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/*
* Copyright (c) 2013 The WebRTC project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "modules/desktop_capture/desktop_region.h"
#include <algorithm>
#include <utility>
#include "rtc_base/checks.h"
namespace webrtc {
DesktopRegion::RowSpan::RowSpan(int32_t left, int32_t right)
: left(left), right(right) {}
DesktopRegion::Row::Row(const Row&) = default;
DesktopRegion::Row::Row(Row&&) = default;
DesktopRegion::Row::Row(int32_t top, int32_t bottom)
: top(top), bottom(bottom) {}
DesktopRegion::Row::~Row() {}
DesktopRegion::DesktopRegion() {}
DesktopRegion::DesktopRegion(const DesktopRect& rect) {
AddRect(rect);
}
DesktopRegion::DesktopRegion(const DesktopRect* rects, int count) {
AddRects(rects, count);
}
DesktopRegion::DesktopRegion(const DesktopRegion& other) {
*this = other;
}
DesktopRegion::~DesktopRegion() {
Clear();
}
DesktopRegion& DesktopRegion::operator=(const DesktopRegion& other) {
Clear();
rows_ = other.rows_;
for (Rows::iterator it = rows_.begin(); it != rows_.end(); ++it) {
// Copy each row.
Row* row = it->second;
it->second = new Row(*row);
}
return *this;
}
bool DesktopRegion::Equals(const DesktopRegion& region) const {
// Iterate over rows of the tow regions and compare each row.
Rows::const_iterator it1 = rows_.begin();
Rows::const_iterator it2 = region.rows_.begin();
while (it1 != rows_.end()) {
if (it2 == region.rows_.end() || it1->first != it2->first ||
it1->second->top != it2->second->top ||
it1->second->bottom != it2->second->bottom ||
it1->second->spans != it2->second->spans) {
return false;
}
++it1;
++it2;
}
return it2 == region.rows_.end();
}
void DesktopRegion::Clear() {
for (Rows::iterator row = rows_.begin(); row != rows_.end(); ++row) {
delete row->second;
}
rows_.clear();
}
void DesktopRegion::SetRect(const DesktopRect& rect) {
Clear();
AddRect(rect);
}
void DesktopRegion::AddRect(const DesktopRect& rect) {
if (rect.is_empty())
return;
// Top of the part of the `rect` that hasn't been inserted yet. Increased as
// we iterate over the rows until it reaches `rect.bottom()`.
int top = rect.top();
// Iterate over all rows that may intersect with `rect` and add new rows when
// necessary.
Rows::iterator row = rows_.upper_bound(top);
while (top < rect.bottom()) {
if (row == rows_.end() || top < row->second->top) {
// If `top` is above the top of the current `row` then add a new row above
// the current one.
int32_t bottom = rect.bottom();
if (row != rows_.end() && row->second->top < bottom)
bottom = row->second->top;
row = rows_.insert(row, Rows::value_type(bottom, new Row(top, bottom)));
} else if (top > row->second->top) {
// If the `top` falls in the middle of the `row` then split `row` into
// two, at `top`, and leave `row` referring to the lower of the two,
// ready to insert a new span into.
RTC_DCHECK_LE(top, row->second->bottom);
Rows::iterator new_row = rows_.insert(
row, Rows::value_type(top, new Row(row->second->top, top)));
row->second->top = top;
new_row->second->spans = row->second->spans;
}
if (rect.bottom() < row->second->bottom) {
// If the bottom of the `rect` falls in the middle of the `row` split
// `row` into two, at `top`, and leave `row` referring to the upper of
// the two, ready to insert a new span into.
Rows::iterator new_row = rows_.insert(
row, Rows::value_type(rect.bottom(), new Row(top, rect.bottom())));
row->second->top = rect.bottom();
new_row->second->spans = row->second->spans;
row = new_row;
}
// Add a new span to the current row.
AddSpanToRow(row->second, rect.left(), rect.right());
top = row->second->bottom;
MergeWithPrecedingRow(row);
// Move to the next row.
++row;
}
if (row != rows_.end())
MergeWithPrecedingRow(row);
}
void DesktopRegion::AddRects(const DesktopRect* rects, int count) {
for (int i = 0; i < count; ++i) {
AddRect(rects[i]);
}
}
void DesktopRegion::MergeWithPrecedingRow(Rows::iterator row) {
RTC_DCHECK(row != rows_.end());
if (row != rows_.begin()) {
Rows::iterator previous_row = row;
previous_row--;
// If `row` and `previous_row` are next to each other and contain the same
// set of spans then they can be merged.
if (previous_row->second->bottom == row->second->top &&
previous_row->second->spans == row->second->spans) {
row->second->top = previous_row->second->top;
delete previous_row->second;
rows_.erase(previous_row);
}
}
}
void DesktopRegion::AddRegion(const DesktopRegion& region) {
// TODO(sergeyu): This function is not optimized - potentially it can iterate
// over rows of the two regions similar to how it works in Intersect().
for (Iterator it(region); !it.IsAtEnd(); it.Advance()) {
AddRect(it.rect());
}
}
void DesktopRegion::Intersect(const DesktopRegion& region1,
const DesktopRegion& region2) {
Clear();
Rows::const_iterator it1 = region1.rows_.begin();
Rows::const_iterator end1 = region1.rows_.end();
Rows::const_iterator it2 = region2.rows_.begin();
Rows::const_iterator end2 = region2.rows_.end();
if (it1 == end1 || it2 == end2)
return;
while (it1 != end1 && it2 != end2) {
// Arrange for `it1` to always be the top-most of the rows.
if (it2->second->top < it1->second->top) {
std::swap(it1, it2);
std::swap(end1, end2);
}
// Skip `it1` if it doesn't intersect `it2` at all.
if (it1->second->bottom <= it2->second->top) {
++it1;
continue;
}
// Top of the `it1` row is above the top of `it2`, so top of the
// intersection is always the top of `it2`.
int32_t top = it2->second->top;
int32_t bottom = std::min(it1->second->bottom, it2->second->bottom);
Rows::iterator new_row = rows_.insert(
rows_.end(), Rows::value_type(bottom, new Row(top, bottom)));
IntersectRows(it1->second->spans, it2->second->spans,
&new_row->second->spans);
if (new_row->second->spans.empty()) {
delete new_row->second;
rows_.erase(new_row);
} else {
MergeWithPrecedingRow(new_row);
}
// If `it1` was completely consumed, move to the next one.
if (it1->second->bottom == bottom)
++it1;
// If `it2` was completely consumed, move to the next one.
if (it2->second->bottom == bottom)
++it2;
}
}
// static
void DesktopRegion::IntersectRows(const RowSpanSet& set1,
const RowSpanSet& set2,
RowSpanSet* output) {
RowSpanSet::const_iterator it1 = set1.begin();
RowSpanSet::const_iterator end1 = set1.end();
RowSpanSet::const_iterator it2 = set2.begin();
RowSpanSet::const_iterator end2 = set2.end();
RTC_DCHECK(it1 != end1 && it2 != end2);
do {
// Arrange for `it1` to always be the left-most of the spans.
if (it2->left < it1->left) {
std::swap(it1, it2);
std::swap(end1, end2);
}
// Skip `it1` if it doesn't intersect `it2` at all.
if (it1->right <= it2->left) {
++it1;
continue;
}
int32_t left = it2->left;
int32_t right = std::min(it1->right, it2->right);
RTC_DCHECK_LT(left, right);
output->push_back(RowSpan(left, right));
// If `it1` was completely consumed, move to the next one.
if (it1->right == right)
++it1;
// If `it2` was completely consumed, move to the next one.
if (it2->right == right)
++it2;
} while (it1 != end1 && it2 != end2);
}
void DesktopRegion::IntersectWith(const DesktopRegion& region) {
DesktopRegion old_region;
Swap(&old_region);
Intersect(old_region, region);
}
void DesktopRegion::IntersectWith(const DesktopRect& rect) {
DesktopRegion region;
region.AddRect(rect);
IntersectWith(region);
}
void DesktopRegion::Subtract(const DesktopRegion& region) {
if (region.rows_.empty())
return;
// `row_b` refers to the current row being subtracted.
Rows::const_iterator row_b = region.rows_.begin();
// Current vertical position at which subtraction is happening.
int top = row_b->second->top;
// `row_a` refers to the current row we are subtracting from. Skip all rows
// above `top`.
Rows::iterator row_a = rows_.upper_bound(top);
// Step through rows of the both regions subtracting content of `row_b` from
// `row_a`.
while (row_a != rows_.end() && row_b != region.rows_.end()) {
// Skip `row_a` if it doesn't intersect with the `row_b`.
if (row_a->second->bottom <= top) {
// Each output row is merged with previously-processed rows before further
// rows are processed.
MergeWithPrecedingRow(row_a);
++row_a;
continue;
}
if (top > row_a->second->top) {
// If `top` falls in the middle of `row_a` then split `row_a` into two, at
// `top`, and leave `row_a` referring to the lower of the two, ready to
// subtract spans from.
RTC_DCHECK_LE(top, row_a->second->bottom);
Rows::iterator new_row = rows_.insert(
row_a, Rows::value_type(top, new Row(row_a->second->top, top)));
row_a->second->top = top;
new_row->second->spans = row_a->second->spans;
} else if (top < row_a->second->top) {
// If the `top` is above `row_a` then skip the range between `top` and
// top of `row_a` because it's empty.
top = row_a->second->top;
if (top >= row_b->second->bottom) {
++row_b;
if (row_b != region.rows_.end())
top = row_b->second->top;
continue;
}
}
if (row_b->second->bottom < row_a->second->bottom) {
// If the bottom of `row_b` falls in the middle of the `row_a` split
// `row_a` into two, at `top`, and leave `row_a` referring to the upper of
// the two, ready to subtract spans from.
int bottom = row_b->second->bottom;
Rows::iterator new_row =
rows_.insert(row_a, Rows::value_type(bottom, new Row(top, bottom)));
row_a->second->top = bottom;
new_row->second->spans = row_a->second->spans;
row_a = new_row;
}
// At this point the vertical range covered by `row_a` lays within the
// range covered by `row_b`. Subtract `row_b` spans from `row_a`.
RowSpanSet new_spans;
SubtractRows(row_a->second->spans, row_b->second->spans, &new_spans);
new_spans.swap(row_a->second->spans);
top = row_a->second->bottom;
if (top >= row_b->second->bottom) {
++row_b;
if (row_b != region.rows_.end())
top = row_b->second->top;
}
// Check if the row is empty after subtraction and delete it. Otherwise move
// to the next one.
if (row_a->second->spans.empty()) {
Rows::iterator row_to_delete = row_a;
++row_a;
delete row_to_delete->second;
rows_.erase(row_to_delete);
} else {
MergeWithPrecedingRow(row_a);
++row_a;
}
}
if (row_a != rows_.end())
MergeWithPrecedingRow(row_a);
}
void DesktopRegion::Subtract(const DesktopRect& rect) {
DesktopRegion region;
region.AddRect(rect);
Subtract(region);
}
void DesktopRegion::Translate(int32_t dx, int32_t dy) {
Rows new_rows;
for (Rows::iterator it = rows_.begin(); it != rows_.end(); ++it) {
Row* row = it->second;
row->top += dy;
row->bottom += dy;
if (dx != 0) {
// Translate each span.
for (RowSpanSet::iterator span = row->spans.begin();
span != row->spans.end(); ++span) {
span->left += dx;
span->right += dx;
}
}
if (dy != 0)
new_rows.insert(new_rows.end(), Rows::value_type(row->bottom, row));
}
if (dy != 0)
new_rows.swap(rows_);
}
void DesktopRegion::Swap(DesktopRegion* region) {
rows_.swap(region->rows_);
}
// static
bool DesktopRegion::CompareSpanRight(const RowSpan& r, int32_t value) {
return r.right < value;
}
// static
bool DesktopRegion::CompareSpanLeft(const RowSpan& r, int32_t value) {
return r.left < value;
}
// static
void DesktopRegion::AddSpanToRow(Row* row, int left, int right) {
// First check if the new span is located to the right of all existing spans.
// This is an optimization to avoid binary search in the case when rectangles
// are inserted sequentially from left to right.
if (row->spans.empty() || left > row->spans.back().right) {
row->spans.push_back(RowSpan(left, right));
return;
}
// Find the first span that ends at or after `left`.
RowSpanSet::iterator start = std::lower_bound(
row->spans.begin(), row->spans.end(), left, CompareSpanRight);
RTC_DCHECK(start < row->spans.end());
// Find the first span that starts after `right`.
RowSpanSet::iterator end =
std::lower_bound(start, row->spans.end(), right + 1, CompareSpanLeft);
if (end == row->spans.begin()) {
// There are no overlaps. Just insert the new span at the beginning.
row->spans.insert(row->spans.begin(), RowSpan(left, right));
return;
}
// Move end to the left, so that it points the last span that ends at or
// before `right`.
end--;
// At this point [start, end] is the range of spans that intersect with the
// new one.
if (end < start) {
// There are no overlaps. Just insert the new span at the correct position.
row->spans.insert(start, RowSpan(left, right));
return;
}
left = std::min(left, start->left);
right = std::max(right, end->right);
// Replace range [start, end] with the new span.
*start = RowSpan(left, right);
++start;
++end;
if (start < end)
row->spans.erase(start, end);
}
// static
bool DesktopRegion::IsSpanInRow(const Row& row, const RowSpan& span) {
// Find the first span that starts at or after `span.left` and then check if
// it's the same span.
RowSpanSet::const_iterator it = std::lower_bound(
row.spans.begin(), row.spans.end(), span.left, CompareSpanLeft);
return it != row.spans.end() && *it == span;
}
// static
void DesktopRegion::SubtractRows(const RowSpanSet& set_a,
const RowSpanSet& set_b,
RowSpanSet* output) {
RTC_DCHECK(!set_a.empty() && !set_b.empty());
RowSpanSet::const_iterator it_b = set_b.begin();
// Iterate over all spans in `set_a` adding parts of it that do not intersect
// with `set_b` to the `output`.
for (RowSpanSet::const_iterator it_a = set_a.begin(); it_a != set_a.end();
++it_a) {
// If there is no intersection then append the current span and continue.
if (it_b == set_b.end() || it_a->right < it_b->left) {
output->push_back(*it_a);
continue;
}
// Iterate over `set_b` spans that may intersect with `it_a`.
int pos = it_a->left;
while (it_b != set_b.end() && it_b->left < it_a->right) {
if (it_b->left > pos)
output->push_back(RowSpan(pos, it_b->left));
if (it_b->right > pos) {
pos = it_b->right;
if (pos >= it_a->right)
break;
}
++it_b;
}
if (pos < it_a->right)
output->push_back(RowSpan(pos, it_a->right));
}
}
DesktopRegion::Iterator::Iterator(const DesktopRegion& region)
: region_(region),
row_(region.rows_.begin()),
previous_row_(region.rows_.end()) {
if (!IsAtEnd()) {
RTC_DCHECK_GT(row_->second->spans.size(), 0);
row_span_ = row_->second->spans.begin();
UpdateCurrentRect();
}
}
DesktopRegion::Iterator::~Iterator() {}
bool DesktopRegion::Iterator::IsAtEnd() const {
return row_ == region_.rows_.end();
}
void DesktopRegion::Iterator::Advance() {
RTC_DCHECK(!IsAtEnd());
while (true) {
++row_span_;
if (row_span_ == row_->second->spans.end()) {
previous_row_ = row_;
++row_;
if (row_ != region_.rows_.end()) {
RTC_DCHECK_GT(row_->second->spans.size(), 0);
row_span_ = row_->second->spans.begin();
}
}
if (IsAtEnd())
return;
// If the same span exists on the previous row then skip it, as we've
// already returned this span merged into the previous one, via
// UpdateCurrentRect().
if (previous_row_ != region_.rows_.end() &&
previous_row_->second->bottom == row_->second->top &&
IsSpanInRow(*previous_row_->second, *row_span_)) {
continue;
}
break;
}
RTC_DCHECK(!IsAtEnd());
UpdateCurrentRect();
}
void DesktopRegion::Iterator::UpdateCurrentRect() {
// Merge the current rectangle with the matching spans from later rows.
int bottom;
Rows::const_iterator bottom_row = row_;
Rows::const_iterator previous;
do {
bottom = bottom_row->second->bottom;
previous = bottom_row;
++bottom_row;
} while (bottom_row != region_.rows_.end() &&
previous->second->bottom == bottom_row->second->top &&
IsSpanInRow(*bottom_row->second, *row_span_));
rect_ = DesktopRect::MakeLTRB(row_span_->left, row_->second->top,
row_span_->right, bottom);
}
} // namespace webrtc