I have two questions about anychart.
(1) I have implemented drawing tools like below (except for "Label") with React
and am wondering if it is possible to implement a functionality for "Label" with React,
i.e. let user modify an existing label's text.
https://www.anychart.com/products/anystock/overview/
Drawing Tools And Annotations
(2) If I select (click on) an existing label, it seems getSelectedAnnotation() can't get the selected one.
The following code is in React functional component, probably is this the reason of that?
chart.listen(`annotationSelect`, function (e) {
if (e.annotation.type === `label`) {
console.log(e.annotation) // this prints e.annotaion object
const s = chart.annotations().getSelectedAnnotation()
console.log(s) // this prints "null"
}
})
A1 - you can implement any logic you need to modify the label annotation and UI approach. The library has all the required API. For example, you can listen for keyboard inputs in the hidden text area and apply text to the label. For details, check the live sample.
Simply select the label and start typing the text.
A similar approach is used in the demo app.
A2 - You need to wait until the next round of the JS event loop. For example, with setTimeout with zero time to schedule a task on the next round. Here is the modified sample.
Related
I currently have a Radar chart in chart.js using the react integration.
I was suprised to note that, when I updated the data, instead of showing a completely new plot, it just transitioned smoothly from the previous dataset to the new one.
What I am interested in is to understand how it works under the hood, which honestly I can't understand, at least from looking at the code.
First: my understanding of React is that, when a prop or state changes, it computes the new DOM, and then merges the new DOM and the current DOM, applying only the difference between the two. However, chartjs seem to be implemented as a Canvas element.
The chartjs integration with react does not do much. Taking the Radar plot, this is what it does
export const Radar = /* #__PURE__ */ createTypedChart('radar', RadarController);
which is nothing but declare a <Chart> element and leave it to ChartJS to plot it. In fact, in ChartJS, we have this code, which basically manages the Canvas element and it is smart to perform transitions using animations and so on. This I understand (relatively): a lot of animation and transition helper functions, but this makes sense to me. However, this part is pure JavaScript. There's nothing that is aware of React.
What does not make sense is therefore how the react synchronization system is integrated with this JavaScript library so that the state invalidation of the props/state is synchronised to an animation, instead of a complete rewrite of the Canvas element. I don't seem to find where this magic happens in react-chartjs-2.
As you explained the canvas element does not get changed so it gets reused. To animate the chart chart.js itself has an update method. React-chartjs-2 uses a useeffect function that checks if the data you pass it has changed. If this is the case it calls the update function from chart.js itself and they handle the animations and updates itself:
useEffect(() => {
if (!chartRef.current) return;
if (redraw) {
destroyChart();
setTimeout(renderChart);
} else {
chartRef.current.update();
}
}, [redraw, options, data.labels, data.datasets]);
https://github.com/reactchartjs/react-chartjs-2/blob/4a010540ac01b1e4b299705ddd93f412df4875d1/src/chart.tsx#L78-L87
This is my understanding of the whole process after diving into the code base quite a bit. I've tried to be as detailed as possible with links to the exact line of code I am talking about. Hope this helps:
Beginning with the code snippet you shared:
export const Radar = /* #__PURE__ */ createTypedChart('radar', RadarController);
If you follow the RadarController via the import statement, you see that it is fetched from chart.js
Now we move to the Chart.js code and look for this controller RadarController. It is found in a file called src/controllers/controller.radar.js.
Within that file, you see an update function
This function then calls updateElements with the points information
This function gets the new point position which is then set in properties and passed into the updateElement function
This updateElement function directly takes us to the core.datasetController
Here you see a condition to check if the chart is in directUpdateMode. If not, it calls a function to _resolveAnimations
Within this function, you will see the new Animations(args) object
This eventually brings us to the core.animations file which consists of all the animation related information and processing.
One interesting bit I found here was: this is what seems to be making the beautiful movement of points to the changed location.
You can explore this Animations class further for more detailed understanding
So yeah essentially, it is the js part under the hood that facilitates the smooth transitions and this is how it does it. React code is essentially just like a wrapper of Chart.js calling this update method with the new values.
You can see here: https://github.com/reactchartjs/react-chartjs-2/blob/master/src/chart.tsx
The react-chartjs-2 library creates a component that adds a canvas and when the props update the component creates/updates an internal Chart object that uses the rendered canvas.
From what I saw the animation starts when the props are changed.
The path is props->react-chartjs-2 component->chart object->animation
I want to use some transition effects in my react js app. I am using function components in my app.
How do I include transition effects in app according to the business requirement these days?
I want to use animation such that on every render I can see the effect. It would be great if someone can help me out with an example.
If you want to use a library, I would suggest react-spring
https://react-spring.io/ it is based on spring physics, If you want to read about that more check this out https://www.joshwcomeau.com/animation/a-friendly-introduction-to-spring-physics/
And there is also another good option which is framer motion https://www.framer.com/motion/ which apparently offers more possibilities maybe out of the box (I personally have never tried it before)
For examples you can check their websites they have good examples.
I'm not sure what effect you are trying to generate.
css can be used by itself to generate animations or transitions.
You want to see the effect on each render?
i.e. You want to tie the effect to the react render cycle?
non-memoized values will change on every render
You could use a simple statement like const trigger = {};
Then react to trigger with a useEffect
useEffect(() => { do something }, [trigger]);
finally, visual effect.. apply a class based on state and use setTimeout to remove the state (and therefore the class)
This could be overly involved for exactly what you are trying to achieve but this works for all possible flows based on the question.
Here is one example with div element is moving to according vertical scroll position .
Look carefully.
First, Set the position using useState and define the window.onscroll function.
const [cardTop, setCardTop] = useState(0);
window.onscroll = function() {
if (window.pageYOffset < 30) {
setCardTop(window.pageYOffset + 'px');
}
};
Second, Set the style's top as state variable.
<div className='card t-card' id='tCard' style={{top:`${cardTop}`}}> ...
Congratulations. It probably act exactly.
It's similar to use Jquery or another Javascript, Only use state variable.
Thanks.
I am trying to hide an element 'GorillaSurfIn' after I click on it.
But also it should fire the 'setShouldGorillaSurfOut' to 'true'. The second part works, but after I added this function:
function hideGorillaSurfIn() {
let element = document.getElementById('gorilla-surf-in');
ReactDOM.findDOMNode(element).style.display =
this.state.isClicked ? 'grid' : 'none';
}
After I click, the code falls apart.
Once I click, the element should be hidden/removed till the next time the App restarts.
Here is the Code Sandbox Link for further explanation.
I am open to any solutions, but also explanations please, as I am still fresh in learning React.
I have changed your code a bit to make it work. You can make further changes according to your need. A few things that I would like to add: -
You should avoid using findDOMNode (in most cases refs can solve your problem) as there are certain drawbacks associated with findDOMNode, such as the react's documentation states "findDOMNode cannot be used with functional components".
I've used refs (forward ref in this case) to make it work.
GorillaSurfIn was called twice, so there were two Gorilla gifs on the screen with same IDs. Not sure if that was the intended behaviour but each element should have unique ID.
Check out the code sandbox.
With react-color https://casesandberg.github.io/react-color/ .
I can use ready-made onChangeComplete function from react-color.
But I wonder how can I create that onChangeComplete by using input type color tag.
I tried onBlur but the color won't change until user clicks or presses tab
On the other hand, using onChange keep firing updates.
Because currently I'm using redux state, so dispatching update continuously when I drag and choose color isn't a good way.
Any ideas how to create onChangeComplete?
It depends on how you'd like to define a change. To prevent continuous updates every time the mouse moves, you'll probably want to update Redux state only when the mouse stops moving. (This seems to be the behaviour on the page you linked to).
You could use the following JavaScript to detect when the mouse stops moving:
let timer;
window.addEventListener('mousemove', function (e) {
console.log('Mouse moving');
clearTimeout(timer);
timer = setTimeout(() => console.log('Mouse stopped'), 300);
});
Then, try putting the above code inside your ComponentDidMount() method and replace console.log('Mouse stopped') with whatever Redux action you want to dispatch!
300 is the number of milliseconds without movement that will trigger the action, which could be changed depending on how sensitive you want your app to feel.
Lastly, remember to remove the event listener in your ComponentWillUnmount() method.
https://github.com/casesandberg/react-color/blob/7ee60d845e5d5e11e4f6ecb895b2d9755c59d09d/src/components/common/ColorWrap.js#L30
Here is the code that how react-color implemented onChangeComplete.
It is hard coded using debounce.
I put the link there for anyone interested in using that solution
I have a specific need to only make one input field in a form (legacy code) a react component. So, I wrap the input with a div and render into it the 'new' input field that needs some special behavior.
The problem arises because the input field is no longer editable. I try to type into it.. nothing. I narrowed it down to the following:
<input type="text" **data-reactid=".2.0.0.0.1.0.0.1.2.0"**
When I remove that "data-reactid....", by editing via console, it works.
So when I am using react to sub out one form input field with a react one, it doesn't work unless I manually remove that data-reactid..
Is there a workaround for this, or a reason why this is happening?
Well its just a data attribute written by react to help them render into the DOM more efficiently so it should have no real impact on a input element or any element (unless there is code or style explicitly disabling the input) - I realize that this is no real help - because it happens to you, but this is not typical of react apps with inputs or element with data-attributes.
But if its the only bit of react on the page then that id is a bit long and I would have expected something like ".0" or ".0.0" if its wrapped in a div that react controls.
The react-id is only used by the React engine to work out what elements of the DOM need to be re-written when there are changes to state or props in your components.
One thing I noticed is, typically there would be an ID or in react a ref that you applied to the input in order to interact with it (such as getting its value).
I include the mark-up from a simple entry box on the user login form of a working app, as you can see it's not significantly different from what you have and works on all browsers Windows and Mac down to IE8 included.. (but not any IE below 8) and you need various shims for getting it work on IE8.
<input class="username-text-field" id="user-id" type="text" data-reactid=".0.0.0.1.3.0.0.2">
If none of these apply or you have them covered then practicably here should be no reason why your input should be disabled. It should just act like any other input. Have tried just dropping you component onto a simple HTML page with only the input on it, just to debug through the component in isolation?
That said,
It does feel that loading the entire React engine and wiring up a component to allow a single input field is a little over-kill. I realize that you're trying not to have to recreate exactly the same functionality you already have in react again on the legacy form, but if your render function is not too onerous then maybe a simple bit of JavaScript or JQuery might be the answer as a one off in the legacy solution (rather than the hit for the library) - just a thought