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Random movement of circles created by the script

I have a function that craeates divs with a circle.
Now they are all created and appear at the beginning of the page and go further in order.
Next, I need each circle to appear in a random place. I did this.
Now I need all of them to move randomly across the entire page, I have difficulties with this.
Here is an example of how everything works for one element that is already on the page.
https://jsfiddle.net/quej8wko/
But when I add this code, all my created circles don't move.
I get an error:
"message": "Uncaught TypeError: Cannot set properties of null (setting 'willChange')",
This is probably due to the fact that initially there are no circles on the page. How can I connect the code so that all created circles move?
//creating circles
var widthHeight = 40; // <-- circle width
var margin = 20; // <-- margin - is it necessary ?
var delta = widthHeight + margin;
function createDiv(id, color) {
let div = document.createElement('div');
var currentTop = 0;
var documentHeight = document.documentElement.clientHeight;
var documentWidth = document.documentElement.clientWidth;
div.setAttribute('class', id);
if (color === undefined) {
let colors = ['#35def2', '#35f242', '#b2f235', '#f2ad35', '#f24735', '#3554f2', '#8535f2', '#eb35f2', '#f2359b', '#f23547'];
div.style.backgroundColor = colors[Math.floor(Math.random() * colors.length)];
}
else {
div.style.backgroundColor = color;
}
div.classList.add("circle");
div.classList.add("animation");
// Get the random positions minus the delta
currentTop = Math.floor(Math.random() * documentHeight) - delta;
currentLeft = Math.floor(Math.random() * documentWidth) - delta;
// Keep the positions between -20px and the current positions
var limitedTop = Math.max(margin * -1, currentTop);
var limitedLeft = Math.max(margin * -1, currentLeft);
div.style.top = limitedTop + "px";
div.style.left = limitedLeft + "px";
document.body.appendChild(div);
}
let i = 0;
const oneSecond = 1000;
setInterval(() => {
i += 1;
createDiv(`circle${i}`)
}, oneSecond);
//move circles
function RandomObjectMover(obj, container) {
this.$object = obj;
this.$container = container;
this.container_is_window = container === window;
this.pixels_per_second = 250;
this.current_position = { x: 0, y: 0 };
this.is_running = false;
}
// Set the speed of movement in Pixels per Second.
RandomObjectMover.prototype.setSpeed = function(pxPerSec) {
this.pixels_per_second = pxPerSec;
}
RandomObjectMover.prototype._getContainerDimensions = function() {
if (this.$container === window) {
return { 'height' : this.$container.innerHeight, 'width' : this.$container.innerWidth };
} else {
return { 'height' : this.$container.clientHeight, 'width' : this.$container.clientWidth };
}
}
RandomObjectMover.prototype._generateNewPosition = function() {
// Get container dimensions minus div size
var containerSize = this._getContainerDimensions();
var availableHeight = containerSize.height - this.$object.clientHeight;
var availableWidth = containerSize.width - this.$object.clientHeight;
// Pick a random place in the space
var y = Math.floor(Math.random() * availableHeight);
var x = Math.floor(Math.random() * availableWidth);
return { x: x, y: y };
}
RandomObjectMover.prototype._calcDelta = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
var dist = Math.sqrt( dx*dx + dy*dy );
return dist;
}
RandomObjectMover.prototype._moveOnce = function() {
// Pick a new spot on the page
var next = this._generateNewPosition();
// How far do we have to move?
var delta = this._calcDelta(this.current_position, next);
// Speed of this transition, rounded to 2DP
var speed = Math.round((delta / this.pixels_per_second) * 100) / 100;
//console.log(this.current_position, next, delta, speed);
this.$object.style.transition='transform '+speed+'s linear';
this.$object.style.transform='translate3d('+next.x+'px, '+next.y+'px, 0)';
// Save this new position ready for the next call.
this.current_position = next;
};
RandomObjectMover.prototype.start = function() {
if (this.is_running) {
return;
}
// Make sure our object has the right css set
this.$object.willChange = 'transform';
this.$object.pointerEvents = 'auto';
this.boundEvent = this._moveOnce.bind(this)
// Bind callback to keep things moving
this.$object.addEventListener('transitionend', this.boundEvent);
// Start it moving
this._moveOnce();
this.is_running = true;
}
RandomObjectMover.prototype.stop = function() {
if (!this.is_running) {
return;
}
this.$object.removeEventListener('transitionend', this.boundEvent);
this.is_running = false;
}
// Init it
var x = new RandomObjectMover(document.querySelector(".circle"), window);
// Start it off
x.start();
.circle {
clip-path: circle(50%);
height: 40px;
width: 40px;
margin: 20px;
position: absolute;
}

I have modified the snippet which works as you expected.
There was a mistake where you were initializing and creating the object instance only once and none of the div elements that you created inside the setInterval function never got Instantiated.
I think you are just starting out with JavaScript with this sample project.
Below are few suggestions:
Learn to debug the code. You should be using dev tools by making use of debugger statement where it takes you to the source code to analyze the variable scope and stack during the runtime. console.log also helps in few situations.
I could see a lot of confusing naming convention (You have named the create div parameter as id but creating a div class using that id)
Try using ES6 features (class syntax is really good when writing OOP in JS although it's just a syntactic sugar for prototype)
//creating circles
var widthHeight = 40; // <-- circle width
var margin = 20; // <-- margin - is it necessary ?
var delta = widthHeight + margin;
function createAndInitializeDivObject(id, color) {
let div = document.createElement('div');
var currentTop = 0;
var documentHeight = document.documentElement.clientHeight;
var documentWidth = document.documentElement.clientWidth;
div.setAttribute('class', id);
if (color === undefined) {
let colors = ['#35def2', '#35f242', '#b2f235', '#f2ad35', '#f24735', '#3554f2', '#8535f2', '#eb35f2', '#f2359b', '#f23547'];
div.style.backgroundColor = colors[Math.floor(Math.random() * colors.length)];
}
else {
div.style.backgroundColor = color;
}
div.classList.add("circle");
div.classList.add("animation");
// Get the random positions minus the delta
currentTop = Math.floor(Math.random() * documentHeight) - delta;
currentLeft = Math.floor(Math.random() * documentWidth) - delta;
// Keep the positions between -20px and the current positions
var limitedTop = Math.max(margin * -1, currentTop);
var limitedLeft = Math.max(margin * -1, currentLeft);
div.style.top = limitedTop + "px";
div.style.left = limitedLeft + "px";
document.body.appendChild(div);
var x = new RandomObjectMover(document.querySelector(`.${id}`), window);
x.start();
}
let i = 0;
const oneSecond = 1000;
setInterval(() => {
i += 1;
createAndInitializeDivObject(`circle${i}`)
}, oneSecond);
//move circles
function RandomObjectMover(obj, container) {
this.$object = obj;
this.$container = container;
this.container_is_window = container === window;
this.pixels_per_second = 250;
this.current_position = { x: 0, y: 0 };
this.is_running = false;
}
// Set the speed of movement in Pixels per Second.
RandomObjectMover.prototype.setSpeed = function(pxPerSec) {
this.pixels_per_second = pxPerSec;
}
RandomObjectMover.prototype._getContainerDimensions = function() {
if (this.$container === window) {
return { 'height' : this.$container.innerHeight, 'width' : this.$container.innerWidth };
} else {
return { 'height' : this.$container.clientHeight, 'width' : this.$container.clientWidth };
}
}
RandomObjectMover.prototype._generateNewPosition = function() {
// Get container dimensions minus div size
var containerSize = this._getContainerDimensions();
var availableHeight = containerSize.height - this.$object.clientHeight;
var availableWidth = containerSize.width - this.$object.clientHeight;
// Pick a random place in the space
var y = Math.floor(Math.random() * availableHeight);
var x = Math.floor(Math.random() * availableWidth);
return { x: x, y: y };
}
RandomObjectMover.prototype._calcDelta = function(a, b) {
var dx = a.x - b.x;
var dy = a.y - b.y;
var dist = Math.sqrt( dx*dx + dy*dy );
return dist;
}
RandomObjectMover.prototype._moveOnce = function() {
// Pick a new spot on the page
var next = this._generateNewPosition();
// How far do we have to move?
var delta = this._calcDelta(this.current_position, next);
// Speed of this transition, rounded to 2DP
var speed = Math.round((delta / this.pixels_per_second) * 100) / 100;
//console.log(this.current_position, next, delta, speed);
this.$object.style.transition='transform '+speed+'s linear';
this.$object.style.transform='translate3d('+next.x+'px, '+next.y+'px, 0)';
// Save this new position ready for the next call.
this.current_position = next;
};
RandomObjectMover.prototype.start = function() {
if (this.is_running) {
return;
}
// Make sure our object has the right css set
this.$object.willChange = 'transform';
this.$object.pointerEvents = 'auto';
this.boundEvent = this._moveOnce.bind(this)
// Bind callback to keep things moving
this.$object.addEventListener('transitionend', this.boundEvent);
// Start it moving
this._moveOnce();
this.is_running = true;
}
RandomObjectMover.prototype.stop = function() {
if (!this.is_running) {
return;
}
this.$object.removeEventListener('transitionend', this.boundEvent);
this.is_running = false;
}
// Init it
var x = new RandomObjectMover(document.querySelector(".circle"), window);
// Start it off
x.start();
.circle {
width: 35px;
height: 35px;
border-radius: 35px;
background-color: #ffffff;
border: 3px solid purple;
position: absolute;
}
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="style.css">
</head>
<body>
<div class="circle"></div>
<script src="app.js"></script>
</body>
</html>

How do I loop through an array of buttons and only continue looping if the user clicks the next button in the array

Not sure if this is exactly the correct approach for this but I have an array of buttons that spawn on the screen and after a few seconds it changes location and I have to click the buttons in the order they appeared initially.
Following is the code:
let arrayButtons = [];
let goButton = document.getElementById("inputButton");
function Buttons(color, height, width, top, left, order) {
this.order = order;
this.btn = document.createElement("button");
this.btn.style.backgroundColor = color;
this.btn.style.height = height;
this.btn.style.width = width;
this.btn.style.position = "absolute";
document.body.appendChild(this.btn);
this.setLocation = function(top, left) {
this.btn.style.top = top;
this.btn.style.left = left;
};
this.setLocation(top, left);
}
function createButtons(numOfButtons) {
console.log(numOfButtons);
let color;
let heightVal;
let widthVal;
let top;
let left;
let currentButton;
for (let i = 0; i < numOfButtons; i++) {
color = "#" + genRandomColor();
heightVal = "60px";
widthVal = "120px";
let x = window.innerWidth - 100;
let y = window.innerHeight - 100;
top = 90 + "px";
left = i * 120 + "px";
currentButton = new Buttons(color, heightVal, widthVal, top, left, i);
arrayButtons.push(currentButton);
}
}
function genRandomColor() {
let randomColor = Math.floor(Math.random() * 16777215).toString(16);
return randomColor;
}
function change() {
setTimeout(function() {
let x = window.innerWidth - 100;
let y = window.innerHeight - 200;
for (let i = 0; i < arrayButtons.length; i++) {
randomX = Math.floor(Math.random() * x + 50);
randomY = Math.floor(Math.random() * y + 50);
arrayButtons[i].setLocation(
randomX + 'px',
randomY + 'px');
}
}, 5000);
}
function isValid(range) {
range = document.getElementById("textField").value;
if (range < 2 || range > 10) {
return false;
} else {
return true;
}
}
// idea.. if the user clicks on the button in the order of the array it works
// for the hint, just make the value equal to the index number + 1
function clickHandler() {
let minMax = isValid();
if (minMax == true) {
createButtons(document.getElementById("textField").value);
change();
} else {
window.alert("Must be between 2 and 10");
}
}
goButton.onclick = clickHandler;
<p>How Many Buttons To Create?</p>
<input id="textField" type="text">
<button type="button" id="inputButton">Go!</button>
<br>
<br>

HTML
<button class="buttonClass">1</button>
JS
let btns = document.querySelectorAll(".buttonClass");
let currentBtn = 0;
btns.forEach(function(btn, crtIndex){
btn.onclick = function(){
if(currentBtn === crtIndex){
currentBtn++;
console.log("correct");
}
};
});

Snap edges of objects to each other and prevent overlap

My goal is to prevent overlapping of two or more rectangles inside my FabricJS canvas.
Imagine two rectangles having info on position and size and you can drag and drop any rectangle inside the canvas.
If rectangle A gets close enough to rectangle B, the position of rectangle A should snap to the edge of rectangle B. This should work for any edge of rectangle B. The vertices do not have to match, cause the sizes of the rectangles are variable.
I have a working example for this snapping on one dimension (x-axes).
My best jsfiddle attempt
See jsfiddle.
But I need it to work around the rectangle on both dimensions. I am quite sure, that my code is not well enough to manage this.
Code-snippets which might help:
object.oCoords.tl.x //top-left corner x position. similar goes for top-right (tr), bottom-left (bl), bottom-right (br) and .y for y-position
mouse_pos = canvas.getPointer(e.e);
mouse_pos.x //pointer x.position
mouse_pos.y //pointer y.position
object.intersectsWithObject(targ) // object = dragged rectangle, targ = targeted rectangle
The snapping should work for an unlimited amount of objects (not only for two rectangles).

I solved the problem on my own.
See jsfiddle: http://jsfiddle.net/gcollect/FD53A/
This is the code:
this.canvas.on('object:moving', function (e) {
var obj = e.target;
obj.setCoords(); //Sets corner position coordinates based on current angle, width and height
canvas.forEachObject(function (targ) {
var objects = this.canvas.getObjects(),
i = objects.length;
activeObject = canvas.getActiveObject();
if (targ === activeObject) return;
if (Math.abs(activeObject.oCoords.tr.x - targ.oCoords.tl.x) < edgedetection) {
activeObject.left = targ.left - activeObject.currentWidth;
}
if (Math.abs(activeObject.oCoords.tl.x - targ.oCoords.tr.x) < edgedetection) {
activeObject.left = targ.left + targ.currentWidth;
}
if (Math.abs(activeObject.oCoords.br.y - targ.oCoords.tr.y) < edgedetection) {
activeObject.top = targ.top - activeObject.currentHeight;
}
if (Math.abs(targ.oCoords.br.y - activeObject.oCoords.tr.y) < edgedetection) {
activeObject.top = targ.top + targ.currentHeight;
}
if (activeObject.intersectsWithObject(targ) && targ.intersectsWithObject(activeObject)) {
targ.strokeWidth = 10;
targ.stroke = 'red';
} else {
targ.strokeWidth = 0;
targ.stroke = false;
}
if (!activeObject.intersectsWithObject(targ)) {
activeObject.strokeWidth = 0;
activeObject.stroke = false;
}
});
Works pretty legit! Cheers!

This is based on gco's answer, updated to work with FabricJS 1.5.0, with the following improvements:
Shapes don't overlap.
Snapping is more responsive.
Shapes are contained within the canvas.
JS Fiddle: https://jsfiddle.net/aphillips8/31qbr0vn/1/
var canvas = new fabric.Canvas('canvas'),
canvasWidth = document.getElementById('canvas').width,
canvasHeight = document.getElementById('canvas').height,
counter = 0,
rectLeft = 0,
snap = 20; //Pixels to snap
canvas.selection = false;
plusrect();
plusrect();
plusrect();
function plusrect(top, left, width, height, fill) {
var rect = new fabric.Rect({
top: 300,
name: 'rectangle ' + counter,
left: 0 + rectLeft,
width: 100,
height: 100,
fill: 'rgba(' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ', 0.75)',
lockRotation: true,
originX: 'left',
originY: 'top',
cornerSize: 15,
hasRotatingPoint: false,
perPixelTargetFind: true,
minScaleLimit: 1,
maxWidth: canvasWidth,
maxHeight: canvasHeight
});
rect.custom = {};
rect.custom.counter = counter;
canvas.add(rect);
counter++;
rectLeft += 200;
}
function findNewPos(distX, distY, target, obj) {
// See whether to focus on X or Y axis
if(Math.abs(distX) > Math.abs(distY)) {
if (distX > 0) {
target.setLeft(obj.getLeft() - target.getWidth());
} else {
target.setLeft(obj.getLeft() + obj.getWidth());
}
} else {
if (distY > 0) {
target.setTop(obj.getTop() - target.getHeight());
} else {
target.setTop(obj.getTop() + obj.getHeight());
}
}
}
canvas.on('object:moving', function (options) {
// Sets corner position coordinates based on current angle, width and height
options.target.setCoords();
// Don't allow objects off the canvas
if(options.target.getLeft() < snap) {
options.target.setLeft(0);
}
if(options.target.getTop() < snap) {
options.target.setTop(0);
}
if((options.target.getWidth() + options.target.getLeft()) > (canvasWidth - snap)) {
options.target.setLeft(canvasWidth - options.target.getWidth());
}
if((options.target.getHeight() + options.target.getTop()) > (canvasHeight - snap)) {
options.target.setTop(canvasHeight - options.target.getHeight());
}
// Loop through objects
canvas.forEachObject(function (obj) {
if (obj === options.target) return;
// If objects intersect
if (options.target.isContainedWithinObject(obj) || options.target.intersectsWithObject(obj) || obj.isContainedWithinObject(options.target)) {
var distX = ((obj.getLeft() + obj.getWidth()) / 2) - ((options.target.getLeft() + options.target.getWidth()) / 2);
var distY = ((obj.getTop() + obj.getHeight()) / 2) - ((options.target.getTop() + options.target.getHeight()) / 2);
// Set new position
findNewPos(distX, distY, options.target, obj);
}
// Snap objects to each other horizontally
// If bottom points are on same Y axis
if(Math.abs((options.target.getTop() + options.target.getHeight()) - (obj.getTop() + obj.getHeight())) < snap) {
// Snap target BL to object BR
if(Math.abs(options.target.getLeft() - (obj.getLeft() + obj.getWidth())) < snap) {
options.target.setLeft(obj.getLeft() + obj.getWidth());
options.target.setTop(obj.getTop() + obj.getHeight() - options.target.getHeight());
}
// Snap target BR to object BL
if(Math.abs((options.target.getLeft() + options.target.getWidth()) - obj.getLeft()) < snap) {
options.target.setLeft(obj.getLeft() - options.target.getWidth());
options.target.setTop(obj.getTop() + obj.getHeight() - options.target.getHeight());
}
}
// If top points are on same Y axis
if(Math.abs(options.target.getTop() - obj.getTop()) < snap) {
// Snap target TL to object TR
if(Math.abs(options.target.getLeft() - (obj.getLeft() + obj.getWidth())) < snap) {
options.target.setLeft(obj.getLeft() + obj.getWidth());
options.target.setTop(obj.getTop());
}
// Snap target TR to object TL
if(Math.abs((options.target.getLeft() + options.target.getWidth()) - obj.getLeft()) < snap) {
options.target.setLeft(obj.getLeft() - options.target.getWidth());
options.target.setTop(obj.getTop());
}
}
// Snap objects to each other vertically
// If right points are on same X axis
if(Math.abs((options.target.getLeft() + options.target.getWidth()) - (obj.getLeft() + obj.getWidth())) < snap) {
// Snap target TR to object BR
if(Math.abs(options.target.getTop() - (obj.getTop() + obj.getHeight())) < snap) {
options.target.setLeft(obj.getLeft() + obj.getWidth() - options.target.getWidth());
options.target.setTop(obj.getTop() + obj.getHeight());
}
// Snap target BR to object TR
if(Math.abs((options.target.getTop() + options.target.getHeight()) - obj.getTop()) < snap) {
options.target.setLeft(obj.getLeft() + obj.getWidth() - options.target.getWidth());
options.target.setTop(obj.getTop() - options.target.getHeight());
}
}
// If left points are on same X axis
if(Math.abs(options.target.getLeft() - obj.getLeft()) < snap) {
// Snap target TL to object BL
if(Math.abs(options.target.getTop() - (obj.getTop() + obj.getHeight())) < snap) {
options.target.setLeft(obj.getLeft());
options.target.setTop(obj.getTop() + obj.getHeight());
}
// Snap target BL to object TL
if(Math.abs((options.target.getTop() + options.target.getHeight()) - obj.getTop()) < snap) {
options.target.setLeft(obj.getLeft());
options.target.setTop(obj.getTop() - options.target.getHeight());
}
}
});
options.target.setCoords();
// If objects still overlap
var outerAreaLeft = null,
outerAreaTop = null,
outerAreaRight = null,
outerAreaBottom = null;
canvas.forEachObject(function (obj) {
if (obj === options.target) return;
if (options.target.isContainedWithinObject(obj) || options.target.intersectsWithObject(obj) || obj.isContainedWithinObject(options.target)) {
var intersectLeft = null,
intersectTop = null,
intersectWidth = null,
intersectHeight = null,
intersectSize = null,
targetLeft = options.target.getLeft(),
targetRight = targetLeft + options.target.getWidth(),
targetTop = options.target.getTop(),
targetBottom = targetTop + options.target.getHeight(),
objectLeft = obj.getLeft(),
objectRight = objectLeft + obj.getWidth(),
objectTop = obj.getTop(),
objectBottom = objectTop + obj.getHeight();
// Find intersect information for X axis
if(targetLeft >= objectLeft && targetLeft <= objectRight) {
intersectLeft = targetLeft;
intersectWidth = obj.getWidth() - (intersectLeft - objectLeft);
} else if(objectLeft >= targetLeft && objectLeft <= targetRight) {
intersectLeft = objectLeft;
intersectWidth = options.target.getWidth() - (intersectLeft - targetLeft);
}
// Find intersect information for Y axis
if(targetTop >= objectTop && targetTop <= objectBottom) {
intersectTop = targetTop;
intersectHeight = obj.getHeight() - (intersectTop - objectTop);
} else if(objectTop >= targetTop && objectTop <= targetBottom) {
intersectTop = objectTop;
intersectHeight = options.target.getHeight() - (intersectTop - targetTop);
}
// Find intersect size (this will be 0 if objects are touching but not overlapping)
if(intersectWidth > 0 && intersectHeight > 0) {
intersectSize = intersectWidth * intersectHeight;
}
// Set outer snapping area
if(obj.getLeft() < outerAreaLeft || outerAreaLeft == null) {
outerAreaLeft = obj.getLeft();
}
if(obj.getTop() < outerAreaTop || outerAreaTop == null) {
outerAreaTop = obj.getTop();
}
if((obj.getLeft() + obj.getWidth()) > outerAreaRight || outerAreaRight == null) {
outerAreaRight = obj.getLeft() + obj.getWidth();
}
if((obj.getTop() + obj.getHeight()) > outerAreaBottom || outerAreaBottom == null) {
outerAreaBottom = obj.getTop() + obj.getHeight();
}
// If objects are intersecting, reposition outside all shapes which touch
if(intersectSize) {
var distX = (outerAreaRight / 2) - ((options.target.getLeft() + options.target.getWidth()) / 2);
var distY = (outerAreaBottom / 2) - ((options.target.getTop() + options.target.getHeight()) / 2);
// Set new position
findNewPos(distX, distY, options.target, obj);
}
}
});
});

I based this fiddle off #Anna Phillips' and #gco's examples. It includes:
Corner snapping
Edge snapping
Objects can overlap
Objects are fully contained within the canvas
Objects cannot have a size larger than the canvas area
Here is the code:
window.canvas = new fabric.Canvas('fabriccanvas');
window.counter = 0;
var newleft = 0,
edgedetection = 20, //pixels to snap
canvasWidth = document.getElementById('fabriccanvas').width,
canvasHeight = document.getElementById('fabriccanvas').height;
canvas.selection = false;
plusrect();
plusrect();
plusrect();
function plusrect(top, left, width, height, fill) {
window.canvas.add(new fabric.Rect({
top: 300,
name: 'rectangle ' + window.counter,
left: 0 + newleft,
width: 100,
height: 100,
fill: 'rgba(' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ',' + (Math.floor(Math.random() * 256)) + ', 0.75)',
lockRotation: true,
originX: 'left',
originY: 'top',
cornerSize: 15,
hasRotatingPoint: false,
perPixelTargetFind: true,
minScaleLimit: 1,
maxHeight: document.getElementById("fabriccanvas").height,
maxWidth: document.getElementById("fabriccanvas").width,
}));
window.counter++;
newleft += 200;
}
this.canvas.on('object:moving', function (e) {
var obj = e.target;
obj.setCoords(); //Sets corner position coordinates based on current angle, width and height
if(obj.getLeft() < edgedetection) {
obj.setLeft(0);
}
if(obj.getTop() < edgedetection) {
obj.setTop(0);
}
if((obj.getWidth() + obj.getLeft()) > (canvasWidth - edgedetection)) {
obj.setLeft(canvasWidth - obj.getWidth());
}
if((obj.getHeight() + obj.getTop()) > (canvasHeight - edgedetection)) {
obj.setTop(canvasHeight - obj.getHeight());
}
canvas.forEachObject(function (targ) {
activeObject = canvas.getActiveObject();
if (targ === activeObject) return;
if (Math.abs(activeObject.oCoords.tr.x - targ.oCoords.tl.x) < edgedetection) {
activeObject.left = targ.left - activeObject.currentWidth;
}
if (Math.abs(activeObject.oCoords.tl.x - targ.oCoords.tr.x) < edgedetection) {
activeObject.left = targ.left + targ.currentWidth;
}
if (Math.abs(activeObject.oCoords.br.y - targ.oCoords.tr.y) < edgedetection) {
activeObject.top = targ.top - activeObject.currentHeight;
}
if (Math.abs(targ.oCoords.br.y - activeObject.oCoords.tr.y) < edgedetection) {
activeObject.top = targ.top + targ.currentHeight;
}
if (activeObject.intersectsWithObject(targ) && targ.intersectsWithObject(activeObject)) {
targ.strokeWidth = 10;
targ.stroke = 'red';
} else {
targ.strokeWidth = 0;
targ.stroke = false;
}
if (!activeObject.intersectsWithObject(targ)) {
activeObject.strokeWidth = 0;
activeObject.stroke = false;
}
});
});
What I'd like to know is if it's possible to extend this to add the following features:
Dynamic snapping. Continuing to drag an object after the initial snap will temporarily disable snapping until the object stops moving. For example, if I drag one box next to another, they will snap together once they are within range. However if I continue moving the first box, I can "drop" it in a position where it is within the snapping range but not aligned to the other box.
Show guide lines when selected object is within range of another object. Currently we add a border around the target object, but it would be better to show guidelines that extend outwards (possibly to the edge of the canvas) to more easily visualize the bounds of the target object.
Parallel snapping. When moving an object that is already snapped to the target object, the selected object should snap to the target object in such a way that the tops, bottoms, or sides of both objects are parallel. For example, assume that the selected square is snapped to the left of the target square and that the top of the selected square is below the top of the target square. Moving the selected square up should cause its top to snap into alignment with the top of the target once in range. The same logic should apply when moving it down, or if the selected object is above/below the target and being moves horizontally.

I needed snapping of unequal sized areas. jsfiddle
var canvas = new fabric.Canvas('c');
canvas.setDimensions({width:window.innerWidth});
var edge_detection_external = 21;
var corner_detection = 5;
canvas.selection = false;
canvas.on('object:moving', function (e) {
var obj = e.target;
obj.setCoords();
function update_position(obj){
return function(targ){
if(targ === obj) return;
// Check overlap case https://www.geeksforgeeks.org/find-two-rectangles-overlap/
if(!(function(targ,obj){
if(obj.aCoords.tl.x > targ.aCoords.br.x || targ.aCoords.tl.x > obj.aCoords.br.x)
return false;
if(targ.aCoords.tl.y > obj.aCoords.br.y || obj.aCoords.tl.y > targ.aCoords.br.y)
return false;
return true;
})(targ,obj)){
// is on RIGHT or LEFT?
if((obj.top > targ.top && obj.top < targ.top + targ.height)
|| (targ.top > obj.top && targ.top < obj.top + obj.height)){
// Object is to the RIGHT and Edge detection
if(obj.aCoords.tl.x > targ.aCoords.br.x
&& obj.aCoords.tl.x - targ.aCoords.br.x < edge_detection_external){
obj.set({left:targ.aCoords.br.x});
// Corner detection
obj.setCoords();
if(Math.abs(targ.aCoords.tr.y - obj.aCoords.tl.y) < corner_detection)
obj.set({top:targ.top});
else if(Math.abs(targ.aCoords.br.y - obj.aCoords.bl.y) < corner_detection)
obj.set({top:targ.top + targ.height - obj.height});
}
// LEFT
if(targ.aCoords.tl.x > obj.aCoords.br.x
&& targ.aCoords.tl.x - obj.aCoords.br.x < edge_detection_external){
obj.set({left:targ.aCoords.tl.x - obj.width});
obj.setCoords();
if(Math.abs(targ.aCoords.tl.y - obj.aCoords.tr.y) < corner_detection)
obj.set({top:targ.top});
else if(Math.abs(targ.aCoords.bl.y - obj.aCoords.br.y) < corner_detection)
obj.set({top:targ.top + targ.height - obj.height});
}
}
// is on TOP or BOTTOM?
if((obj.left > targ.left && obj.left < targ.left + targ.width)
|| (targ.left > obj.left && targ.left < obj.left + obj.width)){
// TOP
if(targ.aCoords.tl.y > obj.aCoords.br.y
&& targ.aCoords.tl.y - obj.aCoords.br.y < edge_detection_external){
obj.set({top:targ.aCoords.tl.y - obj.height});
obj.setCoords();
if(Math.abs(targ.aCoords.tl.x - obj.aCoords.bl.x) < corner_detection)
obj.set({left:targ.left});
else if(Math.abs(targ.aCoords.tr.x - obj.aCoords.br.x) < corner_detection)
obj.set({left:targ.left + targ.width - obj.width});
}
// BOTTOM
if(obj.aCoords.tl.y > targ.aCoords.br.y
&& obj.aCoords.tl.y - targ.aCoords.br.y < edge_detection_external){
obj.set({top:targ.aCoords.br.y});
obj.setCoords();
if(Math.abs(targ.aCoords.bl.x - obj.aCoords.tl.x) < corner_detection)
obj.set({left:targ.left});
else if(Math.abs(targ.aCoords.br.x - obj.aCoords.tr.x) < corner_detection)
obj.set({left:targ.left + targ.width - obj.width});
}
}
}
}
}
canvas.getObjects('group').some(update_position(obj));
});
String.prototype.to_inches = function(){
return this.split('-').map(function(value,index){
value = Number(value);
if(index == 0)
return value * 12
else
return value
}).reduce(function(total,current){
return total + current;
});
}
Array.prototype.to_object_list = function(){
const preserved = [...this];
var header = this.splice(0,1)[0];
for(var i = 0;i < this.length; i++){
var obj = {};
for(var j = 0;j < header.length; j++){
obj[header[j].toLowerCase()] = this[i][j];
}
this[i] = obj;
}
return preserved;
}
function draw_areas(){
var offset = 0;
return function(area_params,index){
if(area_params.area.indexOf('>') === -1){
var area = new fabric.Rect({
fill: 'red',
width:area_params.width.to_inches(),
height:area_params.length.to_inches(),
});
var text = new fabric.Text(area_params.area + '\n' + area_params.width + ' x ' + area_params.length,{
fontSize:12,
fill:"white"
});
if(text.width - area.width > 0){
text.set('width',area.width);
}
if(text.height - area.height > 0){
text.set('height',area.height);
}
var group_name = 'group_' + area_params.area.split(' ').join('-');
var group = new fabric.Group([area,text],{
name: group_name,
left: 5,
top: 5*(index++) + offset,
});
canvas.add(group);
offset = area_params.length.to_inches() + offset;
canvas.setDimensions({height:5*(index++) + offset});
}
}
}
function handler_get_data(data){
data = JSON.parse(data);
data.to_object_list();
data.forEach(draw_areas());
}
var d = '[["Area","Width","Length"],["Bedroom 1","19-5.5","14"],["Kitchen","14","16-3"],["Bedroom 2","13-6","12-9"]]';
handler_get_data(d);

JavaScript rectangle follow cursor in menu

I wrote a code in JS for my future site and it's all fine but the only bad thing here is in menu the rectangle (div) moves with brakes. I mean it must be like in a site some features of which I want to have on my own. http://lusens.ru/ There on main menu the rectangle mouse very smoothly. I can't understand why in my case it doesn't happen.
This is a part of html
<body>
<ul >
<li id="a1" onmouseover="highlightMenu('a1')">Первый пункт</li>
<li id="a2" onmouseover="highlightMenu('a2')">Второй пункт точка</li>
<li id="a3" onmouseover="highlightMenu('a3')">Третьий пункт точка и запятая</li>
<li id="a4" onmouseover="highlightMenu('a4')">Четвёртый пункт</li>
</ul>
<div id="d1"></div>
and the JS file
function highlightMenu(id) {
time = 0;
var rect = document.getElementById(id).getBoundingClientRect();
var width = document.getElementById(id).offsetWidth;
var idTop = rect.top;
var idLeft = rect.left;
var rect1 = document.getElementById('d1').getBoundingClientRect();
var shadowWidth = document.getElementById('d1').offsetWidth;
var shadowLeft = rect1.left;
var shadowTop = rect1.top;
if (shadowLeft < idLeft) {
for (i = shadowLeft, time = 50; i < idLeft - 3; i++, time += 5) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
} else {
for (i = shadowLeft, time = 50; i > idLeft - 3; i--, time += 5) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
}
if (shadowWidth < width) {
for (i = shadowWidth; i < width + 10; i++, time += 0.01) {
setTimeout("document.getElementById('d1').style.width='" + i + "px'", time);
}
} else {
for (i = shadowWidth; i > width + 10; i--, time += 0.01) {
setTimeout("document.getElementById('d1').style.width='" + i + "px'", time);
}
}
if (shadowLeft < idLeft) {
for (i = idLeft + 3; i < idLeft + 20; i++, time += 25) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
for (i = idLeft + 20; i > idLeft - 5; i--, time += 50) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
} else {
for (i = idLeft - 3; i > idLeft - 20; i--, time += 25) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
for (i = idLeft - 20; i < idLeft - 5; i++, time += 50) {
setTimeout("document.getElementById('d1').style.left='" + i + "px'", time);
}
}
}
http://jsfiddle.net/m2SBm/

Using the onmouseover causes to fire the event handler function multiple times, here is better to use the onmouseenter event. And also instead of scheduling 50 timeouts, rather use single timeout and global variables, so that the animation will be stoppable.
HTML:
<ul id="menu">
<li>Первый пункт</li>
<li>Второй пункт точка</li>
<li>Третьий пункт точка и запятая</li>
<li>Четвёртый пункт</li>
</ul>
<div id="d1"></div>
Javascript:
var rect, rect1; // rectangles
var shadow; // shadow div
var bpos; // begin position
var epos; // end position
var width, shadowWidth;
var step; // animation step 1..50
var timer = null;
function animateRect() {
step++;
if (step > 50) {
clearInterval(timer);
timer = null;
return;
}
var t = bpos.t + Math.round((epos.t - bpos.t) * step / 50);
var l = bpos.l + Math.round((epos.l - bpos.l) * step / 50);
var w = shadowWidth + Math.round((width - shadowWidth) * step / 50);
shadow.style.top = t + "px";
shadow.style.left = l + "px";
shadow.style.width = w + "px";
}
function highlightMenu(e) {
e = e || window.event; // for IE8,7 compatibility
var item = e.target || e.srcElement; // for IE8,7
if (timer) {
clearInterval(timer);
}
step = 0;
rect = item.getBoundingClientRect();
width = item.offsetWidth;
epos = {
t: rect.top,
l: rect.left
};
rect1 = shadow.getBoundingClientRect();
shadowWidth = shadow.offsetWidth;
bpos = {
t: rect1.top,
l: rect1.left
};
timer = setInterval(animateRect, 5);
}
function init() {
var menu = document.getElementById('menu');
var items = menu.getElementsByTagName('li');
for (var i = 0; i < items.length; i++) {
items[i].onmouseenter = highlightMenu;
}
shadow = document.getElementById('d1');
shadow.style.width = items[0].offsetWidth + 'px';
shadow.style.top = items[0].getBoundingClientRect().top + 'px';
shadow.style.left = items[0].getBoundingClientRect().left + 'px';
}
if (window.addEventListener) {
window.addEventListener('load', init, false);
} else if (window.attachEvent) {
window.attachEvent('onload', init);
}
JSFiddle: http://jsfiddle.net/m2SBm/6/ (using the getBoundingClientRect function)
Update:
To make your menu work correctly also with eventual scrollbars, compute the element offset position rather than using the getBoundingClientRect function as shown in the following answer:
finding element's position relative to the document
Here is additional CSS for transparency in menu:
ul#menu, ul#menu li {
position:relative;
background-color:transparent;
}
#d1 {
z-index:-10;
}
The complete menu here: http://jsfiddle.net/m2SBm/8/

Move text up with javascript

So I need function like this one, -link- but just to move text up, not left. How to achieve this?
So, this is code that moves text left:
//Text fade
var bgcolor;
var fcolor;
var heading;
//Number of steps to fade
var steps;
var colors;
var color = 0;
var step = 1;
var interval1;
var interval2;
//fade: fader function
// Fade from backcolor to forecolor in specified number of steps
function fade(headingtext,backcolor,forecolor,numsteps) {
if (color == 0) {
steps = numsteps;
heading = "<font color='{COLOR}'>"+headingtext+"</strong></font>";
bgcolor = backcolor;
fcolor = forecolor;
colors = new Array(steps);
getFadeColors(bgcolor,fcolor,colors);
}
// insert fader color into message
var text_out = heading.replace("{COLOR}", colors[color]);
// write the message to the document
document.getElementById("fader").innerHTML = text_out;
// select next fader color
color += step;
if (color >= steps) clearInterval(interval1);
}
//getFadeColors: fills colors, using predefined Array, with color hex strings fading from ColorA to ColorB
//Note: Colors.length equals the number of steps to fade
function getFadeColors(ColorA, ColorB, Colors) {
len = Colors.length;
//Strip '#' from colors if present
if (ColorA.charAt(0)=='#') ColorA = ColorA.substring(1);
if (ColorB.charAt(0)=='#') ColorB = ColorB.substring(1);
//Substract red green and blue components from hex string
var r = HexToInt(ColorA.substring(0,2));
var g = HexToInt(ColorA.substring(2,4));
var b = HexToInt(ColorA.substring(4,6));
var r2 = HexToInt(ColorB.substring(0,2));
var g2 = HexToInt(ColorB.substring(2,4));
var b2 = HexToInt(ColorB.substring(4,6));
// calculate size of step for each color component
var rStep = Math.round((r2 - r) / len);
var gStep = Math.round((g2 - g) / len);
var bStep = Math.round((b2 - b) / len);
// fill Colors array with fader colors
for (i = 0; i < len-1; i++) {
Colors[i] = "#" + IntToHex(r) + IntToHex(g) + IntToHex(b);
r += rStep;
g += gStep;
b += bStep;
}
Colors[len-1] = ColorB; // make sure we finish exactly at ColorB
}
//IntToHex: converts integers between 0 - 255 into a two digit hex string.
function IntToHex(n) {
var result = n.toString(16);
if (result.length==1) result = "0"+result;
return result;
}
//HexToInt: converts two digit hex strings into integer.
function HexToInt(hex) {
return parseInt(hex, 16);
}
var startwidth = 0;
//scroll: Make the text scroll using the marginLeft element of the div container
function scroll(startw) {
if (startwidth == 0) {
startwidth=startw;
}
document.getElementById("fader").style.marginLeft = startwidth + "px";
if (startwidth > 1) {
startwidth -= 1;
} else {
clearInterval(interval2);
}
}
function fadeandscroll(txt,color1,color2,numsteps,fademilli,containerwidth,scrollmilli) {
interval1 = setInterval("fade('"+txt+"','"+color1+"','"+color2+"',"+numsteps+")",fademilli);
interval2 = setInterval("scroll("+containerwidth+")",scrollmilli);
}

Something like this seems to do what you want, but jQuery would have been easier.
Demo: Vertical Marquee Demo
window.document.addEventListener("DOMContentLoaded", function()
{
var elm = window.document.querySelectorAll("#display span")[0], height = elm.parentNode.offsetHeight;
elm.style.position = "relative";
elm.style.top = "0px";
var timer = setInterval(function()
{
var top = Number(elm.style.top.replace(/[^\d\-]/g, ''));
top = top > -height ? top - 1 : height;
elm.style.top = top + "px";
}, 50);
/*
* If you want to stop scrolling, call clearInterval(timer);
*
* Example set to stop when clicked.
*/
elm.addEventListener("click", function()
{
clearInterval(timer);
}, false);
}, false);