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#include <mbgl/map/tile_id.hpp>
#include <mbgl/util/string.hpp>
#include <cassert>
namespace mbgl {
TileID TileID::parent(int8_t parent_z, int8_t sourceMaxZoom) const {
assert(parent_z < z);
auto newX = x;
auto newY = y;
for (auto newZ = z; newZ > parent_z; newZ--) {
if (newZ > sourceMaxZoom) {
// the id represents an overscaled tile, return the same coordinates with a lower z
// do nothing
} else {
newX = newX / 2;
newY = newY / 2;
}
}
return TileID{parent_z, newX, newY, parent_z > sourceMaxZoom ? sourceMaxZoom : parent_z};
}
std::forward_list<TileID> TileID::children(int8_t sourceMaxZoom) const {
auto childZ = z + 1;
std::forward_list<TileID> child_ids;
if (z >= sourceMaxZoom) {
// return a single tile id representing a an overscaled tile
child_ids.emplace_front(childZ, x, y, sourceMaxZoom);
} else {
auto childX = x * 2;
auto childY = y * 2;
child_ids.emplace_front(childZ, childX, childY, childZ);
child_ids.emplace_front(childZ, childX + 1, childY, childZ);
child_ids.emplace_front(childZ, childX, childY + 1, childZ);
child_ids.emplace_front(childZ, childX + 1, childY + 1, childZ);
}
return child_ids;
}
TileID TileID::normalized() const {
int32_t dim = std::pow(2, sourceZ);
int32_t nx = x, ny = y;
while (nx < 0) nx += dim;
while (nx >= dim) nx -= dim;
return TileID { z, nx, ny, sourceZ};
}
bool TileID::isChildOf(const TileID &parent_id) const {
if (parent_id.z >= z || parent_id.w != w) {
return false;
}
int32_t scale = std::pow(2, z - parent_id.z);
return parent_id.x == ((x < 0 ? x - scale + 1 : x) / scale) &&
parent_id.y == y / scale;
}
TileID::operator std::string() const {
return util::toString(z) + "/" + util::toString(x) + "/" + util::toString(y);
}
}
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