Jungfraujoch/viewer/image_viewer/JFJochFollowerImage.h

// SPDX-FileCopyrightText: 2026 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#pragma once

#include <memory>

#include <QGraphicsView>
#include <QImage>

#include "../../reader/JFJochReaderImage.h"

class JFJochImageItem;

// A second view of a frame that a JFJochImage has already rendered: the same pixels, with its own
// zoom and centre. Nothing is converted or coloured here and there is no second full-size buffer,
// so following the main view costs a pointer assignment per frame rather than a whole render.
//
// Zoomed in far enough it writes the per-pixel counts over the image. Those are read straight from
// the detector's int32 buffer - the same source the main view colours from - so no float copy of
// the image is needed either.
//
// It draws no overlays and has no ROI tools: those belong to the view that owns the data.
class JFJochFollowerImage : public QGraphicsView {
    Q_OBJECT

    static constexpr int kMaxLabels = 2000;

    JFJochImageItem *item_ = nullptr;
    std::shared_ptr<const QImage> frame_;
    QSize frame_size_;   // size the scene rect was set from
    std::shared_ptr<const JFJochReaderImage> values_;
    double zoom_ = 12.0;
    int label_font_px_ = 0;   // 0 = no per-pixel labels
    QPointF center_;
    bool center_set_ = false;

    void wheelEvent(QWheelEvent *event) override;
    void resizeEvent(QResizeEvent *event) override;
    void drawForeground(QPainter *painter, const QRectF &rect) override;
public:
    explicit JFJochFollowerImage(QWidget *parent = nullptr);

    void SetFrame(std::shared_ptr<const QImage> frame);
    void SetPixelValues(std::shared_ptr<const JFJochReaderImage> image);
    void CenterAt(QPointF scenePos);
    // Screen pixels per detector pixel, and the pixel size of the value labels (0 = none)
    void SetZoom(double zoom, int label_font_px);
signals:
    // The area of the image the view shows, in detector pixels
    void fieldChanged(QSizeF size);
};