blame: src/imagemodel.cpp

#include "imagemodel.h"

#include "thumbnailworker.h"

#include <QDir>

#include <QImageReader>

#include <QFileInfo>

#include <QFileIconProvider>

ImageModel::ImageModel(QObject *parent)

    : QAbstractListModel(parent)

{

    // Limit 1 thread for thumbnail loading to avoid excessive disk I/O on harddrives. SSDs are so fast the extra threads don't help much anyway.

    m_threadPool.setMaxThreadCount(1);  //QThread::idealThreadCount()

    m_placeholder = QPixmap(128, 128);

    m_placeholder.fill(Qt::lightGray);

    QFileIconProvider iconProvider;

    m_folderIcon = iconProvider.icon(QFileIconProvider::Folder);

}

ImageModel::~ImageModel()

{

    m_cancelFlag = true;

    m_threadPool.waitForDone();

}

void ImageModel::setCacheMaxSize(int n)

{

    m_cacheMaxSize = std::max(0, n);

    while (m_cacheOrder.size() > m_cacheMaxSize)

        m_folderThumbnailCache.remove(m_cacheOrder.takeFirst());

}

void ImageModel::setDirectory(const QString &path)

{

    m_cancelFlag = true;

    m_threadPool.waitForDone();

    m_cancelFlag = false;

    // Save current folder's thumbnails to cache before discarding them

    if (!m_currentDir.isEmpty()) {

        ThumbnailMap map;

        for (const Item &item : m_items)

            if (item.loaded && !item.isFolder)

                map[item.path] = item.thumbnail;

        if (!map.isEmpty()) {

            if (!m_cacheOrder.contains(m_currentDir)) {

                m_cacheOrder.append(m_currentDir);

                if (m_cacheOrder.size() > m_cacheMaxSize)

                    m_folderThumbnailCache.remove(m_cacheOrder.takeFirst());

            }

            m_folderThumbnailCache[m_currentDir] = std::move(map);

        }

    }

    beginResetModel();

    m_items.clear();

    m_pendingRows.clear();

    m_currentDir = path;

    QDir dir(path);

    // Add subdirectories first

    dir.setFilter(QDir::AllDirs | QDir::NoDot);

    dir.setSorting(QDir::Name);

    const auto dirs = dir.entryInfoList();

    QPixmap folderPixmap = m_folderIcon.pixmap(128, 128);

    for (const QFileInfo &d : dirs)

    {

        QString name = d.fileName();  // preserves ".." for the parent entry

        m_items.append({d.absoluteFilePath(), name, folderPixmap, true, true});

    }

    // Then add image files

    QStringList filters;

    const auto formats = QImageReader::supportedImageFormats();

    for (const QByteArray &fmt : formats)

        filters << "*." + fmt;

    dir.setNameFilters(filters);

    dir.setFilter(QDir::Files);

    dir.setSorting(QDir::Name);

    const auto files = dir.entryInfoList();

    // Restore cached thumbnails for this folder if available

    const ThumbnailMap *cached = m_folderThumbnailCache.contains(path)

        ? &m_folderThumbnailCache[path]

        : nullptr;

    for (const QFileInfo &file : files)

    {

        QPixmap thumb = m_placeholder;

        bool loaded = false;

        if (cached) {

            auto it = cached->find(file.absoluteFilePath());

            if (it != cached->end()) {

                thumb = it.value();

                loaded = true;

            }

        }

        m_items.append({file.absoluteFilePath(), file.fileName(), thumb, loaded, false});

    }

    endResetModel();

}

void ImageModel::requestThumbnails(int firstRow, int lastRow)

{

    if (m_items.isEmpty())

        return;

    firstRow = std::max(0, firstRow);

    lastRow = std::min(lastRow, static_cast<int>(m_items.size()) - 1);

    for (int row = firstRow; row <= lastRow; ++row)

    {

        if (!m_items[row].loaded && !m_items[row].isFolder)

            queueRow(row);

    }

    // Optional: preload nearby rows

    int buffer = 20;

    for (int row = firstRow - buffer; row < firstRow; ++row)

        if (row >= 0 && !m_items[row].loaded && !m_items[row].isFolder)

            queueRow(row);

    for (int row = lastRow + 1; row <= lastRow + buffer; ++row)

        if (row < m_items.size() && !m_items[row].loaded && !m_items[row].isFolder)

            queueRow(row);

}

void ImageModel::queueRow(int row)

{

    if (m_pendingRows.contains(row))

        return;

    m_pendingRows.insert(row);

    auto *worker = new ThumbnailWorker(

        m_items[row].path,

        row,

        &m_cancelFlag);

    connect(worker, &ThumbnailWorker::finished,

            this, &ImageModel::thumbnailReady,

            Qt::QueuedConnection);

    m_threadPool.start(worker);

}

QString ImageModel::filePath(const QModelIndex &index) const

{

    if (!index.isValid())

        return {};

    return m_items[index.row()].path;

}

bool ImageModel::isFolder(const QModelIndex &index) const

{

    if (!index.isValid() || index.row() >= m_items.size())

        return false;

    return m_items[index.row()].isFolder;

}

QString ImageModel::currentDirectory() const

{

    return m_currentDir;

}

int ImageModel::rowCount(const QModelIndex &) const

{

    return m_items.size();

}

QVariant ImageModel::data(const QModelIndex &index, int role) const

{

    if (!index.isValid())

        return {};

    const Item &item = m_items[index.row()];

    if (role == Qt::DecorationRole)

        return item.thumbnail;

    if (role == Qt::DisplayRole)

        return item.displayName;

    return {};

}

void ImageModel::thumbnailReady(int row, const QImage &image)

{

    if (m_cancelFlag)

        return;

    if (row < 0 || row >= m_items.size())

        return;

    m_items[row].thumbnail = QPixmap::fromImage(image);

    m_items[row].loaded = true;

    m_pendingRows.remove(row);

    QModelIndex idx = index(row);

    emit dataChanged(idx, idx, {Qt::DecorationRole});

}