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//! Parse Mapbox Vector Tile (.mvt) files and return their
//! contents as a Scalable Vector Graphic (.svg) fragment.
//! Provides a single function `process(r: Read)` to convert
//! files.
//! Intended to be run in the browser.
// Exported functions are passed to the asm.js linker.
extern crate protobuf;
use std::ffi::CString;
use std::io::Read;
use std::os::raw::c_char;
use std::slice;
use protobuf::ProtobufResult;
use storage::Storage;
use layer::Layer;
use vector_tile::Tile;
pub mod cursor;
pub mod feature;
pub mod storage;
pub mod tag;
pub mod layer;
pub mod vector_tile;
/// Reads a Vector File and produces an SVG fragment for a tile.
pub fn process<R: Read>(mut r: R) -> ProtobufResult<String> {
let tile: Tile = protobuf::parse_from_reader(&mut r)?;
let mut storage = Storage::new();
for raw_layer in tile.get_layers() {
let mut layer = Layer::new(raw_layer);
layer.paint(&mut storage)?;
// Only the functions listed here are callable from JS.
link_args="-s EXPORTED_FUNCTIONS=['_process_web','_free_cstring_web']")]
extern {}
/// Process a map tile.
/// Takes an array as a pointer and a length.
/// Returns a C string.
pub extern fn process_web(p: *const u8, len: usize) -> *const c_char {
let input = unsafe {
slice::from_raw_parts(p, len)
let output = process(input).expect("input file is valid");
CString::new(output).expect("string contains no internal NULL").into_raw()
/// CString must not be just freed but the drop function must run according to docs.
/// Note: The Drop impl writes 0 in the byte of string and makes it unusable.
pub extern fn free_cstring_web(p: *mut c_char) {
unsafe {
if p.is_null() { return }
/// asm.js expects a main function.
fn main() {}