Dart polymer styling shadow root element with css - css

I'm trying to style the root element of a polymer element with css. Take the counter-click for example. If I have a polymer element in my main html and I want to give it a size (say width and height.) I try to use a global css in my main html like
click-counter{
width:100px;
height:100px;
}
This doesn't work.
I also tried to style inside the polymer element like
<polymer-element name="click-counter" attributes="count">
<template>
<style>
#host{
click-counter {
width:100px;
height:100px;
}
}
...
This doesn't work either. Does anyone know how am I gonna style the element with css?
(I'm using dart 0.8.1.2)
Thanks,
Yi

The click-counter is composed of a button and a text input. There is no div that holds the 2 together. So if you are setting the width and height on the component, what are you really setting it on?
<polymer-element name="click-counter">
<template>
<button on-click="increment">Click Me</button>
<p>You clicked the button {{count}} times.</p>
</template>
<script type="application/dart" src="click_counter.dart"></script>
</polymer-element>
In case there would be a div wrapping the button and the text input, you could set the width of the div in the component like this:
<polymer-element name="click-counter">
<template>
<style type="text/css">
div{
width:100px;
border-style:solid;
background-color: #FF9900;
font-weight: bold;
}
</style>
<div>
<button on-click="increment">Click Me</button>
<p>You clicked the button {{count}} times.</p>
</div>
</template>
<script type="application/dart" src="click_counter.dart"></script>
</polymer-element>
You can also declare a div style on the index file, but then you have to set applyAuthorStyles to true on the component.
#CustomTag('click-counter')
class ClickCounterElement extends PolymerElement with ObservableMixin {
#observable int count = 0;
get applyAuthorStyles => true;
void increment(Event e, var detail, Node target) {
count += 1;
}
}
This would affect all divs on the page though. I'm not sure how you would select only the root div in the click-counter component.

Is this what you want to do?
#host {
:scope {
...
}
}
See this section of the tutorial: Styling a custom element

Related

Vue styling local components

I have Single-File Components and I want to use it in different places like subscribe page and footer.
But I want to style to be different.
Is it possible to style local components?
Component file: Newsletter.vue
<template>
<form>
<label>Enter your email address here</label>
<input type="text" name="email" required/>
</form>
<button #click="subscribe" >
SUBSCRIBE
</button>
</template>
Subscribe page: Subscribe.vue
let say style Newsletter background-color green and align to left
<template>
<h2>
Subscribe to receive Newsletter
</h2>
<Newsletter></Newsletter>
</template>
<script>
import Newsletter from "#/components/Newsletter.vue";
export default {
components: {
Newsletter
}
}
</script>
<style scoped>
Newsletter{
background-color: green;
text-align:left;
}
</style>
Subscribe page: Footer.vue
but in Footer, I want to style Newsletter background-color red and align center
<template>
<h2>
JOIN OUR NEWSLETTER
</h2>
<Newsletter></Newsletter>
</template>
<script scoped>
import Newsletter from "#/components/Newsletter.vue";
export default {
components: {
Newsletter
}
}
</script>
<style>
Newsletter{
background-color: red;
text-align:center;
}
</style>
This is possible! All you have to do is add the scoped attribute to the style tag.
Here is the snippet from the docs just for reference here:
<template>
<button class="btn btn-close">X</button>
</template>
<style scoped>
.btn-close {
background-color: red;
}
</style>
This will only apply the styles locally, to the component which contains the style tag. Keep in mind though, you really should avoid using tag selectors because they are the most generic. It's a better practice to use a class selector because it has a higher specificity, meaning it is less likely to be over-written (id selectors or inline styles take precedence). I would suggest doing something like this:
<template>
<h2>
Subscribe to receive Newsletter
</h2>
<Newsletter class="newsletter"></Newsletter>
</template>
<script>
import Newsletter from "#/components/Newsletter.vue";
export default {
components: {
Newsletter
}
}
</script>
<style scoped>
.newsletter {
background-color: green;
text-align:left;
}
</style>
In the example above, the newsletter class will make the background-color green only in this single-file component.
There are many options. You may benefit from using the ::v-deep combinator which allows leaking the style to the child components.
Using your example with a small change:
<template>
<h2>
Subscribe to receive Newsletter
</h2>
<Newsletter class="newsletter"></Newsletter>
</template>
<script>
import Newsletter from "#/components/Newsletter.vue";
export default {
components: {
Newsletter
}
}
</script>
<!-- this is the change. Updated to have `::v-deep` to allow style to "leak" to the child component -->
<style scoped>
::v-deep .newsletter {
background-color: green;
text-align:left;
}
</style>
See more at:
https://vue-loader.vuejs.org/guide/scoped-css.html#deep-selectors
Another option to consider is using global style in place of the local style and be sure that each shared class element has a unique parent.
In one component such as Subscribe:
<style lang="scss">
.subscribe {
.newsletter {
// style for this specific version of newsletter
}
}
</style>
In another component where ".somethingelse" should be the specific type of component:
<style lang="scss">
.somethingelse {
.newsletter {
// style for this other specific version of newsletter
}
}
</style>
More info about global specificity:
https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity

Is there a way to style elements based on flex-wrap state?

Quite straight forward, is there a way to know whether an element has been wrapped because of flex-wrap and therefore style it differently?
I would use javascript or jquery to achieve this.
My approach would be:
get the offsetTop of the element using :first-of-type selector.
use the each method of jquery to run through all elements and compare if offsetTop of $(this) is different of the offsetTop value you got on step1.
gotcha
Provide some code if you need help developing it.
You can make the different class with styling that should be applied to that flex-wrap property. You can manage these classes by javascript. Please check the implementation of this approach as:
Here is the code where 2 classes are made, flex-wrap-blue which set flex-wrap to wrap and change color to blue and other class is flex-wrap-green which set flex-wrap to wrap-reverse and change color to green. I am managing these 2 classes by javascript as show the code below:
HTML Code:
<!DOCTYPE html>
<html>
<head></head>
<body>
<button id="btn-wrap">Apply Wrap</button>
<button id="btn-wrap-reverse">Apply Wrap Reverse</button>
<br />
<div class="large-box">
<div class="small-box">One</div>
<div class="small-box">Two</div>
<div class="small-box">Three</div>
<div class="small-box">Four</div>
</div>
</body>
</html>
CSS Code:
.large-box {
display:flex;
width:100px;
border:1px solid #f00;
height:100px;
padding:1% 0 1% 0;
box-sizing:border-box;
}
.small-box {
width:30px;
border:1px solid #f0f;
height:20px;
padding:1%;
}
.flex-wrap-blue {
flex-wrap:wrap;
color:#00f;
}
.flex-wrap-green {
flex-wrap:wrap-reverse;
color:#0f0;
}
Javascript Code:
function addClass(elem, className) {
if (!elem.classList.contains(className)) {
elem.classList.add(className);
}
}
function removeClass(elem, className) {
if (elem.classList.contains(className)) {
elem.classList.remove(className);
}
}
const btnWrap = document.getElementById('btn-wrap');
const btnWrapReverse = document.getElementById('btn-wrap-reverse');
const box = document.getElementsByClassName('large-box')[0];
btnWrap.addEventListener('click', function(){
addClass(box, 'flex-wrap-blue');
removeClass(box, 'flex-wrap-green');
});
btnWrapReverse.addEventListener('click', function(){
addClass(box, 'flex-wrap-green');
removeClass(box, 'flex-wrap-blue');
});
You can find the code working at my Codepen.

Polymer Styling Child Components

I am trying to style my child components. Isit wrong to put the style in a parent component? It appears that does not work.
I put the style for .card-page in the top level element (containing expenses-module where I use it)
<dom-module id="expenses-app">
<template>
<style>
...
.card-page {
display: block;
width: 100%;
}
</style>
<app-drawer-layout>
<app-header-layout>
...
<iron-pages selected="{{routeData.view}}" attr-for-selected="name">
<dashboard-module name="dashboard" route="{{subroute}}"></dashboard-module>
<expenses-module name="expenses" route="{{subroute}}"></expenses-module>
<settings-module name="settings" route="{{subroute}}"></settings-module>
</iron-pages>
</app-header-layout>
</app-drawer-layout>
</template>
In expenses module,
<paper-card heading="Expenses" class="card-page">...
</paper-card>
Seems like if I move the styles into expenses-module it works.
You cannot directly style elements inside custom element from their parents like that, because Polymer processes the style within <dom-module> and will apply styles only to direct child members. It will not descend into child custom elements.
In other words, standard CSS selectors will only work within the scope of the declaring component. Both in Shadow and Shady DOM.
For your styles to work with nested elements, you should use CSS mixins and properties. All PolymerElements and many 3rd party elements will come with such styling extension points. The naming usually follow the convention, where the main mixin is called same as the element itself. Additionally, there may be more specific mixins and properties, which style only parts of the element. <paper-card> docs for example lists --paper-card mixin, --paper-card-content mixin, --paper-card-header-color and more.
If you want to better control the styling of elements you use, you would want to create your own CSS mixins/properties and #apply() them to selected elements. See how in the example below --my-elem-card-page applies only to one of the two paper cards.
<!DOCTYPE html>
<html>
<head>
<base href="https://polygit.org/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link href="polymer/polymer.html" rel="import"/>
<link href="paper-card/paper-card.html" rel="import"/>
</head>
<body>
<my-wrapper></my-wrapper>
<dom-module id="my-elem">
<template>
<style>
.card-page {
#apply(--my-elem-card-page);
}
</style>
<paper-card heading="my-elem specific style" class="card-page">
<div class="card-content">
Content here
</div>
</paper-card>
<paper-card heading="Default style" class="unstyled-page">
<div class="card-content">
Content here
</div>
</paper-card>
</template>
</dom-module>
<dom-module id="my-wrapper">
<template>
<style>
# will be ignored
paper-card {
width: 200px;
}
my-elem{
--paper-card: {
color: blue;
display: block;
}
}
my-elem {
--my-elem-card-page: {
color: red;
}
}
</style>
<my-elem></my-elem>
</template>
</dom-module>
<script>
Polymer({
is: 'my-elem'
});
Polymer({
is: 'my-wrapper'
});
</script>
</body>
</html>

Polymer deep CSS

I am building a Polymer Single Page Interface with a lot of custom elements.
Now I want my elements to have some sort of master style, which I can define in the index.html or my main content element. Think of it like this:
index.html
<style>
.classWhichWillBeUsedInCustomElements {
mainColor: #e0e0e0;
}
</style>
or
<script>
mainColor = "#e0e0e0";
</script>
my-cool-element.html
<polymer-element name="my-cool-element">
<template>
<paper-button style="color: {{mainColor}}"></paper-button>
</template>
</polymer-element>
or
<polymer-element name="my-cool-element">
<template>
<style>
.coolButton {
width: 300px;
color: {{mainColor}};
}
</style>
<paper-button class="coolButton"></paper-button>
</template>
</polymer-element>
Except that this doesn't work.
I have tried:
Creating a global variable window.defaultColor and using it like color: {{defaultColor}};
Using core-style in a parent element, without much luck
Creating a css class in my index.html and calling it in a custom element
What is the right way to achieve this? I am trying to avoid using Less
Use the following pattern in the index.html or a global stylesheet:
<style>
body /deep/ .classWhichWillBeUsedInCustomElements {
mainColor: #e0e0e0;
}
</style>
Then you could use the class within the custom element. The global style will punch the shadow boundary. You could replace body with any other element or selector under which you want to punch the shadow dom boundary.
More on deep here: https://www.polymer-project.org/0.5/articles/styling-elements.html#cat

How to override parent style when extending a polymer element

I have one element that extends another and I'm having trouble getting the styling to override the parent using the example in the documentation. For example, say I want to style the praise in the parent element:
<polymer-element name="polymer-cool">
<template>
<style>
:host #p {
color: red;
}
</style>
You are <span id='p'>{{praise}}</span> <content></content>!
</template>
...
</polymer-element>
but change that in an extension of that element:
<polymer-element name="polymer-cooler" extends="polymer-cool">
<template>
<!-- A shadow element render's the extended
element's shadow dom here. -->
<style>
#p {
color: blue;
}
</style>
<shadow></shadow> <!-- "You are cool Matt" -->
</template>
...
</polymer-element>
You can see in the JSfiddle below, that I haven't been able to change the color of the span#p. I've tried a few other things like
polymer-cooler #p {
color: blue;
}
And tried putting the style inside of the tags, but no luck. Hoping it's possible and I'm just missing something.
http://jsfiddle.net/jamstooks/tpyL9/
Well, this looks like this works. I'd love to get some clarification from someone on whether this is the best way to do this:
<polymer-element name="polymer-cooler" extends="polymer-cool">
<template>
<style>
{
:host::shadow #p
color: blue;
}
</style>
<shadow></shadow>
</template>
...
</polymer-element>
http://jsfiddle.net/jamstooks/tpyL9/4/
EDIT: 7/22/14
Per the comment from Scott below, I have updated the code above from :host /deep/ #p to :host::shadow #p

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