// JavaScript Document /* To use this file, add this line to the html page, in the section, after the jsHeadPictVars.js script, and any other variable declaration scripts (e.g. jsHeadMenuVars.js). */ /* The functions in this file are used to choose pictures from random folders in the images/departments folder. This file is included via the page templates. It is a separate js file so that the code can be changed without the template having to be changed. */ // This function intializes the deptArray array, that is // used to keep track of which pictures in which folders have // be displayed on the page border. This is a the value is // essentially boolean - if the folder hasn't been used, its // value is 0, and if the folder has been used the value is 1. // It also initializes the array containing the "index" into // the pictures in the folder. This will be a random number // corresponding to a picture. function initPicArrays () { var m; var pIndex; for (m = 0; m < numDepts; m++) { deptArray [m] = 0; // deptFolderLen is an array with the number of pictures // in each of the picture folders. So, to get a starting // point for choosing pictures out of the folder, get // a random number between 0 and the number of pictures // in the folder. pIndex = Math.round (Math.random() * deptFolderLen [m]); // If we do get a number that is the total number of pictures // in the folder, this will be a problem for a 0-based array // indexing, so reset the number to 0. if (pIndex == deptFolderLen [m]) pIndex = 0; // This holds the place we will start in each picture folder. // This is an "index" into which pictures in the folder have // been used. It is simply incremented as a picture is used, then // started over when the number of pictures have been exhausted. // We start each folder from a different spot by using the random number. picArray [m] = pIndex; } } // This function resets the folders array so that any folder // can be chosen again. function clearDeptArray () { var m; for (m = 0; m < numDepts; m++) deptArray [m] = 0; } // This function chooses one of the pictures on the border // to swap out. function pickPicToChange () { var num; var idName; num = (Math.round (Math.random() * 4)) -1; if (num < 0) num = 0; idName = "borderNum" + num; return idName; } // This function picks a random folder to pull a picture from. It // attempts to get different folders every time it is called until // pictures have been pulled from all possible folders. If it takes // a really long time to come up with a folder that hasn't been used, // the deptArray is cleared so the next random pick will be OK. function pickNewFolder () { var dIndex =0; var numFound = 0; while (numFound < 1) { // First, get a potential picture folder; get a random number and multiply // by the number of potential folders and round it to a whole number to get // a number between 0 and the number of potential folders. Note that this // is inclusive; we could get the number of potiential folders, which is a // problem if we are trying to use this number as an index since all arrays // use 0-based indexing. We fix that problem by making the number 0 if we // get the maximum instead. dIndex = Math.round (Math.random() * numDepts); if (dIndex == numDepts) dIndex = 0; // Increment the number of tries. numTries ++; // If we haven't used this folder before, we'll know because the first // element of the array associated with the folder will be 0. If this is // the case, this is a good "hit", so we set the value of the first // element to 1, and remember this folder index in the array we are using // to keep track of which folders we will pull pictures from for this set // of pictures. Then we increment the number of "good" folders found. if (deptArray [dIndex] == 0) { deptArray [dIndex] = 1; numFound ++; } // If we already got a picture from this folder, then we check to see // how many times we've tried to get a unique folder. If this is 3 times // the number of potential folders, we clear the deptArray array so that // the changes are much higher that we get folders that haven't been used. else { if (numTries > (3 * numDepts)) clearDeptArray (); } } return dIndex; } // This function picks a new picture from a random folder. It simply goes // through all the pictures in a folder sequentially, starting from some // random picture (see initPicArrays()). It cycles through the pictures. // This function has a timeout in it so that it will continue swapping out // random pictures. function changeAPic () { var picIDName = ""; var picName = ""; var pictureIndex = 0; var evalString = ""; picIDName = pickPicToChange(); newFolderIndex = pickNewFolder (); pictureIndex = picArray[newFolderIndex] + 1; picName = "images/departments/" + deptFolderNames [newFolderIndex] + "/small/" + pictureIndex + "_150x113.jpg"; picArray[newFolderIndex]++; if (picArray[newFolderIndex] == deptFolderLen[newFolderIndex]) picArray[newFolderIndex] = 0; evalString = "document." + picIDName + ".src = \"" + picName + "\";"; eval(evalString); // Set a timeout for another picture to be swapped out. self.setTimeout ("changeAPic();", (1 + (Math.random() * 2) * 2000)); }