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Add some comments in the "articles nearby" algorithm

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mossroy 2013-11-24 11:19:55 +01:00
parent d195cc9413
commit cab27028ec
1 changed files with 43 additions and 11 deletions
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54
js/lib/archive.js
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@ -716,11 +716,12 @@ define(function(require) {
};
/**
* Finds articles that are located inside the given rectangle
* Finds titles that are located inside the given rectangle
* This is the main function, that has to be called from the application
*
* @param {type} rect Rectangle where to look for articles
* @param {type} maxTitles Maximum number of articles to find
* @param callbackFunction Function to call with the list of articles found
* @param {type} rect Rectangle where to look for titles
* @param {type} maxTitles Maximum number of titles to find
* @param callbackFunction Function to call with the list of titles found
*/
LocalArchive.prototype.getTitlesInCoords = function(rect, maxTitles, callbackFunction) {
var normalizedRectangle = rect.normalized();
@ -728,6 +729,20 @@ define(function(require) {
LocalArchive.getTitlesInCoordsInt(this, i, 0, normalizedRectangle, GLOBE_RECTANGLE, maxTitles, new Array(), callbackFunction, LocalArchive.callbackGetTitlesInCoordsInt);
};
/**
* Callback function called by getTitlesInCoordsInt (or by itself), in order
* to loop through every coordinate file, and search titles nearby in each
* of them.
* When all the coordinate files are searched, or when enough titles are
* found, the callbackFunction is called
*
* @param {type} localArchive
* @param {type} titlesFound
* @param {type} i : index of the coordinate file
* @param {type} maxTitles
* @param {type} normalizedRectangle
* @param {type} callbackFunction
*/
LocalArchive.callbackGetTitlesInCoordsInt = function(localArchive, titlesFound, i, maxTitles, normalizedRectangle, callbackFunction) {
i++;
if (titlesFound.length < maxTitles && i < localArchive.coordinateFiles.length) {
@ -740,8 +755,8 @@ define(function(require) {
};
/**
* Reads 4 bytes in given byteArray, starting at startIndex, and convert
* these 4 bytes into latitude and longitude (each uses 2 bytes, little endian)
* Reads 8 bytes in given byteArray, starting at startIndex, and convert
* these 8 bytes into latitude and longitude (each uses 4 bytes, little endian)
* @param {type} byteArray
* @param {type} startIndex
* @returns {_L23.geometry.point}
@ -753,6 +768,19 @@ define(function(require) {
return point;
};
/**
* Searches in a coordinate file some titles in a target rectangle.
* This function recursively calls itself, in order to browse all the quadtree
* @param {type} localArchive
* @param {type} coordinateFileIndex
* @param {type} coordFilePos
* @param {type} targetRect
* @param {type} thisRect
* @param {type} maxTitles
* @param {type} titlesFound
* @param {type} callbackFunction
* @param {type} callbackGetTitlesInCoordsInt
*/
LocalArchive.getTitlesInCoordsInt = function(localArchive, coordinateFileIndex, coordFilePos, targetRect, thisRect, maxTitles, titlesFound, callbackFunction, callbackGetTitlesInCoordsInt) {
var reader = new FileReader();
reader.onerror = errorHandler;
@ -768,21 +796,22 @@ define(function(require) {
// 0xFFFF = 65535 in decimal
if (selector === 65535) {
// not enough articles, further subdivision needed
// This is an innernode : let's browse it subdivisions
var center = readCoordinates(byteArray, 2);
var lensw = util.readIntegerFrom4Bytes(byteArray, 10);
var lense = util.readIntegerFrom4Bytes(byteArray, 14);
var lennw = util.readIntegerFrom4Bytes(byteArray, 18);
// compute the 4 positions
// Compute the 4 positions in coordinate file
var pos0 = coordFilePos + 22;
var pos1 = pos0 + lensw;
var pos2 = pos1 + lense;
var pos3 = pos2 + lennw;
// compute the 4 rectangles
// Compute the 4 rectangles around
var rectSW = new geometry.rect(thisRect.origin(), center);
var rectSE = (new geometry.rect(thisRect.topRight(), center)).normalized();
var rectNW = (new geometry.rect(thisRect.bottomLeft(), center)).normalized();
var rectNE = (new geometry.rect(thisRect.corner(), center)).normalized();
// Recursively call this function for each rectangle around
if (targetRect.intersect(rectSW)) {
LocalArchive.getTitlesInCoordsInt(localArchive, coordinateFileIndex, pos0, targetRect, rectSW, maxTitles, titlesFound, callbackFunction, callbackGetTitlesInCoordsInt);
}
@ -797,6 +826,9 @@ define(function(require) {
}
}
else {
// This is a leaf node : let's see if its articles are in the
// target rectangle
// TODO this part needs to be reworked.
// It computes coordinates and title positions correctly, but
// I can not push titles found in the list with a simple for loop because of the asynchronous read
@ -827,11 +859,11 @@ define(function(require) {
// As there can be up to 65535 different coordinates, we have to read 22*65535 bytes = 1.44MB
// TODO : This should be improved by reading the file in 2 steps :
// - first read the selector
// - the read the coordinates (reading only the exact necessary bytes)
// - then read the coordinates (reading only the exact necessary bytes)
var blob = localArchive.coordinateFiles[coordinateFileIndex].slice(coordFilePos, coordFilePos + 22*65535);
// Read in the file as a binary string
reader.readAsArrayBuffer(blob);
};
/**