// Copyright 2018 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "ash/accessibility/ui/accessibility_focus_ring_group.h"
#include <memory>
#include <set>
#include <vector>
#include "ash/accessibility/ui/accessibility_focus_ring.h"
#include "ash/accessibility/ui/accessibility_focus_ring_layer.h"
#include "ash/accessibility/ui/accessibility_layer.h"
#include "ash/accessibility/ui/layer_animation_info.h"
#include "ash/public/cpp/accessibility_focus_ring_info.h"
#include "base/memory/values_equivalent.h"
#include "base/time/time.h"
#include "third_party/skia/include/core/SkColor.h"
#include "ui/gfx/geometry/rect.h"
namespace ash {
namespace {
// The number of DIPs the focus ring is outset from the object it outlines,
// which also determines the border radius of the rounded corners.
constexpr int kAccessibilityFocusRingMargin = 7;
// Time to transition between one location and the next.
constexpr int kTransitionTimeMilliseconds = 300;
// Focus constants.
constexpr int kFocusFadeInTimeMilliseconds = 100;
constexpr int kFocusFadeOutTimeMilliseconds = 1600;
// A Region is an unordered collection of Rects that maintains its
// bounding box. Used in the middle of an algorithm that groups
// adjacent and overlapping rects.
struct Region {
explicit Region(gfx::Rect initial_rect) {
bounds = initial_rect;
rects.push_back(initial_rect);
}
gfx::Rect bounds;
std::vector<gfx::Rect> rects;
};
} // namespace
AccessibilityFocusRingGroup::AccessibilityFocusRingGroup() {
focus_animation_info_.fade_in_time =
base::Milliseconds(kFocusFadeInTimeMilliseconds);
focus_animation_info_.fade_out_time =
base::Milliseconds(kFocusFadeOutTimeMilliseconds);
}
AccessibilityFocusRingGroup::~AccessibilityFocusRingGroup() {}
void AccessibilityFocusRingGroup::UpdateFocusRingsFromInfo(
AccessibilityLayerDelegate* delegate) {
previous_focus_rings_.swap(focus_rings_);
focus_rings_.clear();
focus_animation_.reset();
RectsToRings(focus_ring_info_->rects_in_screen, &(focus_rings_));
focus_layers_.resize(focus_rings_.size());
if (focus_rings_.empty())
return;
for (size_t i = 0; i < focus_rings_.size(); ++i) {
if (!focus_layers_[i])
focus_layers_[i] =
std::make_unique<AccessibilityFocusRingLayer>(delegate);
}
if (focus_ring_info_->behavior == FocusRingBehavior::PERSIST &&
!no_fade_for_testing_) {
// In PERSIST mode, animate the first ring to its destination
// location, then set the rest of the rings directly.
// If no_fade_for_testing_ is set, don't wait for animation.
for (size_t i = 1; i < focus_rings_.size(); ++i)
focus_layers_[i]->Set(focus_rings_[i]);
} else {
// In FADE mode, set all focus rings to their destination location.
for (size_t i = 0; i < focus_rings_.size(); ++i)
focus_layers_[i]->Set(focus_rings_[i]);
}
for (size_t i = 0; i < focus_rings_.size(); ++i) {
focus_layers_[i]->SetAppearance(
focus_ring_info_->type, focus_ring_info_->stacking_order,
focus_ring_info_->color, focus_ring_info_->secondary_color,
focus_ring_info_->background_color);
}
// Start watching for animations.
if (!no_fade_for_testing_) {
focus_animation_ = std::make_unique<AccessibilityAnimationOneShot>(
focus_rings_[0].GetBounds(),
base::BindRepeating(&AccessibilityFocusRingGroup::AnimateFocusRings,
base::Unretained(this)));
}
}
bool AccessibilityFocusRingGroup::AnimateFocusRings(base::TimeTicks timestamp) {
CHECK(!focus_rings_.empty());
CHECK(!focus_layers_.empty());
CHECK(focus_layers_[0]);
// It's quite possible for the first 1 or 2 animation frames to be
// for a timestamp that's earlier than the time we received the
// focus change, so we just treat those as a delta of zero.
if (timestamp < focus_animation_info_.change_time)
timestamp = focus_animation_info_.change_time;
if (focus_ring_info_->behavior == FocusRingBehavior::PERSIST) {
base::TimeDelta delta = timestamp - focus_animation_info_.change_time;
base::TimeDelta transition_time =
base::Milliseconds(kTransitionTimeMilliseconds);
if (delta >= transition_time) {
focus_layers_[0]->Set(focus_rings_[0]);
return true;
}
// Ease-in effect.
const double fraction = pow(delta / transition_time, 0.3);
// Handle corner case where we're animating but we don't have previous
// rings.
if (previous_focus_rings_.empty())
previous_focus_rings_ = focus_rings_;
focus_layers_[0]->Set(AccessibilityFocusRing::Interpolate(
previous_focus_rings_[0], focus_rings_[0], fraction));
} else {
ash::ComputeOpacity(&(focus_animation_info_), timestamp);
for (auto& focus_layer : focus_layers_)
focus_layer->SetOpacity(focus_animation_info_.opacity);
}
return false;
}
bool AccessibilityFocusRingGroup::UpdateFocusRing(
std::unique_ptr<AccessibilityFocusRingInfo> focus_ring,
AccessibilityLayerDelegate* delegate) {
// Remove duplicate rects.
if (focus_ring && focus_ring->rects_in_screen.size() > 1) {
std::vector<gfx::Rect> rects(focus_ring->rects_in_screen);
std::set<gfx::Rect> rects_set(rects.begin(), rects.end());
focus_ring->rects_in_screen.assign(rects_set.begin(), rects_set.end());
}
// If there is no change, don't do any work.
if (base::ValuesEquivalent(focus_ring_info_, focus_ring))
return false;
focus_ring_info_ = std::move(focus_ring);
UpdateFocusRingsFromInfo(delegate);
return true;
}
void AccessibilityFocusRingGroup::ClearFocusRects(
AccessibilityLayerDelegate* delegate) {
focus_ring_info_->rects_in_screen.clear();
UpdateFocusRingsFromInfo(delegate);
}
int AccessibilityFocusRingGroup::GetMargin() const {
return kAccessibilityFocusRingMargin;
}
void AccessibilityFocusRingGroup::RectsToRings(
const std::vector<gfx::Rect>& src_rects,
std::vector<ash::AccessibilityFocusRing>* rings) const {
if (src_rects.empty())
return;
// Give all of the rects a margin.
std::vector<gfx::Rect> rects;
rects.resize(src_rects.size());
for (size_t i = 0; i < src_rects.size(); ++i) {
rects[i] = src_rects[i];
rects[i].Inset(-GetMargin());
}
// Split the rects into contiguous regions.
std::vector<Region> regions;
regions.push_back(Region(rects[0]));
for (size_t i = 1; i < rects.size(); ++i) {
bool found = false;
for (size_t j = 0; j < regions.size(); ++j) {
if (Intersects(rects[i], regions[j].bounds)) {
regions[j].rects.push_back(rects[i]);
regions[j].bounds.Union(rects[i]);
found = true;
}
}
if (!found) {
regions.push_back(Region(rects[i]));
}
}
// Keep merging regions that intersect.
// TODO(dmazzoni): reduce the worst-case complexity! This appears like
// it could be O(n^3), make sure it's not in practice.
bool merged;
do {
merged = false;
for (size_t i = 0; i < regions.size() - 1 && !merged; ++i) {
for (size_t j = i + 1; j < regions.size() && !merged; ++j) {
if (Intersects(regions[i].bounds, regions[j].bounds)) {
regions[i].rects.insert(regions[i].rects.end(),
regions[j].rects.begin(),
regions[j].rects.end());
regions[i].bounds.Union(regions[j].bounds);
regions.erase(regions.begin() + j);
merged = true;
}
}
}
} while (merged);
for (size_t i = 0; i < regions.size(); ++i) {
std::sort(regions[i].rects.begin(), regions[i].rects.end());
rings->push_back(RingFromSortedRects(regions[i].rects));
}
}
// Given a vector of rects that all overlap, already sorted from top to bottom
// and left to right, split them into three shapes covering the top, middle,
// and bottom of a "paragraph shape".
//
// Input:
//
// +---+---+
// | 1 | 2 |
// +---------------------+---+---+
// | 3 |
// +--------+---------------+----+
// | 4 | 5 |
// +--------+---------------+--+
// | 6 |
// +---------+-----------------+
// | 7 |
// +---------+
//
// Output:
//
// +-------+
// | Top |
// +---------------------+-------+
// | |
// | |
// | Middle |
// | |
// | |
// +---------+-------------------+
// | Bottom |
// +---------+
//
// When there's no clear "top" or "bottom" segment, split the overall rect
// evenly so that some of the area still fits into the "top" and "bottom"
// segments.
void AccessibilityFocusRingGroup::SplitIntoParagraphShape(
const std::vector<gfx::Rect>& rects,
gfx::Rect* top,
gfx::Rect* middle,
gfx::Rect* bottom) const {
size_t n = rects.size();
// Figure out how many rects belong in the top portion.
gfx::Rect top_rect = rects[0];
int top_middle = (top_rect.y() + top_rect.bottom()) / 2;
size_t top_count = 1;
while (top_count < n && rects[top_count].y() < top_middle) {
top_rect.Union(rects[top_count]);
top_middle = (top_rect.y() + top_rect.bottom()) / 2;
top_count++;
}
// Figure out how many rects belong in the bottom portion.
gfx::Rect bottom_rect = rects[n - 1];
int bottom_middle = (bottom_rect.y() + bottom_rect.bottom()) / 2;
size_t bottom_count = std::min(static_cast<size_t>(1), n - top_count);
while (bottom_count + top_count < n &&
rects[n - bottom_count - 1].bottom() > bottom_middle) {
bottom_rect.Union(rects[n - bottom_count - 1]);
bottom_middle = (bottom_rect.y() + bottom_rect.bottom()) / 2;
bottom_count++;
}
// Whatever's left goes to the middle rect, but if there's no middle or
// bottom rect, split the existing rects evenly to make one.
gfx::Rect middle_rect;
if (top_count + bottom_count < n) {
middle_rect = rects[top_count];
for (size_t i = top_count + 1; i < n - bottom_count; i++)
middle_rect.Union(rects[i]);
} else if (bottom_count > 0) {
gfx::Rect enclosing_rect = top_rect;
enclosing_rect.Union(bottom_rect);
int middle_top = (top_rect.y() + top_rect.bottom() * 2) / 3;
int middle_bottom = (bottom_rect.y() * 2 + bottom_rect.bottom()) / 3;
top_rect.set_height(middle_top - top_rect.y());
bottom_rect.set_height(bottom_rect.bottom() - middle_bottom);
bottom_rect.set_y(middle_bottom);
middle_rect = gfx::Rect(enclosing_rect.x(), middle_top,
enclosing_rect.width(), middle_bottom - middle_top);
} else {
int middle_top = (top_rect.y() * 2 + top_rect.bottom()) / 3;
int middle_bottom = (top_rect.y() + top_rect.bottom() * 2) / 3;
middle_rect = gfx::Rect(top_rect.x(), middle_top, top_rect.width(),
middle_bottom - middle_top);
bottom_rect = gfx::Rect(top_rect.x(), middle_bottom, top_rect.width(),
top_rect.bottom() - middle_bottom);
top_rect.set_height(middle_top - top_rect.y());
}
if (middle_rect.y() > top_rect.bottom()) {
middle_rect.set_height(middle_rect.height() + middle_rect.y() -
top_rect.bottom());
middle_rect.set_y(top_rect.bottom());
}
if (middle_rect.bottom() < bottom_rect.y()) {
middle_rect.set_height(bottom_rect.y() - middle_rect.y());
}
*top = top_rect;
*middle = middle_rect;
*bottom = bottom_rect;
}
AccessibilityFocusRing AccessibilityFocusRingGroup::RingFromSortedRects(
const std::vector<gfx::Rect>& rects) const {
if (rects.size() == 1)
return AccessibilityFocusRing::CreateWithRect(rects[0], GetMargin());
gfx::Rect top;
gfx::Rect middle;
gfx::Rect bottom;
SplitIntoParagraphShape(rects, &top, &middle, &bottom);
return AccessibilityFocusRing::CreateWithParagraphShape(top, middle, bottom,
GetMargin());
}
bool AccessibilityFocusRingGroup::Intersects(const gfx::Rect& r1,
const gfx::Rect& r2) const {
int slop = GetMargin();
return (r2.x() <= r1.right() + slop && r2.right() >= r1.x() - slop &&
r2.y() <= r1.bottom() + slop && r2.bottom() >= r1.y() - slop);
}
} // namespace ash
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