Jungfraujoch/viewer/image_viewer/JFJochDiffractionImage.cpp

// SPDX-FileCopyrightText: 2025 Filip Leonarski, Paul Scherrer Institute <filip.leonarski@psi.ch>
// SPDX-License-Identifier: GPL-3.0-only

#include <set>

#include "JFJochDiffractionImage.h"
#include "../../common/DiffractionGeometry.h"
#include "../../common/JFJochMath.h"
#include "../../common/ROIAzimuthal.h"
#include "../../image_analysis/bragg_integration/SystematicAbsence.h"
#include "../widgets/ROIColorPalette.h"

#include <QPainterPath>
#include <QBrush>
#include <QKeyEvent>
#include <QGraphicsPixmapItem>
#include <QGraphicsSimpleTextItem>
#include <QGraphicsScene>
#include <QWheelEvent>
#include <QScrollBar>
#include <QMenu>
#include <cmath>
#include <limits>
#include <QMouseEvent>

#include "JFJochSimpleImage.h"

// Constructor
static bool InPhiSector(float phi, float phi_min, float phi_max) {
    if (phi_min <= phi_max)
        return phi >= phi_min && phi <= phi_max;
    return phi >= phi_min || phi <= phi_max;
}

JFJochDiffractionImage::JFJochDiffractionImage(QWidget *parent) : JFJochImage(parent) {
    setFocusPolicy(Qt::StrongFocus);   // so the Delete key reaches the view
}

JFJochImage::ResizeHandle JFJochDiffractionImage::hitTestBoxHandle(const QRectF &r, const QPointF &p, qreal tol) const {
    auto on = [&](qreal a, qreal b) { return std::abs(a - b) <= tol; };
    const bool L = on(p.x(), r.left()),  R = on(p.x(), r.right());
    const bool T = on(p.y(), r.top()),   B = on(p.y(), r.bottom());
    const bool inX = p.x() >= r.left() - tol && p.x() <= r.right() + tol;
    const bool inY = p.y() >= r.top() - tol && p.y() <= r.bottom() + tol;
    if (L && T) return ResizeHandle::TopLeft;
    if (R && T) return ResizeHandle::TopRight;
    if (L && B) return ResizeHandle::BottomLeft;
    if (R && B) return ResizeHandle::BottomRight;
    if (L && inY) return ResizeHandle::Left;
    if (R && inY) return ResizeHandle::Right;
    if (T && inX) return ResizeHandle::Top;
    if (B && inX) return ResizeHandle::Bottom;
    if (r.contains(p)) return ResizeHandle::Inside;
    return ResizeHandle::None;
}

void JFJochDiffractionImage::azimuthalHandles(const ROIAzimuthal &az, const DiffractionGeometry &geom,
        QPointF &inner, QPointF &outer, QPointF &phimin, QPointF &phimax) const {
    const float d2r = static_cast<float>(PI) / 180.0f;
    const float phi0 = az.GetPhiMin_deg();
    const float phi1 = az.GetPhiMax_deg();
    const float mid_phi = az.HasPhi()
        ? (phi1 >= phi0 ? (phi0 + phi1) / 2.0f : std::fmod((phi0 + phi1 + 360.0f) / 2.0f, 360.0f))
        : 0.0f;
    const float r_inner = geom.ResToPxl(az.GetDMax_A());
    const float r_outer = geom.ResToPxl(az.GetDMin_A());
    const float d_mid = geom.PxlToRes((r_inner + r_outer) / 2.0f);
    auto pt = [&](float d, float phi_deg) -> QPointF {
        try {
            auto [x, y] = geom.ResPhiToPxl(d, phi_deg * d2r);
            return QPointF(x, y);
        } catch (...) {
            return QPointF(-1e9, -1e9);   // off-image: never matches a handle hit-test
        }
    };
    inner  = pt(az.GetDMax_A(), mid_phi);
    outer  = pt(az.GetDMin_A(), mid_phi);
    phimin = pt(d_mid, phi0);
    phimax = pt(d_mid, phi1);
}

void JFJochDiffractionImage::mouseHover(const QPointF &coord, Qt::KeyboardModifiers) {

    if (image && (coord.x() >= 0)
        && (coord.x() < image->Dataset().experiment.GetXPixelsNum())
        && (coord.y() >= 0)
        && (coord.y() < image->Dataset().experiment.GetYPixelsNum())) {
        float res = image->Dataset().experiment.GetDiffractionGeometry().PxlToRes(coord.x(), coord.y());

        int32_t intensity = image->Image()[std::floor(coord.x()) +
                                           std::floor(coord.y()) * image->Dataset().experiment.GetXPixelsNum()];

        QString intensity_str = QString("I=%1").arg(intensity, 9);

        if (intensity == SATURATED_PXL_VALUE)
            intensity_str = "I=Saturated";
        else if (intensity == GAP_PXL_VALUE)
            intensity_str = "    Gap    ";
        else if (intensity == ERROR_PXL_VALUE)
            intensity_str = "  Bad pxl  ";
        else if (intensity == BEAM_STOP_PXL_VALUE)
            intensity_str = " Beam stop ";

        emit writeStatusBar(QString("x=%1 y=%2 %3 d=%4 Å")
            .arg(coord.x(), 0, 'f', 1)
            .arg(coord.y(), 0, 'f', 1)
            .arg(intensity_str)
            .arg(res, 0, 'f', 2));

        // Update hovered resolution text without rebuilding the whole overlay
        hover_resolution = res;
        DrawResolutionText();
        } else {
            emit writeStatusBar("");

            // Clear hover resolution text when outside image
            if (std::isfinite(hover_resolution)) {
                hover_resolution = NAN;
                DrawResolutionText();
            }
        }
}


void JFJochDiffractionImage::LoadImageInternal() {
    if (!image)
        return;

    W = image->Dataset().experiment.GetXPixelsNum();
    H = image->Dataset().experiment.GetYPixelsNum();

}

void JFJochDiffractionImage::ColorRow(size_t y, const PixelColorMap &map, QRgb *out) const {
    const int32_t *row = &image->Image()[y * W];

    for (size_t x = 0; x < W; ++x) {
        const int32_t v = row[x];

        // The markers occupy the extremes of the int32 range, so one range test separates them
        // from every real pixel value (MIN_REAL_PXL_VALUE moves when a marker is added)
        rgb c;
        if (v >= MIN_REAL_PXL_VALUE && v < SATURATED_PXL_VALUE)
            c = map.Apply(static_cast<float>(v));
        else if (v == GAP_PXL_VALUE)
            c = map.gap;
        else if (v == BEAM_STOP_PXL_VALUE)
            c = map.beam_stop;
        else
            c = (v == ERROR_PXL_VALUE) ? map.bad : map.saturated;

        out[x] = qRgb(c.r, c.g, c.b);
    }
}


void JFJochDiffractionImage::DrawSpots() {
    // Compute current visible area in scene coordinates
    const QRectF visibleRect = mapToScene(viewport()->geometry()).boundingRect();

    QPen casing_pen(Qt::black, 3 + MARKER_CASING_EXTRA_WIDTH);
    casing_pen.setCosmetic(true);

    for (const auto &s: image->ImageData().spots) {
        // Skip reflections outside the viewport
        if (!visibleRect.contains(QPointF{s.x, s.y}))
            continue;

        if (hide_unindexed_spots && !s.indexed)
            continue;
        if (hide_ice_ring_spots && s.ice_ring)
            continue;

        const qreal desired_half_px = 8.0;
        const qreal spot_size = desired_half_px / std::sqrt(std::max(0.0001, scale_factor));

        QColor pen_color = spot_color;
        if (s.indexed)
            pen_color = (s.lattice >= 1) ? second_lattice_color : feature_color;
        else if (highlight_ice_rings && s.ice_ring)
            pen_color = ice_ring_color;

        QPen pen(pen_color, 3);
        pen.setCosmetic(true);

        const QRectF box(s.x - spot_size + 0.5, s.y - spot_size + 0.5, 2 * spot_size, 2 * spot_size);
        addOverlayItem(scene()->addRect(box, casing_pen));   // added first, so it stays underneath
        addOverlayItem(scene()->addRect(box, pen));
    }
}

void JFJochDiffractionImage::DrawPredictions() {
    QFont font("Arial", 2); // Font for pixel value text
    font.setPixelSize(2); // This will render very small text (1-pixel high).

    const qreal desired_half_px = 8.0;
    const qreal spot_size = desired_half_px / std::sqrt(std::max(0.0001, scale_factor));

    QColor pen_color = prediction_color;

    QPen pen(pen_color, 3);
    pen.setCosmetic(true);

    // Compute current visible area in scene coordinates
    const QRectF visibleRect = mapToScene(viewport()->geometry()).boundingRect();

    // In space-group search mode the centering-absent reflections are integrated (to confirm the
    // centering), but they are not real predictions - keep them out of the overlay.
    const char centering = image->ImageData().lattice_type.has_value()
                               ? image->ImageData().lattice_type->centering : 'P';

    for (const auto &s: image->ImageData().reflections) {
        if (systematic_absence(s.h, s.k, s.l, centering))
            continue;
        // Skip reflections outside the viewport
        if (!visibleRect.contains(QPointF{s.predicted_x, s.predicted_y}))
            continue;

        auto *ellipse = scene()->addEllipse(s.predicted_x - spot_size + 0.5f,
                                        s.predicted_y - spot_size + 0.5f,
                                        2.0f * spot_size,
                                        2.0f * spot_size,
                                        pen);
        addOverlayItem(ellipse);

        // When zoomed in enough, draw "h k l" above the box
        if (scale_factor >= 10.0) {
            // Format label
            QString label = QString("%1, %2, %3").arg(s.h).arg(s.k).arg(s.l);

            // Position slightly above the top side of the box
            const qreal text_x = s.predicted_x - 5.5f;
            const qreal text_y = s.predicted_y - 10.0f;

            // Use QGraphicsSimpleTextItem for much better performance
            auto *textItem = new QGraphicsSimpleTextItem(label);
            textItem->setFont(font);
            textItem->setBrush(pen_color);
            textItem->setPos(text_x, text_y);
            scene()->addItem(textItem);
            addOverlayItem(textItem);
        }
    }
}

void JFJochDiffractionImage::DrawResolutionRings() {
    if (ring_mode == RingMode::None)
        return;

    // Get the visible area in the scene coordinates (viewport()->rect(), not geometry():
    // mapToScene takes viewport coordinates, and geometry() is offset by the viewport's
    // position in its parent).
    QRectF visibleRect = mapToScene(viewport()->rect()).boundingRect();

    int startX = std::max(0, static_cast<int>(std::floor(visibleRect.left())));
    int endX = std::min(static_cast<int>(image->Dataset().experiment.GetXPixelsNum()),
                        static_cast<int>(std::ceil(visibleRect.right())));
    int startY = std::max(0, static_cast<int>(std::floor(visibleRect.top())));
    int endY = std::min(static_cast<int>(image->Dataset().experiment.GetYPixelsNum()),
                        static_cast<int>(std::ceil(visibleRect.bottom())));

    auto geom = image->Dataset().experiment.GetDiffractionGeometry();

    QColor ring_color = feature_color;
    if (ring_mode == RingMode::IceRings) {
        ring_color = ice_ring_color;
        res_ring = QVector<float>{ICE_RING_RES_A.begin(), ICE_RING_RES_A.end()};
    } else if (ring_mode == RingMode::Auto) {
        float radius_x_0 = geom.GetBeamX_pxl() - startX;
        float radius_x_1 = endX - geom.GetBeamX_pxl();

        float radius_x = std::max(radius_x_0, radius_x_1);

        float radius_y_0 = geom.GetBeamY_pxl() - startY;
        float radius_y_1 = endY - geom.GetBeamY_pxl();

        float radius_y = std::max(radius_y_0, radius_y_1);

        float radius = std::min(radius_x, radius_y);
        if (radius_x <= 0)
            radius = radius_y;
        if (radius_y <= 0)
            radius = radius_x;

        if (radius > 0)
            res_ring = {
                geom.PxlToRes(radius / 2.0f),
                geom.PxlToRes(radius / 1.02f)
            };
        else
            res_ring = {};
    } else if (ring_mode == RingMode::Estimation) {
        if (image
            && image->ImageData().resolution_estimate
            && std::isfinite(image->ImageData().resolution_estimate.value())
            && image->ImageData().resolution_estimate.value() > 0.0)
            res_ring = {*image->ImageData().resolution_estimate};
        else
            res_ring = {};
    }

    if (res_ring.empty())
        return;

    QPen pen(ring_color, 5);
    pen.setCosmetic(true);

    QVector<qreal> dashPattern = {10, 15};
    pen.setDashPattern(dashPattern);

    int label_stagger = 0;

    // Tracing the contours costs 361 geometry evaluations per ring, and they only move when the
    // ring list or the geometry changes - not when the view is panned or zoomed, which is when
    // most overlay rebuilds happen. Keep them until the ring list changes; loadImage() clears
    // the cache so a new geometry re-traces.
    if (ring_cache_key_ != res_ring) {
        ring_cache_key_ = res_ring;
        ring_cache_.clear();

        float res1 = geom.PxlToRes(0,0);
        float res2 = geom.PxlToRes(image->Dataset().experiment.GetXPixelsNum(),0);
        float res3 = geom.PxlToRes(image->Dataset().experiment.GetXPixelsNum(),image->Dataset().experiment.GetYPixelsNum());
        float res4 = geom.PxlToRes(0,image->Dataset().experiment.GetYPixelsNum());

        float min_res = std::min({res1, res2, res3, res4});

        for (const auto &d: res_ring) {
            if (d < min_res)
                continue;

            // Trace the constant-d contour through the geometry - a circle on an untilted detector,
            // a conic on a tilted one - the same way an azimuthal ROI arc is drawn, instead of
            // approximating it with an axis-aligned bounding-box ellipse. ResPhiToPxl throws when d is
            // too high for the wavelength, and returns NaN where the contour leaves the detector plane.
            QPainterPath path;
            bool started = false;
            bool valid = true;
            constexpr int steps = 360;
            for (int i = 0; i <= steps; i++) {
                const float phi = 2.0f * static_cast<float>(PI) * static_cast<float>(i) / static_cast<float>(steps);
                try {
                    auto [x, y] = geom.ResPhiToPxl(d, phi);
                    if (!std::isfinite(x) || !std::isfinite(y)) {
                        started = false;   // break the subpath where the ring leaves the detector
                        continue;
                    }
                    if (!started) { path.moveTo(x, y); started = true; }
                    else path.lineTo(x, y);
                } catch (...) {
                    valid = false;
                    break;
                }
            }
            if (!valid || path.isEmpty())
                continue;

            ring_cache_.push_back({d, path});
        }
    }

    for (const auto &[d, path]: ring_cache_) {
        addOverlayItem(scene()->addPath(path, pen));

        // The "d Å" label follows the application font (View -> Font size) and is white cased in
        // black, like the spot markers, so it reads on any colour map and on the ring's own
        // colour. The item lives in scene coordinates, so dividing by the view scale keeps it a
        // constant size on screen - 1.2x the application font at every zoom. It is centred on the
        // first sampled azimuth (staggered per ring) where the whole text fits in the viewport;
        // failing that, on the visible ring point closest to the viewport centre, clamped inside -
        // never half a label off the edge.
        QFont font = this->font();
        const qreal f = std::clamp(scale_factor, 0.05, 500.0);
        font.setPointSizeF(font.pointSizeF() * 1.2 / f);

        auto *textItem = new QGraphicsSimpleTextItem(
            QString("%1 Å").arg(QString::number(d, 'f', 2)));
        textItem->setFont(font);
        textItem->setBrush(Qt::white);
        textItem->setPen(QPen(Qt::black, font.pointSizeF() / 8.0));
        const QSizeF sz = textItem->boundingRect().size();

        QRectF inner = visibleRect.adjusted(sz.height() * 0.3, sz.height() * 0.3,
                                            -sz.height() * 0.3, -sz.height() * 0.3);
        if (!inner.isValid())
            inner = visibleRect;

        bool have_label = false;
        bool fits = false;
        QPointF label_center;
        double best_dist = std::numeric_limits<double>::max();
        // Walk the ring's own traced points (dense enough that a narrow visible arc is never
        // missed), starting at a per-ring stagger so neighbouring rings label different azimuths.
        const int n = path.elementCount();
        for (int k = 0; k < n; k++) {
            const auto e = path.elementAt((k + label_stagger) % n);
            const QPointF p(e.x, e.y);
            if (!visibleRect.contains(p))
                continue;
            const QRectF r(p - QPointF(sz.width() / 2, sz.height() / 2), sz);
            if (inner.contains(r)) {
                label_center = p;
                have_label = true;
                fits = true;
                break;
            }
            const double dist = QLineF(p, visibleRect.center()).length();
            if (dist < best_dist) {
                best_dist = dist;
                label_center = p;
                have_label = true;
            }
        }

        if (have_label) {
            QRectF r(label_center - QPointF(sz.width() / 2, sz.height() / 2), sz);
            if (!fits) {
                if (r.left() < inner.left()) r.moveLeft(inner.left());
                if (r.right() > inner.right()) r.moveRight(inner.right());
                if (r.top() < inner.top()) r.moveTop(inner.top());
                if (r.bottom() > inner.bottom()) r.moveBottom(inner.bottom());
            }
            textItem->setPos(r.topLeft());
            scene()->addItem(textItem);
            addOverlayItem(textItem);
        } else {
            delete textItem;
        }
        label_stagger += 29;
    }
}

void JFJochDiffractionImage::DrawBeamCenter() {
    auto geom = image->Dataset().experiment.GetDiffractionGeometry();

    auto [beam_x, beam_y] = geom.GetDirectBeam_pxl();
    // + 0.5 as everywhere else in the overlay: our coordinates are pixel-centred, the scene's are
    // pixel-cornered (pixel i covers [i, i+1)), so the cross would otherwise sit half a pixel off the
    // spots and the image.
    DrawCross(beam_x + 0.5f, beam_y + 0.5f, 25, 5, 2);
}

void JFJochDiffractionImage::DrawTopPixels() {
    int i = 0;
    for (const auto& p : image->GetTopPixels()) {
        if (i >= show_highest_pixels)
            break;

        const int32_t idx = p.second;
        DrawCross(idx % image->Dataset().experiment.GetXPixelsNum() + 0.5,
                  idx / image->Dataset().experiment.GetXPixelsNum() + 0.5, 15, 3);
        i++;
    }
}


void JFJochDiffractionImage::addCustomOverlay() {
    DrawResolutionRings();
    DrawROIs();
    DrawTopPixels();

    DrawBeamCenter();
    if (show_spots)
        DrawSpots();
    if (show_predictions)
        DrawPredictions();
    if (show_saturation)
        DrawSaturation();
}

void JFJochDiffractionImage::DrawROIs() {
    if (!image)
        return;

    const auto &rois = image->Dataset().experiment.ROI().GetROIDefinition();
    auto geom = image->Dataset().experiment.GetDiffractionGeometry();

    // Distinct colours per ROI (shared with the ROI-list swatches via ROIAnnotationColor); loaded
    // ROIs use solid lines (the interactively drawn scratch ROI keeps its dashed feature_color).
    // TODO: align this palette with the ROI colours in the bottom-panel plots.
    int color_index = 0;

    auto fill_brush = [&](const QColor &c) {
        return show_roi_fill ? QBrush(QColor(c.red(), c.green(), c.blue(), 60)) : QBrush(Qt::NoBrush);
    };
    auto draw_handle = [&](const QPointF &p, const QColor &c) {
        const qreal s = 4.0 / std::sqrt(std::max(1e-4, scale_factor));
        addOverlayItem(scene()->addRect(QRectF(p.x() - s, p.y() - s, 2 * s, 2 * s), QPen(c, 1), QBrush(c)));
    };

    for (const auto &b : rois.boxes) {
        QColor c = ROIAnnotationColor(color_index++);
        const bool selected = (QString::fromStdString(b.GetName()) == selected_roi_);
        const bool editing = b.GetName() == edit_name_.toStdString()
                             && (roi_edit_ == RoiEdit::MoveBox || roi_edit_ == RoiEdit::ResizeBox);
        QPen pen(c, selected ? 3 : 2);
        pen.setCosmetic(true);
        if (selected) pen.setStyle(Qt::DashLine);   // highlight the editable ROI
        const QRectF rect = editing ? edit_box_
                                    : QRectF(b.GetXMin(), b.GetYMin(), b.GetWidth(), b.GetHeight());
        addOverlayItem(scene()->addRect(rect, pen, fill_brush(c)));
        AddROILabel(b.GetName(), c, rect.left(), rect.top());
        if (selected) {
            draw_handle(rect.topLeft(), c);    draw_handle(rect.topRight(), c);
            draw_handle(rect.bottomLeft(), c); draw_handle(rect.bottomRight(), c);
            draw_handle({rect.center().x(), rect.top()}, c);
            draw_handle({rect.center().x(), rect.bottom()}, c);
            draw_handle({rect.left(), rect.center().y()}, c);
            draw_handle({rect.right(), rect.center().y()}, c);
        }
    }

    for (const auto &c_roi : rois.circles) {
        QColor c = ROIAnnotationColor(color_index++);
        const bool selected = (QString::fromStdString(c_roi.GetName()) == selected_roi_);
        const bool editing = c_roi.GetName() == edit_name_.toStdString()
                             && (roi_edit_ == RoiEdit::MoveCircle || roi_edit_ == RoiEdit::ResizeCircle);
        QPen pen(c, selected ? 3 : 2);
        pen.setCosmetic(true);
        if (selected) pen.setStyle(Qt::DashLine);
        const QPointF center = editing ? edit_center_ : QPointF(c_roi.GetX(), c_roi.GetY());
        const double r = editing ? edit_radius_ : c_roi.GetRadius_pxl();
        addOverlayItem(scene()->addEllipse(center.x() - r, center.y() - r, 2 * r, 2 * r, pen, fill_brush(c)));
        AddROILabel(c_roi.GetName(), c, center.x(), center.y());
        if (selected) {
            draw_handle({center.x() + r, center.y()}, c);
            draw_handle({center.x() - r, center.y()}, c);
            draw_handle({center.x(), center.y() + r}, c);
            draw_handle({center.x(), center.y() - r}, c);
        }
    }

    for (const auto &az_committed : rois.azimuthal) {
        QColor c = ROIAnnotationColor(color_index++);
        const bool selected = (QString::fromStdString(az_committed.GetName()) == selected_roi_);
        const bool editing = az_committed.GetName() == edit_name_.toStdString()
                             && (roi_edit_ == RoiEdit::AzimInner || roi_edit_ == RoiEdit::AzimOuter
                                 || roi_edit_ == RoiEdit::RotatePhiMin || roi_edit_ == RoiEdit::RotatePhiMax);
        const ROIAzimuthal az = editing
            ? (edit_has_phi_ ? ROIAzimuthal(az_committed.GetName(), edit_d_min_, edit_d_max_, edit_phi_min_, edit_phi_max_)
                             : ROIAzimuthal(az_committed.GetName(), edit_d_min_, edit_d_max_))
            : az_committed;
        DrawAzimuthalROI(az, c, geom);
        if (selected) {
            QPointF inner, outer, pmin, pmax;
            azimuthalHandles(az, geom, inner, outer, pmin, pmax);
            draw_handle(inner, c);
            draw_handle(outer, c);
            if (az.HasPhi()) {
                draw_handle(pmin, c);
                draw_handle(pmax, c);
            }
        }
    }
}

void JFJochDiffractionImage::AddROILabel(const std::string &name, const QColor &color, float px, float py) {
    if (!show_roi_labels)
        return;

    // Just the name; per-ROI statistics are shown in the side-panel ROI list.
    auto *text = scene()->addText(QString::fromStdString(name));
    text->setDefaultTextColor(color);
    text->setFlag(QGraphicsItem::ItemIgnoresTransformations);   // constant on-screen size
    text->setPos(px, py);
    addOverlayItem(text);
}

void JFJochDiffractionImage::DrawAzimuthalROI(const ROIAzimuthal &az, const QColor &color,
                                              const DiffractionGeometry &geom) {
    const bool selected = (QString::fromStdString(az.GetName()) == selected_roi_);
    QPen pen(color, selected ? 3 : 2); pen.setCosmetic(true);
    if (selected) pen.setStyle(Qt::DashLine);
    QBrush brush = show_roi_fill ? QBrush(QColor(color.red(), color.green(), color.blue(), 60))
                                 : QBrush(Qt::NoBrush);

    const float d_inner = az.GetDMax_A();   // larger d -> smaller radius
    const float d_outer = az.GetDMin_A();
    auto deg2rad = [](float d) { return d * static_cast<float>(PI) / 180.0f; };

    // Sample the boundary through the geometry so the wedge matches the ROI footprint.
    // ResPhiToPxl throws when the resolution is too high for the wavelength; skip such ROIs.
    // move_to_start == true begins a new subpath (no connecting line); false continues
    // the current one (used for the radial edge between a sector's outer and inner arc).
    auto add_arc = [&](QPainterPath &path, float d, float phi_a, float phi_b, int steps, bool move_to_start) -> bool {
        for (int i = 0; i <= steps; i++) {
            float phi = phi_a + (phi_b - phi_a) * static_cast<float>(i) / static_cast<float>(steps);
            try {
                auto [px, py] = geom.ResPhiToPxl(d, phi);
                if (move_to_start && i == 0)
                    path.moveTo(px, py);
                else
                    path.lineTo(px, py);
            } catch (...) { return false; }
        }
        return true;
    };

    QPainterPath path;
    if (az.HasPhi()) {
        float phi0 = deg2rad(az.GetPhiMin_deg());
        float phi1 = deg2rad(az.GetPhiMax_deg());
        if (phi1 < phi0) phi1 += 2.0f * static_cast<float>(PI);   // unwrap the sector
        int steps = std::max(8, static_cast<int>((phi1 - phi0) * 180.0f / static_cast<float>(PI) / 2.0f));
        if (!add_arc(path, d_outer, phi0, phi1, steps, true)) return;    // outer arc
        if (!add_arc(path, d_inner, phi1, phi0, steps, false)) return;   // inner arc; radial edges close it
        path.closeSubpath();
    } else {
        path.setFillRule(Qt::OddEvenFill);                        // annulus: two concentric rings
        const float two_pi = 2.0f * static_cast<float>(PI);
        if (!add_arc(path, d_outer, 0, two_pi, 180, true)) return;
        path.closeSubpath();
        if (!add_arc(path, d_inner, 0, two_pi, 180, true)) return;
        path.closeSubpath();
    }

    addOverlayItem(scene()->addPath(path, pen, brush));

    if (show_roi_labels) {
        try {
            auto [px, py] = geom.ResPhiToPxl(d_outer, az.HasPhi() ? deg2rad(az.GetPhiMin_deg()) : 0.0f);
            AddROILabel(az.GetName(), color, px, py);
        } catch (...) {}
    }
}

void JFJochDiffractionImage::showROILabels(bool input) {
    show_roi_labels = input;
    updateOverlay();
}

void JFJochDiffractionImage::showROIFill(bool input) {
    show_roi_fill = input;
    updateOverlay();
}

void JFJochDiffractionImage::setSelectedROI(QString name) {
    selected_roi_ = name;
    updateOverlay();
}

bool JFJochDiffractionImage::roiEditPress(const QPointF &scenePos) {
    if (!image)
        return false;

    const auto &rois = image->Dataset().experiment.ROI().GetROIDefinition();
    auto geom = image->Dataset().experiment.GetDiffractionGeometry();
    const qreal tol = 6.0 / std::sqrt(std::max(1e-4, scale_factor));

    auto start = [&](const std::string &name) {
        edit_name_ = QString::fromStdString(name);
        selected_roi_ = edit_name_;
        move_last_ = scenePos;
        emit roiSelected(edit_name_);
        setCursor(Qt::ClosedHandCursor);
    };

    // Box: corners/edges resize, interior moves.
    for (const auto &b : rois.boxes) {
        const QRectF r(QPointF(b.GetXMin(), b.GetYMin()), QPointF(b.GetXMax(), b.GetYMax()));
        const ResizeHandle h = hitTestBoxHandle(r, scenePos, tol);
        if (h == ResizeHandle::None)
            continue;
        start(b.GetName());
        edit_box_ = r;
        if (h == ResizeHandle::Inside) {
            roi_edit_ = RoiEdit::MoveBox;
        } else {
            roi_edit_ = RoiEdit::ResizeBox;
            box_handle_ = h;
        }
        return true;
    }

    // Circle: perimeter resizes, interior moves.
    for (const auto &c : rois.circles) {
        const QPointF center(c.GetX(), c.GetY());
        const double dist = QLineF(center, scenePos).length();
        if (dist > c.GetRadius_pxl() + tol)
            continue;
        start(c.GetName());
        edit_center_ = center;
        edit_radius_ = c.GetRadius_pxl();
        roi_edit_ = (std::abs(dist - c.GetRadius_pxl()) <= tol) ? RoiEdit::ResizeCircle : RoiEdit::MoveCircle;
        return true;
    }

    // Azimuthal: grab one of the discrete handles to resize Q/d (inner/outer arc) or
    // rotate a phi edge. Larger tolerance than the thin arcs would give.
    const qreal tol_h = 9.0 / std::sqrt(std::max(1e-4, scale_factor));
    for (const auto &az : rois.azimuthal) {
        QPointF inner, outer, pmin, pmax;
        azimuthalHandles(az, geom, inner, outer, pmin, pmax);
        auto grab = [&](const QPointF &h) { return QLineF(h, scenePos).length() <= tol_h; };

        RoiEdit mode = RoiEdit::None;
        if (grab(inner))                       mode = RoiEdit::AzimInner;
        else if (grab(outer))                  mode = RoiEdit::AzimOuter;
        else if (az.HasPhi() && grab(pmin))    mode = RoiEdit::RotatePhiMin;
        else if (az.HasPhi() && grab(pmax))    mode = RoiEdit::RotatePhiMax;
        if (mode == RoiEdit::None)
            continue;

        start(az.GetName());
        edit_d_min_ = az.GetDMin_A();
        edit_d_max_ = az.GetDMax_A();
        edit_has_phi_ = az.HasPhi();
        edit_phi_min_ = az.GetPhiMin_deg();
        edit_phi_max_ = az.GetPhiMax_deg();
        roi_edit_ = mode;
        return true;
    }

    // Inside an azimuthal ROI but not on a handle: select it and let the base pan
    // (these ROIs are large and should not capture the panning gesture).
    for (const auto &az : rois.azimuthal) {
        const auto [bx, by] = geom.GetDirectBeam_pxl();
        const double cursor_r = QLineF(QPointF(bx, by), scenePos).length();
        const float phi = geom.Phi_rad(scenePos.x(), scenePos.y()) * 180.0f / static_cast<float>(PI);
        if (cursor_r < geom.ResToPxl(az.GetDMax_A()) || cursor_r > geom.ResToPxl(az.GetDMin_A()))
            continue;
        if (az.HasPhi() && !InPhiSector(phi, az.GetPhiMin_deg(), az.GetPhiMax_deg()))
            continue;
        selected_roi_ = QString::fromStdString(az.GetName());
        emit roiSelected(selected_roi_);
        break;
    }
    return false;
}

void JFJochDiffractionImage::roiEditMove(const QPointF &scenePos) {
    if (!image)
        return;
    auto geom = image->Dataset().experiment.GetDiffractionGeometry();
    const auto [bx, by] = geom.GetDirectBeam_pxl();
    const float cursor_r = QLineF(QPointF(bx, by), scenePos).length();

    switch (roi_edit_) {
        case RoiEdit::MoveBox:
            edit_box_.translate(scenePos - move_last_);
            move_last_ = scenePos;
            break;
        case RoiEdit::ResizeBox: {
            QRectF r = edit_box_;
            switch (box_handle_) {
                case ResizeHandle::Left:        r.setLeft(scenePos.x()); break;
                case ResizeHandle::Right:       r.setRight(scenePos.x()); break;
                case ResizeHandle::Top:         r.setTop(scenePos.y()); break;
                case ResizeHandle::Bottom:      r.setBottom(scenePos.y()); break;
                case ResizeHandle::TopLeft:     r.setTopLeft(scenePos); break;
                case ResizeHandle::TopRight:    r.setTopRight(scenePos); break;
                case ResizeHandle::BottomLeft:  r.setBottomLeft(scenePos); break;
                case ResizeHandle::BottomRight: r.setBottomRight(scenePos); break;
                default: break;
            }
            edit_box_ = r.normalized();
            break;
        }
        case RoiEdit::MoveCircle:
            edit_center_ += (scenePos - move_last_);
            move_last_ = scenePos;
            break;
        case RoiEdit::ResizeCircle:
            edit_radius_ = std::max(1.0, QLineF(edit_center_, scenePos).length());
            break;
        case RoiEdit::AzimInner:
            edit_d_max_ = geom.PxlToRes(cursor_r);
            break;
        case RoiEdit::AzimOuter:
            edit_d_min_ = geom.PxlToRes(cursor_r);
            break;
        case RoiEdit::RotatePhiMin:
            edit_phi_min_ = geom.Phi_rad(scenePos.x(), scenePos.y()) * 180.0f / static_cast<float>(PI);
            break;
        case RoiEdit::RotatePhiMax:
            edit_phi_max_ = geom.Phi_rad(scenePos.x(), scenePos.y()) * 180.0f / static_cast<float>(PI);
            break;
        default:
            return;   // None: select only, nothing to drag
    }
    updateOverlay();

    // Live recompute, but keep at most one in flight (cleared in loadImage) so the
    // worker is not flooded with edits faster than it can recompute them.
    if (!live_pending_) {
        live_pending_ = true;
        emit roiGeometryEdited(BuildEditedROIDefinition());
    }
}

void JFJochDiffractionImage::roiEditRelease() {
    if (roi_edit_ == RoiEdit::None)
        return;
    const ROIDefinition rois = BuildEditedROIDefinition();
    roi_edit_ = RoiEdit::None;
    setCursor(Qt::ArrowCursor);
    emit roiGeometryEdited(rois);   // final, exact geometry
}

ROIDefinition JFJochDiffractionImage::BuildEditedROIDefinition() const {
    ROIDefinition rois;
    if (image)
        rois = image->Dataset().experiment.ROI().GetROIDefinition();
    const std::string sel = edit_name_.toStdString();
    switch (roi_edit_) {
        case RoiEdit::MoveBox:
        case RoiEdit::ResizeBox:
            for (auto &b : rois.boxes)
                if (b.GetName() == sel) {
                    b = ROIBox(sel, std::lround(edit_box_.left()), std::lround(edit_box_.right()),
                                    std::lround(edit_box_.top()), std::lround(edit_box_.bottom()));
                    break;
                }
            break;
        case RoiEdit::MoveCircle:
        case RoiEdit::ResizeCircle:
            for (auto &c : rois.circles)
                if (c.GetName() == sel) {
                    c = ROICircle(sel, edit_center_.x(), edit_center_.y(), edit_radius_);
                    break;
                }
            break;
        case RoiEdit::AzimInner:
        case RoiEdit::AzimOuter:
        case RoiEdit::RotatePhiMin:
        case RoiEdit::RotatePhiMax:
            for (auto &a : rois.azimuthal)
                if (a.GetName() == sel) {
                    a = edit_has_phi_
                          ? ROIAzimuthal(sel, edit_d_min_, edit_d_max_, edit_phi_min_, edit_phi_max_)
                          : ROIAzimuthal(sel, edit_d_min_, edit_d_max_);
                    break;
                }
            break;
        default:
            break;
    }
    return rois;
}

void JFJochDiffractionImage::roiScratchDrawn() {
    // The base just drew a scratch box/circle (roiBox/roi_type, in pixel coords);
    // turn it into a new persistent ROI in the list.
    if (!image || roiBox.isNull() || roiBox.width() <= 0 || roiBox.height() <= 0)
        return;

    ROIDefinition rois = image->Dataset().experiment.ROI().GetROIDefinition();
    if (rois.boxes.size() + rois.circles.size() + rois.azimuthal.size() >= 16)
        return;

    std::set<std::string> used;
    for (const auto &b : rois.boxes) used.insert(b.GetName());
    for (const auto &c : rois.circles) used.insert(c.GetName());
    for (const auto &a : rois.azimuthal) used.insert(a.GetName());
    std::string name;
    for (int i = 1; ; i++) {
        name = "roi" + std::to_string(i);
        if (!used.count(name)) break;
    }

    if (roi_type == RoiType::RoiBox) {
        const QRectF r = roiBox.normalized();
        rois.boxes.emplace_back(name, std::lround(r.left()), std::lround(r.right()),
                                      std::lround(r.top()), std::lround(r.bottom()));
    } else {
        const QPointF c = roiBox.center();
        const double rad = 0.5 * std::min(roiBox.width(), roiBox.height());
        rois.circles.emplace_back(name, c.x(), c.y(), std::max(0.1, rad));
    }

    roiBox = QRectF();   // clear the scratch overlay
    selected_roi_ = QString::fromStdString(name);
    emit roiSelected(selected_roi_);
    emit roiGeometryEdited(rois);
}

void JFJochDiffractionImage::keyPressEvent(QKeyEvent *event) {
    // Home/End/PageUp/PageDown dataset navigation lives in the main window's application-wide
    // event filter, so it works with any panel focused - this handler never sees those keys.

    if (event->key() == Qt::Key_Delete && image && !selected_roi_.isEmpty()) {
        ROIDefinition rois = image->Dataset().experiment.ROI().GetROIDefinition();
        const std::string sel = selected_roi_.toStdString();
        auto erase = [&sel](auto &vec) {
            for (auto it = vec.begin(); it != vec.end(); ++it)
                if (it->GetName() == sel) { vec.erase(it); return true; }
            return false;
        };
        if (erase(rois.boxes) || erase(rois.circles) || erase(rois.azimuthal)) {
            selected_roi_.clear();
            emit roiGeometryEdited(rois);
        }
        event->accept();
        return;
    }
    QGraphicsView::keyPressEvent(event);
}


std::optional<float> JFJochDiffractionImage::AutoForegroundValue() const {
    if (!image)
        return {};
    if (!hdr_mode)
        return static_cast<float>(image->GetAutoContrastValue());
    const auto val_range = image->ValidMinMax();
    if (!val_range.has_value())
        return {};
    return static_cast<float>(val_range->second);
}

void JFJochDiffractionImage::UpdateForeground() {
    if (!image || !auto_fg)
        return;
    if (const auto val = AutoForegroundValue())
        foreground = *val;
    emit foregroundChanged(foreground);
}

void JFJochDiffractionImage::setHDRMode(bool input) {
    hdr_mode = input;
    UpdateForeground();
    RenderImage();
    Redraw();
}

void JFJochDiffractionImage::loadImage(std::shared_ptr<const JFJochReaderImage> in_image) {
    live_pending_ = false;   // a live ROI edit (if any) has now been recomputed
    ring_cache_key_.clear();   // geometry may differ, re-trace the resolution rings
    one_shot_auto_ = false;    // a new image has its own auto value: `A` is a one-shot again
    if (in_image) {
        image = in_image;
        UpdateForeground();
        LoadImageInternal();
        RenderImage();
        Redraw();
    } else {
        image.reset();
        W = 0; H = 0;
        ClearFrame();   // followers (magnifier) must not keep showing the old frame
        if (scene())
            scene()->clear();
        resetScenePointers();
        hover_resolution = NAN;
        DrawResolutionText();
    }
}

void JFJochDiffractionImage::setAutoForeground(bool input) {
    auto_fg = input;
    one_shot_auto_ = false;   // whatever `A` did before, the next press starts as a one-shot again
    // If auto_foreground is not set, then view stays with the current settings till these are explicitly changed
    UpdateForeground();
    RenderImage();
    Redraw();
    emit autoForegroundChanged(auto_fg);
}

void JFJochDiffractionImage::oneShotAutoForeground() {
    if (auto_fg)
        return;   // Auto already follows every image: there is nothing to apply, and nothing to undo

    if (one_shot_auto_) {
        setAutoForeground(true);   // second press on the same image: keep it on from now on
        return;
    }

    const auto val = AutoForegroundValue();
    if (!val)
        return;
    // Unlike a manual foreground change this leaves auto_fg alone (it is off here either way).
    foreground = *val;
    one_shot_auto_ = true;
    ScheduleRenderImage();
    emit foregroundChanged(foreground);
}

void JFJochDiffractionImage::setResolutionRing(QVector<float> v) {
    res_ring = v;
    ring_mode = RingMode::Manual;
    updateOverlay();
}

void JFJochDiffractionImage::showSpots(bool input) {
    show_spots = input;
    updateOverlay();
}

void JFJochDiffractionImage::showPredictions(bool input) {
    show_predictions = input;
    updateOverlay();
}

void JFJochDiffractionImage::setSpotColor(QColor input) {
    spot_color = input;
    updateOverlay();
}

void JFJochDiffractionImage::setPredictionColor(QColor input) {
    prediction_color = input;
    updateOverlay();
}

void JFJochDiffractionImage::showHighestPixels(int32_t v) {
    show_highest_pixels = v;
    updateOverlay();
}

void JFJochDiffractionImage::DrawSaturation() {
    // Cull to the viewport like DrawSpots/DrawPredictions, and cap the count. Unlike spots, the
    // saturated set is unbounded - an over-exposed frame or a missing beamstop saturates a
    // sizeable fraction of the detector - and every cross is two QGraphicsLineItems rebuilt on
    // each pan, zoom and frame change.
    constexpr size_t max_crosses = 5000;

    const QRectF visibleRect = mapToScene(viewport()->geometry()).boundingRect();
    const auto x_pixels = image->Dataset().experiment.GetXPixelsNum();

    size_t drawn = 0;
    for (const auto &iter: image->SaturatedPixels()) {
        const float x = iter % x_pixels + 0.5;
        const float y = iter / x_pixels + 0.5;
        if (!visibleRect.contains(QPointF{x, y}))
            continue;
        if (drawn++ >= max_crosses)
            break;
        DrawCross(x, y, 20, 4);
    }
}

void JFJochDiffractionImage::DrawCross(float x, float y, float size, float width, float z) {
    float sc_size = size / sqrt(scale_factor);

    QPen pen(feature_color, width);
    pen.setCosmetic(true);

    QGraphicsLineItem *horizontalLine = scene()->addLine(x - sc_size, y, x + sc_size, y, pen);
    QGraphicsLineItem *verticalLine = scene()->addLine(x, y - sc_size, x, y + sc_size, pen);

    horizontalLine->setZValue(z); // Ensure it appears above other items
    verticalLine->setZValue(z); // Ensure it appears above other items

    addOverlayItem(horizontalLine);
    addOverlayItem(verticalLine);
}

void JFJochDiffractionImage::showSaturation(bool input) {
    show_saturation = input;
    RenderImage();
    updateOverlay();
}

void JFJochDiffractionImage::showBeamStop(bool input) {
    show_beam_stop = input;
    RenderImage();
    updateOverlay();
}

void JFJochDiffractionImage::highlightIceRings(bool input) {
    highlight_ice_rings = input;
    updateOverlay();
}

void JFJochDiffractionImage::hideUnindexedSpots(bool input) {
    hide_unindexed_spots = input;
    updateOverlay();
}

void JFJochDiffractionImage::hideIceRingSpots(bool input) {
    hide_ice_ring_spots = input;
    updateOverlay();
}

void JFJochDiffractionImage::setResolutionRingMode(RingMode mode) {
    ring_mode = mode;
    updateOverlay();
}

static QFont HoverResolutionFont() {
    QFont font("Arial");
    font.setPixelSize(32);   // big, constant size on screen
    return font;
}

QString JFJochDiffractionImage::HoverResolutionLabel() const {
    if (!image || !std::isfinite(hover_resolution) || hover_resolution <= 0.0f)
        return {};
    return QString("d = %1 \u00C5").arg(QString::number(hover_resolution, 'f', 2));
}



QString JFJochDiffractionImage::PixelLabel(int x, int y) const {
    if (!image)
        return {};

    const int32_t v = image->Image()[static_cast<size_t>(y) * W + x];
    if (v == GAP_PXL_VALUE)
        return QStringLiteral("Gap");
    if (v == ERROR_PXL_VALUE)
        return QStringLiteral("Err");
    if (v == BEAM_STOP_PXL_VALUE)
        return QStringLiteral("Stop");
    if (v == SATURATED_PXL_VALUE)
        return QStringLiteral("Sat");
    return QString::number(v);
}

void JFJochDiffractionImage::drawForeground(QPainter *painter, const QRectF &rect) {
    JFJochImage::drawForeground(painter, rect);

    const QString label = HoverResolutionLabel();
    if (label.isEmpty())
        return;

    painter->save();
    painter->resetTransform();          // lay the readout out in viewport pixels, not scene units
    painter->setFont(HoverResolutionFont());
    painter->setPen(feature_color);
    painter->drawText(hover_text_rect_, Qt::AlignLeft | Qt::AlignTop, label);
    painter->restore();
}

void JFJochDiffractionImage::scrollContentsBy(int dx, int dy) {
    JFJochImage::scrollContentsBy(dx, dy);
    if (hover_text_rect_.isEmpty())
        return;
    // QWidget::scroll moves the pending update region too, so the repaint DrawResolutionText asked for
    // is dragged away from the corner along with the pixels already there. Dirty both places.
    viewport()->update(hover_text_rect_.united(hover_text_rect_.translated(dx, dy)).adjusted(-2, -2, 2, 2));
}

void JFJochDiffractionImage::DrawResolutionText() {
    const QRect previous = hover_text_rect_;
    const QString label = HoverResolutionLabel();

    if (label.isEmpty())
        hover_text_rect_ = QRect();
    else {
        constexpr int margin_px = 10;
        const QFontMetrics fm(HoverResolutionFont());
        hover_text_rect_ = QRect(QPoint(margin_px, margin_px), fm.size(0, label));
    }

    // Repaint just the readout. The previous version was a QGraphicsItem flagged
    // ItemIgnoresTransformations, which makes Qt mark the whole viewport dirty every time the
    // item moves or its text changes - and it moved on every mouse motion.
    const QRect dirty = previous.united(hover_text_rect_).adjusted(-2, -2, 2, 2);
    if (!dirty.isEmpty())
        viewport()->update(dirty);
}

void JFJochDiffractionImage::leaveEvent(QEvent *event) {
    // Mouse left the view: clear hover resolution and hide text
    if (std::isfinite(hover_resolution)) {
        hover_resolution = NAN;
        DrawResolutionText();
    }
    JFJochImage::leaveEvent(event);
}