
}

PaintAggregator::PaintAggregator() {
}

bool PaintAggregator::HasPendingUpdate() const {
  return !update_.scroll_rect.IsEmpty() || !update_.paint_rects.empty();
}

void PaintAggregator::ClearPendingUpdate() {
  update_ = InternalPaintUpdate();
}

PaintAggregator::PaintUpdate PaintAggregator::GetPendingUpdate() {
  // Convert the internal paint update to the external one, which includes a
  // bit more precomputed info for the caller.
  PaintUpdate ret;
  ret.scroll_delta = update_.scroll_delta;
  ret.scroll_rect = update_.scroll_rect;
  ret.has_scroll = ret.scroll_delta.x() != 0 || ret.scroll_delta.y() != 0;

  // Include the scroll damage (if any) in the paint rects.
  // Code invalidates damaged rect here, it pick it up from the list of paint
  // rects in the next block.
  if (ret.has_scroll  && !update_.synthesized_scroll_damage_rect_) {
    update_.synthesized_scroll_damage_rect_ = true;
    pp::Rect scroll_damage = update_.GetScrollDamage();
    InvalidateRectInternal(scroll_damage, false);
  }

  ret.paint_rects.reserve(update_.paint_rects.size() + 1);
  for (size_t i = 0; i < update_.paint_rects.size(); i++)
    ret.paint_rects.push_back(update_.paint_rects[i]);

  return ret;
}

void PaintAggregator::SetIntermediateResults(
    const std::vector<ReadyRect>& ready,
    const std::vector<pp::Rect>& pending) {
  update_.ready_rects.insert(
      update_.ready_rects.end(), ready.begin(), ready.end());
  update_.paint_rects = pending;
}

std::vector<PaintAggregator::ReadyRect> PaintAggregator::GetReadyRects() const {
  return update_.ready_rects;
}

void PaintAggregator::InvalidateRect(const pp::Rect& rect) {
  InvalidateRectInternal(rect, true);
}

void PaintAggregator::ScrollRect(const pp::Rect& clip_rect,
                                 const pp::Point& amount) {
  // We only support scrolling along one axis at a time.
  if (amount.x() != 0 && amount.y() != 0) {
    InvalidateRect(clip_rect);
    return;
  }

  // We can only scroll one rect at a time.
  if (!update_.scroll_rect.IsEmpty() && update_.scroll_rect != clip_rect) {
    InvalidateRect(clip_rect);
    return;
  }

  // Again, we only support scrolling along one axis at a time.  Make sure this
  // update doesn't scroll on a different axis than any existing one.
  if ((amount.x() && update_.scroll_delta.y()) ||
      (amount.y() && update_.scroll_delta.x())) {
    InvalidateRect(clip_rect);
    return;
  }

  // The scroll rect is new or isn't changing (though the scroll amount may
  // be changing).
  update_.scroll_rect = clip_rect;
  update_.scroll_delta += amount;

  // We might have just wiped out a pre-existing scroll.
  if (update_.scroll_delta == pp::Point()) {
    update_.scroll_rect = pp::Rect();
    return;
  }

  // Adjust any paint rects that intersect the scroll. For the portion of the
  // paint that is inside the scroll area, move it by the scroll amount and
  // replace the existing paint with it. For the portion (if any) that is
  // outside the scroll, just invalidate it.
  std::vector<pp::Rect> leftover_rects;
  for (size_t i = 0; i < update_.paint_rects.size(); ++i) {
    if (!update_.scroll_rect.Intersects(update_.paint_rects[i]))
      continue;

    pp::Rect intersection =
        update_.paint_rects[i].Intersect(update_.scroll_rect);
    pp::Rect rect = update_.paint_rects[i];
    while (!rect.IsEmpty()) {
      pp::Rect leftover = rect.Subtract(intersection);
      if (leftover.IsEmpty())
        break;
      // Don't want to call InvalidateRectInternal now since it'll modify
      // update_.paint_rects, so keep track of this and do it below.
      leftover_rects.push_back(leftover);
      rect = rect.Subtract(leftover);
    }

    update_.paint_rects[i] = ScrollPaintRect(intersection, amount);

    // The rect may have been scrolled out of view.
    if (update_.paint_rects[i].IsEmpty()) {
      update_.paint_rects.erase(update_.paint_rects.begin() + i);
      i--;
    }
  }

  for (size_t i = 0; i < leftover_rects.size(); ++i)
    InvalidateRectInternal(leftover_rects[i], false);

  for (size_t i = 0; i < update_.ready_rects.size(); ++i) {
    if (update_.scroll_rect.Contains(update_.ready_rects[i].rect)) {
      update_.ready_rects[i].rect =
          ScrollPaintRect(update_.ready_rects[i].rect, amount);
    }
  }

  if (update_.synthesized_scroll_damage_rect_) {
    pp::Rect damage = update_.GetScrollDamage();
    InvalidateRect(damage);
  }
}

pp::Rect PaintAggregator::ScrollPaintRect(const pp::Rect& paint_rect,
                                          const pp::Point& amount) const {
  pp::Rect result = paint_rect;
  result.Offset(amount);
  result = update_.scroll_rect.Intersect(result);
  return result;
}

void PaintAggregator::InvalidateScrollRect() {
  pp::Rect scroll_rect = update_.scroll_rect;
  update_.scroll_rect = pp::Rect();
  update_.scroll_delta = pp::Point();
  InvalidateRect(scroll_rect);
}

void PaintAggregator::InvalidateRectInternal(const pp::Rect& rect_old,
                                             bool check_scroll) {
  pp::Rect rect = rect_old;
  // Check if any rects that are ready to be painted overlap.
  for (size_t i = 0; i < update_.ready_rects.size(); ++i) {
    const pp::Rect& existing_rect = update_.ready_rects[i].rect;
    if (rect.Intersects(existing_rect)) {
      // Re-invalidate in case the union intersects other paint rects.
      rect = existing_rect.Union(rect);
      update_.ready_rects.erase(update_.ready_rects.begin() + i);
      break;
    }
  }

  bool add_paint = true;

  // Combine overlapping paints using smallest bounding box.
  for (size_t i = 0; i < update_.paint_rects.size(); ++i) {
    const pp::Rect& existing_rect = update_.paint_rects[i];
    if (existing_rect.Contains(rect))  // Optimize out redundancy.
      add_paint = false;
    if (rect.Intersects(existing_rect) || rect.SharesEdgeWith(existing_rect)) {
      // Re-invalidate in case the union intersects other paint rects.
      pp::Rect combined_rect = existing_rect.Union(rect);
      update_.paint_rects.erase(update_.paint_rects.begin() + i);
      InvalidateRectInternal(combined_rect, check_scroll);
      add_paint = false;
    }
  }

  if (add_paint) {
    // Add a non-overlapping paint.
    update_.paint_rects.push_back(rect);
  }

  // If the new paint overlaps with a scroll, then also invalidate the rect in
  // its new position.
  if (check_scroll &&
      !update_.scroll_rect.IsEmpty() &&
      update_.scroll_rect.Intersects(rect)) {
    InvalidateRectInternal(ScrollPaintRect(rect, update_.scroll_delta), false);
  }
}