Develop Reference

Form element Iteration, in Javascript

I've been working on a code snippet for a template module that I have been creating and I've hit a wall so to speak. I'm trying to loop through all textareas on my page, and apply formatting with some very basic validation.
Javascript is not my strongest suit but I can understand it to a point, my question is how do I collect the ID's and then use them to apply the formatting.
For example,
for each (textarea)
{
collect character restriction from html
display character restriction in a formatted manner
}
I have included my JSFiddle which I have been using to build this snippet.

I would suggest creating a prototype class for this, that can be extended to do other things aswell:
var CharWatcher = function(input){
this.max = input.getAttribute('max-length');
this.input = input;
input.onKeyDown = this.update.bind(this);
this.wrapper = document.createElement('div');
this.wrapper.innerHTML = 'Chars left: '+ (max - input.value.length);
/* style wrapper element */
/* append around input */
};
CharWatcher.prototype = {
update: function(){
this.wrapper.innerHTML = 'Chars left: ' + (this.max - this.input.value.length);
}
};
/* Somewhere else */
var textareas = document.getElementsByTagName('textarea');
for(var i = 0, l = textareas.length; i < l; i++)
new CharWatcher(textareas[i]);

I've based on #FodorZoltán's class. My class does now:
append the counter below the textarea;
position the counter in the below part of the textarea;
Yeah, I'm lazy and the code has grown up. I added some events and renamed the class name to "TextAreaRanger". It's working here:
var TextAreaRanger = function(input) {
this.MAX = parseInt(input.getAttribute('maxlength'));
this.INPUT = input;
// add input events
input["oncut"] =
input["onpaste"] =
input["onkeydown"] =
input["onkeyup"] = this.update.bind(this);
// create wrapper element
this.wrapper = document.createElement('div');
this.wrapper.innerHTML = 'Chars left: '+ (this.MAX - input.value.length);
/* input parent element */
var ipar = input.parentNode;
// find input's i
for (var i = 0, el; el = ipar.children[i]; i ++) {
if(el === input) break;
}
// append wrapper below the input
if (ipar.children[++i]) {
ipar.insertBefore(this.wrapper, ipar.children[i]);
} else ipar.appendChild(this.wrapper);
/* stylize wrapper */
this.wrapper.style.position = "relative";
this.wrapper.style.color = '#f00';
this.wrapper.style.fontSize = '11px';
this.wrapper.style.left = (input.offsetLeft + (input.offsetWidth - 100)) + "px";
this.wrapper.style.top = (-parseInt(this.wrapper.style.fontSize) * 2) + "px";
};
// Update the counter
TextAreaRanger.prototype["update"] = function() {
this.wrapper.innerHTML = 'Chars left: ' + (this.MAX - this.INPUT.value.length);
};

My javascript canvas map script and poor performance

Basically below is my script for a prototype which uses 128x128 tiles to draw a map on a canvas which user can drag to move around.
Script does work. However I have a few problems to be solved:
1. Poor performance and I can't figure out why.
2. I am missing a method to buffer the tiles before the actual drawing.
3. If you notice any other issues also that could help me to make things run more smoothly it would be fantastic.
Some explanations for the script:
variables
coordinates - Defines the actual images to be displayed. Image file names are type of '0_1.jpg', where 0 is Y and 1 is X.
mouse_position - As name says, is keeping record of mouse position.
position - This is a poorly named variable. It defines the position of the context drawn on canvas. This changes when user drags the view.
Any assistance would be appreciated greatly. Thank you.
var coordinates = [0, 0];
var mouse_position = [0, 0];
var position = [-128, -128];
var canvas = document.getElementById('map_canvas');
var context = canvas.getContext('2d');
var buffer = [];
var buffer_x = Math.floor(window.innerWidth/128)+4;
var buffer_y = Math.floor(window.innerHeight/128)+4;
var animation_frame_request = function() {
var a = window.requestAnimationFrame;
var b = window.webkitRequestAnimationFrame;
var c = window.mozRequestAnimationFrame;
var d = function(callback) {
window.setTimeout(callback, 1000/60);
}
return a || b || c || d;
}
var resizeCanvas = function() {
window.canvas.width = window.innerWidth;
window.canvas.height = window.innerHeight;
window.buffer_x = Math.floor(window.innerWidth/128)+4;
window.buffer_y = Math.floor(window.innerHeight/128)+4;
window.buffer = [];
for (row = 0; row < window.buffer_y; row++) {
x = [];
for (col = 0; col < window.buffer_x; col++) {
x.push(new Image());
}
window.buffer.push(x);
}
}
var render = function() {
animation_frame_request(render);
for (row = 0; row < window.buffer_y; row++) {
for (col = 0; col < window.buffer_x; col++) {
cy = window.coordinates[1]+row;
cx = window.coordinates[0]+col;
window.buffer[row][col].src = 'map/'+cy+'_'+cx+'.jpg';
}
}
for (row = 0; row < window.buffer_y; row++) {
for (col = 0; col < window.buffer_x; col++) {
window.context.drawImage(window.buffer[row][col],
window.position[0]+col*128,
window.position[1]+row*128, 128, 128);
}
}
}
var events = function() {
window.canvas.onmousemove = function(e) {
if (e['buttons'] == 1) {
window.position[0] += (e.clientX-window.mouse_position[0]);
window.position[1] += (e.clientY-window.mouse_position[1]);
if (window.position[0] >= 0) {
window.position[0] = -128;
window.coordinates[0] -= 1;
} else if (window.position[0] < -128) {
window.position[0] = 0;
window.coordinates[0] += 1;
}
if (window.position[1] >= 0) {
window.position[1] = -128;
window.coordinates[1] -= 1;
} else if (window.position[1] < -128) {
window.position[1] = 0;
window.coordinates[1] += 1;
}
render();
}
window.mouse_position[0] = e.clientX;
window.mouse_position[1] = e.clientY;
}
}
window.addEventListener('resize', resizeCanvas, false);
window.addEventListener('load', resizeCanvas, false);
window.addEventListener('mousemove', events, false);
resizeCanvas();

To get better performance you should avoid changing the src of img nodes and move them around instead.
A simple way to minimize the number of img nodes handled and modified (except for screen positioning) is to use an LRU (Least Recently Used) cache.
Basically you keep a cache of last say 100 image nodes (they must be enough to cover at least one screen) by using a dictionary mapping the src url to a node object and also keeping them all in a doubly-linked list.
When a tile is required you first check in the cache, and if it's already there just move it to the front of LRU list and move the img coordinates, otherwise create a new node and set the source or, if you already hit the cache limit, reuse the last node in the doubly-linked list instead. In code:
function setTile(x, y, src) {
var t = cache[src];
if (!t) {
if (cache_count == MAXCACHE) {
t = lru_last;
t.prev.next = null;
lru_last = t.prev;
t.prev = t.next = null;
delete cache[t.src]
t.src = src;
t.img.src = src;
cache[t.src] = t;
} else {
t = { prev: null,
next: null,
img: document.createElement("img") };
t.src = src;
t.img.src = src;
t.img.className = "tile";
scr.appendChild(t.img);
cache[t.src] = t;
cache_count += 1;
}
} else {
if (t.prev) t.prev.next = t.next; else lru_first = t.next;
if (t.next) t.next.prev = t.prev; else lru_last = t.prev;
}
t.prev = null; t.next = lru_first;
if (t.next) t.next.prev = t; else lru_last = t;
lru_first = t;
t.img.style.left = x + "px";
t.img.style.top = y + "px";
scr.appendChild(t.img);
}
I'm also always appending the requested tile to the container so that it goes in front of all other existing tiles; this way I don't need to remove old tiles and they're simply left behind.
To update the screen I just iterate over all the tiles I need and request them:
function setView(x0, y0) {
var w = scr.offsetWidth;
var h = scr.offsetHeight;
var iy0 = y0 >> 7;
var ix0 = x0 >> 7;
for (var y=iy0; y*128 < y0+h; y++) {
for (var x=ix0; x*128 < x0+w; x++) {
setTile(x*128-x0, y*128-y0, "tile_" + y + "_" + x + ".jpg");
}
}
}
most of the time the setTile request will just update the x and y coordinates of an existing img tag, without changing anything else. At the same time no more than MAXCACHE image nodes will be present on the screen.
You can see a full working example in
http://raksy.dyndns.org/tiles/tiles.html

How do i change default orientation in infovis spacetree?

I'm trying to change the default orientation in a space tree but can't figure out where to add:
st.switchPosition("top", "animate", {
onComplete: function() {
alert('completed!');
}
});
So that the tree will start from the top instead of the default of right.
In the examples i've seen, the switchPosition is only used with an event handler, which i do not intend to have.
So in the example (taken from the infovis site:Infovis - spacetree ), where should i add the code (or any code) in order to change the default orientation?
var labelType, useGradients, nativeTextSupport, animate;
(function() {
var ua = navigator.userAgent,
iStuff = ua.match(/iPhone/i) || ua.match(/iPad/i),
typeOfCanvas = typeof HTMLCanvasElement,
nativeCanvasSupport = (typeOfCanvas == 'object' || typeOfCanvas == 'function'),
textSupport = nativeCanvasSupport
&& (typeof document.createElement('canvas').getContext('2d').fillText == 'function');
//I'm setting this based on the fact that ExCanvas provides text support for IE
//and that as of today iPhone/iPad current text support is lame
labelType = (!nativeCanvasSupport || (textSupport && !iStuff))? 'Native' : 'HTML';
nativeTextSupport = labelType == 'Native';
useGradients = nativeCanvasSupport;
animate = !(iStuff || !nativeCanvasSupport);
})();
var Log = {
elem: false,
write: function(text){
if (!this.elem)
this.elem = document.getElementById('log');
this.elem.innerHTML = text;
this.elem.style.left = (500 - this.elem.offsetWidth / 2) + 'px';
}
};
function init(){
//init data
var json = {....removed due to space here in the group....}
//end
//A client-side tree generator
var getTree = (function() {
var i = 0;
return function(nodeId, level) {
var subtree = eval('(' + json.replace(/id:\"([a-zA-Z0-9]+)\"/g,
function(all, match) {
return "id:\"" + match + "_" + i + "\""
}) + ')');
$jit.json.prune(subtree, level); i++;
return {
'id': nodeId,
'children': subtree.children
};
};
})();
//Implement a node rendering function called 'nodeline' that plots a straight line
//when contracting or expanding a subtree.
$jit.ST.Plot.NodeTypes.implement({
'nodeline': {
'render': function(node, canvas, animating) {
if(animating === 'expand' || animating === 'contract') {
var pos = node.pos.getc(true), nconfig = this.node, data = node.data;
var width = nconfig.width, height = nconfig.height;
var algnPos = this.getAlignedPos(pos, width, height);
var ctx = canvas.getCtx(), ort = this.config.orientation;
ctx.beginPath();
if(ort == 'left' || ort == 'right') {
ctx.moveTo(algnPos.x, algnPos.y + height / 2);
ctx.lineTo(algnPos.x + width, algnPos.y + height / 2);
} else {
ctx.moveTo(algnPos.x + width / 2, algnPos.y);
ctx.lineTo(algnPos.x + width / 2, algnPos.y + height);
}
ctx.stroke();
}
}
}
});
//init Spacetree
//Create a new ST instance
var st = new $jit.ST({
'injectInto': 'infovis',
//set duration for the animation
duration: 800,
//set animation transition type
transition: $jit.Trans.Quart.easeInOut,
//set distance between node and its children
levelDistance: 50,
//set max levels to show. Useful when used with
//the request method for requesting trees of specific depth
levelsToShow: 2,
//set node and edge styles
//set overridable=true for styling individual
//nodes or edges
Node: {
height: 20,
width: 40,
//use a custom
//node rendering function
type: 'nodeline',
color:'#23A4FF',
lineWidth: 2,
align:"center",
overridable: true
},
Edge: {
type: 'bezier',
lineWidth: 2,
color:'#23A4FF',
overridable: true
},
//Add a request method for requesting on-demand json trees.
//This method gets called when a node
//is clicked and its subtree has a smaller depth
//than the one specified by the levelsToShow parameter.
//In that case a subtree is requested and is added to the dataset.
//This method is asynchronous, so you can make an Ajax request for that
//subtree and then handle it to the onComplete callback.
//Here we just use a client-side tree generator (the getTree function).
request: function(nodeId, level, onComplete) {
var ans = getTree(nodeId, level);
onComplete.onComplete(nodeId, ans);
},
onBeforeCompute: function(node){
Log.write("loading " + node.name);
},
onAfterCompute: function(){
Log.write("done");
},
//This method is called on DOM label creation.
//Use this method to add event handlers and styles to
//your node.
onCreateLabel: function(label, node){
label.id = node.id;
label.innerHTML = node.name;
label.onclick = function(){
st.onClick(node.id);
};
//set label styles
var style = label.style;
style.width = 40 + 'px';
style.height = 17 + 'px';
style.cursor = 'pointer';
style.color = '#fff';
//style.backgroundColor = '#1a1a1a';
style.fontSize = '0.8em';
style.textAlign= 'center';
style.textDecoration = 'underline';
style.paddingTop = '3px';
},
//This method is called right before plotting
//a node. It's useful for changing an individual node
//style properties before plotting it.
//The data properties prefixed with a dollar
//sign will override the global node style properties.
onBeforePlotNode: function(node){
//add some color to the nodes in the path between the
//root node and the selected node.
if (node.selected) {
node.data.$color = "#ff7";
}
else {
delete node.data.$color;
}
},
//This method is called right before plotting
//an edge. It's useful for changing an individual edge
//style properties before plotting it.
//Edge data proprties prefixed with a dollar sign will
//override the Edge global style properties.
onBeforePlotLine: function(adj){
if (adj.nodeFrom.selected && adj.nodeTo.selected) {
adj.data.$color = "#eed";
adj.data.$lineWidth = 3;
}
else {
delete adj.data.$color;
delete adj.data.$lineWidth;
}
}
});
//load json data
st.loadJSON(eval( '(' + json + ')' ));
//compute node positions and layout
st.compute();
//emulate a click on the root node.
st.onClick(st.root);
//end
//Add event handlers to switch spacetree orientation. - Which i do not want...
// function get(id) {
// return document.getElementById(id);
// };
// var top = get('r-top'),
// left = get('r-left'),
// bottom = get('r-bottom'),
// right = get('r-right');
// function changeHandler() {
// if(this.checked) {
// top.disabled = bottom.disabled = right.disabled = left.disabled = true;
// st.switchPosition(this.value, "animate", {
// onComplete: function(){
// top.disabled = bottom.disabled = right.disabled = left.disabled = false;
// }
// });
// }
// };
// top.onchange = left.onchange = bottom.onchange = right.onchange = changeHandler;
//end
}

You can drop in orientation:'top', shortly into the new $jit.ST function, ie:
var st = new $jit.ST({
//id of viz container element
injectInto: 'infovis',
//SET THE TREE TO VERTICAL
orientation:"top",
//set duration for the animation
duration: 800,
Source: https://groups.google.com/forum/#!searchin/javascript-information-visualization-toolkit/top/javascript-information-visualization-toolkit/MhXSXJUmaIk/V5JNwSe359gJ

Bind events to all elements in class instead of just to one id

I developed this interaction / script that scales whatever element is passed to it and if that element is pinched in on, it scales down / less.
This is how the script is initialised ( passing two arguments the container and the item to be scaled / transformed:
$(function(){
var zoom = new collapse('#zoom','#zoom :first');
var zoom2 = new collapse('#zoom2','#zoom2 :first');
var zoom3 = new collapse('#zoom3','#zoom3 :first');
});
It works fine as above on single IDs, but I need it to work on a class.
I tried this:
$(function(){
var zoom = new collapse('#zoom','.polaroid');
});
But that causes the whole script not to work because all the elements in that class are being passed instead of one as with an id.
This would only select the first item in the class so it won't work:
$(function(){
var zoom = new collapse('#zoom','.polaroid :first');
});
How can I change my script so that it is applied to all members of the .polaroid class in the #main container?
Here is my script:
function collapse(container, element){
container = $(container).hammer({
prevent_default: true,
scale_threshold: 0
});
element = $(element);
var displayWidth = container.width();
var displayHeight = container.height();
var MIN_ZOOM = 0;
var MAX_ZOOM = 1;
var scaleFactor = 1;
var previousScaleFactor = 1;
var startX = 0;
var startY = 0;
var translateX = 0;
var translateY = 0;
var previousTranslateX = 0;
var previousTranslateY = 0;
var time = 1;
var tch1 = 0,
tch2 = 0,
tcX = 0,
tcY = 0,
toX = 0,
toY = 0,
cssOrigin = "";
container.bind("transformstart", function(event){
e = event;
tch1 = [e.touches[0].x, e.touches[0].y],
tch2 = [e.touches[1].x, e.touches[1].y];
tcX = (tch1[0]+tch2[0])/2,
tcY = (tch1[1]+tch2[1])/2;
toX = tcX;
toY = tcY;
var left = $(element).offset().left;
var top = $(element).offset().top;
cssOrigin = (-(left) + toX)/scaleFactor +"px "+ (-(top) + toY)/scaleFactor +"px";
});
container.bind("transform", function(event){
scaleFactor = previousScaleFactor * event.scale;
scaleFactor = Math.max(MIN_ZOOM, Math.min(scaleFactor, MAX_ZOOM));
transform(event);
});
container.bind("transformend", function(event){
previousScaleFactor = scaleFactor;
if(scaleFactor > 0.42){
$(element).css('-webkit-transform', 'scaleY(1.0)').css('transform', 'scaleY(1.0)');
}
});
function transform(e){
var cssScale = "scaleY("+ scaleFactor +")";
element.css({
webkitTransform: cssScale,
webkitTransformOrigin: cssOrigin,
transform: cssScale,
transformOrigin: cssOrigin,
});
if(scaleFactor <= 0.42){
$(element).animate({height:0}, function(){
$(this).remove();
});
}
}
}

Wrap it as a jquery plugin:
$.fn.collapse = function(filter) {
return this.each(function(){
collapse(this,filter);
});
}
$("#zoom,#zoom1,#zoom2").collapse(".polaroid");
or if each of the zoom elements had a common class,
$(".zoomel").collapse(".polaroid");

You have to run collapse for each element.
element = $(element);
element.each(function(){
//each element would be this here
var $this= $(this);
//do whatever you want with $this
})

webGL story sphere popups

I am trying to adapt the really cool looking WebGL Story Sphere, source code and css here. There's one big problem: once you click on a news article, the text of the article in the popup is always the same. I want to modify the code so that when you click on an article, the right text appears in the popup.
I'm working from a set of article texts that I specify in the code, e.g. var captions = ["good","better","best"]. Though the article titles and images populate correctly in the popup, I can't get the text to do so. Can you help me?? Here's what I've got:
// function code
var passvar = null; // failed attempt to store texts for later
function initialize() {
math = tdl.math;
fast = tdl.fast;
canvas = document.getElementById("canvas");
g_fpsTimer = new tdl.fps.FPSTimer();
hack();
canvas.addEventListener("mousedown", handleMouseDown, false);
canvas.addEventListener("mousemove", handleMouseMove, false);
canvas.addEventListener("mouseup", handleMouseUp, false);
// Create a canvas 2d for making textures with text.
g_canvas2d = document.createElement('canvas');
window.two2w = window.two2h = g_tilesize;
g_canvas2d.width = two2w;
g_canvas2d.height = two2h;
g_ctx2d = g_canvas2d.getContext("2d");
window.gl = wu.create3DContext(canvas);
if (g_debug) {
gl = wd.makeDebugContext(gl, undefined, LogGLCall);
}
//gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, gl.TRUE);
// Here is where I specify article titles, images, captions
// Titles and images populate the popup correctly, captions don't...
var titles = ["a","b","c"];
var captions = ["good","better","best"];
var images = ['imagesphere/assets/1.jpg',
'imagesphere/assets/bp/2.png',
'imagesphere/assets/bp/3.png'
];
var headlines = titles.concat( titles);
var blurbs = captions.concat( captions);
var tmpImages = [];
var tmpHeadlines = [];
var tmpCaptions = [];
// make a bunch of textures.
for (var ii = 0; ii < g_imagesDownGrid; ++ii) {
var textures = [];
for (var jj = 0; jj < g_imagesAcrossGrid; ++jj) {
var imgTexture = new ImgTexture();
textures.push(imgTexture);
if (tmpImages.length == 0) {
tmpImages = images.slice();
}
if (tmpHeadlines.length == 0) {
tmpHeadlines = headlines.slice();
}
if (tmpCaptions.length == 0) {
tmpCaptions = blurbs.slice();
}
var rando = math.randomInt(tmpImages.length);
var img = tmpImages.splice(rando, 1)[0];
var headline = tmpHeadlines.splice(rando, 1)[0];
var caption = tmpCaptions.splice(rando, 1)[0];
passvar = caption;
if (img.indexOf('videoplay.jpg') > -1){
window.vidtexture = imgTexture;
images = images.slice(1); // dont use that thumb again.
headlines = 'WebGL Brings Video To the Party as Well'
}
imgTexture.load(img, /* "[" + jj + "/" + ii + "]" + */ headline);
}
g_textures.push(textures);
}
// And here's where I try to put this in a popup, finally
// But passvar, the stored article text, never refreshes!!!
<div id="story" class="prettybox" style="display:none">
<img class="close" src="imagesphere/assets/close.png">
<div id="storyinner">
<input id = "mytext">
<script>document.getElementById("mytext").value = passvar;</script>
</div>
</div>
And here is my click handler code:
function sphereClick(e){
window.console && console.log('click!', e, e.timeStamp);
var selected = g_textures[sel.y][sel.x];
window.selected = selected;
animateGL('eyeRadius', glProp('eyeRadius'), 4, 500);
var wwidth = $(window).width(),
wheight = $(window).height(),
story = $('#story').width( ~~(wwidth / 7 * 4) ).height( ~~(wheight / 6 * 5) ),
width = story.width(),
height = story.height(),
miniwidth = 30;
story.detach()
.find('#storyinner').find('h3,img,caption').remove().end().end()
.show();
story.css({
left : e.pageX,
top : e.pageY,
marginLeft : - width / 2,
marginTop : - height / 2
}).appendTo($body); // we remove and put back on the DOM to reset it to the correct position.
$('style.anim.story').remove();
$('<style class="anim story">')
.text( '.storyopen #story { left : ' + (wwidth / 3 * 2) + 'px !important; top : ' + wheight / 2 + 'px !important; }' )
.appendTo($body);
$(selected.img).prependTo('#storyinner').parent();
$('<h3>').text(selected.msg.replace(/\(.*/,'')).prependTo('#storyinner');
$body.addClass('storyopen');
} // eo sphereClick()

There's a lot wrong here, but here's a start. It won't solve your problem, but it will help you avoid issues like this.
var passvar = null; is a global variable.
Your loop for (var ii = 0; ... sets that global variable to a new value on every iteration.
Later, you click something and the global variable passvar is never changed.
If you want to use this pattern, you need to set passvar from your click handler so it has the value that was clicked. Since you didn't actually post your click handlers, it's hard to advise more.
But this is also a bad pattern, functions take arguments for a good reason. Since you have to find your clicked item in the click handler anyway, why not pass it directly which does involve a shared global variable at all?
var handleMouseUp = function(event) {
var story = findClickedThing(event);
if (obj) {
showPopup(story.texture, story.caption);
}
}
Which brings me to this:
var titles = ["a","b","c"];
var captions = ["good","better","best"];
var images = ['imagesphere/assets/1.jpg',
'imagesphere/assets/bp/2.png',
'imagesphere/assets/bp/3.png'
];
When you have 3 arrays, all of the same length, each array describing a different property of an object, you are doing it wrong. What you want, is one array of objects instead.
var stories = [
{
title: "a",
caption: "good",
image: "imagesphere/assets/1.jpg"
}, {
title: "b",
caption: "better",
image: "imagesphere/assets/bp/2.jpg"
}, {
title: "c",
caption: "best",
image: "imagesphere/assets/bp/3.jpg"
},
];
console.log(stories[1].caption); // "better"
Now once you find the clicked object, you can just ask it what it's caption is. And you can pass the whole object to the popup maker. And no field is handled differently or passed around in a different manner, because you are not passing around the fields. You are passsing the entire object.