void SelectionQuery::process(const View& _view, const FrameBuffer& _framebuffer, const MarkerManager& _markerManager,
const TileManager& _tileManager, const Labels& _labels, std::vector<SelectionColorRead>& _colorCache) const {
float radius = m_radius * _view.pixelScale();
glm::vec2 windowCoordinates = _view.normalizedWindowCoordinates(m_position.x - radius, m_position.y + radius);
glm::vec2 windowSize = _view.normalizedWindowCoordinates(m_position.x + radius, m_position.y - radius) - windowCoordinates;
GLuint color = 0;
auto it = std::find_if(_colorCache.begin(), _colorCache.end(), [=](const auto& _colorRead) {
return (m_position == _colorRead.position) && (m_radius == _colorRead.radius);
});
if (it == _colorCache.end()) {
// Find the first non-zero color nearest to the position and within the selection radius.
auto rect = _framebuffer.readRect(windowCoordinates.x, windowCoordinates.y, windowSize.x, windowSize.y);
float minDistance = std::fmin(rect.width, rect.height);
float hw = static_cast<float>(rect.width) / 2.f, hh = static_cast<float>(rect.height) / 2.f;
for (int32_t row = 0; row < rect.height; row++) {
for (int32_t col = 0; col < rect.width; col++) {
uint32_t sample = rect.pixels[row * rect.width + col];
float distance = std::hypot(row - hw, col - hh);
if (sample != 0 && distance < minDistance) {
color = sample;
minDistance = distance;
}
}
}
// Cache the resulting color for other queries.
_colorCache.push_back({color, m_radius, m_position});
} else {
color = it->color;
}
switch (type()) {
case QueryType::feature: {
auto& cb = m_queryCallback.get<FeaturePickCallback>();
if (color == 0) {
cb(nullptr);
return;
}
for (const auto& tile : _tileManager.getVisibleTiles()) {
if (auto props = tile->getSelectionFeature(color)) {
FeaturePickResult queryResult(props, {{m_position.x, m_position.y}});
cb(&queryResult);
return;
}
}
cb(nullptr);
} break;
case QueryType::marker: {
auto& cb = m_queryCallback.get<MarkerPickCallback>();
if (color == 0) {
cb(nullptr);
return;
}
auto marker = _markerManager.getMarkerOrNullBySelectionColor(color);
if (!marker) {
cb(nullptr);
return;
}
glm::dvec2 bbCenter = marker->bounds().center();
glm::dvec2 lonLat = _view.getMapProjection().MetersToLonLat(bbCenter);
MarkerPickResult markerResult(marker->id(), {lonLat.x, lonLat.y}, {{m_position.x, m_position.y}});
cb(&markerResult);
} break;
case QueryType::label: {
auto& cb = m_queryCallback.get<LabelPickCallback>();
if (color == 0) {
cb(nullptr);
return;
}
auto label = _labels.getLabel(color);
if (!label.first || !label.second) {
cb(nullptr);
return;
}
auto props = label.second->getSelectionFeature(label.first->options().featureId);
if (!props) {
cb(nullptr);
return;
}
auto coordinate = label.second->coordToLngLat(label.first->modelCenter());
LabelPickResult queryResult(label.first->renderType(), LngLat{coordinate.x, coordinate.y},
FeaturePickResult(props, {{m_position.x, m_position.y}}));
cb(&queryResult);
} break;
default: break;
}
}
