importScripts('zlib.js');
importScripts('png.js');
importScripts('ElevDecompress.js');
importScripts('jpglib2.js');
self.addEventListener('message', function (e) {
var data = e.data;
data.rejected = false;
//data.zeroLevel = false; //for rejected data (when using MPT) - There are 6 mpt requests at the begining that should not be parsed for elevation. Nevertheless, we MUST NOT mark them as unavailiable tiles.
if (isPNG(data)) {
var png = new PNG(new Uint8Array(data.buffer));
//postMessage(JSON.stringify({ type: 'debug', msg: data.deferedId + " 1" }));
var pixels = png.decodePixels();
var out = new Int16Array(pixels.length / 2);
for (var i = 0; i < pixels.length / 2; i++) {
out[i] = (pixels[i * 2] << 8 | pixels[i * 2 + 1]);
// -1 is null value, do not change
if (out[i] != 65535) // -1 sint16
out[i] = out[i] * 0.3048;
}
data.buffer = out;
postMessage(data/*, [data.buffer.buffer]*/);
}
else if (isMPT(data)) {
var bBoxSize = 96;
var dv = new DataView(data.buffer);
var dataBeginOffset = dv.getUint32(64, true);
var dataSize = dv.getUint32(68, true);
var extend = dv.getUint32(72, true);
var parts = dv.getUint32(76, true);
var sizeColor = (dv.getUint32(bBoxSize + 4, true) & 0xffffff) - (dv.getUint32(bBoxSize + 0, true) & 0xffffff);
var sizeElevation = (dv.getUint32(bBoxSize + 8, true) & 0xffffff) - (dv.getUint32(bBoxSize + 4, true) & 0xffffff);
var dataStreamBegin = bBoxSize + sizeColor + dataBeginOffset;
var channelOffset = (dv.getUint32(dataStreamBegin + 0, true) & 0x00FFFFFF); //16
var channelType = dv.getUint32(dataStreamBegin + 4, true);
var channelData = String.fromCharCode((channelType) >> 24);
var dataStartPoint = dataStreamBegin + channelOffset;
var dataEndPoint = dataStartPoint + sizeElevation;
if (channelData == 'N') { // PNG16.8
var result = PNG16_8Decompress(data.buffer.slice(dataStartPoint, dataEndPoint));
data.buffer = result;
postMessage(data);
}
else if (channelData == 'B') { //JPEG
var result = JPEGDecompress(data.buffer.slice(dataStartPoint, dataEndPoint));
var out = new Float32Array(256*256);
for (var i = 0; i < (256*256); i++) {
out[i] = result[i];
}
// // for (var i = 0; i < 256 * 256; i++) {
// var value = Math.fmod(result[i], Math.pow(2, 32));
// if (value != 65535) {
// out[i] = value;
// }
// }
data.buffer = out;
postMessage(data);
}
else if (channelData == 'A') { //PNG16
var out = PNGDecompress(data.buffer.slice(dataStartPoint, dataEndPoint));
data.buffer = out;
postMessage(data);
} else { // debugging and other formats currently not supported
data.rejected = true;
postMessage(data);
//var len = this.heightMapWidth * this.heightMapHeight;
//var buf = new Int16Array(len);
//var val = 0;
//for (var i = 0; i < len; i++)
// buf[i] = val;
//data.buffer = buf;
//postMessage(data/*, [data.buffer.buffer]*/);
}
}
else {
// I dont know. reject.
data.rejected = true;
postMessage(data);
}
});
function isPNG(data) {
if (data.buffer.byteLength > 2) {
var PNGArray = new Uint8Array(data.buffer.byteLength > 0 ? data.buffer.slice(1, 4) : 0);
var _isPNG = ((PNGArray.length == 0) || (PNGArray[0] == 'P'.charCodeAt() && PNGArray[1] == 'N'.charCodeAt() && PNGArray[2] == 'G'.charCodeAt()));
return _isPNG;
}
return false;
}
function isMPT(data) {
if (data.buffer.byteLength > 80) {
var bBoxSize = 96;
var dv = new DataView(data.buffer);
var dataBeginOffset = dv.getUint32(64, true);
var dataSize = dv.getUint32(68, true);
var extend = dv.getUint32(72, true);
var parts = dv.getUint32(76, true);
if (parts == 1) // There should be only one part
return true;
else
return false;
}
return false;
}
//fmod
Math.fmod = function (a, b) { return Number((a - (Math.floor(a / b) * b)).toPrecision(8)); };
//random buffer should not be used... only for debugging
function getRandomIntInclusive(min, max) {
return Math.floor(Math.random() * (max - min + 1)) + min;
}
//decompress JPEG - use jpglib2.js
function JPEGDecompress(array) {
var minval = 0;
var maxval = 0;
var m_prelist;
var byteArray = new Uint8Array(array);
var dvJPEG = new DataView(byteArray.buffer);
minval = dvJPEG.getFloat32(0,true);
maxval = dvJPEG.getFloat32(4, true);
m_prelist = byteArray.slice(8, 8 + 256); // 2* sizeof(float) + PRE_LISTSIZE
var buffer8 = byteArray.slice(256 + 8, byteArray.byteLength);
var jpegDecompressed = decode(buffer8, true, 1);
if (!isNaN(jpegDecompressed.data[0])) {
var jpegElev = new JPEGElevDecompress();
var result = jpegElev.ElevDecompress(jpegDecompressed, m_prelist, minval, maxval);
return result;
} else {
console.error("Error while JPEG Decompressing");
}
}
//decompress png - use png.js library
function PNGDecompress(array) {
var byteArray = new Uint8Array(array);
var dvPNG = new DataView(array);
var min = dvPNG.getFloat32(0, true);
var max = dvPNG.getFloat32(4, true);
var delta = max - min;
var slicedArray = byteArray.slice(8, byteArray.buffer.byteLength);
var png = new PNG(new Uint8Array(slicedArray));
var pixels = png.decodePixels();
var out = new Float32Array(pixels.length / 2);
var dvwords = new DataView(pixels.buffer);
for (var i = 0; i < pixels.length / 2; i++) {
out[i] = dvwords.getUint16(i * 2);
//out[i] = ( pixels[i*2]<<8 | pixels[i*2+1] );
// if (out[i] != 65535) // -1 sint
out[i] = out[i] * delta/65535.0 + min;
}
return out;
}
// decompress PNG16.8
function PNG16_8Decompress(array) {
var sizeOne = 0;
var sizeTwo = 0;
var byteArray = new Uint8Array(array);
var dv168 = new DataView(byteArray.buffer);
sizeOne = dv168.getUint32(0,true);
sizeTwo = dv168.getUint32(4,true);
var channelSizeN = 8 + sizeOne + sizeTwo;
//first buffer (words)
var firstBuffer = byteArray.slice(8, 8 + sizeOne);
var firstPNG = new PNG(new Uint8Array(firstBuffer));
var pixels = firstPNG.decodePixels();
var pixels1View = new DataView(pixels.buffer);
//second buffer (bytes)
var secondBuffer = byteArray.slice(8 + sizeOne,channelSizeN);
var secondPNG = new PNG(new Uint8Array(secondBuffer));
var pixels2 = secondPNG.decodePixels();
var pixels2View = new DataView(pixels.buffer);
var floatArray = new Float32Array(256*256);
var feet2meter = 0.3048;
for (var iii = 0; iii < 256; iii++)
for (var jjj = 0; jjj < 256 ; jjj++) {
floatArray[jjj + iii * 256] = (pixels1View.getInt16((jjj + iii * 256)*2) + pixels2[jjj + iii * 256] / 256) * feet2meter;
}
return floatArray;
}
