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// Copyright (c) 2012 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 "ash/wm/workspace/magnetism_matcher.h"
#include <algorithm>
#include <cmath>
namespace ash {
namespace internal {
namespace {
// Returns true if |a| is close enough to |b| that the two edges snap.
bool IsCloseEnough(int a, int b) {
return abs(a - b) <= MagnetismMatcher::kMagneticDistance;
}
// Returns true if the specified SecondaryMagnetismEdge can be matched with a
// primary edge of |primary|. |edges| is a bitmask of the allowed
// MagnetismEdges.
bool CanMatchSecondaryEdge(MagnetismEdge primary,
SecondaryMagnetismEdge secondary,
uint32 edges) {
// Convert |secondary| to a MagnetismEdge so we can compare it to |edges|.
MagnetismEdge secondary_as_magnetism_edge = MAGNETISM_EDGE_TOP;
switch (primary) {
case MAGNETISM_EDGE_TOP:
case MAGNETISM_EDGE_BOTTOM:
if (secondary == SECONDARY_MAGNETISM_EDGE_LEADING)
secondary_as_magnetism_edge = MAGNETISM_EDGE_LEFT;
else if (secondary == SECONDARY_MAGNETISM_EDGE_TRAILING)
secondary_as_magnetism_edge = MAGNETISM_EDGE_RIGHT;
else
NOTREACHED();
break;
case MAGNETISM_EDGE_LEFT:
case MAGNETISM_EDGE_RIGHT:
if (secondary == SECONDARY_MAGNETISM_EDGE_LEADING)
secondary_as_magnetism_edge = MAGNETISM_EDGE_TOP;
else if (secondary == SECONDARY_MAGNETISM_EDGE_TRAILING)
secondary_as_magnetism_edge = MAGNETISM_EDGE_BOTTOM;
else
NOTREACHED();
break;
}
return (edges & secondary_as_magnetism_edge) != 0;
}
} // namespace
// MagnetismEdgeMatcher --------------------------------------------------------
MagnetismEdgeMatcher::MagnetismEdgeMatcher(const gfx::Rect& bounds,
MagnetismEdge edge)
: bounds_(bounds),
edge_(edge) {
ranges_.push_back(GetSecondaryRange(bounds_));
}
MagnetismEdgeMatcher::~MagnetismEdgeMatcher() {
}
bool MagnetismEdgeMatcher::ShouldAttach(const gfx::Rect& bounds) {
if (is_edge_obscured())
return false;
if (IsCloseEnough(GetPrimaryCoordinate(bounds_, edge_),
GetPrimaryCoordinate(bounds, FlipEdge(edge_)))) {
const Range range(GetSecondaryRange(bounds));
Ranges::const_iterator i =
std::lower_bound(ranges_.begin(), ranges_.end(), range);
// Close enough, but only attach if some portion of the edge is visible.
if ((i != ranges_.begin() && RangesIntersect(*(i - 1), range)) ||
(i != ranges_.end() && RangesIntersect(*i, range))) {
return true;
}
}
// NOTE: this checks against the current bounds, we may want to allow some
// flexibility here.
const Range primary_range(GetPrimaryRange(bounds));
if (primary_range.first <= GetPrimaryCoordinate(bounds_, edge_) &&
primary_range.second >= GetPrimaryCoordinate(bounds_, edge_)) {
UpdateRanges(GetSecondaryRange(bounds));
}
return false;
}
void MagnetismEdgeMatcher::UpdateRanges(const Range& range) {
Ranges::const_iterator it =
std::lower_bound(ranges_.begin(), ranges_.end(), range);
if (it != ranges_.begin() && RangesIntersect(*(it - 1), range))
--it;
if (it == ranges_.end())
return;
for (size_t i = it - ranges_.begin();
i < ranges_.size() && RangesIntersect(ranges_[i], range); ) {
if (range.first <= ranges_[i].first &&
range.second >= ranges_[i].second) {
ranges_.erase(ranges_.begin() + i);
} else if (range.first < ranges_[i].first) {
DCHECK_GT(range.second, ranges_[i].first);
ranges_[i] = Range(range.second, ranges_[i].second);
++i;
} else {
Range existing(ranges_[i]);
ranges_[i].second = range.first;
++i;
if (existing.second > range.second) {
ranges_.insert(ranges_.begin() + i,
Range(range.second, existing.second));
++i;
}
}
}
}
// MagnetismMatcher ------------------------------------------------------------
// static
const int MagnetismMatcher::kMagneticDistance = 8;
MagnetismMatcher::MagnetismMatcher(const gfx::Rect& bounds, uint32 edges)
: edges_(edges) {
if (edges & MAGNETISM_EDGE_TOP)
matchers_.push_back(new MagnetismEdgeMatcher(bounds, MAGNETISM_EDGE_TOP));
if (edges & MAGNETISM_EDGE_LEFT)
matchers_.push_back(new MagnetismEdgeMatcher(bounds, MAGNETISM_EDGE_LEFT));
if (edges & MAGNETISM_EDGE_BOTTOM) {
matchers_.push_back(new MagnetismEdgeMatcher(bounds,
MAGNETISM_EDGE_BOTTOM));
}
if (edges & MAGNETISM_EDGE_RIGHT)
matchers_.push_back(new MagnetismEdgeMatcher(bounds, MAGNETISM_EDGE_RIGHT));
}
MagnetismMatcher::~MagnetismMatcher() {
}
bool MagnetismMatcher::ShouldAttach(const gfx::Rect& bounds,
MatchedEdge* edge) {
for (size_t i = 0; i < matchers_.size(); ++i) {
if (matchers_[i]->ShouldAttach(bounds)) {
edge->primary_edge = matchers_[i]->edge();
AttachToSecondaryEdge(bounds, edge->primary_edge,
&(edge->secondary_edge));
return true;
}
}
return false;
}
bool MagnetismMatcher::AreEdgesObscured() const {
for (size_t i = 0; i < matchers_.size(); ++i) {
if (!matchers_[i]->is_edge_obscured())
return false;
}
return true;
}
void MagnetismMatcher::AttachToSecondaryEdge(
const gfx::Rect& bounds,
MagnetismEdge edge,
SecondaryMagnetismEdge* secondary_edge) const {
const gfx::Rect& src_bounds(matchers_[0]->bounds());
if (edge == MAGNETISM_EDGE_LEFT || edge == MAGNETISM_EDGE_RIGHT) {
if (CanMatchSecondaryEdge(edge, SECONDARY_MAGNETISM_EDGE_LEADING, edges_) &&
IsCloseEnough(bounds.y(), src_bounds.y())) {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_LEADING;
} else if (CanMatchSecondaryEdge(edge, SECONDARY_MAGNETISM_EDGE_TRAILING,
edges_) &&
IsCloseEnough(bounds.bottom(), src_bounds.bottom())) {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_TRAILING;
} else {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_NONE;
}
} else {
if (CanMatchSecondaryEdge(edge, SECONDARY_MAGNETISM_EDGE_LEADING, edges_) &&
IsCloseEnough(bounds.x(), src_bounds.x())) {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_LEADING;
} else if (CanMatchSecondaryEdge(edge, SECONDARY_MAGNETISM_EDGE_TRAILING,
edges_) &&
IsCloseEnough(bounds.right(), src_bounds.right())) {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_TRAILING;
} else {
*secondary_edge = SECONDARY_MAGNETISM_EDGE_NONE;
}
}
}
} // namespace internal
} // namespace ash
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