scatterplot.cpp

#include "scatterplot.h"

#include <algorithm>
#include <cmath>
#include <limits>

#include <QSGGeometryNode>
#include <QSGSimpleRectNode>

#include "continuouscolorscale.h"
#include "geometry.h"

// Glyphs settings
static const QColor DEFAULT_GLYPH_COLOR(255, 255, 255);
static const float DEFAULT_GLYPH_SIZE = 8.0f;
static const qreal GLYPH_OPACITY = 1.0;
static const qreal GLYPH_OPACITY_SELECTED = 1.0;

static const float GLYPH_OUTLINE_WIDTH = 2.0f;
static const QColor GLYPH_OUTLINE_COLOR(0, 0, 0);
static const QColor GLYPH_OUTLINE_COLOR_SELECTED(20, 255, 225);

// Brush settings
static const float BRUSHING_MAX_DIST = 20.0f;
static const float CROSSHAIR_LENGTH = 8.0f;
static const float CROSSHAIR_THICKNESS1 = 1.0f;
static const float CROSSHAIR_THICKNESS2 = 0.5f;
static const QColor CROSSHAIR_COLOR1(255, 255, 255);
static const QColor CROSSHAIR_COLOR2(0, 0, 0);

// Selection settings
static const QColor SELECTION_COLOR(128, 128, 128, 96);

// Mouse buttons
static const Qt::MouseButton NORMAL_BUTTON = Qt::LeftButton;
static const Qt::MouseButton SPECIAL_BUTTON = Qt::RightButton;

class QuadTree
{
public:
    QuadTree(const QRectF &bounds);
    ~QuadTree();
    bool insert(float x, float y, int value);
    int query(float x, float y) const;
    void query(const QRectF &rect, std::vector<int> &result) const;
    int nearestTo(float x, float y) const;

private:
    bool subdivide();
    void nearestTo(float x, float y, int &nearest, float &dist) const;

    QRectF m_bounds;
    float m_x, m_y;
    int m_value;
    QuadTree *m_nw, *m_ne, *m_sw, *m_se;
};

Scatterplot::Scatterplot(QQuickItem *parent)
    : QQuickItem(parent)
    , m_glyphSize(DEFAULT_GLYPH_SIZE)
    , m_colorScale(0)
    , m_autoScale(true)
    , m_sx(0, 1, 0, 1)
    , m_sy(0, 1, 0, 1)
    , m_anySelected(false)
    , m_brushedItem(-1)
    , m_interactionState(StateNone)
    , m_dragEnabled(false)
    , m_shouldUpdateGeometry(false)
    , m_shouldUpdateMaterials(false)
    , m_quadtree(0)
{
    setClip(true);
    setFlag(QQuickItem::ItemHasContents);
}

Scatterplot::~Scatterplot()
{
    if (m_quadtree) {
        delete m_quadtree;
    }
}

void Scatterplot::setColorScale(const ColorScale *colorScale)
{
    m_colorScale = colorScale;
    if (m_colorData.n_elem > 0) {
        m_shouldUpdateMaterials = true;
        update();
    }
}

arma::mat Scatterplot::XY() const
{
    return m_xy;
}

void Scatterplot::setXY(const arma::mat &xy)
{
    if (xy.n_cols != 2) {
        return;
    }

    m_xy = xy;
    emit xyChanged(m_xy);

    if (m_autoScale) {
        autoScale();
    }

    updateQuadTree();

    if (m_selection.size() != m_xy.n_rows) {
        m_selection.assign(m_xy.n_rows, false);
    }

    if (m_opacityData.n_elem != m_xy.n_rows) {
        // Reset opacity data
        m_opacityData.resize(xy.n_rows);
        m_opacityData.fill(GLYPH_OPACITY);
        emit opacityDataChanged(m_opacityData);
    }

    m_shouldUpdateGeometry = true;
    update();
}

void Scatterplot::setColorData(const arma::vec &colorData)
{
    if (m_xy.n_rows > 0
        && (colorData.n_elem > 0 && colorData.n_elem != m_xy.n_rows)) {
        return;
    }

    m_colorData = colorData;
    emit colorDataChanged(m_colorData);

    m_shouldUpdateMaterials = true;
    update();
}

void Scatterplot::setOpacityData(const arma::vec &opacityData)
{
    if (m_xy.n_rows > 0 && opacityData.n_elem != m_xy.n_rows) {
        return;
    }

    m_opacityData = opacityData;
    emit opacityDataChanged(m_opacityData);
    update();
}

void Scatterplot::setScale(const LinearScale<float> &sx, const LinearScale<float> &sy)
{
    m_sx = sx;
    m_sy = sy;
    emit scaleChanged(m_sx, m_sy);

    updateQuadTree();

    m_shouldUpdateGeometry = true;
    update();
}

void Scatterplot::setAutoScale(bool autoScale)
{
    m_autoScale = autoScale;
    if (autoScale) {
        this->autoScale();
    }
}

void Scatterplot::autoScale()
{
    m_sx.setDomain(m_xy.col(0).min(), m_xy.col(0).max());
    m_sy.setDomain(m_xy.col(1).min(), m_xy.col(1).max());
    emit scaleChanged(m_sx, m_sy);
}

void Scatterplot::setGlyphSize(float glyphSize)
{
    if (m_glyphSize == glyphSize || glyphSize < 2.0f) {
        return;
    }

    m_glyphSize = glyphSize;
    emit glyphSizeChanged(m_glyphSize);

    m_shouldUpdateGeometry = true;
    update();
}

QSGNode *Scatterplot::newSceneGraph()
{
    // NOTE:
    // The hierarchy in the scene graph is as follows:
    // root [[splatNode] [glyphsRoot [glyph [...]]] [selectionNode]]
    QSGNode *root = new QSGNode;
    QSGNode *glyphTreeRoot = newGlyphTree();
    if (glyphTreeRoot) {
        root->appendChildNode(glyphTreeRoot);
    }

    QSGSimpleRectNode *selectionRectNode = new QSGSimpleRectNode;
    selectionRectNode->setColor(SELECTION_COLOR);
    root->appendChildNode(selectionRectNode);

    QSGTransformNode *brushNode = new QSGTransformNode;

    QSGGeometryNode *whiteCrossHairNode = new QSGGeometryNode;
    QSGGeometry *whiteCrossHairGeom = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 12);
    whiteCrossHairGeom->setDrawingMode(GL_POLYGON);
    whiteCrossHairGeom->setVertexDataPattern(QSGGeometry::DynamicPattern);
    updateCrossHairGeometry(whiteCrossHairGeom, 0, 0, CROSSHAIR_THICKNESS1, CROSSHAIR_LENGTH);
    QSGFlatColorMaterial *whiteCrossHairMaterial = new QSGFlatColorMaterial;
    whiteCrossHairMaterial->setColor(CROSSHAIR_COLOR1);
    whiteCrossHairNode->setGeometry(whiteCrossHairGeom);
    whiteCrossHairNode->setMaterial(whiteCrossHairMaterial);
    whiteCrossHairNode->setFlags(QSGNode::OwnsGeometry | QSGNode::OwnsMaterial);
    brushNode->appendChildNode(whiteCrossHairNode);

    QSGGeometryNode *blackCrossHairNode = new QSGGeometryNode;
    QSGGeometry *blackCrossHairGeom = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), 12);
    blackCrossHairGeom->setDrawingMode(GL_POLYGON);
    blackCrossHairGeom->setVertexDataPattern(QSGGeometry::DynamicPattern);
    updateCrossHairGeometry(blackCrossHairGeom, 0, 0, CROSSHAIR_THICKNESS2, CROSSHAIR_LENGTH);
    QSGFlatColorMaterial *blackCrossHairMaterial = new QSGFlatColorMaterial;
    blackCrossHairMaterial->setColor(CROSSHAIR_COLOR2);
    blackCrossHairNode->setGeometry(blackCrossHairGeom);
    blackCrossHairNode->setMaterial(blackCrossHairMaterial);
    blackCrossHairNode->setFlags(QSGNode::OwnsGeometry | QSGNode::OwnsMaterial);
    brushNode->appendChildNode(blackCrossHairNode);

    root->appendChildNode(brushNode);

    return root;
}

QSGNode *Scatterplot::newGlyphTree()
{
    // NOTE:
    // The glyph graph is structured as:
    // root [opacityNode [outlineNode fillNode] ...]
    if (m_xy.n_rows < 1) {
        return 0;
    }

    QSGNode *node = new QSGNode;
    int vertexCount = calculateCircleVertexCount(m_glyphSize);

    for (arma::uword i = 0; i < m_xy.n_rows; i++) {
        QSGGeometry *glyphOutlineGeometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount);
        glyphOutlineGeometry->setDrawingMode(GL_POLYGON);
        glyphOutlineGeometry->setVertexDataPattern(QSGGeometry::DynamicPattern);
        QSGGeometryNode *glyphOutlineNode = new QSGGeometryNode;
        glyphOutlineNode->setGeometry(glyphOutlineGeometry);
        glyphOutlineNode->setFlag(QSGNode::OwnsGeometry);

        QSGFlatColorMaterial *material = new QSGFlatColorMaterial;
        material->setColor(GLYPH_OUTLINE_COLOR);
        glyphOutlineNode->setMaterial(material);
        glyphOutlineNode->setFlag(QSGNode::OwnsMaterial);

        QSGGeometry *glyphGeometry = new QSGGeometry(QSGGeometry::defaultAttributes_Point2D(), vertexCount);
        glyphGeometry->setDrawingMode(GL_POLYGON);
        glyphGeometry->setVertexDataPattern(QSGGeometry::DynamicPattern);
        QSGGeometryNode *glyphNode = new QSGGeometryNode;
        glyphNode->setGeometry(glyphGeometry);
        glyphNode->setFlag(QSGNode::OwnsGeometry);

        material = new QSGFlatColorMaterial;
        material->setColor(DEFAULT_GLYPH_COLOR);
        glyphNode->setMaterial(material);
        glyphNode->setFlag(QSGNode::OwnsMaterial);

        // Place the glyph geometry node under an opacity node
        QSGOpacityNode *glyphOpacityNode = new QSGOpacityNode;
        glyphOpacityNode->appendChildNode(glyphOutlineNode);
        glyphOpacityNode->appendChildNode(glyphNode);
        node->appendChildNode(glyphOpacityNode);
    }

    return node;
}

QSGNode *Scatterplot::updatePaintNode(QSGNode *oldNode, UpdatePaintNodeData *)
{
    QSGNode *root = oldNode ? oldNode : newSceneGraph();

    if (m_xy.n_rows < 1) {
        return root;
    }

    // This keeps track of where we are in the scene when updating
    QSGNode *node = root->firstChild();

    updateGlyphs(node);
    node = node->nextSibling();

    if (m_shouldUpdateGeometry) {
        m_shouldUpdateGeometry = false;
    }
    if (m_shouldUpdateMaterials) {
        m_shouldUpdateMaterials = false;
    }

    // Selection
    QSGSimpleRectNode *selectionNode = static_cast<QSGSimpleRectNode *>(node);
    if (m_interactionState == StateSelecting) {
        selectionNode->setRect(QRectF(m_dragOriginPos, m_dragCurrentPos));
        selectionNode->markDirty(QSGNode::DirtyGeometry);
    } else {
        // Hide selection rect
        selectionNode->setRect(QRectF(-1, -1, 0, 0));
    }
    node = node->nextSibling();

    // Brushing
    updateBrush(node);
    node = node->nextSibling();

    return root;
}

void Scatterplot::updateGlyphs(QSGNode *glyphsNode)
{
    qreal x, y, tx, ty, moveTranslationF;

    if (!m_shouldUpdateGeometry && !m_shouldUpdateMaterials) {
        return;
    }

    if (m_interactionState == StateMoving) {
        tx = m_dragCurrentPos.x() - m_dragOriginPos.x();
        ty = m_dragCurrentPos.y() - m_dragOriginPos.y();
    } else {
        tx = ty = 0;
    }

    m_sx.setRange(PADDING, width() - PADDING);
    m_sy.setRange(height() - PADDING, PADDING);

    QSGNode *node = glyphsNode->firstChild();
    for (arma::uword i = 0; i < m_xy.n_rows; i++) {
        const arma::rowvec &row = m_xy.row(i);
        bool isSelected = m_selection[i];

        QSGOpacityNode *glyphOpacityNode = static_cast<QSGOpacityNode *>(node);
        glyphOpacityNode->setOpacity(m_opacityData[i]);

        QSGGeometryNode *glyphOutlineNode = static_cast<QSGGeometryNode *>(node->firstChild());
        QSGGeometryNode *glyphNode = static_cast<QSGGeometryNode *>(node->firstChild()->nextSibling());
        if (m_shouldUpdateGeometry) {
            moveTranslationF = isSelected ? 1.0 : 0.0;
            x = m_sx(row[0]) + tx * moveTranslationF;
            y = m_sy(row[1]) + ty * moveTranslationF;

            QSGGeometry *geometry = glyphOutlineNode->geometry();
            updateCircleGeometry(geometry, m_glyphSize, x, y);
            glyphOutlineNode->markDirty(QSGNode::DirtyGeometry);

            geometry = glyphNode->geometry();
            updateCircleGeometry(geometry, m_glyphSize - 2*GLYPH_OUTLINE_WIDTH, x, y);
            glyphNode->markDirty(QSGNode::DirtyGeometry);
        }
        if (m_shouldUpdateMaterials) {
            QSGFlatColorMaterial *material = static_cast<QSGFlatColorMaterial *>(glyphOutlineNode->material());
            material->setColor(isSelected ? GLYPH_OUTLINE_COLOR_SELECTED
                                          : GLYPH_OUTLINE_COLOR);
            glyphOutlineNode->markDirty(QSGNode::DirtyMaterial);

            material = static_cast<QSGFlatColorMaterial *>(glyphNode->material());
            if (m_colorData.n_elem > 0) {
                material->setColor(m_colorScale->color(m_colorData[i]));
            } else {
                material->setColor(DEFAULT_GLYPH_COLOR);
            }
            glyphNode->markDirty(QSGNode::DirtyMaterial);
        }

        node = node->nextSibling();
    }

    // XXX: Beware: QSGNode::DirtyForceUpdate is undocumented
    //
    // This causes the scene graph to correctly update the materials of glyphs,
    // even though we individually mark dirty materials. Used to work in Qt 5.5,
    // though.
    glyphsNode->markDirty(QSGNode::DirtyForceUpdate);
}

void Scatterplot::updateBrush(QSGNode *node)
{
    QMatrix4x4 transform;
    if (m_brushedItem < 0
        || (m_interactionState != StateNone
            && m_interactionState != StateSelected)) {
        transform.translate(-width(), -height());
    } else {
        const arma::rowvec &row = m_xy.row(m_brushedItem);
        transform.translate(m_sx(row[0]), m_sy(row[1]));
    }

    QSGTransformNode *brushNode = static_cast<QSGTransformNode *>(node);
    brushNode->setMatrix(transform);
}

void Scatterplot::mousePressEvent(QMouseEvent *event)
{
    switch (m_interactionState) {
    case StateNone:
    case StateSelected:
        switch (event->button()) {
        case NORMAL_BUTTON:
            if (event->modifiers() == Qt::ShiftModifier && m_dragEnabled) {
                m_interactionState = StateMoving;
                m_dragOriginPos = event->localPos();
                m_dragCurrentPos = m_dragOriginPos;
            } else {
                // We say 'brushing', but we mean 'selecting the current brushed
                // item'
                m_interactionState = StateBrushing;
            }
            break;
        case SPECIAL_BUTTON:
            m_interactionState = StateNone;
            m_selection.assign(m_selection.size(), false);
            emit selectionInteractivelyChanged(m_selection);
            m_shouldUpdateMaterials = true;
            update();
            break;
        }
        break;
    case StateBrushing:
    case StateSelecting:
    case StateMoving:
        // Probably shouldn't reach these
        break;
    }
}

void Scatterplot::mouseMoveEvent(QMouseEvent *event)
{
    switch (m_interactionState) {
    case StateBrushing:
        // Move while brushing becomes selecting, hence the 'fall through'
        m_interactionState = StateSelecting;
        m_dragOriginPos = event->localPos();
        // fall through
    case StateSelecting:
        m_dragCurrentPos = event->localPos();
        update();
        break;
    case StateMoving:
        m_dragCurrentPos = event->localPos();
        m_shouldUpdateGeometry = true;
        update();
        break;
    case StateNone:
    case StateSelected:
        break;
    }
}

void Scatterplot::mouseReleaseEvent(QMouseEvent *event)
{
    bool mergeSelection = (event->modifiers() == Qt::ControlModifier);

    switch (m_interactionState) {
    case StateBrushing:
        // Mouse clicked with brush target; set new selection or append to
        // current
        if (!mergeSelection) {
            m_selection.assign(m_selection.size(), false);
        }

        if (m_brushedItem == -1) {
            m_interactionState = StateNone;
            if (m_anySelected && !mergeSelection) {
                m_anySelected = false;
                emit selectionInteractivelyChanged(m_selection);
                m_shouldUpdateMaterials = true;
                update();
            }
        } else {
            m_interactionState = StateSelected;
            m_selection[m_brushedItem] = !m_selection[m_brushedItem];
            if (m_selection[m_brushedItem]) {
                m_anySelected = true;
            }

            emit selectionInteractivelyChanged(m_selection);
            m_shouldUpdateMaterials = true;
            update();
        }
        break;
    case StateSelecting:
        {
        // Selecting points and mouse is now released; update selection and
        // brush
        interactiveSelection(mergeSelection);
        m_interactionState = m_anySelected ? StateSelected : StateNone;
        QPoint pos = event->pos();
        m_brushedItem = m_quadtree->nearestTo(pos.x(), pos.y());

        emit itemInteractivelyBrushed(m_brushedItem);
        m_shouldUpdateMaterials = true;
        update();
        }
        break;
    case StateMoving:
        // Moving points and now stopped; apply manipulation
        m_interactionState = StateSelected;
        applyManipulation();
        m_shouldUpdateGeometry = true;
        update();

        m_dragOriginPos = m_dragCurrentPos;
        break;
    case StateNone:
    case StateSelected:
        break;
    }
}

void Scatterplot::hoverEnterEvent(QHoverEvent *event)
{
    QPointF pos = event->posF();
    m_brushedItem = m_quadtree->nearestTo(pos.x(), pos.y());
    emit itemInteractivelyBrushed(m_brushedItem);

    update();
}

void Scatterplot::hoverMoveEvent(QHoverEvent *event)
{
    QPointF pos = event->posF();
    m_brushedItem = m_quadtree->nearestTo(pos.x(), pos.y());
    emit itemInteractivelyBrushed(m_brushedItem);

    update();
}

void Scatterplot::hoverLeaveEvent(QHoverEvent *event)
{
    m_brushedItem = -1;
    emit itemInteractivelyBrushed(m_brushedItem);

    update();
}

void Scatterplot::interactiveSelection(bool mergeSelection)
{
    if (!mergeSelection) {
        m_selection.assign(m_selection.size(), false);
    }

    std::vector<int> selected;
    m_quadtree->query(QRectF(m_dragOriginPos, m_dragCurrentPos), selected);
    for (auto i: selected) {
        m_selection[i] = true;
    }

    for (auto isSelected: m_selection) {
        if (isSelected) {
            m_anySelected = true;
            break;
        }
    }

    emit selectionInteractivelyChanged(m_selection);
}

void Scatterplot::setSelection(const std::vector<bool> &selection)
{
    if (m_selection.size() != selection.size()) {
        return;
    }

    m_selection = selection;
    emit selectionChanged(m_selection);

    m_shouldUpdateMaterials = true;
    update();
}

void Scatterplot::brushItem(int item)
{
    m_brushedItem = item;
    update();
}

void Scatterplot::applyManipulation()
{
    m_sx.inverse();
    m_sy.inverse();
    LinearScale<float> rx = m_sx;
    LinearScale<float> ry = m_sy;
    m_sy.inverse();
    m_sx.inverse();

    float tx = m_dragCurrentPos.x() - m_dragOriginPos.x();
    float ty = m_dragCurrentPos.y() - m_dragOriginPos.y();

    for (std::vector<bool>::size_type i = 0; i < m_selection.size(); i++) {
        if (m_selection[i]) {
            arma::rowvec row = m_xy.row(i);
            row[0] = rx(m_sx(row[0]) + tx);
            row[1] = ry(m_sy(row[1]) + ty);
            m_xy.row(i) = row;
        }
    }

    updateQuadTree();

    emit xyInteractivelyChanged(m_xy);
}

void Scatterplot::updateQuadTree()
{
    m_sx.setRange(PADDING, width() - PADDING);
    m_sy.setRange(height() - PADDING, PADDING);

    if (m_quadtree) {
        delete m_quadtree;
    }

    m_quadtree = new QuadTree(QRectF(x(), y(), width(), height()));
    for (arma::uword i = 0; i < m_xy.n_rows; i++) {
        const arma::rowvec &row = m_xy.row(i);
        m_quadtree->insert(m_sx(row[0]), m_sy(row[1]), (int) i);
    }
}

QuadTree::QuadTree(const QRectF &bounds)
    : m_bounds(bounds)
    , m_value(-1)
    , m_nw(0), m_ne(0), m_sw(0), m_se(0)
{
}

QuadTree::~QuadTree()
{
    if (m_nw) {
        delete m_nw;
        delete m_ne;
        delete m_sw;
        delete m_se;
    }
}

bool QuadTree::subdivide()
{
    float halfWidth = m_bounds.width() / 2;
    float halfHeight = m_bounds.height() / 2;

    m_nw = new QuadTree(QRectF(m_bounds.x(),
                               m_bounds.y(),
                               halfWidth,
                               halfHeight));
    m_ne = new QuadTree(QRectF(m_bounds.x() + halfWidth,
                               m_bounds.y(),
                               halfWidth,
                               halfHeight));
    m_sw = new QuadTree(QRectF(m_bounds.x(),
                               m_bounds.y() + halfHeight,
                               halfWidth,
                               halfHeight));
    m_se = new QuadTree(QRectF(m_bounds.x() + halfWidth,
                               m_bounds.y() + halfHeight,
                               halfWidth,
                               halfHeight));

    int value = m_value;
    m_value = -1;
    return m_nw->insert(m_x, m_y, value)
        || m_ne->insert(m_x, m_y, value)
        || m_sw->insert(m_x, m_y, value)
        || m_se->insert(m_x, m_y, value);
}

bool QuadTree::insert(float x, float y, int value)
{
    if (!m_bounds.contains(x, y)) {
        return false;
    }

    if (m_nw) {
        return m_nw->insert(x, y, value)
            || m_ne->insert(x, y, value)
            || m_sw->insert(x, y, value)
            || m_se->insert(x, y, value);
    }

    if (m_value >= 0) {
        subdivide();
        return insert(x, y, value);
    }

    m_x = x;
    m_y = y;
    m_value = value;
    return true;
}

int QuadTree::nearestTo(float x, float y) const
{
    if (!m_bounds.contains(x, y)) {
        return -1;
    }

    int q;
    if (m_nw) {
        q = m_nw->nearestTo(x, y);
        if (q >= 0) return q;
        q = m_ne->nearestTo(x, y);
        if (q >= 0) return q;
        q = m_sw->nearestTo(x, y);
        if (q >= 0) return q;
        q = m_se->nearestTo(x, y);
        if (q >= 0) return q;
    }

    float dist = std::numeric_limits<float>::infinity();
    nearestTo(x, y, q, dist);
    if (dist < BRUSHING_MAX_DIST * BRUSHING_MAX_DIST)
        return q;
    return -1;
}

void QuadTree::nearestTo(float x, float y, int &nearest, float &dist) const
{
    if (m_nw) {
        m_nw->nearestTo(x, y, nearest, dist);
        m_ne->nearestTo(x, y, nearest, dist);
        m_sw->nearestTo(x, y, nearest, dist);
        m_se->nearestTo(x, y, nearest, dist);
    } else if (m_value >= 0) {
        float d = (m_x - x)*(m_x - x) + (m_y - y)*(m_y - y);
        if (d < dist) {
            nearest = m_value;
            dist = d;
        }
    }
}

int QuadTree::query(float x, float y) const
{
    if (!m_bounds.contains(x, y)) {
        // There is no way we could find the point
        return -1;
    }

    if (m_nw) {
        int q = -1;
        q = m_nw->query(x, y);
        if (q >= 0) return q;
        q = m_ne->query(x, y);
        if (q >= 0) return q;
        q = m_sw->query(x, y);
        if (q >= 0) return q;
        q = m_se->query(x, y);
        return q;
    }

    return m_value;
}

void QuadTree::query(const QRectF &rect, std::vector<int> &result) const
{
    if (!m_bounds.intersects(rect)) {
        return;
    }

    if (m_nw) {
        m_nw->query(rect, result);
        m_ne->query(rect, result);
        m_sw->query(rect, result);
        m_se->query(rect, result);
    } else if (rect.contains(m_x, m_y) && m_value != -1) {
        result.push_back(m_value);
    }
}