We Keep Coding

Fill window with divs. Div pixel height displayed incorrectly in google chrome. Width works

I want to fill the window size with divs. For a specified div size in px, the screen will be filled as much as it can be, leaving a remainder edge amount of px on the side and bottom. This remainder amount is then divided by the number of cells in the row (or column) and that is then added to the height (or width) of each cell in the row (or column).
For the width this works perfectly but when the same logic is applied to the height, it breaks. Both width and height work in firefox.
Screenshot: http://i.imgur.com/mpDCM0G.png
JSfiddle of making the divs: https://jsfiddle.net/xb82c4zt/
Live: http://conwaygameoflife.heroku.com/
var windowWidth = window.innerWidth;
var windowHeight = window.innerHeight;
var size = 100;
// Calculate the number of cells we can fit in the width
//and height (there will be extra space)
w = Math.floor(windowWidth / size);
h = Math.floor(windowHeight / size);
// Calculate the extra space
var widthDiff = windowWidth % size;
var heightDiff = windowHeight % size;
// Add the needed amount of height and width to each cell to fill the window
var widthSize = size + widthDiff / w;
var heightSize = size + heightDiff / h;
// Begin to alter the DOM
var parentDiv = document.createElement('div');
parentDiv.className = 'grid';
for(var y = 0; y < h; y++) {
for(var x = 0; x < w; x++) {
var cellDiv = document.createElement('div')
cellDiv.className = 'cellDiv'
cellDiv.style.height = heightSize + 'px';
cellDiv.style.width = widthSize + 'px';
parentDiv.appendChild(cellDiv)
}
}
document.body.appendChild(parentDiv)

In Chrome (and probably other browsers), height and width pixel values are truncated! See this stackoverflow answer with the related jsFiddle
Precentage values are truncated too, but not as severely. So, to solve this you can convert pixels to percentages as I did in this jsFiddle.
The main thing I added was:
var widthPercent = widthSize / windowWidth * 100;
var heightPercent = heightSize / windowHeight * 100;
Because we're using percentages now, the parent container must have width/height:
parentDiv.style.height = windowHeight + 'px';
parentDiv.style.width = windowWidth + 'px';
And changed the loop to:
for(var x = 0; x < w*h; x++) {
var cellDiv = document.createElement('div');
cellDiv.className = 'cellDiv';
cellDiv.style.height = heightPercent + '%';
cellDiv.style.width = widthPercent + '%';
parentDiv.appendChild(cellDiv)
}
Now this doesn't always work in chrome perfectly. However, it does make it perfect in some cases... basically depends on when (and how drastic) the truncation of percentages is.
After further reflection, it looks like percentages get resolved to fractional pixel values as well... which still get truncated in Chrome. So, let's make our math better, and figure out the biggest non-fractional pixel value we can use... it's actually really easy. See here
Basically, we just floor the values, then center the grid so that we can make it look nice.
edit: wasn't very happy with this answer, so screwed with it some more. Added a function that found the closest multiple of window size and made it so that it would prefer that number. Makes it work in most screen sizes, and has a fallback to the percentage method if it doesn't perfectly work. See here. However, because it relies on a recursive (naive) algorithm to find the closest multiple, it's really easy to screw your browser performance. Limiting to only 5-10 pixels of search space helps. The gist of it:
function closestMultiple(width, size, n, limit) {
if(n > limit) {
return {m: width/size, s:size};
}
if((width % (size+n)) == 0) {
return {m: width / (size+n), s: size+n};
} else if((width % (size-n)) == 0) {
return {m: width / (size-n), s: size-n};
}
return closestMultiple(width, size, n+1, limit);
}
It's very naive and ignores things like "an odd width will never be divisible by an even number"... so there's a ton of room for improvement. Check out this discussion and this discussion for more on this.

Efficiently get an element's visible area coordinates

StackOverflow is loaded with questions about how to check if an element is really visible in the viewport, but they all seek for a boolean answer. I'm interested in getting the element's actual areas that are visible.
function getVisibleAreas(e) {
...
return rectangleSet;
}
Putting it more formally - the visible areas of elements is the set of (preferably non-overlapping) rectangles in CSS coordinates for which elementFromPoint(x, y) will return the element if the point (x, y) is contained in (at least) one of the rectangles in the set.
The outcome of calling this function on all DOM elements (including iframes) should be a set of non-overlapping area sets which union is the entire viewport area.
My goal is to create some kind of a viewport "dump" data structure, which can efficiently return a single element for a given point in the viewport, and vice versa - for a given element in the dump, it will return the set of visible areas.
(The data structure will be passed to a remote client application, so I will not necessarily have access to the actual document when I need to query the viewport structure).
Implementation requirements:
Obviously, the implementation should consider element's hidden state, z-index, header & footer etc.
I am looking for an implementation that works in all common used browsers, especially mobile - Android's Chrome and iOS's Safari.
Preferably doesn't use external libraries.
Of course, I could be naïve and call elementFromPoint for every discrete point in the viewport, But performance is crucial since I iterate over all of the elements, and will do it quite often.
Please direct me as to how I can achieve this goal.
Disclaimer: I'm pretty noob to web programming concepts, so I might have used wrong technical terms.
Progress:
I came up with an implementation. The algorithm is pretty simple:
Iterate over all elements, and add their vertical / horizontal lines to a coordinates map (if the coordinate is within the viewport).
Call `document.elementFromPoint` for each "rectangle" center position. A rectangle is an area between two consecutive vertical and two consecutive horizontal coordinates in the map from step 1.
This produces a set of areas / rectangles, each pointing to a single element.
The problems with my implementation are:
It is inefficient for complicated pages (can take up to 2-4 minutes for a really big screen and gmail inbox).
It produces a large amount of rectangles per a single element, which makes it inefficient to stringify and send over a network, and also inconvenient to work with (I would want to end up with a set with as few rectangles as possible per element).
As much as I can tell, the elementFromPoint call is the one that takes a lot of time and causes my algorithm to be relatively useless...
Can anyone suggest a better approach?
Here is my implementation:
function AreaPortion(l, t, r, b, currentDoc) {
if (!currentDoc) currentDoc = document;
this._x = l;
this._y = t;
this._r = r;
this._b = b;
this._w = r - l;
this._h = b - t;
center = this.getCenter();
this._elem = currentDoc.elementFromPoint(center[0], center[1]);
}
AreaPortion.prototype = {
getName: function() {
return "[x:" + this._x + ",y:" + this._y + ",w:" + this._w + ",h:" + this._h + "]";
},
getCenter: function() {
return [this._x + (this._w / 2), this._y + (this._h / 2)];
}
}
function getViewport() {
var viewPortWidth;
var viewPortHeight;
// IE6 in standards compliant mode (i.e. with a valid doctype as the first line in the document)
if (
typeof document.documentElement != 'undefined' &&
typeof document.documentElement.clientWidth != 'undefined' &&
document.documentElement.clientWidth != 0) {
viewPortWidth = document.documentElement.clientWidth,
viewPortHeight = document.documentElement.clientHeight
}
// the more standards compliant browsers (mozilla/netscape/opera/IE7) use window.innerWidth and window.innerHeight
else if (typeof window.innerWidth != 'undefined') {
viewPortWidth = window.innerWidth,
viewPortHeight = window.innerHeight
}
// older versions of IE
else {
viewPortWidth = document.getElementsByTagName('body')[0].clientWidth,
viewPortHeight = document.getElementsByTagName('body')[0].clientHeight
}
return [viewPortWidth, viewPortHeight];
}
function getLines() {
var onScreen = [];
var viewPort = getViewport();
// TODO: header & footer
var all = document.getElementsByTagName("*");
var vert = {};
var horz = {};
vert["0"] = 0;
vert["" + viewPort[1]] = viewPort[1];
horz["0"] = 0;
horz["" + viewPort[0]] = viewPort[0];
for (i = 0 ; i < all.length ; i++) {
var e = all[i];
// TODO: Get all client rectangles
var rect = e.getBoundingClientRect();
if (rect.width < 1 && rect.height < 1) continue;
var left = Math.floor(rect.left);
var top = Math.floor(rect.top);
var right = Math.floor(rect.right);
var bottom = Math.floor(rect.bottom);
if (top > 0 && top < viewPort[1]) {
vert["" + top] = top;
}
if (bottom > 0 && bottom < viewPort[1]) {
vert["" + bottom] = bottom;
}
if (right > 0 && right < viewPort[0]) {
horz["" + right] = right;
}
if (left > 0 && left < viewPort[0]) {
horz["" + left] = left;
}
}
hCoords = [];
vCoords = [];
//TODO:
for (var v in vert) {
vCoords.push(vert[v]);
}
for (var h in horz) {
hCoords.push(horz[h]);
}
return [hCoords, vCoords];
}
function getAreaPortions() {
var portions = {}
var lines = getLines();
var hCoords = lines[0];
var vCoords = lines[1];
for (i = 1 ; i < hCoords.length ; i++) {
for (j = 1 ; j < vCoords.length ; j++) {
var portion = new AreaPortion(hCoords[i - 1], vCoords[j - 1], hCoords[i], vCoords[j]);
portions[portion.getName()] = portion;
}
}
return portions;
}

Try
var res = [];
$("body *").each(function (i, el) {
if ((el.getBoundingClientRect().bottom <= window.innerHeight
|| el.getBoundingClientRect().top <= window.innerHeight)
&& el.getBoundingClientRect().right <= window.innerWidth) {
res.push([el.tagName.toLowerCase(), el.getBoundingClientRect()]);
};
});
jsfiddle http://jsfiddle.net/guest271314/ueum30g5/
See Element.getBoundingClientRect()
$.each(new Array(180), function () {
$("body").append(
$("<img>"))
});
$.each(new Array(180), function () {
$("body").append(
$("<img>"))
});
var res = [];
$("body *").each(function (i, el) {
if ((el.getBoundingClientRect().bottom <= window.innerHeight || el.getBoundingClientRect().top <= window.innerHeight)
&& el.getBoundingClientRect().right <= window.innerWidth) {
res.push(
[el.tagName.toLowerCase(),
el.getBoundingClientRect()]);
$(el).css(
"outline", "0.15em solid red");
$("body").append(JSON.stringify(res, null, 4));
console.log(res)
};
});
body {
width : 1000px;
height : 1000px;
}
img {
width : 50px;
height : 50px;
background : navy;
}
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

I don't know if the performance will be sufficient (especially on a mobile device), and the result is not quite a rectangle-set as you requested, but did you consider using a bitmap to store the result?
Note some elements may have 3d css transform (eg. skew, rotate), some elements may have border radius, and some elements may have invisible background - if you want to include these features as well for your "element from pixel" function then a rectangle set can't help you - but the bitmap can accommodate all of the visual features.
The solution to generate the bitmap is rather simple (I imagine... not tested):
Create a Canvas the size of the visible screen.
iterate over all the elements recursively, sorted by z-order, ignore hidden
for each element draw a rectangle in the canvas, the color of the of the rectangle is an identifier of the element (eg. could be incremental counter). If you want you can modify the rectangle based on the visual features of the element (skew, rotate, border radius, etc...)
save the canvas as lossless format, eg png not jpg
send the bitmap as the meta data of elements on screen
To query which element is at point (x,y) you could check the color of the bitmap at pixel (x,y) and the color will tell you what is the element.

If you can jettison IE, here's a simple one:
function getElementVisibleRect(el) {
return new Promise((resolve, reject) => {
el.style.overflow = "hidden";
requestAnimationFrame((timeStamp) => {
var br = el.getBoundingClientRect();
el.style.overflow = "";
resolve(br);
});
});
}
Even then, Promises are easily polyfillable and requestAnimationFrame() works as far back as IE 8. And by 2016, the only thing you should bother to give any poor souls on older IE is a legible experience.

Position D3 SVG Canvas x/y and Zoom Level On Load

I'm using D3 to create an organization chart. I've got the data loading fine and have figured out how to make the canvas move by dragging the mouse as well a zoom with the mouse wheel.
My problem is that the org chart is rather large so when the document first loads the root node is out of the browser's view area and the zoom level is set fairly high.
I need to figure out how to set the viewable area of the canvas around the first node and set the initial zoom level to 100%.

I was able to create a solution thanks to #Lars Kotthoff.
I retrieved the root node's x value from it's translate attribute (i.e. translate(x,y)) and then took the browser's width / 2 - the x value. I applied this value to the parent group's translate attribute which centers the document around the root node.
var windowWidth = $(window).width();
var node0 = d3.select("#node-0");
var translate = parseTranslate(node0.attr("transform"));
var translateX = translate.x - (windowWidth / 2);
var svgGroup = d3.select("#svg_g");
svgGroup.attr("transform", "translate(-" + translateX + ",22) scale(1)"); // with 20 y padding
NOTE: Because I'm new to SVG and D3 I am still not sure how to get just the "x" value of a node's translate attribute so I created a function that parses the translate attribute with regex. I'm sure there is a better way of getting this value so if anyone wants to update my answer or add a comment for future readers that would increase the value of this question.
The function I created is:
function parseTranslate(str) {
var translate = {
x: 0,
y: 0,
scale: 0
}
var pattern = /\((.+?)\)/g;
var matches = [];
while (match = pattern.exec(str)) {
matches.push(match[1]);
}
if (matches.length) {
if (matches.length == 1) {
if (matches[0].indexOf(",") > -1) {
var p = matches[0].split(',');
translate.x = p[0];
translate.y = p[1];
} else {
translate.scale = matches[0];
}
} else if (matches.length == 2) {
var p = matches[0].split(',');
translate.x = p[0];
translate.y = p[1];
translate.scale = matches[1];
}
}
return translate;
}
I'm also using jQuery in my project to get the width of the browser (ex: $(window).width();)

KineticJS and pinch and zoom

I would like to achieve this effect outlined here: http://www.html5canvastutorials.com/labs/html5-canvas-multi-touch-scale-stage-with-kineticjs/
But on a Layer in KineticJS
I have already got it working to a degree (using basically the same code as in the link), but it seems the Layer scales around the 0,0 origin point and I cannot see any doco about changing the transform origin?
How can I effectively pinch and zoom a Layer such that it scales around it center point?

I made a plugin for this kind of behavior: https://github.com/eduplus/pinchlayer
It is probably a little outdated now with the recent changes, but the logic in layerTouchMove function is most likely still sound. Here:
var touch1 = event.touches[0];
var touch2 = event.touches[1];
if (touch1 && touch2) {
self.setDraggable(false);
if (self.trans != undefined) { self.trans.stop(); }
if (self.startDistance === undefined) {
self.startDistance = self.getDistance(touch1, touch2);
self.touchPosition.x = (touch1.clientX + touch2.clientX) / 2;
self.touchPosition.y = (touch1.clientY + touch2.clientY) / 2;
self.layerPosition.x = (Math.abs(self.getX()) + self.touchPosition.x) / self.startScale;
self.layerPosition.y = (Math.abs(self.getY()) + self.touchPosition.y) / self.startScale;
}
else {
var dist = self.getDistance(touch1, touch2);
var scale = (dist / self.startDistance) * self.startScale;
if (scale < self.minScale) { scale = self.minScale; }
if (scale > self.maxScale) { scale = self.maxScale; }
self.setScale(scale, scale);
var x = (self.layerPosition.x * scale) - self.touchPosition.x;
var y = (self.layerPosition.y * scale) - self.touchPosition.y;
var pos = self.checkBounds({ x: -x, y: -y });
self.setPosition(pos.x, pos.y);
self.draw();
}
Basically it will record the starting point and the distance (how long the pinch is) and then scale and set the layer position accordingly. Hope this helps.

Dragging & Resizing CSS Transformed Elements

If for instance, we set a -vendor-transform: rotate(40deg) css attribute on a rectangle <div>, all the sudden dragging and resizing becomes very weird and flawed.
Here is an example with a simple jQueryUI: http://jsfiddle.net/Ja4dY/1/
You will notice, that if you drag or resize that rectangle when transformed, it will jump up or down and the cursor will not remain in the correct place. In my real code I'm using custom code for resizing and dragging, however I encountered the same problems.
Well, of course the "problem" is that the direction of an Element will change. So left can be right, top gets bottom and something inbetween and the Javascript code still handles each direction as it would be not transformed.
So, the question: How can we compensate transformed / rotated Elements ?
Any good resources / books / blogs are also very welcome.

You can get the current transformation matrix that is applied to an element by using getComputedStyle(). You can use this to transform the current mouse position to its position in transformed space and see whether the click/drag events are within the element boundary and/or corners. Good resources for this:
http://www.useragentman.com/blog/2011/01/07/css3-matrix-transform-for-the-mathematically-challenged/
http://www.eleqtriq.com/2010/05/css-3d-matrix-transformations/
BTW, as you're experiencing, this is non-trivial to code. We had to do it for Sencha Animator, and it was a beast.

The problem is that functions that make elements draggable, wether using jQuery UI or not, relies heavily on the native getBoundingClientRect() function to figure out the position of the element etc.
When applying CSS3 transforms, like rotation, the values of getBoundingClientRect() or the equalent jQuery offset() function used in jQuery UI no longer works as expected, and the position of the mouse pointer gets messed up because the size of the element is suddenly wrong after it has been rotated.
To fix it you need to add some sort of helper function that recalculates the values, and there is a monkey patch available for this that works with jQuery UI's draggable.
It's hard to say anything about how to make the same patch work for custom code, but you'll probably have to integrate it in your custom function somehow, and it will take some coding on your part, and it's even harder to come up with something that works as a helper function out of the box for custom code one has not seen, and be aware that it is rather involved doing these calculations, see the code below :
function monkeyPatch_mouseStart() {
var oldFn = $.ui.draggable.prototype._mouseStart ;
$.ui.draggable.prototype._mouseStart = function(event) {
var o = this.options;
function getViewOffset(node) {
var x = 0, y = 0, win = node.ownerDocument.defaultView || window;
if (node) addOffset(node);
return { left: x, top: y };
function getStyle(node) {
return node.currentStyle || // IE
win.getComputedStyle(node, '');
}
function addOffset(node) {
var p = node.offsetParent, style, X, Y;
x += parseInt(node.offsetLeft, 10) || 0;
y += parseInt(node.offsetTop, 10) || 0;
if (p) {
x -= parseInt(p.scrollLeft, 10) || 0;
y -= parseInt(p.scrollTop, 10) || 0;
if (p.nodeType == 1) {
var parentStyle = getStyle(p)
, localName = p.localName
, parent = node.parentNode;
if (parentStyle.position != 'static') {
x += parseInt(parentStyle.borderLeftWidth, 10) || 0;
y += parseInt(parentStyle.borderTopWidth, 10) || 0;
if (localName == 'TABLE') {
x += parseInt(parentStyle.paddingLeft, 10) || 0;
y += parseInt(parentStyle.paddingTop, 10) || 0;
}
else if (localName == 'BODY') {
style = getStyle(node);
x += parseInt(style.marginLeft, 10) || 0;
y += parseInt(style.marginTop, 10) || 0;
}
}
else if (localName == 'BODY') {
x += parseInt(parentStyle.borderLeftWidth, 10) || 0;
y += parseInt(parentStyle.borderTopWidth, 10) || 0;
}
while (p != parent) {
x -= parseInt(parent.scrollLeft, 10) || 0;
y -= parseInt(parent.scrollTop, 10) || 0;
parent = parent.parentNode;
}
addOffset(p);
}
}
else {
if (node.localName == 'BODY') {
style = getStyle(node);
x += parseInt(style.borderLeftWidth, 10) || 0;
y += parseInt(style.borderTopWidth, 10) || 0;
var htmlStyle = getStyle(node.parentNode);
x -= parseInt(htmlStyle.paddingLeft, 10) || 0;
y -= parseInt(htmlStyle.paddingTop, 10) || 0;
}
if ((X = node.scrollLeft)) x += parseInt(X, 10) || 0;
if ((Y = node.scrollTop)) y += parseInt(Y, 10) || 0;
}
}
}
this.helper = this._createHelper(event);
this._cacheHelperProportions();
if($.ui.ddmanager)
$.ui.ddmanager.current = this;
this._cacheMargins();
this.cssPosition = this.helper.css("position");
this.scrollParent = this.helper.scrollParent();
this.offset = this.positionAbs = getViewOffset(this.element[0]);
this.offset = {
top: this.offset.top - this.margins.top,
left: this.offset.left - this.margins.left
};
$.extend(this.offset, {
click: {
left: event.pageX - this.offset.left,
top: event.pageY - this.offset.top
},
parent: this._getParentOffset(),
relative: this._getRelativeOffset()
});
this.originalPosition = this.position = this._generatePosition(event);
this.originalPageX = event.pageX;
this.originalPageY = event.pageY;
(o.cursorAt && this._adjustOffsetFromHelper(o.cursorAt));
if(o.containment)
this._setContainment();
if(this._trigger("start", event) === false) {
this._clear();
return false;
}
this._cacheHelperProportions();
if ($.ui.ddmanager && !o.dropBehaviour)
$.ui.ddmanager.prepareOffsets(this, event);
this.helper.addClass("ui-draggable-dragging");
this._mouseDrag(event, true);
if ( $.ui.ddmanager ) $.ui.ddmanager.dragStart(this, event);
return true;
};
}
monkeyPatch_mouseStart();
And here's a FIDDLE showing it working as expected with jQuery UI's draggable and resizeable !

I found this... It's a working example plus info, demo and download link.
jquery-ui-rotation-using-css-transform -> live-demo
He use his own libraries, but if you are interest in the subject, you can read and learn how he get it.
cheers and good luck.
Gmo.-
Btw, the web is in Russian, but with google translate you can manage ;-)

It is not bug in jQuery. Simply it is not supported. If you check jQuery UI source code you will figure out that it doesn't use transformation matrix to calculate difference between transformed object and page.
Your example, and probably every jQ UI drag implementation suffer from this issue cause of 2 methods in JQ UI source code (around 314 line of jquery.ui.draggable.js file v1.8.23 ). Calculated offset do not matter about change in offset since rotation is done over center of element.
You have to calculate what is that change. Here is workaround, quick and dirty. The idea is to check what is difference in bounding box of transformed element.
Check sample here http://jsfiddle.net/mjaric/9Nqrh/
Ignore part with first two rotations, they are just done to minimize lines of code. Third involves translation of coordinate system for calculated difference. It will offset left and top after translation is performed (note it is first in filter).
If you want to avoid first two rotation filters, You could make code using formula for 2D rotation:
x' = x cos f - y sin f
y' = y cos f + x sin f
where f is angle of rotation, but it's not that simple and also includes more lines of code where you have to calculate what is diagonal angle of original bounding box since you need initial angle of top left corner which x and y coords are comparing to x axis (positive part). Then calculate change in x-x' and y-y'. But I'm predicting some issues with sign of change and coding/debugging would take more time then I have right now. Sorry cause of that but I'm sure you can figure out what to do after reading this post.

It looks better if we override the cursorAt:
$("#foo").mousedown(function (e) {
var x = e.pageX - this.offsetLeft;
var y = e.pageY - this.offsetTop;
console.log(x);
$("#foo").draggable("option", "cursorAt", {left: x, top:y});
});
Updated fiddle: http://jsfiddle.net/johnkoer/Ja4dY/8/
​

You said you are not interested with JQuery solutions then,
One solution is;
I recommend you to write your own drag and resize functions. You can
handle resizing and draging on rotated objects to add their top and left with sine and cosine of that degree.
Another solution is;
You can use libraries like Raphael JS to create objects to transform,
drag and resize. Raphael JS uses svg!
For more information about Raphael JS
Yet another solution is;
If you do not want to use library like Raphael JS, you can directly use SVG with JQuery
For more information about SVG
Cannot write more details now, I expand this solutions tomorrow.
Hope these help for now.

This, indeed, seems to be a bug in jQuery. An easy workaround would be: surround the resizable div with a container div. Set the .draggable() to the outer div and .resizable() to the inner div. This seems to be working fine in Chromium running on Ubuntu. See Fiddle.
I've colored the outer div to give you an idea what's happening under the hood.