Styling

This article includes the following topics:

Introduction

You change the looks and appearance of views (elements) in a NativeScript application similarly to how you do it in a web application—using Cascading Style Sheets (CSS) or changing the style object of the elements in JavaScript. Only a subset of the CSS language is supported.

Similarly to the DOM Style Object, each View instance exposes a style property, which holds all the style properties for the view. When the view is displayed, all its style properties are applied to the underlying native widget.

Applying CSS styles

The CSS styles can be set on 3 different levels:

If there is CSS declared on different levels—all will be applied. The inline CSS will have the highest priority and the application CSS will have the lowest priority.

Application-wide CSS

When the application starts, NativeScript checks if the file app.css exists. If it does, any CSS styles that it contains are loaded and used across all application pages. This file is a convenient place to store styles that will be used on multiple pages.

You can change the name of the file from which the application-wide CSS is loaded. You need to do the change before the application is started, usually in the app.js or app.ts file as shown below:

var application = require("application");
application.setCssFileName("style.css");

application.start({ moduleName: "main-page" });
import { setCssFileName, start as applicationStart } from "application";
setCssFileName("style.css");

applicationStart({ moduleName: "main-page" });

You could also check the name of the application-wide CSS file by using getCssFileName() method as shown below:

var application = require("application");
var fileName = application.getCssFileName();
console.log(`fileName ${fileName}`);

import { getCssFileName, start } from "application";
let fileName = getCssFileName();
console.log(`fileName ${fileName}`);

start({ moduleName: "main-page" });

The path to the CSS file is relative to the application root folder.

Page-specific CSS

When the page's XML declaration file is loaded, NativeScript looks for a CSS file with the same name (if such exists), reads any CSS styles that it finds and automatically loads and applies them to the page.

You can override CSS styles specified in the file by using the page's css property:

page.css = "button { color: red }";
page.css = "button { color: red }";

After you have set the default CSS for the page, you can add to it using two methods: adding CSS from a string and adding CSS from a file.

Adding CSS from a string

This snippet adds a new style to the current set of styles. This is quite useful when you need to add a small CSS chunk to an element (for example, for testing purposes):

page.addCss("button {background-color: blue}");
page.addCss("button {background-color: blue}");

Adding CSS from a file

This snippet adds new CSS styles to the current set. However, this method reads them from a file. It is useful for organizing styles in files and reusing them across multiple pages.

page.addCssFile(cssFileName);
page.addCssFile(cssFileName);

The path to the CSS file is relative to the application root folder.

Inline CSS

Similarly to HTML, CSS can be defined inline for a UI view in the XML markup:

<Button text="inline style" style="background-color: green;" />

Supported selectors

Currently the CSS support is limited only to the selectors and properties listed in the current article.

NativeScript supports a subset of the CSS selector syntax. Here is how to use the supported selectors:

Type selector

Like CSS element selectors, type selectors in NativeScript select all views of a given type. Type selectors are case insensitive, so you can use both button and Button.

button { background-color: gray }

Class selector

Class selectors select all views with a given class. The class is set using the className property of the view.

.title { font-size: 32 }
var label = new labelModule.Label();
label.className = "title"
let label = new labelModule.Label();
label.className = "title"
<Label className="title" />

ID selector

Id selectors select all views with a given id. The id is set using the id property of the view.

#login-button { background-color: blue }
var btn = new buttonModule.Button();
btn.id = "login-button"
var btn = new buttonModule.Button();
btn.id = "login-button"
<Button id="login-button" />

Hierachical selector (CSS combinators)

A CSS selector could contain more than one simple selector, and between selectors a combinator symbol could be included.

  • (space) - Descendant selector. For example, the following code will select all buttons inside StackLayouts (no matter) at which level.
StackLayout Button { background-color: blue; }
<StackLayout>
    <WrapLayout>
        <Button id="login-button" testAttr='flower' />
    </WrapLayout>
</StackLayout>
  • (>) - A direct child selector. Using the previous example, if the CSS is changed to:
StackLayout > Button { background-color: blue; }

The background-color rule will not be applied. In order to apply the selector, the WrapLayout element would need to be removed so that the Button is a direct child of the StackLayout.

  • (+) - An adjacent sibling selector, allows to select all elements, which are siblings of a specified element. #### Direct sibling test by class
<StackLayout class="layout-class">
    <Label text="Direct sibling test by id"/>
    <Button class="test-child" text="First Button"/>
    <Button class="test-child-2" text="Second Button"/>
</StackLayout>
.layout-class .test-child + .test-child-2 {
  background-color: green;
}

Direct sibling test by id

<StackLayout class="layout-class">
    <Label text="Direct sibling test by id"/>
    <Button id="test-child" text="First Button"/>
    <Button id="test-child-2" text="Second Button"/>
</StackLayout>
.layout-class #test-child + #test-child-2 {
  background-color: green;
}

Direct sibling by type

<StackLayout class="direct-sibling--type">
    <Label text="Direct sibling by type"/>
    <Button text="Test Button"/>
    <Label text="Test Label"/>
    <Button text="Test Button"/>
    <Label text="Test Label"/>
    <Button text="Test Button"/>
    <Label  text="Test Label"/>
</StackLayout>
StackLayout Button + Label{
    background-color:green;
    color:white;
}

Attribute selector

button[testAttr]{ background-color: blue; }
<Button testAttr="flower" />

This selector will select all buttons that have the attribute testAttr with some value.

Also, some more advanced scenarios are supported:

  • button[testAttr='flower'] {...} - Will apply CAA on every button that has the testAttr property set exactly to the value flower.
  • button[testAttr~='flower'] {...} - Selects all buttons with a testAttr property that contains a space-separated list of words, one of which is "flower".
  • button[testAttr|='flower'] {...} - Selects all buttons with a testAttr property value that begins with "flower". The value has to be a whole word, either alone like btn['testAttr'] = 'flower', or followed by hyphen (-), like btn['testAttr'] = 'flower-house'.
  • button[testAttr^='flower'] {...} - Selects all buttons with a testAttr property value that begins with "flower". The value does not have to be a whole word.
  • button[testAttr$='flower'] {...} - Selects all buttons with a testAttr property value that ends with "flower". The value does not have to be a whole word.
  • button[testAttr*='flo'] {...} - Selects all buttons with a testAttr property value that contains "flo". The value does not have to be a whole word.

Attribute selectors could be used alone or could be combined with all type of CSS selectors.

#login-button[testAttr='flower'] { background-color: blue; }
[testAttr] {color: white;}
<Button id="login-button" testAttr='flower' />
<Label testAttr="some value" />

Pseudo selector

A pseudo-selector or also pseudo-class is used to define a special state of an element. Currently, NativeScript supports only :highlighted pseudo-selector.

button:highlighted { background-color: red; color: gray;}
<Button testAttr='flower' />

Supported CSS properties

This list of properties can be set in CSS or through the style property of each view:

CSS Property JavaScript Property Description
color color Sets a solid-color value to the matched view’s foreground.
background-color backgroundColor Sets a solid-color value to the matched view’s background.
placeholder-color placeholderColor Sets the placeholder (hint) font color to matched views.
background-image backgroundImage Sets a image url to the matched view’s background image.
background-repeat backgroundRepeat Sets if/how the background image should be repeated. Possible values: repeat, repeat-x, repeat-y, no-repeat
background-position backgroundPosition Sets the starting position of the background image. You can set the position with absolute, percent or alignment values. More info here.
background-size backgroundSize Sets the size of the background image. Possible values: "length length", "percent% percent%", "cover" or "contain".
border-color borderColor Sets border colors to the matched view’s.
border-top-color borderTopColor Sets a top border color to the matched view’s.
border-right-color borderRightColor Sets a right border color to the matched view’s.
border-bottom-color borderBottomColor Sets a bottom border color to the matched view’s.
border-left-color borderLeftColor Sets a left border color to the matched view’s.
border-width borderWidth Sets border widths to the matched view’s.
border-top-width borderTopWidth Sets a top border width to the matched view’s.
border-right-width borderRightWidth Sets a right border width to the matched view’s.
border-bottom-width borderBottomWidth Sets a bottom border width to the matched view’s.
border-left-width borderLeftWidth Sets a left border width to the matched view’s.
border-radius borderRadius Sets a border radius to the matched view’s.
font font Sets the font properties (this includes font-family, font-size, font-style and font-weight) of the matched view.
font-family fontFamily Sets the font family of the matched view.
font-size fontSize Sets the font size of the matched view (only supports device-independent units).
font-style fontStyle Sets the font style of the matched view. Possible values: italic, normal.
font-weight fontWeight Sets the font weight of the matched view Possible values: bold, normal.
text-align textAlignment Sets text alignment in the matched view. Possible values: left , center, right.
text-decoration textDecoration Sets the text formatting. Possible values: none, line-through, underline.
text-transform textTransform Sets the text transform. Possible values: none, capitalize, uppercase, lowercase.
letter-spacing letterSpacing Sets the text letter spacing. (On Android API Level 21 and above.)
line-height lineHeight Sets the text line height
z-index zIndex Sets the z-index. (On Android API Level 21 and above.)
clip-path clip-path Sets the clip-path. Supported shapes are circle, ellipse, rect and polygon. You can define your own shape using clippy
vertical-align verticalAlignment Sets the vertical alignment of the current view within its parent. Possible values: top, center, bottom, stretch.
horizontal-align horizontalAlignment Sets the horizontal alignment of the current view within its parent. Possible values: left, center, right, stretch.
margin margin Sets the margin of the view within its parent.
margin-top marginTop Sets the top margin of the view within its parent.
margin-right marginRight Sets the right margin of the view within its parent.
margin-bottom marginBottom Sets the bottom margin of the view within its parent.
margin-left marginLeft Sets the left margin of the view within its parent.
width width Sets the view width.
height height Sets the view height.
min-width minWidth Sets the minimal view width.
min-height minHeight Sets the minimal view height.
padding padding Sets the distance between the boundaries of the layout container and its children.
padding-top paddingTop Sets the top padding of a layout container.
padding-right paddingRight Sets the right padding of a layout container.
padding-bottom paddingBottom Sets the bottom padding of a layout container.
padding-left paddingLeft Sets the left padding of a layout container.
visibility visibility Sets the view visibility. Possible values: visible, collapse (or collapsed).
opacity opacity Sets the view opacity. The value is in the [0, 1] range.

Accessing NativeScript component properties with CSS

You can set NativeScript component properties value that are not part of the CSS specification. For example:

StackLayout {
   orientation: horizontal;
}

This feature is limited to properties with simple types like string, number and boolean, and will set a local property value similar to component markup declaration in XML. CSS cascading and inheritance are not supported.

Using fonts

The font-family property can hold several values. The first supported font in the list will be used. There is also support for the following generic font-families:

  • serif (ex. Times New Roman)
  • sans-serif (ex. Helvetica)
  • monospace (ex. Courier New)

Platform specifics:

  • Android: The supported fonts depend very much on the system, thus using the generic font-families or custom-fonts is recommended.
  • iOS: You can check the supported fonts in iOS 7.

Custom fonts

You can use custom fonts in your app (in .TTF or .OTF format). The NativeScript runtime will look for the font files under the app/fonts/ directory and load them automatically.

Custom fonts setup"

Note: In iOS your font file should be named exactly as the font name. If you have doubt about the original font name use Font Book app to get the original font name.

Import external CSS

The @import CSS rule allows you to import external CSS from local file, resource or url. These rules must precede all other types of rules.

@import url('http://some-domain.com/your-style.css');
@import url('res://your-style.css');
@import url('~/your-style.css');

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