slippy

type Grid interface {
	// SRID returns the SRID of the coordinate system of the
	// implementer. The geomtries returned by the other methods
	// will be in these coordinates.
	SRID() uint

	// Size returns a tile where the X and Y are the size of that zoom's
	// tile grid. AKA:
	//	Tile{z, MaxX + 1, MaxY + 1
	Size(z uint) (*Tile, bool)

	// FromNative converts from a point (in the Grid's coordinates system) and zoom
	// to a tile. ok will be false if the point is not valid for this coordinate
	// system.
	FromNative(z uint, pt geom.Point) (tile *Tile, ok bool)

	// ToNative returns the tiles upper left point. ok will be false if
	// the tile is not valid. A note on implemetation is that this method
	// should be able to take tiles with x and y values 1 higher than the max,
	// this is to fetch the bottom right corner of the grid
	ToNative(*Tile) (pt geom.Point, ok bool)
}

type Iterator func(*Tile) error

type Tile struct {
	// zoom
	Z uint
	// column
	X uint
	// row
	Y uint
}