Sådan bruges animation med Angular 6

Introduktion

Animation defineres som overgangen fra en indledende tilstand til en endelig tilstand. Det er en integreret del af enhver moderne webapplikation. Animation hjælper os ikke kun med at skabe et fantastisk brugergrænseflade, men det gør applikationen også interessant og sjov at bruge. En velstruktureret animation holder brugeren engageret i applikationen og forbedrer brugeroplevelsen.

Angular giver os mulighed for at oprette animationer, der giver os lignende native præstationer som CSS-animationer. I denne artikel lærer vi, hvordan vi kan skabe animation ved hjælp af Angular 6.

Vi bruger Visual Studio-kode til vores demo.

Forudsætninger

Installer VS-kode og Angular CLI.

Hvis du er ny med Angular, skal du henvise til min tidligere artikel Kom godt i gang med Angular 6.0 for at konfigurere Angular 6-udviklingsmiljøet på din maskine.

Kildekode

Download kildekoden fra GitHub.

Forståelse af vinklede animationsstater

Animation involverer overgang fra en tilstand af et element til en anden tilstand. Vinkel definerer tre forskellige tilstande for et element:

  1. Void state - repræsenterer tilstanden for et element, der ikke er en del af DOM. Denne tilstand opstår, når et element oprettes, men endnu ikke er placeret i DOM, eller når elementet fjernes fra DOM. Denne tilstand er nyttig, når vi vil oprette animation, mens vi tilføjer eller fjerner et element fra vores DOM. For at definere denne tilstand i vores kode bruger vi nøgleordet void.
  2. Jokertegnetilstanden - Dette er også kendt som elementets standardtilstand. De typografier, der er defineret for denne tilstand, gælder for elementet uanset dets aktuelle animationstilstand. For at definere denne tilstand i vores kode bruger vi *symbolet.
  3. Brugerdefineret tilstand - Dette er elementets brugerdefinerede tilstand, og det skal defineres eksplicit i koden. For at definere denne tilstand i vores kode kan vi bruge ethvert brugerdefineret navn efter eget valg.

Animation Overgangstiming

For at vise overgangen til animation fra en tilstand til en anden definerer vi timing for overgang til animation i vores applikation.

Angular giver følgende tre timingegenskaber:

Varighed

Denne egenskab repræsenterer den tid, det tager vores animation at fuldføre fra start (indledende tilstand) til slut (endelig tilstand). Vi kan definere animationens varighed på følgende tre måder:

  • Brug af et heltal til at repræsentere tiden i millisekunder. F.eks. 500
  • Brug af en strengværdi til at repræsentere tiden i millisekunder. F.eks. - '500 ms'
  • Brug af en strengværdi til at repræsentere tiden i sekunder. F.eks. - '0,5s'

Forsinke

Denne egenskab repræsenterer varigheden mellem animationsudløseren og begyndelsen af ​​den aktuelle overgang. Denne egenskab følger også den samme syntaks som varighed. For at definere forsinkelsen skal vi tilføje forsinkelsesværdien efter varighedsværdien i et strengformat - 'Varighed forsinkelse'. Forsinkelse er en valgfri egenskab.

For eksempel:

  • '0.3s 500ms'. Dette betyder, at overgangen vil vente i 500 ms og derefter køre i 0,3 sek.

Nemmere

Denne egenskab repræsenterer, hvordan animationen accelererer eller decelererer under udførelsen. Vi kan definere lempelsen ved at tilføje den som den tredje variabel i strengen efter varighed og forsinkelse. Hvis forsinkelsesværdien ikke er til stede, vil lempelse være den anden værdi. Dette er også en valgfri egenskab.

For eksempel:

  • '0.3s 500ms eas-in' - Dette betyder, at overgangen venter på 500ms og derefter kører i 0,3s (300ms) med let-in-effekt.
  • '300ms let ud'. - Dette betyder, at overgangen kører i 300 ms (0,3 sek.) Med let ud-effekt.

Oprettelse af Angular 6-applikationen

Åbn kommandoprompt på din maskine, og udfør følgende sæt kommandoer:

  • mkdir ngAnimationDemo
  • cd ngAnimationDemo
  • ng ny ngAnimation

Disse kommandoer opretter en mappe med navnet ngAnimationDemoog opretter derefter en kantet applikation med navnet ngAnimationinde i den mappe.

Åbn ngAnimation-appen ved hjælp af VS-kode. Nu opretter vi vores komponent.

Naviger til View >> Integrated Terminal. Dette åbner et terminalvindue i VS-kode.

Udfør følgende kommando for at oprette komponenten.

ng g c animationdemo

Dette opretter vores komponent animationdemoinde i /src/appmappen.

For at bruge Angular animation skal vi importere, BrowserAnimationsModulehvilket er et animationsspecifikt modul i vores applikation. Åbn filen app.module.ts, og inkluder importdefinitionen som vist nedenfor:

import { BrowserAnimationsModule } from '@angular/platform-browser/animations'; // other import definitions @NgModule({ imports: [BrowserAnimationsModule // other imports]})

Forståelse af Angular Animation Syntax

Vi skriver vores animationskode inde i komponentens metadata. Syntaksen for animationen er vist nedenfor:

@Component({ // other component properties. animations: [ trigger('triggerName'), [ state('stateName', style()) transition('stateChangeExpression', [Animation Steps]) ] ] })

Her bruger vi en egenskab kaldet animations. Denne egenskab tager en matrix som input. Arrayet indeholder en eller flere “trigger”. Hver trigger har et unikt navn og en implementering. Tilstanden og overgange til vores animation skal defineres i triggerimplementeringen.

Hver tilstandsfunktion har et "stateName" defineret til entydigt at identificere tilstanden og en stilfunktion til at vise elementets stil i denne tilstand.

Each transition function has a stateChangeExpression defined to show the change of the state of an element and the corresponding array of animation steps to show how the transition will take place. We can include multiple trigger functions inside the animation property as comma separated values.

These functions trigger, and state and transition are defined in the @angular/animations module. Hence, we need to import this module in our component.

To apply animation on an element, we need to include the trigger name in the element definition. Include the trigger name followed by @ symbol in the element tag. Refer to the sample code below:

This will apply the trigger changeSize to the iv> element.

Let us create a few animations to get a better understanding of the Angular animation concepts.

Change Size Animation

We will create an animation to change the size of a iv> element on a button click.

Open the animationdemo.component.ts file and add the following import definition:

import { trigger, state, style, animate, transition } from '@angular/animations';

Add the following animation property definition in the component metadata:

animations: [ trigger('changeDivSize', [ state('initial', style({ backgroundColor: 'green', width: '100px', height: '100px' })), state('final', style({ backgroundColor: 'red', width: '200px', height: '200px' })), transition('initial=>final', animate('1500ms')), transition('final=>initial', animate('1000ms')) ]), ]

Here we have defined a trigger changeDivSize and two state functions inside the trigger. The element will be green in the “initial” state and will be red with an increased width and height in the “final” state.

We have defined transitions for the state change. Transition from “initial” state to “final” will take 1500ms and from “final” state to “initial” will take 1000ms.

To change the state of our element we will define a function in the class definition of our component. Include the following code in the AnimationdemoComponent class:

currentState = 'initial'; changeState() { this.currentState = this.currentState === 'initial' ? 'final' : 'initial'; }

Here we have defined a changeState method which will switch the state of the element.

Open animationdemo.component.html file and add the following code:

Change the div size

Change Size

We have defined a button which will invoke the changeState function when clicked. We have defined a iv> element and applied the animation tr igger changeDivSize to it. When we click on the button it will flip the state o f the element and its size will change with a transition effect.

Before executing the application, we need to include the reference to our Animationdemo component inside the app.component.html file.

Open app.component.html file. You can see we have some default HTML code in this file. Delete all the code and put the selector of our component as shown below:

To execute the code run the ng serve command in the VS code terminal window. After running this command, it will ask to open //localhost:4200 in the browser. So, open any browser on your machine and navigate to this URL. You can see a webpage as shown below. Click on the button to see the animation.

Balloon effect animation

In the previous animation, the transition happened in two directions. In this section, we will learn how to change the size from all directions. It will be similar to inflating and deflating a balloon, hence the name balloon effect animation.

Add the following trigger definition in the animation property:

trigger('balloonEffect', [ state('initial', style({ backgroundColor: 'green', transform: 'scale(1)' })), state('final', style({ backgroundColor: 'red', transform: 'scale(1.5)' })), transition('final=>initial', animate('1000ms')), transition('initial=>final', animate('1500ms')) ]),

Here, instead of defining the width and height property, we are using the transform property to change the size from all directions. The transition will occur when the state of the element is changed.

Add the following HTML code in the app.component.html file:

Balloon Effect

Here we have defined a div and applied the CSS style to make it a circle. Clicking on the div will invoke the changeState method to switch the element’s state.

Open the browser to see the animation in action as shown below:

Fade In and Fade Out animation

Sometimes we want to show animation while adding or removing an element on the DOM. We will see how to animate the addition and removal of an item to a list with a fade-in and fade-out effect.

Add the following code inside the AnimationdemoComponent class definition for adding and removing the element in a list:

listItem = []; list_order: number = 1; addItem() { var listitem = "ListItem " + this.list_order; this.list_order++; this.listItem.push(listitem); } removeItem() { this.listItem.length -= 1; }

Add the following trigger definition in the animation property:

trigger('fadeInOut', [ state('void', style({ opacity: 0 })), transition('void  *', animate(1000)), ]),

Here we have defined the trigger fadeInOut. When the element is added to the DOM it is a transition from void to wildcard (*) state. This is denoted using void =>; *. When the element is removed from the DOM, it is a transition from wildcard (*) to void state. This is denoted using * =>; void.

When we use the same animation timing for both directions of the animation, we use the shorthand syntax <;=>. As defined in this trigger, the animation from void =&gt; * and * => void will take 1000ms to complete.

Add the following HTML code in app.component.html file.

Fade-In and Fade-Out animation

Add List Remove List
  • {{list}}

Here we are defining two buttons to add items to and remove them from the list. We are binding the fadeInOut trigger to the <li> element, which will show a fade-in and fade-out effect while being added and removed from the DOM.

Open the browser to see the animation in action as shown below:

Enter and Leave animation

When adding to the DOM, the element will enter the screen from the left. When deleting, the element will leave the screen from the right.

The transition from void => * and * => void is very common. Therefore, Angular provides aliases for these animations:

  • for void => * we can use ‘:enter’
  • for * => void we can use ‘:leave’

The aliases make these transitions more readable and easier to understand.

Add the following trigger definition in the animation property:

trigger('EnterLeave', [ state('flyIn', style({ transform: 'translateX(0)' })), transition(':enter', [ style({ transform: 'translateX(-100%)' }), animate('0.5s 300ms ease-in') ]), transition(':leave', [ animate('0.3s ease-out', style({ transform: 'translateX(100%)' })) ]) ])

Here we have defined the trigger EnterLeave. The ‘:enter’ transition will wait for 300ms and then run for 0.5s with an ease-in effect. Whereas the ‘:leave transition will run for 0.3s with an ease-out effect.

Add the following HTML code in the app.component.html file:

Enter and Leave animation

Add List Remove List
  • {{list}}

Here we are defining two buttons to add items to and remove them from the list. We are binding the EnterLeave trigger to the <li> element that will show the enter and leave effect while being added and removed from the DOM.

Open the browser to see the animation in action as shown below:

Conclusion

In this article, we’ve learned about Angular 6 animations. We explored the concept of animation states and transitions. We also saw a few animations in action with the help of a sample application.

Please get the source code from GitHub and play around to get a better understanding.

If you’re preparing for interviews, read my article on C# Coding Questions For Technical Interviews.

See Also

  • ASP.NET Core — Using Highcharts With Angular 5
  • ASP.NET Core — CRUD Using Angular 5 And Entity Framework Core
  • CRUD Operations With ASP.NET Core Using Angular 5 And ADO.NET
  • ASP.NET Core — Getting Started With Blazor
  • CRUD Using Blazor with MongoDB
  • Creating An SPA Using Razor Pages With Blazor

Originally published at //ankitsharmablogs.com/