view.cpp

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/*
 * This file is part of the PulseView project.
 *
 * Copyright (C) 2012 Joel Holdsworth <joel@airwebreathe.org.uk>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#ifdef ENABLE_DECODE
#include <libsigrokdecode/libsigrokdecode.h>
#endif

#include <extdef.h>

#include <algorithm>
#include <cassert>
#include <climits>
#include <cmath>
#include <iostream>
#include <iterator>

#include <QApplication>
#include <QDebug>
#include <QEvent>
#include <QFontMetrics>
#include <QMenu>
#include <QMouseEvent>
#include <QScrollBar>
#include <QVBoxLayout>

#include <libsigrokcxx/libsigrokcxx.hpp>

#include "view.hpp"

#include "pv/globalsettings.hpp"
#include "pv/metadata_obj.hpp"
#include "pv/session.hpp"
#include "pv/util.hpp"
#include "pv/data/logic.hpp"
#include "pv/data/logicsegment.hpp"
#include "pv/data/signalbase.hpp"
#include "pv/devices/device.hpp"
#include "pv/views/trace/mathsignal.hpp"
#include "pv/views/trace/analogsignal.hpp"
#include "pv/views/trace/header.hpp"
#include "pv/views/trace/logicsignal.hpp"
#include "pv/views/trace/ruler.hpp"
#include "pv/views/trace/signal.hpp"
#include "pv/views/trace/tracegroup.hpp"
#include "pv/views/trace/triggermarker.hpp"
#include "pv/views/trace/viewport.hpp"

#ifdef ENABLE_DECODE
#include "pv/views/trace/decodetrace.hpp"
#endif

using pv::data::SignalBase;
using pv::data::SignalData;
using pv::data::Segment;
using pv::util::TimeUnit;
using pv::util::Timestamp;

using std::back_inserter;
using std::copy_if;
using std::count_if;
using std::inserter;
using std::lock_guard;
using std::max;
using std::make_pair;
using std::make_shared;
using std::min;
using std::numeric_limits;
using std::pair;
using std::set;
using std::set_difference;
using std::shared_ptr;
using std::vector;

namespace pv {
namespace views {
namespace trace {

const Timestamp View::MaxScale("1e9");
const Timestamp View::MinScale("1e-14");

const int View::MaxScrollValue = INT_MAX / 2;

/* Area at the top and bottom of the view that can't be scrolled out of sight */
const int View::ViewScrollMargin = 50;

const int View::ScaleUnits[3] = {1, 2, 5};

CustomScrollArea::CustomScrollArea(QWidget *parent) :
    QAbstractScrollArea(parent)
{
}

bool CustomScrollArea::viewportEvent(QEvent *event)
{
    switch (event->type()) {
    case QEvent::Paint:
    case QEvent::MouseButtonPress:
    case QEvent::MouseButtonRelease:
    case QEvent::MouseButtonDblClick:
    case QEvent::MouseMove:
    case QEvent::Wheel:
    case QEvent::TouchBegin:
    case QEvent::TouchUpdate:
    case QEvent::TouchEnd:
        return false;
    default:
        return QAbstractScrollArea::viewportEvent(event);
    }
}

View::View(Session &session, bool is_main_view, QMainWindow *parent) :
    ViewBase(session, is_main_view, parent),

    // Note: Place defaults in View::reset_view_state(), not here
    splitter_(new QSplitter()),
    header_was_shrunk_(false),  // The splitter remains unchanged after a reset, so this goes here
    sticky_scrolling_(false),  // Default setting is set in MainWindow::setup_ui()
    scroll_needs_defaults_(true)
{
    QVBoxLayout *root_layout = new QVBoxLayout(this);
    root_layout->setContentsMargins(0, 0, 0, 0);
    root_layout->addWidget(splitter_);

    viewport_ = new Viewport(*this);
    scrollarea_ = new CustomScrollArea(splitter_);
    scrollarea_->setViewport(viewport_);
    scrollarea_->setFrameShape(QFrame::NoFrame);

    ruler_ = new Ruler(*this);

    header_ = new Header(*this);
    header_->setMinimumWidth(10);  // So that the arrow tips show at least

    // We put the header into a simple layout so that we can add the top margin,
    // allowing us to make it line up with the bottom of the ruler
    QWidget *header_container = new QWidget();
    header_container->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    QVBoxLayout *header_layout = new QVBoxLayout(header_container);
    header_layout->setContentsMargins(0, ruler_->sizeHint().height(), 0, 0);
    header_layout->addWidget(header_);

    // To let the ruler and scrollarea be on the same split pane, we need a layout
    QWidget *trace_container = new QWidget();
    trace_container->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
    QVBoxLayout *trace_layout = new QVBoxLayout(trace_container);
    trace_layout->setSpacing(0);  // We don't want space between the ruler and scrollarea
    trace_layout->setContentsMargins(0, 0, 0, 0);
    trace_layout->addWidget(ruler_);
    trace_layout->addWidget(scrollarea_);

    splitter_->addWidget(header_container);
    splitter_->addWidget(trace_container);
    splitter_->setHandleWidth(1);  // Don't show a visible rubber band
    splitter_->setCollapsible(0, false);  // Prevent the header from collapsing
    splitter_->setCollapsible(1, false);  // Prevent the traces from collapsing
    splitter_->setStretchFactor(0, 0);  // Prevent the panes from being resized
    splitter_->setStretchFactor(1, 1);  // when the entire view is resized
    splitter_->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);

    viewport_->installEventFilter(this);
    ruler_->installEventFilter(this);
    header_->installEventFilter(this);

    // Set up settings and event handlers
    GlobalSettings settings;
    colored_bg_ = settings.value(GlobalSettings::Key_View_ColoredBG).toBool();
    snap_distance_ = settings.value(GlobalSettings::Key_View_SnapDistance).toInt();

    GlobalSettings::add_change_handler(this);

    // Set up metadata objects and event handlers
    if (is_main_view) {
        session_.metadata_obj_manager()->create_object(MetadataObjMainViewRange);
        session_.metadata_obj_manager()->create_object(MetadataObjMousePos);
    }

    // Set up UI event handlers
    connect(scrollarea_->horizontalScrollBar(), SIGNAL(valueChanged(int)),
        this, SLOT(h_scroll_value_changed(int)));
    connect(scrollarea_->verticalScrollBar(), SIGNAL(valueChanged(int)),
        this, SLOT(v_scroll_value_changed()));

    connect(header_, SIGNAL(selection_changed()),
        ruler_, SLOT(clear_selection()));
    connect(ruler_, SIGNAL(selection_changed()),
        header_, SLOT(clear_selection()));

    connect(header_, SIGNAL(selection_changed()),
        this, SIGNAL(selection_changed()));
    connect(ruler_, SIGNAL(selection_changed()),
        this, SIGNAL(selection_changed()));

    connect(splitter_, SIGNAL(splitterMoved(int, int)),
        this, SLOT(on_splitter_moved()));

    connect(&lazy_event_handler_, SIGNAL(timeout()),
        this, SLOT(process_sticky_events()));
    lazy_event_handler_.setSingleShot(true);
    lazy_event_handler_.setInterval(1000 / ViewBase::MaxViewAutoUpdateRate);

    // Set up local keyboard shortcuts
    zoom_in_shortcut_ = new QShortcut(QKeySequence(Qt::Key_Plus), this,
        SLOT(on_zoom_in_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);
    zoom_in_shortcut_->setAutoRepeat(false);

    zoom_out_shortcut_ = new QShortcut(QKeySequence(Qt::Key_Minus), this,
        SLOT(on_zoom_out_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);
    zoom_out_shortcut_->setAutoRepeat(false);

    zoom_in_shortcut_2_ = new QShortcut(QKeySequence(Qt::Key_Up), this,
        SLOT(on_zoom_in_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);
    zoom_out_shortcut_2_ = new QShortcut(QKeySequence(Qt::Key_Down), this,
        SLOT(on_zoom_out_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);

    home_shortcut_ = new QShortcut(QKeySequence(Qt::Key_Home), this,
        SLOT(on_scroll_to_start_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);
    home_shortcut_->setAutoRepeat(false);

    end_shortcut_ = new QShortcut(QKeySequence(Qt::Key_End), this,
        SLOT(on_scroll_to_end_shortcut_triggered()), nullptr, Qt::WidgetWithChildrenShortcut);
    end_shortcut_->setAutoRepeat(false);

    grab_ruler_left_shortcut_ = new QShortcut(QKeySequence(Qt::Key_1), this,
        nullptr, nullptr, Qt::WidgetWithChildrenShortcut);
    connect(grab_ruler_left_shortcut_, &QShortcut::activated,
        this, [=]{on_grab_ruler(1);});
    grab_ruler_left_shortcut_->setAutoRepeat(false);

    grab_ruler_right_shortcut_ = new QShortcut(QKeySequence(Qt::Key_2), this,
        nullptr, nullptr, Qt::WidgetWithChildrenShortcut);
    connect(grab_ruler_right_shortcut_, &QShortcut::activated,
        this, [=]{on_grab_ruler(2);});
    grab_ruler_right_shortcut_->setAutoRepeat(false);

    cancel_grab_shortcut_ = new QShortcut(QKeySequence(Qt::Key_Escape), this,
        nullptr, nullptr, Qt::WidgetWithChildrenShortcut);
    connect(cancel_grab_shortcut_, &QShortcut::activated,
        this, [=]{grabbed_widget_ = nullptr;});
    cancel_grab_shortcut_->setAutoRepeat(false);

    // Trigger the initial event manually. The default device has signals
    // which were created before this object came into being
    signals_changed();

    // Make sure the transparent widgets are on the top
    ruler_->raise();
    header_->raise();

    reset_view_state();
}

View::~View()
{
    GlobalSettings::remove_change_handler(this);
}

ViewType View::get_type() const
{
    return ViewTypeTrace;
}

void View::reset_view_state()
{
    ViewBase::reset_view_state();

    segment_display_mode_ = Trace::ShowLastSegmentOnly;
    segment_selectable_ = false;
    scale_ = 1e-3;
    offset_ = 0;
    ruler_offset_ = 0;
    zero_offset_ = 0;
    custom_zero_offset_set_ = false;
    updating_scroll_ = false;
    restoring_state_ = false;
    always_zoom_to_fit_ = false;
    tick_period_ = 0;
    tick_prefix_ = pv::util::SIPrefix::yocto;
    tick_precision_ = 0;
    time_unit_ = util::TimeUnit::Time;
    show_cursors_ = false;
    cursors_ = make_shared<CursorPair>(*this);
    next_flag_text_ = 'A';
    trigger_markers_.clear();
    hover_widget_ = nullptr;
    grabbed_widget_ = nullptr;
    hover_point_ = QPoint(-1, -1);
    scroll_needs_defaults_ = true;
    scale_at_acq_start_ = 0;
    offset_at_acq_start_ = 0;

    show_cursors_ = false;
    cursor_state_changed(show_cursors_);
    flags_.clear();

    // Update the zoom state
    calculate_tick_spacing();

    // Make sure the standard bar's segment selector is in sync
    set_segment_display_mode(segment_display_mode_);

    scrollarea_->verticalScrollBar()->setRange(-100000000, 100000000);
}

Session& View::session()
{
    return session_;
}

const Session& View::session() const
{
    return session_;
}

vector< shared_ptr<Signal> > View::signals() const
{
    return signals_;
}

shared_ptr<Signal> View::get_signal_by_signalbase(shared_ptr<data::SignalBase> base) const
{
    shared_ptr<Signal> ret_val;

    for (const shared_ptr<Signal>& s : signals_)
        if (s->base() == base) {
            ret_val = s;
            break;
        }

    return ret_val;
}

void View::clear_signalbases()
{
    ViewBase::clear_signalbases();
    signals_.clear();
}

void View::add_signalbase(const shared_ptr<data::SignalBase> signalbase)
{
    ViewBase::add_signalbase(signalbase);

    shared_ptr<Signal> signal;

    switch (signalbase->type()) {
    case SignalBase::LogicChannel:
        signal = shared_ptr<Signal>(new LogicSignal(session_, signalbase));
        break;

    case SignalBase::AnalogChannel:
        signal = shared_ptr<Signal>(new AnalogSignal(session_, signalbase));
        break;

    case SignalBase::MathChannel:
        signal = shared_ptr<Signal>(new MathSignal(session_, signalbase));
        break;

    default:
        qDebug() << "Unknown signalbase type:" << signalbase->type();
        assert(false);
        break;
    }

    signals_.push_back(signal);

    signal->set_segment_display_mode(segment_display_mode_);
    signal->set_current_segment(current_segment_);

    // Secondary views use the signal's settings in the main view
    if (!is_main_view()) {
        shared_ptr<View> main_tv = dynamic_pointer_cast<View>(session_.main_view());
        shared_ptr<Signal> main_signal = main_tv->get_signal_by_signalbase(signalbase);
        if (main_signal)
            signal->restore_settings(main_signal->save_settings());
    }

    connect(signal->base().get(), SIGNAL(name_changed(const QString&)),
        this, SLOT(on_signal_name_changed()));
}

void View::remove_signalbase(const shared_ptr<data::SignalBase> signalbase)
{
    ViewBase::remove_signalbase(signalbase);

    shared_ptr<Signal> signal = get_signal_by_signalbase(signalbase);

    if (signal)
        remove_trace(signal);
}

#ifdef ENABLE_DECODE
void View::clear_decode_signals()
{
    ViewBase::clear_decode_signals();
    decode_traces_.clear();
}

void View::add_decode_signal(shared_ptr<data::DecodeSignal> signal)
{
    ViewBase::add_decode_signal(signal);

    shared_ptr<DecodeTrace> d(
        new DecodeTrace(session_, signal, decode_traces_.size()));
    decode_traces_.push_back(d);

    d->set_segment_display_mode(segment_display_mode_);
    d->set_current_segment(current_segment_);

    connect(signal.get(), SIGNAL(name_changed(const QString&)),
        this, SLOT(on_signal_name_changed()));
}

void View::remove_decode_signal(shared_ptr<data::DecodeSignal> signal)
{
    for (auto i = decode_traces_.begin(); i != decode_traces_.end(); i++)
        if ((*i)->base() == signal) {
            decode_traces_.erase(i);
            break;
        }

    ViewBase::remove_decode_signal(signal);
}
#endif

void View::remove_trace(shared_ptr<Trace> trace)
{
    TraceTreeItemOwner *const owner = trace->owner();
    assert(owner);
    owner->remove_child_item(trace);

    for (auto i = signals_.begin(); i != signals_.end(); i++)
        if ((*i) == trace) {
            signals_.erase(i);
            break;
        }

    if (!header_was_shrunk_)
        resize_header_to_fit();

    update_layout();

    header_->update();
    viewport_->update();
}

shared_ptr<Signal> View::get_signal_under_mouse_cursor() const
{
    return signal_under_mouse_cursor_;
}

View* View::view()
{
    return this;
}

const View* View::view() const
{
    return this;
}

Viewport* View::viewport()
{
    return viewport_;
}

const Viewport* View::viewport() const
{
    return viewport_;
}

QAbstractScrollArea* View::scrollarea() const
{
    return scrollarea_;
}

const Ruler* View::ruler() const
{
    return ruler_;
}

void View::save_settings(QSettings &settings) const
{
    settings.setValue("scale", scale_);
    settings.setValue("v_offset",
        scrollarea_->verticalScrollBar()->sliderPosition());

    settings.setValue("splitter_state", splitter_->saveState());
    settings.setValue("segment_display_mode", segment_display_mode_);

    GlobalSettings::store_timestamp(settings, "offset", offset_);

    if (custom_zero_offset_set_)
        GlobalSettings::store_timestamp(settings, "zero_offset", -zero_offset_);
    else
        settings.remove("zero_offset");

    for (const shared_ptr<Signal>& signal : signals_) {
        settings.beginGroup(signal->base()->internal_name());
        signal->save_settings(settings);
        settings.endGroup();
    }
}

void View::restore_settings(QSettings &settings)
{
    // Note: It is assumed that this function is only called once,
    // immediately after restoring a previous session.

    if (settings.contains("scale"))
        set_scale(settings.value("scale").toDouble());

    if (settings.contains("offset")) {
        // This also updates ruler_offset_
        set_offset(GlobalSettings::restore_timestamp(settings, "offset"));
    }

    if (settings.contains("zero_offset"))
        set_zero_position(GlobalSettings::restore_timestamp(settings, "zero_offset"));

    if (settings.contains("splitter_state"))
        splitter_->restoreState(settings.value("splitter_state").toByteArray());

    if (settings.contains("segment_display_mode"))
        set_segment_display_mode(
            (Trace::SegmentDisplayMode)(settings.value("segment_display_mode").toInt()));

    for (shared_ptr<Signal> signal : signals_) {
        settings.beginGroup(signal->base()->internal_name());
        signal->restore_settings(settings);
        settings.endGroup();
    }

    if (settings.contains("v_offset")) {
        // Note: see eventFilter() for additional information
        saved_v_offset_ = settings.value("v_offset").toInt();
        scroll_needs_defaults_ = false;
    }

    restoring_state_ = true;

    // Update the ruler so that it uses the new scale
    calculate_tick_spacing();
}

vector< shared_ptr<TimeItem> > View::time_items() const
{
    const vector<shared_ptr<Flag>> f(flags());
    vector<shared_ptr<TimeItem>> items(f.begin(), f.end());

    if (cursors_) {
        items.push_back(cursors_);
        items.push_back(cursors_->first());
        items.push_back(cursors_->second());
    }

    for (auto& trigger_marker : trigger_markers_)
        items.push_back(trigger_marker);

    return items;
}

double View::scale() const
{
    return scale_;
}

void View::set_scale(double scale)
{
    if (scale_ != scale) {
        scale_ = scale;

        update_view_range_metaobject();

        scale_changed();
    }
}

void View::set_offset(const pv::util::Timestamp& offset, bool force_update)
{
    if ((offset_ != offset) || force_update) {
        offset_ = offset;
        ruler_offset_ = offset_ + zero_offset_;

        update_view_range_metaobject();

        offset_changed();
    }
}

const Timestamp& View::offset() const
{
    return offset_;
}

const Timestamp& View::ruler_offset() const
{
    return ruler_offset_;
}

void View::set_zero_position(const pv::util::Timestamp& position)
{
    zero_offset_ = -position;
    custom_zero_offset_set_ = true;

    // Force an immediate update of the offsets
    set_offset(offset_, true);
    ruler_->update();
}

void View::reset_zero_position()
{
    zero_offset_ = 0;

    // When enabled, the first trigger for this segment is used as the zero position
    GlobalSettings settings;
    bool trigger_is_zero_time = settings.value(GlobalSettings::Key_View_TriggerIsZeroTime).toBool();

    if (trigger_is_zero_time) {
        vector<util::Timestamp> triggers = session_.get_triggers(current_segment_);

        if (triggers.size() > 0)
            zero_offset_ = triggers.front();
    }

    custom_zero_offset_set_ = false;

    // Force an immediate update of the offsets
    set_offset(offset_, true);
    ruler_->update();
}

pv::util::Timestamp View::zero_offset() const
{
    return zero_offset_;
}

int View::owner_visual_v_offset() const
{
    return -scrollarea_->verticalScrollBar()->sliderPosition();
}

void View::set_v_offset(int offset)
{
    scrollarea_->verticalScrollBar()->setSliderPosition(offset);
    header_->update();
    viewport_->update();
}

void View::set_h_offset(int offset)
{
    scrollarea_->horizontalScrollBar()->setSliderPosition(offset);
    header_->update();
    viewport_->update();
}

int View::get_h_scrollbar_maximum() const
{
    return scrollarea_->horizontalScrollBar()->maximum();
}

unsigned int View::depth() const
{
    return 0;
}

uint32_t View::current_segment() const
{
    return current_segment_;
}

pv::util::SIPrefix View::tick_prefix() const
{
    return tick_prefix_;
}

void View::set_tick_prefix(pv::util::SIPrefix tick_prefix)
{
    if (tick_prefix_ != tick_prefix) {
        tick_prefix_ = tick_prefix;
        tick_prefix_changed();
    }
}

unsigned int View::tick_precision() const
{
    return tick_precision_;
}

void View::set_tick_precision(unsigned tick_precision)
{
    if (tick_precision_ != tick_precision) {
        tick_precision_ = tick_precision;
        tick_precision_changed();
    }
}

const pv::util::Timestamp& View::tick_period() const
{
    return tick_period_;
}

unsigned int View::minor_tick_count() const
{
    return minor_tick_count_;
}

void View::set_tick_period(const pv::util::Timestamp& tick_period)
{
    if (tick_period_ != tick_period) {
        tick_period_ = tick_period;
        tick_period_changed();
    }
}

TimeUnit View::time_unit() const
{
    return time_unit_;
}

void View::set_time_unit(pv::util::TimeUnit time_unit)
{
    if (time_unit_ != time_unit) {
        time_unit_ = time_unit;
        time_unit_changed();
    }
}

void View::set_current_segment(uint32_t segment_id)
{
    current_segment_ = segment_id;

    for (const shared_ptr<Signal>& signal : signals_)
        signal->set_current_segment(current_segment_);
#ifdef ENABLE_DECODE
    for (shared_ptr<DecodeTrace>& dt : decode_traces_)
        dt->set_current_segment(current_segment_);
#endif

    vector<util::Timestamp> triggers = session_.get_triggers(current_segment_);

    trigger_markers_.clear();
    for (util::Timestamp timestamp : triggers)
        trigger_markers_.push_back(make_shared<TriggerMarker>(*this, timestamp));

    if (!custom_zero_offset_set_)
        reset_zero_position();

    viewport_->update();

    segment_changed(segment_id);
}

bool View::segment_is_selectable() const
{
    return segment_selectable_;
}

Trace::SegmentDisplayMode View::segment_display_mode() const
{
    return segment_display_mode_;
}

void View::set_segment_display_mode(Trace::SegmentDisplayMode mode)
{
    segment_display_mode_ = mode;

    for (const shared_ptr<Signal>& signal : signals_)
        signal->set_segment_display_mode(mode);

    uint32_t last_segment = session_.get_highest_segment_id();

    switch (mode) {
    case Trace::ShowLastSegmentOnly:
        if (current_segment_ != last_segment)
            set_current_segment(last_segment);
        break;

    case Trace::ShowLastCompleteSegmentOnly:
        // Do nothing if we only have one segment so far
        if (last_segment > 0) {
            // If the last segment isn't complete, the previous one must be
            uint32_t segment_id =
                (session_.all_segments_complete(last_segment)) ?
                last_segment : last_segment - 1;

            if (current_segment_ != segment_id)
                set_current_segment(segment_id);
        }
        break;

    case Trace::ShowSingleSegmentOnly:
    case Trace::ShowAllSegments:
    case Trace::ShowAccumulatedIntensity:
    default:
        // Current segment remains as-is
        break;
    }

    segment_selectable_ = true;

    if ((mode == Trace::ShowAllSegments) || (mode == Trace::ShowAccumulatedIntensity))
        segment_selectable_ = false;

    viewport_->update();

    segment_display_mode_changed((int)mode, segment_selectable_);
}

void View::zoom(double steps)
{
    zoom(steps, viewport_->width() / 2);
}

void View::zoom(double steps, int offset)
{
    set_zoom(scale_ * pow(3.0 / 2.0, -steps), offset);
}

void View::zoom_fit(bool gui_state)
{
    // Act as one-shot when stopped, toggle along with the GUI otherwise
    if (session_.get_capture_state() == Session::Stopped) {
        always_zoom_to_fit_ = false;
        always_zoom_to_fit_changed(false);
    } else {
        always_zoom_to_fit_ = gui_state;
        always_zoom_to_fit_changed(gui_state);
    }

    const pair<Timestamp, Timestamp> extents = get_time_extents();
    const Timestamp delta = extents.second - extents.first;
    if (delta < Timestamp("1e-12"))
        return;

    assert(viewport_);
    const int w = viewport_->width();
    if (w <= 0)
        return;

    const Timestamp scale = max(min(delta / w, MaxScale), MinScale);
    set_scale_offset(scale.convert_to<double>(), extents.first);
}

void View::focus_on_range(uint64_t start_sample, uint64_t end_sample)
{
    assert(viewport_);
    const uint64_t w = viewport_->width();
    if (w <= 0)
        return;

    const double samplerate = session_.get_samplerate();
    const double samples_per_pixel = samplerate * scale_;
    const uint64_t viewport_samples = w * samples_per_pixel;

    const uint64_t sample_delta = (end_sample - start_sample);

    // Note: We add 20% margin on the left and 5% on the right
    const uint64_t ext_sample_delta = sample_delta * 1.25;

    // Check if we can keep the zoom level and just center the supplied range
    if (viewport_samples >= ext_sample_delta) {
        // Note: offset is the left edge of the view so to center, we subtract half the view width
        const int64_t sample_offset = (start_sample + (sample_delta / 2) - (viewport_samples / 2));
        const Timestamp offset = sample_offset / samplerate;
        set_scale_offset(scale_, offset);
    } else {
        const Timestamp offset = (start_sample - sample_delta * 0.20) / samplerate;
        const Timestamp delta = ext_sample_delta / samplerate;
        const Timestamp scale = max(min(delta / w, MaxScale), MinScale);
        set_scale_offset(scale.convert_to<double>(), offset);
    }
}

void View::set_scale_offset(double scale, const Timestamp& offset)
{
    // Disable sticky scrolling / always zoom to fit when acquisition runs
    // and user drags the viewport
    if ((scale_ == scale) && (offset_ != offset) &&
        (session_.get_capture_state() == Session::Running)) {

        if (sticky_scrolling_) {
            sticky_scrolling_ = false;
            sticky_scrolling_changed(false);
        }

        if (always_zoom_to_fit_) {
            always_zoom_to_fit_ = false;
            always_zoom_to_fit_changed(false);
        }
    }

    set_scale(scale);
    set_offset(offset);

    calculate_tick_spacing();

    update_scroll();
    ruler_->update();
    viewport_->update();
}

vector< shared_ptr<SignalData> > View::get_visible_data() const
{
    // Make a set of all the visible data objects
    vector< shared_ptr<SignalData> > visible_data;
    for (const shared_ptr<Signal>& sig : signals_)
        if (sig->enabled())
            visible_data.push_back(sig->base()->data());

    return visible_data;
}

pair<Timestamp, Timestamp> View::get_time_extents() const
{
    boost::optional<Timestamp> left_time, right_time;

    vector< shared_ptr<SignalData> > data;
    if (signals_.size() == 0)
        return make_pair(0, 0);

    for (const shared_ptr<Signal>& s : signals_)
        if (s->base()->data() && (s->base()->data()->segments().size() > 0))
            data.push_back(s->base()->data());

    for (const shared_ptr<SignalData>& d : data) {
        const vector< shared_ptr<Segment> > segments = d->segments();
        for (const shared_ptr<Segment>& s : segments) {
            double samplerate = s->samplerate();
            samplerate = (samplerate <= 0.0) ? 1.0 : samplerate;

            const Timestamp start_time = s->start_time();
            left_time = left_time ?
                min(*left_time, start_time) :
                                start_time;
            right_time = right_time ?
                max(*right_time, start_time + d->max_sample_count() / samplerate) :
                                 start_time + d->max_sample_count() / samplerate;
        }
    }

    if (!left_time || !right_time)
        return make_pair(0, 0);

    assert(*left_time <= *right_time);
    return make_pair(*left_time, *right_time);
}

bool View::colored_bg() const
{
    return colored_bg_;
}

bool View::cursors_shown() const
{
    return show_cursors_;
}

void View::show_cursors(bool show)
{
    if (show_cursors_ != show) {
        show_cursors_ = show;

        cursor_state_changed(show);
        ruler_->update();
        viewport_->update();
    }
}

void View::set_cursors(pv::util::Timestamp& first, pv::util::Timestamp& second)
{
    assert(cursors_);

    cursors_->first()->set_time(first);
    cursors_->second()->set_time(second);

    ruler_->update();
    viewport_->update();
}

void View::center_cursors()
{
    assert(cursors_);

    const double time_width = scale_ * viewport_->width();
    cursors_->first()->set_time(offset_ + time_width * 0.4);
    cursors_->second()->set_time(offset_ + time_width * 0.6);

    ruler_->update();
    viewport_->update();
}

shared_ptr<CursorPair> View::cursors() const
{
    return cursors_;
}

shared_ptr<Flag> View::add_flag(const Timestamp& time)
{
    shared_ptr<Flag> flag =
        make_shared<Flag>(*this, time, QString("%1").arg(next_flag_text_));
    flags_.push_back(flag);

    next_flag_text_ = (next_flag_text_ >= 'Z') ? 'A' :
        (next_flag_text_ + 1);

    time_item_appearance_changed(true, true);
    return flag;
}

void View::remove_flag(shared_ptr<Flag> flag)
{
    flags_.remove(flag);
    time_item_appearance_changed(true, true);
}

vector< shared_ptr<Flag> > View::flags() const
{
    vector< shared_ptr<Flag> > flags(flags_.begin(), flags_.end());
    stable_sort(flags.begin(), flags.end(),
        [](const shared_ptr<Flag> &a, const shared_ptr<Flag> &b) {
            return a->time() < b->time();
        });

    return flags;
}

const QPoint& View::hover_point() const
{
    return hover_point_;
}

const QWidget* View::hover_widget() const
{
    return hover_widget_;
}

int64_t View::get_nearest_level_change(const QPoint &p)
{
    // Is snapping disabled?
    if (snap_distance_ == 0)
        return -1;

    struct entry_t {
        entry_t(shared_ptr<Signal> s) :
            signal(s), delta(numeric_limits<int64_t>::max()), sample(-1), is_dense(false) {}
        shared_ptr<Signal> signal;
        int64_t delta;
        int64_t sample;
        bool is_dense;
    };

    vector<entry_t> list;

    // Create list of signals to consider
    if (signal_under_mouse_cursor_)
        list.emplace_back(signal_under_mouse_cursor_);
    else
        for (shared_ptr<Signal> s : signals_) {
            if (!s->enabled())
                continue;

            list.emplace_back(s);
        }

    // Get data for listed signals
    for (entry_t &e : list) {
        // Calculate sample number from cursor position
        const double samples_per_pixel = e.signal->base()->get_samplerate() * scale();
        const int64_t x_offset = offset().convert_to<double>() / scale();
        const int64_t sample_num = max(((x_offset + p.x()) * samples_per_pixel), 0.0);

        vector<data::LogicSegment::EdgePair> edges =
            e.signal->get_nearest_level_changes(sample_num);

        if (edges.empty())
            continue;

        // Check first edge
        const int64_t first_sample_delta = abs(sample_num - edges.front().first);
        const int64_t first_delta = first_sample_delta / samples_per_pixel;
        e.delta = first_delta;
        e.sample = edges.front().first;

        // Check second edge if available
        if (edges.size() == 2) {
            // Note: -1 because this is usually the right edge and sample points are left-aligned
            const int64_t second_sample_delta = abs(sample_num - edges.back().first - 1);
            const int64_t second_delta = second_sample_delta / samples_per_pixel;

            // If both edges are too close, we mark this signal as being dense
            if ((first_delta + second_delta) <= snap_distance_)
                e.is_dense = true;

            if (second_delta < first_delta) {
                e.delta = second_delta;
                e.sample = edges.back().first;
            }
        }
    }

    // Look for the best match: non-dense first, then dense
    entry_t *match = nullptr;

    for (entry_t &e : list) {
        if (e.delta > snap_distance_ || e.is_dense)
            continue;

        if (match) {
            if (e.delta < match->delta)
                match = &e;
        } else
            match = &e;
    }

    if (!match) {
        for (entry_t &e : list) {
            if (!e.is_dense)
                continue;

            if (match) {
                if (e.delta < match->delta)
                    match = &e;
            } else
                match = &e;
        }
    }

    if (match) {
        // Somewhat ugly hack to make TimeItem::drag_by() work
        signal_under_mouse_cursor_ = match->signal;

        return match->sample;
    }

    return -1;
}

void View::restack_all_trace_tree_items()
{
    // Make a list of owners that is sorted from deepest first
    const vector<shared_ptr<TraceTreeItem>> items(
        list_by_type<TraceTreeItem>());
    set< TraceTreeItemOwner* > owners;
    for (const auto &r : items)
        owners.insert(r->owner());
    vector< TraceTreeItemOwner* > sorted_owners(owners.begin(), owners.end());
    sort(sorted_owners.begin(), sorted_owners.end(),
        [](const TraceTreeItemOwner* a, const TraceTreeItemOwner *b) {
            return a->depth() > b->depth(); });

    // Restack the items recursively
    for (auto &o : sorted_owners)
        o->restack_items();

    // Animate the items to their destination
    for (const auto &i : items)
        i->animate_to_layout_v_offset();
}

int View::header_width() const
{
     return header_->extended_size_hint().width();
}

void View::on_setting_changed(const QString &key, const QVariant &value)
{
    GlobalSettings settings;

    if (key == GlobalSettings::Key_View_ColoredBG) {
        colored_bg_ = settings.value(GlobalSettings::Key_View_ColoredBG).toBool();
        viewport_->update();
    }

    if ((key == GlobalSettings::Key_View_ShowSamplingPoints) ||
       (key == GlobalSettings::Key_View_ShowAnalogMinorGrid))
        viewport_->update();

    if (key == GlobalSettings::Key_View_TriggerIsZeroTime)
        on_settingViewTriggerIsZeroTime_changed(value);

    if (key == GlobalSettings::Key_View_SnapDistance)
        snap_distance_ = settings.value(GlobalSettings::Key_View_SnapDistance).toInt();
}

void View::trigger_event(int segment_id, util::Timestamp location)
{
    // TODO This doesn't work if we're showing multiple segments at once
    if ((uint32_t)segment_id != current_segment_)
        return;

    if (!custom_zero_offset_set_)
        reset_zero_position();

    trigger_markers_.push_back(make_shared<TriggerMarker>(*this, location));
}

void View::get_scroll_layout(double &length, Timestamp &offset) const
{
    const pair<Timestamp, Timestamp> extents = get_time_extents();
    length = ((extents.second - extents.first) / scale_).convert_to<double>();
    offset = offset_ / scale_;
}

void View::set_zoom(double scale, int offset)
{
    // Reset the "always zoom to fit" feature as the user changed the zoom
    always_zoom_to_fit_ = false;
    always_zoom_to_fit_changed(false);

    const Timestamp cursor_offset = offset_ + scale_ * offset;
    const Timestamp new_scale = max(min(Timestamp(scale), MaxScale), MinScale);
    const Timestamp new_offset = cursor_offset - new_scale * offset;
    set_scale_offset(new_scale.convert_to<double>(), new_offset);
}

void View::calculate_tick_spacing()
{
    const double SpacingIncrement = 10.0f;
    const double MinValueSpacing = 40.0f;

    // Figure out the highest numeric value visible on a label
    const QSize areaSize = viewport_->size();
    const Timestamp max_time = max(fabs(offset_),
        fabs(offset_ + scale_ * areaSize.width()));

    double min_width = SpacingIncrement;
    double label_width, tick_period_width;

    QFontMetrics m(QApplication::font());

    // Copies of the member variables with the same name, used in the calculation
    // and written back afterwards, so that we don't emit signals all the time
    // during the calculation.
    pv::util::Timestamp tick_period = tick_period_;
    pv::util::SIPrefix tick_prefix = tick_prefix_;
    unsigned tick_precision = tick_precision_;

    do {
        const double min_period = scale_ * min_width;

        const int order = (int)floorf(log10f(min_period));
        const pv::util::Timestamp order_decimal =
            pow(pv::util::Timestamp(10), order);

        // Allow for a margin of error so that a scale unit of 1 can be used.
        // Otherwise, for a SU of 1 the tick period will almost always be below
        // the min_period by a small amount - and thus skipped in favor of 2.
        // Note: margin assumes that SU[0] and SU[1] contain the smallest values
        double tp_margin = (ScaleUnits[0] + ScaleUnits[1]) / 2.0;
        double tp_with_margin;
        unsigned int unit = 0;

        do {
            tp_with_margin = order_decimal.convert_to<double>() *
                (ScaleUnits[unit++] + tp_margin);
        } while (tp_with_margin < min_period && unit < countof(ScaleUnits));

        minor_tick_count_ = (unit == 2) ? 4 : 5;
        tick_period = order_decimal * ScaleUnits[unit - 1];
        tick_prefix = static_cast<pv::util::SIPrefix>(
            (order - pv::util::exponent(pv::util::SIPrefix::yocto)) / 3);

        // Precision is the number of fractional digits required, not
        // taking the prefix into account (and it must never be negative)
        tick_precision = max(ceil(log10(1 / tick_period)).convert_to<int>(), 0);

        tick_period_width = (tick_period / scale_).convert_to<double>();

        const QString label_text = Ruler::format_time_with_distance(
            tick_period, max_time, tick_prefix, time_unit_, tick_precision);

        label_width = m.boundingRect(0, 0, INT_MAX, INT_MAX,
            Qt::AlignLeft | Qt::AlignTop, label_text).width() +
                MinValueSpacing;

        min_width += SpacingIncrement;
    } while (tick_period_width < label_width);

    set_tick_period(tick_period);
    set_tick_prefix(tick_prefix);
    set_tick_precision(tick_precision);
}

void View::adjust_top_margin()
{
    assert(viewport_);

    const QSize areaSize = viewport_->size();

    const pair<int, int> extents = v_extents();
    const int top_margin = owner_visual_v_offset() + extents.first;
    const int trace_bottom = owner_visual_v_offset() + extents.first + extents.second;

    // Do we have empty space at the top while the last trace goes out of screen?
    if ((top_margin > 0) && (trace_bottom > areaSize.height())) {
        const int trace_height = extents.second - extents.first;

        // Center everything vertically if there is enough space
        if (areaSize.height() >= trace_height)
            set_v_offset(extents.first -
                ((areaSize.height() - trace_height) / 2));
        else
            // Remove the top margin to make as many traces fit on screen as possible
            set_v_offset(extents.first);
    }
}

void View::update_scroll()
{
    assert(viewport_);
    QScrollBar *hscrollbar = scrollarea_->horizontalScrollBar();
    QScrollBar *vscrollbar = scrollarea_->verticalScrollBar();

    const QSize areaSize = viewport_->size();

    // Set the horizontal scroll bar
    double length = 0;
    Timestamp offset;
    get_scroll_layout(length, offset);
    length = max(length - areaSize.width(), 0.0);

    int major_tick_distance = (tick_period_ / scale_).convert_to<int>();

    hscrollbar->setPageStep(areaSize.width() / 2);
    hscrollbar->setSingleStep(major_tick_distance);

    updating_scroll_ = true;

    if (length < MaxScrollValue) {
        hscrollbar->setRange(0, length);
        hscrollbar->setSliderPosition(offset.convert_to<double>());
    } else {
        hscrollbar->setRange(0, MaxScrollValue);
        hscrollbar->setSliderPosition(
            (offset_ * MaxScrollValue / (scale_ * length)).convert_to<double>());
    }

    updating_scroll_ = false;

    // Set the vertical scrollbar
    vscrollbar->setPageStep(areaSize.height());
    vscrollbar->setSingleStep(areaSize.height() / 8);

    const pair<int, int> extents = v_extents();

    // Don't change the scrollbar range if there are no traces
    if (extents.first != extents.second) {
        int top_margin = ViewScrollMargin;
        int btm_margin = ViewScrollMargin;

        vscrollbar->setRange(extents.first - areaSize.height() + top_margin,
            extents.second - btm_margin);
    }

    if (scroll_needs_defaults_) {
        set_scroll_default();
        scroll_needs_defaults_ = false;
    }
}

void View::reset_scroll()
{
    scrollarea_->verticalScrollBar()->setRange(0, 0);
}

void View::set_scroll_default()
{
    assert(viewport_);

    const QSize areaSize = viewport_->size();

    const pair<int, int> extents = v_extents();
    const int trace_height = extents.second - extents.first;

    // Do all traces fit in the view?
    if (areaSize.height() >= trace_height)
        // Center all traces vertically
        set_v_offset(extents.first -
            ((areaSize.height() - trace_height) / 2));
    else
        // Put the first trace at the top, letting the bottom ones overflow
        set_v_offset(extents.first);
}

void View::determine_if_header_was_shrunk()
{
    const int header_pane_width =
        splitter_->sizes().front();  // clazy:exclude=detaching-temporary

    // Allow for a slight margin of error so that we also accept
    // slight differences when e.g. a label name change increased
    // the overall width
    header_was_shrunk_ = (header_pane_width < (header_width() - 10));
}

void View::resize_header_to_fit()
{
    // Setting the maximum width of the header widget doesn't work as
    // expected because the splitter would allow the user to make the
    // pane wider than that, creating empty space as a result.
    // To make this work, we stricly enforce the maximum width by
    // expanding the header unless the user shrunk it on purpose.
    // As we're then setting the width of the header pane, we set the
    // splitter to the maximum allowed position.

    int splitter_area_width = 0;
    for (int w : splitter_->sizes())  // clazy:exclude=range-loop
        splitter_area_width += w;

    // Make sure the header has enough horizontal space to show all labels fully
    QList<int> pane_sizes;
    pane_sizes.push_back(header_->extended_size_hint().width());
    pane_sizes.push_back(splitter_area_width - header_->extended_size_hint().width());
    splitter_->setSizes(pane_sizes);
}

void View::update_layout()
{
    update_scroll();

    update_view_range_metaobject();
}

TraceTreeItemOwner* View::find_prevalent_trace_group(
    const shared_ptr<sigrok::ChannelGroup> &group,
    const map<shared_ptr<data::SignalBase>, shared_ptr<Signal> > &signal_map)
{
    assert(group);

    set<TraceTreeItemOwner*> owners;
    vector<TraceTreeItemOwner*> owner_list;

    // Make a set and a list of all the owners
    for (const auto& channel : group->channels()) {
        for (auto& entry : signal_map) {
            if (entry.first->channel() == channel) {
                TraceTreeItemOwner *const o = (entry.second)->owner();
                owner_list.push_back(o);
                owners.insert(o);
            }
        }
    }

    // Iterate through the list of owners, and find the most prevalent
    size_t max_prevalence = 0;
    TraceTreeItemOwner *prevalent_owner = nullptr;
    for (TraceTreeItemOwner *owner : owners) {
        const size_t prevalence = count_if(
            owner_list.begin(), owner_list.end(),
            [&](TraceTreeItemOwner *o) { return o == owner; });
        if (prevalence > max_prevalence) {
            max_prevalence = prevalence;
            prevalent_owner = owner;
        }
    }

    return prevalent_owner;
}

vector< shared_ptr<Trace> > View::extract_new_traces_for_channels(
    const vector< shared_ptr<sigrok::Channel> > &channels,
    const map<shared_ptr<data::SignalBase>, shared_ptr<Signal> > &signal_map,
    set< shared_ptr<Trace> > &add_list)
{
    vector< shared_ptr<Trace> > filtered_traces;

    for (const auto& channel : channels) {
        for (auto& entry : signal_map) {
            if (entry.first->channel() == channel) {
                shared_ptr<Trace> trace = entry.second;
                const auto list_iter = add_list.find(trace);
                if (list_iter == add_list.end())
                    continue;

                filtered_traces.push_back(trace);
                add_list.erase(list_iter);
            }
        }
    }

    return filtered_traces;
}

void View::determine_time_unit()
{
    // Check whether we know the sample rate and hence can use time as the unit
    if (time_unit_ == util::TimeUnit::Samples) {
        // Check all signals but...
        for (const shared_ptr<Signal>& signal : signals_) {
            const shared_ptr<SignalData> data = signal->base()->data();

            // ...only check first segment of each
            const vector< shared_ptr<Segment> > segments = data->segments();
            if (!segments.empty())
                if (segments[0]->samplerate()) {
                    set_time_unit(util::TimeUnit::Time);
                    break;
                }
        }
    }
}

bool View::eventFilter(QObject *object, QEvent *event)
{
    const QEvent::Type type = event->type();

    if (type == QEvent::MouseMove) {

        if (object)
            hover_widget_ = qobject_cast<QWidget*>(object);

        const QMouseEvent *const mouse_event = (QMouseEvent*)event;
        if (object == viewport_)
            hover_point_ = mouse_event->pos();
        else if (object == ruler_)
            hover_point_ = mouse_event->pos();
        else if (object == header_)
#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
            hover_point_ = QPoint(0, mouse_event->pos().y());
#else
            hover_point_ = QPoint(0, mouse_event->y());
#endif
        else
            hover_point_ = QPoint(-1, -1);

        update_hover_point();

        if (grabbed_widget_) {
            int64_t nearest = get_nearest_level_change(hover_point_);
            pv::util::Timestamp mouse_time = offset_ + hover_point_.x() * scale_;

            if (nearest == -1) {
                grabbed_widget_->set_time(mouse_time);
            } else {
                grabbed_widget_->set_time(nearest / get_signal_under_mouse_cursor()->base()->get_samplerate());
            }
        }

    } else if (type == QEvent::MouseButtonPress) {
        grabbed_widget_ = nullptr;

        const QMouseEvent *const mouse_event = (QMouseEvent*)event;
        if ((object == viewport_) && (mouse_event->button() & Qt::LeftButton)) {
            // Send event to all trace tree items
            const vector<shared_ptr<TraceTreeItem>> trace_tree_items(
                list_by_type<TraceTreeItem>());
            for (const shared_ptr<TraceTreeItem>& r : trace_tree_items)
                r->mouse_left_press_event(mouse_event);
        }
    } else if (type == QEvent::Leave) {
        hover_point_ = QPoint(-1, -1);
        update_hover_point();
    } else if (type == QEvent::Show) {

        // This is somewhat of a hack, unfortunately. We cannot use
        // set_v_offset() from within restore_settings() as the view
        // at that point is neither visible nor properly sized.
        // This is the least intrusive workaround I could come up
        // with: set the vertical offset (or scroll defaults) when
        // the view is shown, which happens after all widgets were
        // resized to their final sizes.
        update_layout();

        if (restoring_state_)
            determine_if_header_was_shrunk();
        else
            resize_header_to_fit();

        if (scroll_needs_defaults_) {
            set_scroll_default();
            scroll_needs_defaults_ = false;
        }

        if (restoring_state_)
            set_v_offset(saved_v_offset_);
    }

    return QObject::eventFilter(object, event);
}

void View::contextMenuEvent(QContextMenuEvent *event)
{
    QPoint pos = event->pos() - QPoint(0, ruler_->sizeHint().height());

    const shared_ptr<ViewItem> r = viewport_->get_mouse_over_item(pos);

    QMenu* menu = nullptr;

    if (!r) {
        context_menu_x_pos_ = pos.x();

        // No view item under cursor, use generic menu
        menu = new QMenu(this);

        QAction *const create_marker_here = new QAction(tr("Create marker here"), this);
        connect(create_marker_here, SIGNAL(triggered()), this, SLOT(on_create_marker_here()));
        menu->addAction(create_marker_here);
    } else {
        menu = r->create_view_context_menu(this, pos);
    }

    if (menu)
        menu->popup(event->globalPos());
}

void View::resizeEvent(QResizeEvent* event)
{
    // Only adjust the top margin if we shrunk vertically
    if (event->size().height() < event->oldSize().height())
        adjust_top_margin();

    update_layout();
}

void View::update_view_range_metaobject() const
{
    const int w = viewport_->width();
    if (w > 0) {
        const double samplerate = session_.get_samplerate();
        // Note: sample_num = time * samplerate
        // Note: samples_per_pixel = samplerate * scale
        const int64_t start_sample = (offset_ * samplerate).convert_to<int64_t>();
        const int64_t end_sample = (offset_ * samplerate).convert_to<int64_t>() +
            (w * session_.get_samplerate() * scale_);

        MetadataObject* md_obj =
            session_.metadata_obj_manager()->find_object_by_type(MetadataObjMainViewRange);

        const int64_t old_start_sample = md_obj->value(MetadataValueStartSample).toLongLong();
        const int64_t old_end_sample = md_obj->value(MetadataValueEndSample).toLongLong();

        if (start_sample != old_start_sample)
            md_obj->set_value(MetadataValueStartSample, QVariant((qlonglong)start_sample));

        if (end_sample != old_end_sample)
            md_obj->set_value(MetadataValueEndSample, QVariant((qlonglong)end_sample));
    }
}

void View::update_hover_point()
{
    // Determine signal that the mouse cursor is hovering over
    signal_under_mouse_cursor_.reset();
    if (hover_widget_ == this) {
        for (const shared_ptr<Signal>& s : signals_) {
            const pair<int, int> extents = s->v_extents();
            const int top = s->get_visual_y() + extents.first;
            const int btm = s->get_visual_y() + extents.second;
            if ((hover_point_.y() >= top) && (hover_point_.y() <= btm)
                && s->base()->enabled())
                signal_under_mouse_cursor_ = s;
        }
    }

    // Update all trace tree items
    const vector<shared_ptr<TraceTreeItem>> trace_tree_items(
        list_by_type<TraceTreeItem>());
    for (const shared_ptr<TraceTreeItem>& r : trace_tree_items)
        r->hover_point_changed(hover_point_);

    // Notify this view's listeners
    hover_point_changed(hover_widget_, hover_point_);

    // Hover point is -1 when invalid and 0 for the header
    if (hover_point_.x() > 0) {
        // Notify global listeners
        pv::util::Timestamp mouse_time = offset_ + hover_point_.x() * scale_;
        int64_t sample_num = (mouse_time * session_.get_samplerate()).convert_to<int64_t>();

        MetadataObject* md_obj =
            session_.metadata_obj_manager()->find_object_by_type(MetadataObjMousePos);
        md_obj->set_value(MetadataValueStartSample, QVariant((qlonglong)sample_num));
    }
}

void View::row_item_appearance_changed(bool label, bool content)
{
    if (label)
        header_->update();
    if (content)
        viewport_->update();
}

void View::time_item_appearance_changed(bool label, bool content)
{
    if (label) {
        ruler_->update();

        // Make sure the header pane width is updated, too
        update_layout();
    }

    if (content)
        viewport_->update();
}

void View::extents_changed(bool horz, bool vert)
{
    sticky_events_ |=
        (horz ? TraceTreeItemHExtentsChanged : 0) |
        (vert ? TraceTreeItemVExtentsChanged : 0);

    if (!lazy_event_handler_.isActive())
        lazy_event_handler_.start();
}

void View::on_signal_name_changed()
{
    if (!header_was_shrunk_)
        resize_header_to_fit();
}

void View::on_splitter_moved()
{
    // The header can only shrink when the splitter is moved manually
    determine_if_header_was_shrunk();

    if (!header_was_shrunk_)
        resize_header_to_fit();
}

void View::on_zoom_in_shortcut_triggered()
{
    zoom(1);
}

void View::on_zoom_out_shortcut_triggered()
{
    zoom(-1);
}

void View::on_scroll_to_start_shortcut_triggered()
{
    set_h_offset(0);
}

void View::on_scroll_to_end_shortcut_triggered()
{
    set_h_offset(get_h_scrollbar_maximum());
}

void View::h_scroll_value_changed(int value)
{
    if (updating_scroll_)
        return;

    // Disable sticky scrolling when user moves the horizontal scroll bar
    // during a running acquisition
    if (sticky_scrolling_ && (session_.get_capture_state() == Session::Running)) {
        sticky_scrolling_ = false;
        sticky_scrolling_changed(false);
    }

    const int range = scrollarea_->horizontalScrollBar()->maximum();
    if (range < MaxScrollValue)
        set_offset(scale_ * value);
    else {
        double length = 0;
        Timestamp offset;
        get_scroll_layout(length, offset);
        set_offset(scale_ * length * value / MaxScrollValue);
    }

    ruler_->update();
    viewport_->update();
}

void View::v_scroll_value_changed()
{
    header_->update();
    viewport_->update();
}

void View::on_grab_ruler(int ruler_id)
{
    if (!cursors_shown()) {
        center_cursors();
        show_cursors();
    }

    // Release the grabbed widget if its trigger hotkey was pressed twice
    if (ruler_id == 1)
        grabbed_widget_ = (grabbed_widget_ == cursors_->first().get()) ?
            nullptr : cursors_->first().get();
    else
        grabbed_widget_ = (grabbed_widget_ == cursors_->second().get()) ?
            nullptr : cursors_->second().get();

    if (grabbed_widget_)
        grabbed_widget_->set_time(ruler_->get_absolute_time_from_x_pos(
            mapFromGlobal(QCursor::pos()).x() - header_width()));
}

void View::signals_changed()
{
    using sigrok::Channel;

    lock_guard<mutex> lock(signal_mutex_);

    vector< shared_ptr<Channel> > channels;
    shared_ptr<sigrok::Device> sr_dev;
    bool signals_added_or_removed = false;

    // Do we need to set the vertical scrollbar to its default position later?
    // We do if there are no traces, i.e. the scroll bar has no range set
    bool reset_scrollbar =
        (scrollarea_->verticalScrollBar()->minimum() ==
            scrollarea_->verticalScrollBar()->maximum());

    if (!session_.device()) {
        reset_scroll();
        signals_.clear();
    } else {
        sr_dev = session_.device()->device();
        assert(sr_dev);
        channels = sr_dev->channels();
    }

    vector< shared_ptr<TraceTreeItem> > new_top_level_items;

    // Make a list of traces that are being added, and a list of traces
    // that are being removed. The set_difference() algorithms require
    // both sets to be in the exact same order, which means that PD signals
    // must always be last as they interrupt the sort order otherwise
    const vector<shared_ptr<Trace>> prev_trace_list = list_by_type<Trace>();
    const set<shared_ptr<Trace>> prev_traces(
        prev_trace_list.begin(), prev_trace_list.end());

    set< shared_ptr<Trace> > traces(signals_.begin(), signals_.end());

#ifdef ENABLE_DECODE
    traces.insert(decode_traces_.begin(), decode_traces_.end());
#endif
    set< shared_ptr<Trace> > add_traces;
    set_difference(traces.begin(), traces.end(),
        prev_traces.begin(), prev_traces.end(),
        inserter(add_traces, add_traces.begin()));

    set< shared_ptr<Trace> > remove_traces;
    set_difference(prev_traces.begin(), prev_traces.end(),
        traces.begin(), traces.end(),
        inserter(remove_traces, remove_traces.begin()));

    // Make a look-up table of sigrok Channels to pulseview Signals
    map<shared_ptr<data::SignalBase>, shared_ptr<Signal> > signal_map;
    for (const shared_ptr<Signal>& sig : signals_)
        signal_map[sig->base()] = sig;

    // Populate channel groups
    if (sr_dev)
        for (auto& entry : sr_dev->channel_groups()) {
            const shared_ptr<sigrok::ChannelGroup> &group = entry.second;

            if (group->channels().size() <= 1)
                continue;

            // Find best trace group to add to
            TraceTreeItemOwner *owner = find_prevalent_trace_group(
                group, signal_map);

            // If there is no trace group, create one
            shared_ptr<TraceGroup> new_trace_group;
            if (!owner) {
                new_trace_group.reset(new TraceGroup());
                owner = new_trace_group.get();
            }

            // Extract traces for the trace group, removing them from
            // the add list
            const vector< shared_ptr<Trace> > new_traces_in_group =
                extract_new_traces_for_channels(group->channels(),
                    signal_map, add_traces);

            // Add the traces to the group
            const pair<int, int> prev_v_extents = owner->v_extents();
            int offset = prev_v_extents.second - prev_v_extents.first;
            for (const shared_ptr<Trace>& trace : new_traces_in_group) {
                assert(trace);
                owner->add_child_item(trace);

                const pair<int, int> extents = trace->v_extents();
                if (trace->enabled())
                    offset += -extents.first;
                trace->force_to_v_offset(offset);
                if (trace->enabled())
                    offset += extents.second;
            }

            if (new_trace_group) {
                // Assign proper vertical offsets to each channel in the group
                new_trace_group->restack_items();

                // If this is a new group, enqueue it in the new top level
                // items list
                if (!new_traces_in_group.empty())
                    new_top_level_items.push_back(new_trace_group);
            }
        }

    // Enqueue the remaining logic channels in a group
    vector< shared_ptr<Channel> > logic_channels;
    copy_if(channels.begin(), channels.end(), back_inserter(logic_channels),
        [](const shared_ptr<Channel>& c) {
            return c->type() == sigrok::ChannelType::LOGIC; });

    const vector< shared_ptr<Trace> > non_grouped_logic_signals =
        extract_new_traces_for_channels(logic_channels, signal_map, add_traces);

    if (non_grouped_logic_signals.size() > 0) {
        const shared_ptr<TraceGroup> non_grouped_trace_group(
            make_shared<TraceGroup>());
        for (const shared_ptr<Trace>& trace : non_grouped_logic_signals)
            non_grouped_trace_group->add_child_item(trace);

        non_grouped_trace_group->restack_items();
        new_top_level_items.push_back(non_grouped_trace_group);
    }

    // Enqueue the remaining channels as free ungrouped traces
    const vector< shared_ptr<Trace> > new_top_level_signals =
        extract_new_traces_for_channels(channels, signal_map, add_traces);
    new_top_level_items.insert(new_top_level_items.end(),
        new_top_level_signals.begin(), new_top_level_signals.end());

    // Enqueue any remaining traces i.e. decode traces
    new_top_level_items.insert(new_top_level_items.end(),
        add_traces.begin(), add_traces.end());

    // Remove any removed traces
    for (const shared_ptr<Trace>& trace : remove_traces) {
        TraceTreeItemOwner *const owner = trace->owner();
        assert(owner);
        owner->remove_child_item(trace);
        signals_added_or_removed = true;
    }

    // Remove any empty trace groups
    for (shared_ptr<TraceGroup> group : list_by_type<TraceGroup>())
        if (group->child_items().size() == 0) {
            remove_child_item(group);
            group.reset();
        }

    // Add and position the pending top levels items
    int offset = v_extents().second;
    for (shared_ptr<TraceTreeItem> item : new_top_level_items) {
        // items may already have gained an owner when they were added to a group above
        if (item->owner())
            continue;

        add_child_item(item);

        // Position the item after the last item or at the top if there is none
        const pair<int, int> extents = item->v_extents();

        if (item->enabled())
            offset += -extents.first;

        item->force_to_v_offset(offset);

        if (item->enabled())
            offset += extents.second;
        signals_added_or_removed = true;
    }


    if (signals_added_or_removed && !header_was_shrunk_)
        resize_header_to_fit();

    update_layout();

    header_->update();
    viewport_->update();

    if (reset_scrollbar)
        set_scroll_default();
}

void View::capture_state_updated(int state)
{
    GlobalSettings settings;

    if (state == Session::Running) {
        set_time_unit(util::TimeUnit::Samples);

        trigger_markers_.clear();
        if (!custom_zero_offset_set_)
            set_zero_position(0);

        scale_at_acq_start_ = scale_;
        offset_at_acq_start_ = offset_;

        // Activate "always zoom to fit" if the setting is enabled and we're
        // the main view of this session (other trace views may be used for
        // zooming and we don't want to mess them up)
        bool state = settings.value(GlobalSettings::Key_View_ZoomToFitDuringAcq).toBool();
        if (is_main_view_ && state && !restoring_state_) {
            always_zoom_to_fit_ = true;
            always_zoom_to_fit_changed(always_zoom_to_fit_);
        }

        // Enable sticky scrolling if the setting is enabled
        sticky_scrolling_ = !restoring_state_ &&
            settings.value(GlobalSettings::Key_View_StickyScrolling).toBool();

        // Reset all traces to segment 0
        current_segment_ = 0;
        set_current_segment(current_segment_);
    }

    if (state == Session::Stopped) {
        // After acquisition has stopped we need to re-calculate the ticks once
        // as it's otherwise done when the user pans or zooms, which is too late
        calculate_tick_spacing();

        // Reset "always zoom to fit", the acquisition has stopped
        if (always_zoom_to_fit_) {
            // Perform a final zoom-to-fit before disabling
            zoom_fit(always_zoom_to_fit_);
            always_zoom_to_fit_ = false;
            always_zoom_to_fit_changed(always_zoom_to_fit_);
        }

        bool zoom_to_fit_after_acq =
            settings.value(GlobalSettings::Key_View_ZoomToFitAfterAcq).toBool();

        // Only perform zoom-to-fit if the user hasn't altered the viewport and
        // we didn't restore settings in the meanwhile
        if (zoom_to_fit_after_acq &&
            !restoring_state_ &&
            (scale_ == scale_at_acq_start_) &&
            (sticky_scrolling_ || (offset_ == offset_at_acq_start_))) {
            zoom_fit(false);  // We're stopped, so the GUI state doesn't matter
        }

        restoring_state_ = false;
    }
}

void View::on_new_segment(int new_segment_id)
{
    on_segment_changed(new_segment_id);
}

void View::on_segment_completed(int segment_id)
{
    on_segment_changed(segment_id);
}

void View::on_segment_changed(int segment)
{
    switch (segment_display_mode_) {
    case Trace::ShowLastSegmentOnly:
    case Trace::ShowSingleSegmentOnly:
        set_current_segment(segment);
        break;

    case Trace::ShowLastCompleteSegmentOnly:
        // Only update if all segments are complete
        if (session_.all_segments_complete(segment))
            set_current_segment(segment);
        break;

    case Trace::ShowAllSegments:
    case Trace::ShowAccumulatedIntensity:
    default:
        break;
    }
}

void View::on_create_marker_here()
{
    const QPoint p = ruler_->mapFrom(this, QPoint(context_menu_x_pos_, 0));

    add_flag(ruler_->get_absolute_time_from_x_pos(p.x()));
}

void View::on_settingViewTriggerIsZeroTime_changed(const QVariant new_value)
{
    (void)new_value;

    if (!custom_zero_offset_set_)
        reset_zero_position();
}

void View::perform_delayed_view_update()
{
    if (always_zoom_to_fit_) {
        zoom_fit(true);
    } else if (sticky_scrolling_) {
        // Make right side of the view sticky
        double length = 0;
        Timestamp offset;
        get_scroll_layout(length, offset);

        const QSize areaSize = viewport_->size();
        length = max(length - areaSize.width(), 0.0);

        set_offset(scale_ * length);
    }

    determine_time_unit();
    update_scroll();
    ruler_->update();
    viewport_->update();
}

void View::process_sticky_events()
{
    if (sticky_events_ & TraceTreeItemHExtentsChanged)
        update_layout();
    if (sticky_events_ & TraceTreeItemVExtentsChanged) {
        restack_all_trace_tree_items();
        update_scroll();
    }

    // Clear the sticky events
    sticky_events_ = 0;
}

} // namespace trace
} // namespace views
} // namespace pv