I have a problem in Javascript: I have an array which changes his elements in each step when I´m clicking with the mouse. My array has for example 5 elements. Now I want to draw 5 rectangles and I want each of the rectangles to have the height of an element of this array. Then I click with the mouse, so the elements change and so the heights change too. How can I realize this?
Thank you for your help!
Maybe you can use a Getter and a Setter. Here an example:
const data = {
_arr: [],
set arr(value) {
this._arr = value;
//inform me
console.log("changed");
},
get arr() {
return this._arr;
}
};
data.arr = [1, 3];
I am using React/Redux and am storing animation data in JSON and trying to get it to display on a React page.
I am using setTimeout (for pauses) and setInterval (for animation movement). However, I seem to be having trouble understanding how to implement the animations correctly and think I'm going about things totally the wrong way.
JSON data:
"objects": [
{
"title": "puppy",
"image_set": [
{
"image": "images/puppy_sitting.png",
"startx": 520,
"starty": 28,
"pause": 1000
},
{
"image": "images/puppy_walking.png",
"startx": 520,
"starty": 28,
"endx": 1,
"endy": 1,
"time": 1000
},
{
"image": "images/puppy_crouching.png",
"startx": 1,
"starty": 1,
"endx": 500,
"endy": 400,
"time": 2000
}
]
},
{
"title": "scorpion",
"image_set": [
{
"image": "images/scorping_sleeping.png",
"startx": 100,
"starty": 400,
"pause": 5000
},
{
"image": "images/scorpion_walking.png",
"startx": 100,
"starty": 400,
"endx": 500,
"endy": 400,
"time": 7000
},
{
"image": "images/scorpion_walking.png",
"startx": 500,
"starty": 400,
"endx": 100,
"endy": 400,
"time": 2000
},
{
"image": "images/scorpion_walking.png",
"startx": 100,
"starty": 400,
"endx": 200,
"endy": 400,
"time": 7000
},
{
"image": "images/scorpion_walking.png",
"startx": 200,
"starty": 400,
"endx": 100,
"endy": 400,
"time": 1000
}
]
}
]
Each object can have several images related to them. The animations will continue to repeat non-stop. Each object should move concurrently with each of the other objects so that I can create a scene of various animals and objects moving around it.
Animation code:
I'm pretty sure I'm barking up the wrong tree here, but my code looks something like this:
// image_set is the list of images for a specific object
// object_num is the array index corresponding to the JSON objects array
// selected is the array index corresponding to which image in the image_set will be displayed
runAnimation(image_set, object_num, selected){
// Uses prevState so that we keep state immutable
this.setState(prevState => {
let images = [...prevState.images];
if (!images[object_num]){
images.push({image: null, x: 0, y: 0})
}
images[object_num].image = image_set[selected].image;
images[object_num].x = this.getFactoredX(image_set[selected].startx);
images[object_num].y = this.getFactoredY(image_set[selected].starty);
return {images: images};
})
if (image_set[selected].endx && image_set[selected].endy && image_set[selected].time){
let x = this.getFactoredX(image_set[selected].startx)
let y = this.getFactoredY(image_set[selected].starty)
let startx = x
let starty = y
let endx = this.getFactoredX(image_set[selected].endx)
let endy = this.getFactoredY(image_set[selected].endy)
let time = image_set[selected].time
let x_increment = (endx - x) / (time / 50)
let y_increment = (endy - y) / (time / 50)
let int = setInterval(function(){
x += x_increment
y += y_increment
if (x > endx || y > endy){
clearInterval(int)
}
this.setState(prevState => {
let images = [...prevState.images]
if (images[object_num]){
images[object_num].x = x
images[object_num].y = y
}
return {images: images};
})
}.bind(this),
50
)
}
if (image_set[selected].pause && image_set[selected].pause > 0){
selected++
if (selected == image_set.length){
selected = 0
}
setTimeout(function() {
this.runAnimation(image_set, object_num, selected)
}.bind(this),
image_set[selected].pause
)
}
else {
selected++
if (selected == image_set.length){
selected = 0
}
setTimeout(function() {
this.runAnimation(image_set, object_num, selected)
}.bind(this),
50
)
}
}
Redux and this.props.data
Redux brings in the data as props. So, I have a function called from my componentDidMount and componentWillReceiveProps functions that passes the original image set into the loadAnimationFunction.
My render()
In my render() function I have something like this:
if (this.state.images.length > 1){
animated = this.state.images.map((image, i) => {
let x_coord = image.x
let y_coord = image.y
return (
<div key={i} style={{transform: "scale(" + this.state.x_factor + ")", transformOrigin: "top left", position: "absolute", left: x_coord, top: y_coord}}>
<img src={`/api/get_image.php?image=${image.image}`} />
</div>
)
})
}
x_factor / y_factor
Throughout my code there is also reference to x and y factor. This is because the background that the animations appear in may be scaled smaller or larger. Therefore I also scale the position of the starting and ending x/y coordinates for each animation as well as scale the animated images themselves.
time and pause time
Time indicates the time in ms that the animation should take. Pause time indicates how long in ms to pause before moving to the next animation.
The problem
The code does not move the animations smoothly and they seem to jump around sporadically.
Also, when I click the mouse anywhere on the page it causes the animations to jump to another position. Why would clicking the mouse affect the animation?
One thing I've noticed is that if I have the console open for debugging purposes, this really slows down the animations.
What can I do to my code so that the animations work as expected?
You are trying to animate your element using a setInterval doing a setState of the coordinates and with an absolute position. All of these cannot achieve great performance.
First, setInterval should never be used for animations, and you should prefer requestAnimationFrame as it will allow 60fps animations since the animation will be run before the next repaint of the browser.
Second, doing a setState would re-render your whole component which could potentially have an impact on the rendering timing as I assume your component doesn't render only your images. You should try to avoid at maximum to re-render things that haven't changed, so try to isolate your images for the animations.
Lastly, when you position your element with left and top properties, but you should stick to that, positioning, and not animating as the browser would do the animation pixel by pixel and would not be able to create good performances. Instead, you should use CSS translate(), as it can do sub-pixel calculation and will work on the GPU instead, allowing you to achieve 60fps animations. There is a good article on that by Paul Irish.
That being said, you should probably use react-motion which would allow you a smooth animation:
import { Motion, spring } from 'react-motion'
<Motion defaultStyle={{ x: 0 }} style={{ x: spring(image.x), y: spring(image.y) }}>
{({ x, y }) => (
<div style={{
transform: `translate(${x}px, ${y}px)`
}}>
<img src={`/api/get_image.php?image=${image.image}`} />
</div>
)}
</Motion>
There is also the React Transition Group, Transition could move your elements using a translate animation like explained above. You should also go take a look at the react animations docs here.
Worth a try too, is React Pose, which is pretty easy to use and also performs quite well with a clean API. Here is the get started page for React.
Here is a quick demo using your concept with a sit/walking/running cycle. Notice how react-motion is the only one to handle the transition in between the frames without hardcoding the duration of the transition, which would go against a fluid UI, the state only handles going through the different steps.
Quoting the react-motion Readme:
For 95% of use-cases of animating components, we don't have to resort to using hard-coded easing curves and duration. Set up a stiffness and damping for your UI element, and let the magic of physics take care of the rest. This way, you don't have to worry about petty situations such as interrupted animation behavior. It also greatly simplifies the API.
If you are not satisfied with the default spring, you can change the dampling and stiffness parameters. There's an app which could help you get the one which satisfy you the most.
Source
React is not exactly meant to be used for animations. I'm not saying you can't animate react components, but it's not part of the problem domain react tries to solve. What it does do is provide you with a nice framework to have the several UI pieces interact with each other. I.e. when creating a game for instance, you'll use react and redux to create and manage the screens, buttons etc. however the game itself, would be separately contained and not use react.
Just a long-winded way to say that if you want to use animations react will not suffice, it's better to use something like greensock's animation library: https://greensock.com/
They provide a tutorial on how to use it in conjunction with react: https://greensock.com/react
Let css do the transitions. Use transform: translate instead of top and left.
The animations you have in your sample are very easy to express with css transition, transition-delay, and transform.
I would put my effort in converting the JSON to css (using a cssInJs solution that allows you to generate the classes on the fly) and apply those classes to the images.
something like this(working example with your JSON sample): https://stackblitz.com/edit/react-animate-json
const App = () =>
<div>
{objects.map(object =>
<Item item={object} />)
}
</div>
Item.js:
class Item extends React.Component {
state = { selected: 0, classNames: {} }
componentDidMount() {
this.nextImage();
this.generateClassNames();
}
generateClassNames = () => {
const stylesArray = this.props.item.image_set.flatMap((image, index) => {
const { startx, starty, endx = startx, endy = starty, time } = image;
return [{
[`image${index}_start`]: {
transform: `translate(${startx}px,${starty}px)`,
transition: `all ${time || 0}ms linear`
}
}, {
[`image${index}_end`]: { transform: `translate(${endx}px,${endy}px)` }
}]
});
const styles = stylesArray.reduce((res, style) => ({ ...res, ...style }), {})
const { classes: classNames } = jss.createStyleSheet(styles).attach();
this.setState({ classNames });
}
nextImage = async () => {
const { image_set } = this.props.item;
let currentImage = image_set[this.state.selected];
await wait(currentImage.pause);
await wait(currentImage.time);
this.setState(({ selected }) =>
({ selected: (selected + 1) % image_set.length }), this.nextImage)
}
render() {
const { selected, classNames } = this.state;
const startClassName = classNames[`image${selected}_start`];
const endClassName = classNames[`image${selected}_end`];
return <img
className={`${startClassName} ${endClassName}`}
src={this.props.item.image_set[selected].image}
/>
}
}
const wait = (ms) => new Promise(res => setTimeout(res, ms));
I believe that your fundamental problem lies in the way React/Redux handle state. React may batch multiple update requests together to make rendering more efficient. Without further diagnostic measures, my guess is that the state handling after setState will just respond too rigidly.
The solution would to update your animation outside the state system, either using a ready-made framework or simply by taking care of the animation yourself; get a reference to the element and update it instead of re-rendering the element every time the state is updated.
without going deep about animations in JS (there are already plently of valid answers here) you should consider how you render your images:
<div key={i} style={{transform: "scale(" + this.state.x_factor + ")", transformOrigin: "top left", position: "absolute", left: x_coord, top: y_coord}}>
<img src={`/api/get_image.php?image=${image.image}`} />
</div>
You should actually see a warning when compiling this (or was it in the docs?) because you use the loop index as the key. This should lead to an image object being rendered in different divs as more images are added/removed. This is especially critically if you have a css-transition effect on the div.
TLDR: use some identifier as the key instead of the variable i (may be generate one when you create the animation?)
Also if you have a css transition on the div, you should remove it, because together with the changes from setInterval the transition calculation won't be able to keep up with the changes.
I am trying to update a stacked bar chart with transitions as the underlying data is changed. It calls the same "render" function each time and works well when no transitions are involved. However, I would like to animate the changes in values, transitioning from its current state to the next.
I have somewhat solved the problem, but feel like my solution is clunky - hoping there is a better way to do this for stacked bar charts.
My approach has been to do the following:
Load the data
Load the initial conditions (req. for transitions)
Load the final conditions (within a transition)
Copy the current data into another array: prevData
Reload data after interval
Using the above approach, if prevData has values, then use these to set the initial conditions. My problems is that finding and setting the initial conditions feels really clunky:
if (prevData.length > 0) {
//get the parent key so we know who's data we are now updating
var devKey = d3.select(this.parentNode).datum().key;
//find the data associated with its PREVIOUS value
var seriesData = seriesPrevData.find(function (s) { return (s.key == devKey); })
if (seriesData != null) {
//now find the date we are currently looking at
var day = seriesData.find(function (element) { return (element.data.Date.getTime() == d.data.Date.getTime()); });
if (day != null) {
//now set the value appropriately
//console.debug("prev height:" + devKey + ":" + day[1]);
return (y(day[0]) - y(day[1]));
}
}
}
All I'm doing, is finding the correct key array (created by d3.stack()), then trying to find the appropriate previous data entry (if it exists). However, searching parent nodes, and searching through arrays to find the required key and the appropriate data element feels very long-winded.
So, my question is, is there a better way to do this? or parts of this?
Find the previously bound data values associated with this element or the current values before it is changed within a function.
Better way to find the current key being updated rather than using: d3.select(this.parentNode)... ? I've tried passing key values but don't seem to be getting it right. The best I have achieved, is passing a key function to the parent, and looking for it the way described above.
Sorry for the long post, I just spent a whole day working out my solution, frustrated by the fact that all I really needed, was the previous values of an item. Having to do all these "gymnastics" to get what I needed seems very "un" D3.js like :-)
Thanks
Following is a simple example for an animated bar chart. It'll iterate over two different versions of the dataset to show how one can handle changes in the underlying data very easily with d3. There is no need (in this example) for any manual data preparation for the transition/animation.
var data = [
[1, 2, 3, 4, 5],
[1, 6, 5, 3]
];
var c = d3.select('#canvas');
var currentDataIndex = -1;
function updateData() {
// change the current data
currentDataIndex = ++currentDataIndex % data.length;
console.info('updating data, index:', currentDataIndex);
var currentData = data[currentDataIndex];
// get our elements and bind the current data to it
var rects = c.selectAll('div.rect').data(currentData);
// remove old items
rects.exit()
.transition()
.style('opacity', 0)
.remove();
// add new items and define their appearance
rects.enter()
.append('div')
.attr('class', 'rect')
.style('width', '0px');
// change new and existing items
rects
// will transition from the previous width to the current one
// for new items, they will transition from 0px to the current value
.transition()
.duration('1000')
.ease('circle')
.style('width', function (d) { return d * 50 + 'px'; });
}
// initially set the data
updateData();
// keep changing the data every 2 seconds
window.setInterval(updateData, 2000);
div.rect {
height: 40px;
background-color: red;
}
div#canvas {
padding: 20px;
border: 1px solid #ccc;
}
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<div id="canvas">
</div>
I my fabric application, I want to align the selected objects, for example, to the left. Because objects might be rotated (and or scaled), thus, aligning objects actually mean align the bounding boxes of the objects to some edge.
For non-rotated objects, that's quite trivial to implement.
See sample code below:
// find the minimum 'left' value
// function 'min' is used to find the minimum value of a
// given array of objects by comparing the property value
// which is returned by a given callback function
const { minValue } = min(objects, object => {
const left = object.get('left');
const originX = object.get('originX');
if (originX === 'center') {
return left - (object.get('width') * object.get('scaleX')) / 2;
}
return left;
});
objects.forEach(object => {
if (object.get('originX') === 'center') {
object.set('left', minValue + (
object.get('width') * object.get('scaleX')
) / 2);
} else {
object.set('left', minValue);
}
});
canvas.renderAll();
However, it's quite complicated for rotated objects. I have to translate the rotated objects either horizontally or vertically to some calculated offset/distance.
Can anybody give some advise on this? thanks.
After a small research, I found this demo on the official fabricjs website.
Basically you can do:
var bound = obj.getBoundingRect();
Then use bound.top, bound.left, bound.width, bound.height as the bounding rectangle coordinates.
i am trying to update a line graph and it is not throwing any error but it is also not updating the graph.
i am deleting a point and adding a new one with an incremented rate and incremented created_at date by a second(trying to follow http://bl.ocks.org/benjchristensen/1148374)
function redrawWithoutAnimation() {
for (var i in chart_data) {
linedata = chart_data[i];
//delete first element of array
linedata.points.reverse().shift();
//create a new point
rate = linedata.points[0].rate + 1;
created_at = linedata.points[0].created_at + 6000;
new_point = {};
new_point.rate = rate;
new_point.created_at = created_at;
linedata.points.push(new_point);
console.log(linedata);
}
// static update without animation
svg.selectAll("path")
.data([linedata.points]); // set the new data
line(linedata.points); // apply the new data values
}
redrawWithoutAnimation();
setInterval(function () {
redrawWithoutAnimation();
}, 8000);
here is my code
http://jsfiddle.net/yr2Nw/8/
Working fiddle: http://jsfiddle.net/reblace/GsaGb/1
There's a few issues here...
First, you were updating all the chart_data in the for loop, but outside the loop, you were only trying to update the line still stored in the linedata variable after loop execution. You should try to avoid having variables with greater scope than they need. It can lead to bugs like this one:
svg.selectAll("path").data([linedata.points]);
line(linedata.points);
You should instead use D3's data joining to rejoin the new data to all the paths at once declaratively like so:
linesGroup.selectAll("path")
.data(chart_data)
.attr("d", function(d){ return line(d.points); });
What that code's doing is it's selecting the paths and then joining each of them to the chart_data elements and then binding the appropriate line generator to the "d" attribute for the appropriate path.
Then, you need to update your x axis and y axis otherwise the plot will just shoot off the drawn area. This code is updating the domains and then rebinding the axes to the dom elements so they redraw:
xAxis.scale().domain([
d3.min(chart_data, function (c) { return d3.min(c.points, function (v) { return v.created_at; }); }),
d3.max(chart_data, function (c) { return d3.max(c.points, function (v) { return v.created_at; }); })
]);
yAxis.scale().domain([
0,
d3.max(chart_data, function (c) { return d3.max(c.points, function (v) { return v.rate; }); })
]);
svg.select(".x.axis").call(xAxis);
svg.select(".y.axis").call(yAxis);
There were a few other bugs I fixed them in the Fiddle. For example, you need to calculate the time for the new point based on the last element in the array, not the first, otherwise the line can't interpolate properly since its no longer a continuous function... and this is a bit more concise way to do your line updates:
for (var i=0; i<chart_data.length; i++) {
linedata = chart_data[i];
//delete first element of array
var removedPoint = linedata.points.shift();
//create a new point
var lastpoint = linedata.points[linedata.points.length-1];
var new_point = {
rate: removedPoint.rate,
created_at: lastpoint.created_at + 6000
};
linedata.points.push(new_point);
}
Also note that you shouldn't use the for(var in) loop for Arrays, that's for iterating over the properties in an object.
There's still some issues, but I think this should help get you over the hurdle you were stuck on. Anyways, it looks cool in action!
Fine fenac.. You facing so many problems since your data is not in good format for your requirements..
as per http://bl.ocks.org/benjchristensen/1148374 The x-axis data must be (data[] (data array))
Your data is something like this
[objects,object,object] where each object holds one element of xaxis value.. so the pushing and shifting is not possible..
try to change the format of the data (linedata.points) to an array (data[]) and try it out sure it works..
You just need to put all the values in linedata.points into an array data[] and use this data[] to animate your line..
Since yours the multiline.. you need to create 2D array and must pass them accordingly...
Cheers..
I updated your jsfiddle
setInterval(function () {
console.log(linedata.points);
var v = linedata.points.shift(); // remove the first element of the array
linedata.points.push(v); // add a new element to the array (we're just taking the number we just shifted off the front and appending to the end)
redrawWithoutAnimation();
}, 3000);
http://jsfiddle.net/yr2Nw/9/
But still it wont works till you do that work...
Personal Suggestion: First Try with single line graph then go with looping for multiline...