blame: src/imageviewwidget.h

#pragma once

#include <QWidget>

#include <QImage>

#include <QPixmap>

#include <QString>

#include <QPoint>

#include <QMap>

#include <QStringList>

#include <QThread>

class ImageLoadWorker : public QThread

{

    Q_OBJECT

public:

    explicit ImageLoadWorker(const QString &path, QObject *parent = nullptr);

    void run() override;

signals:

    void imageLoaded(const QString &path, const QPixmap &pixmap);

private:

    QString m_path;

};

class ImageViewWidget : public QWidget

{

    Q_OBJECT

public:

    // Number of images to read ahead and keep behind the current image

    static constexpr int CacheReadAhead = 2;

    static constexpr int CacheKeepBehind = 2;

    enum ZoomMode { FitToScreen, OriginalSize, CustomZoom };

    explicit ImageViewWidget(QWidget *parent = nullptr);

    void setImage(const QString &path);

    void setBackgroundColor(const QString &color);

    void zoomIn();

    void zoomOut();

    void zoomOriginal();

    void zoomFitToScreen();

    void prefetchImage(const QString &path);

    void setNeighborPaths(const QStringList &paths);

    void clearCache();

signals:

    void closeRequested();

    void nextRequested();

    void previousRequested();

protected:

    void paintEvent(QPaintEvent *event) override;

    void keyPressEvent(QKeyEvent *event) override;

    void mousePressEvent(QMouseEvent *event) override;

    void mouseMoveEvent(QMouseEvent *event) override;

    void mouseReleaseEvent(QMouseEvent *event) override;

    void mouseDoubleClickEvent(QMouseEvent *event) override;

private:

    void clampOffset(int imgW, int imgH);

    QPixmap loadImageFromDisk(const QString &path);

    void onImageLoaded(const QString &path, const QPixmap &pixmap);

    QPixmap m_pixmap;

    ZoomMode m_zoomMode = FitToScreen;

    double m_zoomFactor = 1.0;

    QString m_backgroundColor = "black";

    QString m_currentPath;

    // Image cache: path -> pixmap

    QMap<QString, QPixmap> m_cache;

    QStringList m_neighborPaths;       // ordered list of paths around current image

    QSet<QString> m_pendingLoads;      // paths currently being loaded in background

    // Panning state

    QPoint m_offset;        // current pan offset (pixels)

    bool   m_dragging = false;

    QPoint m_dragStart;

    QPoint m_offsetAtDragStart;

};