Jungfraujoch/viewer/image_viewer/JFJochFollowerImage.cpp

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

#include "JFJochFollowerImage.h"
#include "JFJochImage.h"
#include "../../common/ColorScale.h"

#include <algorithm>
#include <cmath>

#include <QGraphicsScene>
#include <QPainter>
#include <QWheelEvent>

// Same wording as the main view's per-pixel labels
static QString PixelValueText(int32_t value) {
    if (value == GAP_PXL_VALUE)
        return QStringLiteral("Gap");
    if (value == ERROR_PXL_VALUE)
        return QStringLiteral("Err");
    if (value == SATURATED_PXL_VALUE)
        return QStringLiteral("Sat");
    return QString::number(value);
}

JFJochFollowerImage::JFJochFollowerImage(QWidget *parent) : QGraphicsView(parent) {
    setScene(new QGraphicsScene(this));
    setTransformationAnchor(QGraphicsView::AnchorViewCenter);
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setTransform(QTransform::fromScale(zoom_, zoom_));
}

void JFJochFollowerImage::SetFrame(std::shared_ptr<const QImage> frame) {
    const bool same_pointer = (frame_ == frame);
    const bool same_size = frame_ && frame && frame_->size() == frame->size();
    frame_ = std::move(frame);

    if (!frame_ || frame_->isNull()) {
        scene()->clear();
        item_ = nullptr;
        return;
    }

    // The producer reuses one buffer, so normally only the pixels changed and the item stays.
    if (!item_ || !same_pointer) {
        scene()->clear();
        item_ = new JFJochImageItem(frame_);
        scene()->addItem(item_);
    }

    if (!same_size) {
        item_->refresh();
        scene()->setSceneRect(0, 0, frame_->width(), frame_->height());
    }

    viewport()->update();
}

void JFJochFollowerImage::SetPixelValues(std::shared_ptr<const JFJochReaderImage> image) {
    values_ = std::move(image);
}

void JFJochFollowerImage::CenterAt(QPointF scenePos) {
    if (!frame_ || frame_->isNull())
        return;
    centerOn(scenePos);
}

void JFJochFollowerImage::wheelEvent(QWheelEvent *event) {
    constexpr double step = 1.15;
    zoom_ *= (event->angleDelta().y() > 0) ? step : 1.0 / step;
    zoom_ = std::clamp(zoom_, 1.0, 200.0);

    const QPointF center = mapToScene(viewport()->rect().center());
    setTransform(QTransform::fromScale(zoom_, zoom_));
    centerOn(center);
}

void JFJochFollowerImage::drawForeground(QPainter *painter, const QRectF &rect) {
    QGraphicsView::drawForeground(painter, rect);

    if (zoom_ < kLabelZoom || !values_ || !frame_ || frame_->isNull())
        return;

    const int W = frame_->width();
    const int H = frame_->height();
    const auto &pixels = values_->Image();
    if (static_cast<int64_t>(pixels.size()) < static_cast<int64_t>(W) * H)
        return;   // values belong to a different frame

    const QRectF visible = mapToScene(viewport()->rect()).boundingRect();
    const int x0 = std::max(0, static_cast<int>(std::floor(visible.left())));
    const int x1 = std::min(W, static_cast<int>(std::ceil(visible.right())));
    const int y0 = std::max(0, static_cast<int>(std::floor(visible.top())));
    const int y1 = std::min(H, static_cast<int>(std::ceil(visible.bottom())));
    if (x1 <= x0 || y1 <= y0 || (x1 - x0) * (y1 - y0) > kMaxLabels)
        return;

    // Lay the text out in viewport pixels so it stays a constant, readable size
    painter->save();
    painter->resetTransform();

    QFont font("DejaVu Sans Mono");
    font.setStyleHint(QFont::TypeWriter);
    font.setPixelSize(std::clamp(static_cast<int>(zoom_ * 0.3), 7, 16));
    painter->setFont(font);

    for (int y = y0; y < y1; y++) {
        for (int x = x0; x < x1; x++) {
            const QRect cell = mapFromScene(QRectF(x, y, 1, 1)).boundingRect();
            const QRgb c = frame_->pixel(x, y);
            const rgb col{.r = static_cast<uint8_t>(qRed(c)),
                          .g = static_cast<uint8_t>(qGreen(c)),
                          .b = static_cast<uint8_t>(qBlue(c))};
            painter->setPen(luminance(col) > 128.0 ? Qt::black : Qt::white);
            painter->drawText(cell, Qt::AlignCenter, PixelValueText(pixels[y * W + x]));
        }
    }

    painter->restore();
}