galleryslide.cpp

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// C++
#include <algorithm>
#include <cmath>       // for roundf
 
// MythTV
#include "libmythbase/mythlogging.h"
#include "libmythbase/sizetliteral.h"
#include "libmythmetadata/imagemetadata.h"
#include "libmythui/mythmainwindow.h"
 
// MythFrontend
#include "galleryslide.h"
 
#define LOC QString("Slide: ")
#define SBLOC QString("SlideBuffer: ")
 
 
// Number of slides to use for buffering image requests.
// When browsing quickly the buffer will load consecutive slides until it fills.
// If too large, rapid browsing will be stodgy (sequential access) for images that
// aren't cached (Cached images are always fast).
// If too small, rapid browsing will result in skipping slides rather than flicking
// quickly through them.
// Minimum is 4: 3 for displaying a transition, 1 to handle load requests
static constexpr size_t SLIDE_BUFFER_SIZE { 9 };
 
 
void AbstractAnimation::Start(bool forwards, float speed)
{
    m_forwards = forwards;
    m_speed    = speed;
    m_running  = true;
}
 
 
void Animation::Set(const QVariant& from, const QVariant& to,
                    std::chrono::milliseconds duration,
                    const QEasingCurve& curve, UIEffects::Centre centre)
{
    setStartValue(from);
    setEndValue(to);
    m_centre = centre;
    setDuration(duration.count());
    setEasingCurve(curve);
}
 
 
void Animation::Start(bool forwards, float speed)
{
    auto duration_ms = std::chrono::milliseconds(duration());
    if (duration_ms == 0ms)
        return;
 
    m_elapsed = forwards ? 0ms : duration_ms;
    setCurrentTime(m_elapsed.count());
 
    AbstractAnimation::Start(forwards, speed);
}
 
 
void Animation::Pulse()
{
    if (!m_running)
        return;
 
    std::chrono::milliseconds current = MythDate::currentMSecsSinceEpochAsDuration();
    std::chrono::milliseconds interval = std::min(current - m_lastUpdate, 50ms);
    m_lastUpdate = current;
    m_elapsed += (m_forwards ? interval : -interval) * static_cast<int>(m_speed);
    setCurrentTime(m_elapsed.count());
 
    // Detect completion
    if ((m_forwards && m_elapsed.count() >= duration()) || (!m_forwards && m_elapsed <= 0ms))
        Finished();
}
 
 
void Animation::updateCurrentValue(const QVariant &value)
{
    if (m_parent && m_running)
    {
        m_parent->SetCentre(m_centre);
 
        switch (m_type)
        {
        case None:           break;
        case Position:       m_parent->SetPosition(value.toPoint()); break;
        case Alpha:          m_parent->SetAlpha(value.toInt()); break;
        case Zoom:           m_parent->SetZoom(value.toFloat()); break;
        case HorizontalZoom: m_parent->SetHorizontalZoom(value.toFloat()); break;
        case VerticalZoom:   m_parent->SetVerticalZoom(value.toFloat()); break;
        case Angle:          m_parent->SetAngle(value.toFloat()); break;
        }
    }
}
 
 
void GroupAnimation::Add(AbstractAnimation *child)
{
    // Signal group when child completes
    m_group.append(child);
    connect(child, &AbstractAnimation::finished, this, &GroupAnimation::Finished);
}
 
 
void GroupAnimation::Clear()
{
    qDeleteAll(m_group);
    m_group.clear();
}
 
 
void SequentialAnimation::Pulse()
{
    if (!m_running || m_current < 0 || m_current >= m_group.size())
        return;
 
    // Pulse current running child
    m_group.at(m_current)->Pulse();
}
 
 
void SequentialAnimation::Start(bool forwards, float speed)
{
    if (m_group.empty())
        return;
 
    m_current = forwards ? 0 : m_group.size() - 1;
 
    // Start group, then first child
    GroupAnimation::Start(forwards, speed);
    m_group.at(m_current)->Start(m_forwards, m_speed);
}
 
 
void SequentialAnimation::SetSpeed(float speed)
{
    // Set group speed for subsequent children
    GroupAnimation::SetSpeed(speed);
 
    // Set active child
    if (!m_running || m_current < 0 || m_current >= m_group.size())
        return;
 
    m_group.at(m_current)->SetSpeed(speed);
}
 
 
void SequentialAnimation::Finished()
{
    bool finished { false };
 
    // Finish group when last child finishes
    if (m_forwards)
    {
        m_current++;
        finished = (m_current == m_group.size());
    }
    else
    {
        m_current--;
        finished = (m_current < 0);
    }
 
    if (finished)
        AbstractAnimation::Finished();
    else
        // Start next child
        m_group.at(m_current)->Start(m_forwards, m_speed);
}
 
 
void ParallelAnimation::Pulse()
{
    if (m_running)
    {
        // Pulse all children
        for (AbstractAnimation *animation : std::as_const(m_group))
            animation->Pulse();
    }
}
 
 
void ParallelAnimation::Start(bool forwards, float speed)
{
    if (m_group.empty())
        return;
 
    m_finished = m_group.size();
 
    // Start group, then all children
    GroupAnimation::Start(forwards, speed);
    for (AbstractAnimation *animation : std::as_const(m_group))
        animation->Start(m_forwards, m_speed);
}
 
 
void ParallelAnimation::SetSpeed(float speed)
{
    // Set group speed, then all children
    GroupAnimation::SetSpeed(speed);
    for (AbstractAnimation *animation : std::as_const(m_group))
        animation->SetSpeed(m_speed);
}
 
 
void ParallelAnimation::Finished()
{
    // Finish group when last child finishes
    if (--m_finished == 0)
        AbstractAnimation::Finished();
}
 
 
void PanAnimation::updateCurrentValue(const QVariant &value)
{
    if (m_parent && m_running)
    {
        Slide *image = m_parent;
        image->SetPan(value.toPoint());
    }
}
 
 
Slide::Slide(MythUIType *parent, const QString& name, MythUIImage *image)
    : MythUIImage(parent, name)
{
    // Clone from image
    CopyFrom(image);
 
    // Null parent indicates we should become a child of the image (after
    // copy to avoid recursion)
    if (!parent)
    {
        // Slides sit on top of parent image area
        SetArea(MythRect(image->GetArea().toQRect()));
        m_area.moveTo(0, 0);
        setParent(image);
        m_parent = image;
        image->AddChild(this);
    }
 
    // Provide animations for pan & zoom
    if (GetPainter()->SupportsAnimation())
    {
        m_zoomAnimation = new Animation(this, Animation::Zoom);
        m_panAnimation  = new PanAnimation(this);
    }
 
    connect(this, &MythUIImage::LoadComplete, this, &Slide::SlideLoaded);
}
 
 
Slide::~Slide()
{
    delete m_zoomAnimation;
    delete m_panAnimation;
    LOG(VB_GUI, LOG_DEBUG, "Deleted Slide " + objectName());
}
 
 
void Slide::Clear()
{
    m_state = kEmpty;
    m_data.clear();
    m_waitingFor.clear();
    SetCropRect(0, 0, 0, 0);
    SetVisible(false);
}
 
 
QChar Slide::GetDebugState() const
{
    switch (m_state)
    {
    case kEmpty:   return 'e';
    case kFailed:  return 'f';
    case kLoaded:  return m_waitingFor ? 'r' : 'a';
    case kLoading: return m_waitingFor ? 'l' : 'p';
    }
    return '?';
}
 
 
bool Slide::LoadSlide(const ImagePtrK& im, int direction, bool notifyCompletion)
{
    m_direction  = direction;
    m_waitingFor = notifyCompletion ? im : ImagePtrK();
 
    if (im == m_data)
    {
        LOG(VB_FILE, LOG_DEBUG, LOC + QString("Already loading/loaded %1 in %2")
            .arg(im->m_filePath, objectName()));
 
        if (m_state >= kLoaded && notifyCompletion)
            // Image has been pre-loaded
            emit ImageLoaded(this);
 
        return (m_state >= kLoaded);
    }
 
    // Is a different image loading ?
    if (m_state == kLoading)
    {
        // Can't abort image loads, so must wait for it to finish
        // before starting new load
        m_waitingFor = im;
 
        LOG(VB_FILE, LOG_DEBUG, LOC + QString("Postponing load of %1 in %2")
            .arg(im->m_filePath, objectName()));
 
        return false;
    }
 
    // Start load
    m_data  = im;
    m_state = kLoading;
 
    if (im->m_type == kVideoFile)
    {
        // Use thumbnail, which has already been orientated
        SetFilename(im->m_thumbNails.at(0).second);
        SetOrientation(1);
    }
    else
    {
        // Load image, compensating for any Qt auto-orientation
        SetFilename(im->m_url);
        SetOrientation(Orientation(m_data->m_orientation).GetCurrent(true));
    }
 
    // Load in background
    Load(true);
    return false;
}
 
 
void Slide::SlideLoaded()
{
    m_state = m_images[0] ? kLoaded : kFailed;
    if (m_state == kFailed)
        LOG(VB_GENERAL, LOG_ERR, LOC +
            QString("Failed to load %1").arg(m_data->m_filePath));
 
    // Ignore superseded requests and preloads
    if (m_data == m_waitingFor)
    {
        // Loaded image is the latest requested
        emit ImageLoaded(this);
    }
    else if (m_waitingFor)
    {
        LOG(VB_FILE, LOG_DEBUG, LOC + QString("Starting delayed load %1")
            .arg(m_waitingFor->m_filePath));
 
        // Start latest postponed load
        LoadSlide(m_waitingFor, m_direction, true);
    }
}
 
 
void Slide::Zoom(int percentage)
{
    // Sentinel indicates reset to default zoom
    float newZoom = (percentage == 0)
            ? 1.0F
            : std::clamp(m_zoom * (1.0F + percentage / 100.0F), MIN_ZOOM, MAX_ZOOM);
    if (newZoom != m_zoom)
    {
        if (m_zoomAnimation)
        {
            m_zoomAnimation->Set(m_zoom, newZoom, 250ms, QEasingCurve::OutQuad);
            m_zoomAnimation->Start();
        }
        else
        {
            SetZoom(newZoom);
        }
    }
}
 
 
void Slide::SetZoom(float zoom)
{
    m_zoom          = zoom;
    m_effects.m_hzoom = m_effects.m_vzoom = zoom;
 
    // TODO
    // MythUIImage displaces widget or doesn't centre for some combinations of
    // zoom centre/cropping so frig centre for now.
    m_effects.m_centre = zoom < 1.0F ? UIEffects::Middle : UIEffects::TopLeft;
 
    SetPan(m_pan);
}
 
 
void Slide::Pan(QPoint offset)
{
    // Panning only possible when zoomed in
    if (m_zoom > 1.0F)
    {
        QPoint start = m_pan;
 
        // Sentinel indicates reset to centre
        // Panning is applied to original (unzoomed) image co-ords.
        // Adjust offset for zoom so that pan moves a constant screen distance rather
        // than constant image distance
        QPoint dest = offset.isNull() ? QPoint(0, 0) : start + offset / m_zoom;
 
        if (m_panAnimation)
        {
            m_panAnimation->Set(start, dest, 250ms, QEasingCurve::Linear);
            m_panAnimation->Start();
        }
        else
        {
            SetPan(dest);
        }
    }
}
 
 
void Slide::SetPan(QPoint pos)
{
    if (m_state == kFailed)
    {
        m_pan = pos;
        return;
    }
 
    // Determine zoom of largest dimension
    QRect imageArea = m_images[m_curPos]->rect();
    float hRatio    = float(imageArea.height()) / m_area.height();
    float wRatio    = float(imageArea.width()) / m_area.width();
    float ratio     = std::max(hRatio, wRatio); // TODO create a Rational number class
 
    if (m_zoom != 0.0F)
        ratio /= m_zoom;
 
    // Determine crop area
    int h = std::min(int(roundf(m_area.height() * ratio)), imageArea.height());
    int w = std::min(int(roundf(m_area.width() * ratio)), imageArea.width());
    int x = imageArea.center().x() - (w / 2);
    int y = imageArea.center().y() - (h / 2);
 
    // Constrain pan to boundaries
    int limitX = (imageArea.width() - w) / 2;
    int limitY = (imageArea.height() - h) / 2;
    m_pan.setX(std::clamp(pos.x(), -limitX, limitX));
    m_pan.setY(std::clamp(pos.y(), -limitY, limitY));
 
    SetCropRect(x + m_pan.x(), y + m_pan.y(), w, h);
    SetRedraw();
}
 
 
void Slide::Pulse()
{
    // Update zoom/pan animations
    if (m_zoomAnimation)
        m_zoomAnimation->Pulse();
 
    if (m_panAnimation)
        m_panAnimation->Pulse();
}
 
 
SlideBuffer::~SlideBuffer()
{
    LOG(VB_GUI, LOG_DEBUG, "Deleted Slidebuffer");
}
 
 
void SlideBuffer::Teardown()
{
    QMutexLocker lock(&m_mutexQ);
    for (Slide *s : std::as_const(m_queue))
        s->Clear();
    LOG(VB_GUI, LOG_DEBUG, "Aborted Slidebuffer");
}
 
 
void SlideBuffer::Initialise(MythUIImage &image)
{
    // Require at least 4 slides: 2 for transitions, 1 to handle further requests
    // and 1 to prevent solitary slide from being used whilst it is loading
    size_t size = std::max(SLIDE_BUFFER_SIZE, 4_UZ);
 
    // Fill buffer with slides cloned from the XML image widget
 
    // Create first as a child of the XML image.
    auto *slide = new Slide(nullptr, "slide0", &image);
 
    // Buffer is notified when it has loaded image
    connect(slide, &Slide::ImageLoaded,
            this, qOverload<Slide*>(&SlideBuffer::Flush));
 
    m_queue.enqueue(slide);
 
    // Rest are simple clones of first
    for (size_t i = 1; i < size; ++i)
    {
        slide = new Slide(&image, QString("slide%1").arg(i), slide);
 
        // All slides (except first) start off hidden
        slide->SetVisible(false);
 
        // Buffer is notified when it has loaded image
        connect(slide, &Slide::ImageLoaded,
                this, qOverload<Slide*>(&SlideBuffer::Flush));
 
        m_queue.enqueue(slide);
    }
 
    m_nextLoad = 1;
}
 
 
QString SlideBuffer::BufferState()
{
    QMutexLocker lock(&m_mutexQ);
 
    QString state;
    for (int i = 0; i < m_queue.size(); ++i)
    {
        QChar code(m_queue.at(i)->GetDebugState());
        state += (i == m_nextLoad ? code.toUpper() : code);
    }
    return QString("[%1] (%2)").arg(state, m_queue.head()->objectName());
}
 
 
bool SlideBuffer::Load(const ImagePtrK& im, int direction)
{
    if (!im)
        return false;
 
    QMutexLocker lock(&m_mutexQ);
 
    // Start loading image in next available slide
    Slide *slide = m_queue.at(m_nextLoad);
 
    // Further load requests will go to same slide if no free ones are available
    if (m_nextLoad < m_queue.size() - 1)
        ++m_nextLoad;
 
    LOG(VB_FILE, LOG_DEBUG, SBLOC + QString("Loading %1 in %2, %3")
        .arg(im->m_filePath, slide->objectName(), BufferState()));
 
    return slide->LoadSlide(im, direction, true);
}
 
 
void SlideBuffer::Preload(const ImagePtrK& im)
{
    if (!im)
        return;
 
    QMutexLocker lock(&m_mutexQ);
 
    // Start loading image in next available slide
    Slide *slide = m_queue.at(m_nextLoad);
 
    LOG(VB_FILE, LOG_DEBUG, SBLOC + QString("Preloading %1 in %2, %3")
        .arg(im->m_filePath, slide->objectName(), BufferState()));
 
    // Load silently
    slide->LoadSlide(im);
}
 
 
void SlideBuffer::ReleaseCurrent()
{
    QMutexLocker lock(&m_mutexQ);
 
    // Reset slide & return to buffer for re-use
    Slide *slide = m_queue.dequeue();
    slide->Clear();
    m_queue.enqueue(slide);
 
    QString name = slide->objectName();
 
    // Free constrained load ptr now a spare slide is available
    if (!m_queue.at(--m_nextLoad)->IsEmpty())
        ++m_nextLoad;
 
    LOG(VB_FILE, LOG_DEBUG, SBLOC + QString("Released %1").arg(name));
 
    // Flush any pending slides that originate from multiple requests (skipping)
    Flush(m_queue.head(), "Pending");
}
 
 
void SlideBuffer::Flush(Slide *slide, const QString& reason)
{
    QMutexLocker lock(&m_mutexQ);
 
    // Determine number of consecutive slides that are now available after head
    // Include last slide to ensure transition speed is consistent: it will never
    // be displayed because queue size is always > 2
    int available = 1;
    while (available < m_queue.size() && m_queue.at(available)->IsLoaded())
        ++available;
 
    if (available == 1)
        return;
 
    // Notify that more slides are available
    ImagePtrK im = slide->GetImageData();
    QString   path = im ? im->m_filePath : "Unknown";
 
    LOG(VB_FILE, LOG_DEBUG, SBLOC + QString("%1 %2 in %3, %4")
        .arg(reason, path, slide->objectName(), BufferState()));
 
    emit SlideReady(--available);
}
 
void SlideBuffer::Flush(Slide *slide)
{
    Flush(slide, "Loaded");
};