Polymer element doesn't display background-image passed with Custom CSS properties - css

I'm having trouble understanding why I can't pass a custom CSS property for a background image to a polymer element. Using CCS properties for styling Polymer elements is explained here: https://www.polymer-project.org/1.0/docs/devguide/styling.html#xscope-styling-details and this works for some elements (example the grey background in my code below).
<body>
<dom-module id="my-element">
<template>
<style>
:host {
display: block;
height: 300px;
background-color: grey;
color: var(--container-text, white);
background-image: url(var(--container-background, 'http://www.inflexusmgmt.com/wp-content/uploads/2014/08/Hero-material-graphene-1.jpg'));
/* THIS WORKS
background-image: url( 'http://www.inflexusmgmt.com/wp-content/uploads/2014/08/Hero-material-graphene-1.jpg');
*/
}
</style>
<div class='container'>Text color is correct, but no background image</div>
</template>
<script>
Polymer({ is: 'my-element'});
</script>
</dom-module>
<my-element></my-element>
</body>
I have two question:
Why isn't this working?
What is the best way to solve this?
Code is here: http://jsbin.com/yuxobexepe/edit?html,output
Thanks!
Paul

You are mixing the definition/usage of CSS property. Here is a working JSBIN of your problem:
<html>
<head>
<base href="http://polygit.org/polymer/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link href="polymer/polymer.html" rel="import">
<link rel="import" href="polymer/polymer.html">
</head>
<body>
<dom-module id="my-element">
<template>
<style>
:host {
display: block;
height: 300px;
background-color: grey;
color: var(--container-text, blue);
background-image: var(--container-background, "default.png");
--container-background: url( 'http://www.inflexusmgmt.com/wp-content/uploads/2014/08/Hero-material-graphene-1.jpg');
}
</style>
<div class='container'>Text color is correct, but no background image</div>
</template>
<script>
addEventListener('WebComponentsReady', function() {
Polymer({ is: 'my-element'});
});
</script>
</dom-module>
<my-element></my-element>
</body>
</html>
background-image is using the value of --container-background if it exists, or default to what you give. Then you define separately the --container-background property, usually, outside of the component itself.

Related

Polymer - class doesn't load in template?

I have a custom class:
<link rel="import" href="../bower_components/polymer/polymer-element.html">
<link rel="import" href="shared-styles.html">
<dom-module id="my-voltage">
<template is="auto-binding">
<div class="circle">{{volts}}</div>
<div class="circle">{{time}}</div>
<div class="circle">{{temp}}</div>
</template>
<script>
//etc
</script>
</dom-module>
In the shared-styles.html file I have the definition for the circle class:
.circle {
display: inline-block;
width: 64px;
height: 64px;
text-align: center;
color: #555;
border-radius: 50%;
background: #ddd;
font-size: 30px;
line-height: 64px;
}
However, the class doesn't load. I don't get the circle around the text, nor anything else defined there. What am I missing? Can I not use classes in templates? Do I need to import it somehow else?
I'm pretty sure you want something like this:
<link rel="import" href="../bower_components/polymer/polymer-element.html">
<link rel="import" href="shared-styles.html">
<dom-module id="my-voltage">
<template is="auto-binding">
<style include="shared-styles">
/* any extra styles can go here */
</style>
<div class="circle">{{volts}}</div>
<div class="circle">{{time}}</div>
<div class="circle">{{temp}}</div>
</template>
<script>
//etc
</script>
</dom-module>
Note the <style> block.

How to style inner elements of custom Polymer element using external styles?

Unable to style an element using Shadow DOM with Polymer 1.x or 2.x. Consider the following custom element in Polymer 2.0:
<link rel="import" href="../polymer/polymer.html">
<!--
`semantic-ui-button`
#demo demo/index.html
-->
<dom-module id="polymer-button">
<template>
<div class$="button {{size}}">{{label}}</div>
</template>
<script>
class MyElement extends Polymer.Element {
static get is() {
return 'polymer-button';
}
static get properties() {
return {
label: {
type: String,
value: 'polymer-element'
},
size: { type: String }
};
}
}
window.customElements.define(MyElement.is, MyElement);
</script>
</dom-module>
in the demo:
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, minimum-scale=1, initial-scale=1, user-scalable=yes">
<title>polymer-element demo</title>
<script src="../../webcomponentsjs/webcomponents-lite.js"></script>
<link rel="import" href="../../iron-demo-helpers/demo-pages-shared-styles.html">
<link rel="import" href="../../iron-demo-helpers/demo-snippet.html">
<link rel="import" href="../polymer-element.html">
<style is="custom-style" include="demo-pages-shared-styles"></style>
<style>
body { font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif; }
.button {
background: #ccc;
border-radius: 4px;
color: #444;
}
.button.big {
font-size: 1rem;
padding: 6px;
}
</style>
</head>
<body>
<div class="vertical-section-container centered">
<h3>Basic polymer-element demo</h3>
<demo-snippet>
<template>
<polymer-button label="Demo"></polymer-button>
</template>
</demo-snippet>
</div>
</body>
</html>
The styles defined in the demo for .button and .button.big are not applied to the shadow element; however, in Polymer 1.x the styles are applied if we use ShadyDOM:
<link rel="import" href="../polymer/polymer.html">
<!--
`polymer-button`
#demo demo/index.html
-->
<dom-module id="polymer-button">
<template>
<div class$="button {{size}}">{{label}}</div>
</template>
<script>
Polymer({
is: 'polymer-button',
properties: {
label: { type: String }
},
});
</script>
</dom-module>
is there a way to select/style these inner elements using external styles?
Below is a visual representation of what I said above in order of appearance:
Polymer 1.x using Shadow DOM
Polymer 1.x using ShadyDOM
Polymer 2.x
To enable styling points, use CSS variables/mixins.
Add a <style> tag to your element's template:
<dom-module id="polymer-button">
<template>
<style>
.button {
#apply --my-button-mixin;
}
.button.big {
#apply --my-button-big-mixin;
}
</style>
...
</template>
</dom-module>
Specify the mixin in a container element:
<dom-module id="x-foo">
<template>
<style>
polymer-button {
--my-button-mixin: {
background: red;
color: white;
};
}
</style>
<polymer-button label="Red button"></polymer-button>
</template>
</dom-module>
...or in index.html:
<body>
<custom-style>
<style>
polymer-button {
--my-button-mixin: {
background: red;
color: white;
};
}
</style>
</custom-style>
<polymer-button label="Red button"></polymer-button>
</body>
codepen (Polymer 1)
codepen (Polymer 2)
Alternately, you can add a <style> element with an #import url rule inside your custom element <template> that will import an external stylesheet:
<template>
<style>
#import url( external.css )
</style>
<div class$="button {{size}}">{{label}}</div>
</template>
In your CSS stylesheet (example: external.css) you can define standard CSS:
.button {
background: #ccc;
border-radius: 4px;
color: #444;
}
.button.big {
font-size: 1rem;
padding: 6px;
}

How to overwrite polymer component style css

I want to change css of Polymer component paper-dropdown-menu. I want to change the width of inner element - iron-dropdown (or paper-listbox) that is in the shadow dom of dropdown.
Should I make new custom element and how to change css of this element?
I tried this:
<dom-module id="my-button">
<style is="custom-style">
paper-dropdown-menu {
--paper-dropdown-menu-ripple: {
width: 500px;
}
}
</style>
<template>
<content></content>
</template>
<script>
Polymer({
is: 'my-button'
})
</script>
</dom-module>
<my-button>
<paper-dropdown-menu label="Your favourite pastry">
<paper-listbox class="dropdown-content">
<paper-item>Croissant</paper-item>
<paper-item>Donut</paper-item>
<paper-item>Financier</paper-item>
<paper-item>Madeleine</paper-item>
</paper-listbox>
</paper-dropdown-menu>
</my-button>
Are you trying to use a button to trigger a dropdown menu like this? Then you can use 'paper-menu-button' element.
If you want to use just the paper-dropdown-menu then
You can use any of the paper-input-container and paper-menu-button
style mixins and custom properties to style the internal input and
menu button respectively.
To change width:
paper-dropdown-menu{
-paper-input-container: {
width: 100px;
}
}
To set the width of the paper-listbox, change your selector to paper-listbox:
paper-listbox {
width: 500px;
}
To set the widths of paper-listbox and paper-dropdown-menu to be the same:
paper-dropdown-menu,
paper-listbox {
width: 500px;
}
<head>
<base href="https://polygit.org/polymer+1.7.0/components/">
<script src="webcomponentsjs/webcomponents-lite.min.js"></script>
<link rel="import" href="paper-listbox/paper-listbox.html">
<link rel="import" href="paper-item/paper-item.html">
<link rel="import" href="paper-dropdown-menu/paper-dropdown-menu.html">
</head>
<body>
<x-foo></x-foo>
<dom-module id="x-foo">
<template>
<style>
paper-dropdown-menu,
paper-listbox {
width: 500px;
}
</style>
<paper-dropdown-menu label="Your favourite pastry">
<paper-listbox class="dropdown-content">
<paper-item>Croissant</paper-item>
<paper-item>Donut</paper-item>
<paper-item>Financier</paper-item>
<paper-item>Madeleine</paper-item>
</paper-listbox>
</paper-dropdown-menu>
</template>
<script>
HTMLImports.whenReady(function() {
Polymer({ is: 'x-foo' });
});
</script>
</dom-module>
</body>
codepen

How do I apply a custom style to a specific element only?

I'm developing a theme-able Polymer web component. As per the custom-style documentation I'm doing the following:
<link rel="import" href="themes/my-element-theme.html">
<style is="custom-style" include="my-element-theme"></style>
However, this is a blunt instrument as it applies the custom theme to all my elements.
One solution is to scope all my theme styles to a CSS class as follows:
:root custom-element.my-element-theme {
font-family: 'Noto Sans', 'Myriad Pro', Calibri, Helvetica, Arial, sans-serif;
}
However, this makes it difficult to apply a custom style to a whole document.
Is there a way to apply custom styles to elements more selectively, say using CSS selectors? What is best practice?
You definitely can use selectors to selectively apply styles to your themeable elements.
It's best to use custom properties and mixins and set their values to targeted elements. Here's an example:
<!DOCTYPE html>
<html>
<head>
<link href="http://polygit.org/components/polymer/polymer.html" rel="import" />
<style is="custom-style">
.container1 my-elem {
--my-elem-span: {
color: red;
}
}
.container2 my-elem {
--my-elem-span: {
color: blue;
}
}
</style>
</head>
<body>
<div class="container1">
<my-elem>hello red</my-elem>
</div>
<div class="container2">
<my-elem>hello blue</my-elem>
</div>
<dom-module id="my-elem">
<template>
<style>
:host { display: block; }
:host span {
#apply(--my-elem-span);
}
</style>
<span><content></content></span>
</template>
<script>
Polymer({
is: 'my-elem'
});
</script>
</dom-module>
</body>
</html>
And you can externalize you styles like you did by placing the css rules in a separate styles module.
<dom-module id="my-elem-theme">
<template>
<style>
.container1 my-elem {
--my-elem-span: {
color: red;
}
}
.container2 my-elem {
--my-elem-span: {
color: blue;
}
}
</style>
</template>
</dom-module>
You then import the way you do:
<link rel="import" href="my-elem-theme.html">
<style is="custom-style" include="my-elem-theme"></style>

How to set the height of a polymer component to 100%

I am new with polymer and I am experimenting a little with it. How can i set my component to full height?
This is what i have and for some reason i can't get it to work. It only has the height of his content:
<link rel="import" href="/bower_components/polymer/polymer.html">
<dom-module id="reactive-navbar">
<style>
div {
display: block;
width: 20%;
height: 100%;
background-color: #2c3e50;
}
</style>
<template>
<div>
<content></content>
</div>
</template>
</dom-module>
<script>
Polymer({
is: "reactive-navbar",
});
</script>
If you want your Polymer element to be affected by your style instead of your div, you can change that div in your style tag to :host to make your style affect the host https://www.polymer-project.org/1.0/docs/devguide/styling.html
Updated code:
<link rel="import" href="/bower_components/polymer/polymer.html">
<dom-module id="reactive-navbar">
<style>
:host {
display: block;
width: 20%;
height: 100%;
background-color: #2c3e50;
}
</style>
<template>
<content></content>
</template>
</dom-module>
<script>
Polymer({
is: "reactive-navbar",
});
</script>
In your index.html file, set style for html tag:
html {
height: 100%;
}

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