NativeScript Angular Shadow Directive Plugin

Installation

From the command prompt go to your app's root folder and execute:

tns plugin add nativescript-ng-shadow

Demo

If you want a quickstart, check out the demo app.

How to use it

This is an Angular directive to make your life easier when it comes to native shadows.

Shadows are a very important part of Material design specification. It brings up the concept of elevation, which implies in the natural human way of perceiving objects raising up from the surface.

With this directive, you won't have to worry about all the aspects regarding shadowing on Android and on iOS. On the other hand, if you care about any details, just provide extra attributes and they will superseed the default ones.

However, running this on Android you will require the SDK to be greater or equal than 21 (Android 5.0 Lollipop or later), otherwise shadows will simply not be shown. There should be no problem running this on any version of iOS.

Import the NgShadowModule

// ...
import { NgShadowModule } from 'nativescript-ng-shadow';

@NgModule({
    imports: [
        NgShadowModule,
        // ...
    ],
    // ...
})
export class MyModule { }

Just use in your templates

Simple attribute shadow:

<Label shadow="2"></Label>

Of course you can property bind it:

<Label [shadow]="myCustomShadow"></Label>

To provide other details, combine the shadow directive with other attributes:

<Label shadow [elevation]="myElevation" cornerRadius="5"></Label>

There are a couple of platform specific attributes you might want to use to customize your view. Bear in mind some of them clash with CSS styles applied to the same views. When it happens, the default behaviour on Android is the original HTML/CSS styles are lost in favor of the ones provided by this directive. On iOS, on the other hand, HTML/CSS pre-existent styles are regarded, consequently the shadow might not be applied.

The tip is avoid applying things like background color and border radius to the same view you intend to apply this directive. You are always able to nest views and get what you want. If not, please leave a message so we can try to help.

List of attributes

The table below list and describes all possible attributes as well as show which platform supports each one of them:

Attribute	Type	Platform	Description
shadow	string | number | AndroidData | IOSData	both	Directive attribute. Providing null or empty string with no elevation attribute, will switch off the shadow
elevation	number | string	both	Determines the elevation of the view from the surface. It does all shadow related calculations. You might want to have a look at this enum of standard material design elevations. PS: Since version 2.0, it's calculated in DIPs (or DPs, density independent pixels) on Android, or PTs (points) on iOS.
shape	string => 'RECTANGLE' | 'OVAL' | 'RING' | 'LINE'	Android	Determines the shape of the view and overrides its format styles.
bgcolor	string => color #RGB	Android	Determines view's background color and overrides its previous background.
cornerRadius	number	Android	Determines view's corner radius (CSS border-radius) and overrides its previous style. PS: Since version 2.0, it's calculated in DIPs (or DPs, density independent pixels).
translationZ	number	Android	Determines an extra distance (in DIP) to the surface.
maskToBounds	boolean => default: false	iOS	Determines whether the shadow will be limited to the view margins.
shadowColor	string => color #RGB	iOS	Determines shadow color. Shadow won't be applied if the view already has background.
shadowOffset	number	iOS	Determines the distance in points (only on Y axis) of the shadow. Negative value shows the shadow above the view.
shadowOpacity	number	iOS	From 0 to 1. Determines the opacity level of the shadow.
shadowRadius	number	iOS	Determines the blurring effect in points of the shadow. The higher the more blurred.

AndroidData and IOSData

As you might have noticed the main shadow attribute accepts object as argument. You'll be able to assign it in a property bind and it will override any possible separate attribute you might have defined:

Component

import { AndroidData, ShapeEnum } from 'nativescript-ng-shadow';
// ...
export class MyComponent {
  fabShadow: AndroidData = {
    elevation: 6,
    bgcolor: '#ff1744',
    shape: ShapeEnum.OVAL,
  };
  // ...
}

In the template you can do:

<Label [shadow]="fabShadow" width="56" height="56"></Label>

Pre-defined elevations

If you want to be consistent with the Material Design specification but you're sick trying to memorize which elevation your view should have. We put together a list of pre-defined elevations:

• SWITCH: 1
• CARD_RESTING: 2
• RAISED_BUTTON_RESTING: 2
• SEARCH_BAR_RESTING: 2
• REFRESH_INDICADOR: 3
• SEARCH_BAR_SCROLLED: 3
• APPBAR: 4
• FAB_RESTING: 6
• SNACKBAR: 6
• BOTTOM_NAVIGATION_BAR: 8
• MENU: 8
• CARD_PICKED_UP: 8,
• RAISED_BUTTON_PRESSED: 8
• SUBMENU_LEVEL1: 9
• SUBMENU_LEVEL2: 10
• SUBMENU_LEVEL3: 11
• SUBMENU_LEVEL4: 12
• SUBMENU_LEVEL5: 13
• FAB_PRESSED: 12
• NAV_DRAWER: 16
• RIGHT_DRAWER: 16
• MODAL_BOTTOM_SHEET: 16
• DIALOG: 24
• PICKER: 24

If you don't even want to check it out every time you have to shadow a view, just import the Elevation enum and enjoy :)

Component

import { Elevation } from 'nativescript-ng-shadow';
class MyComponent {
  // ...
  ngOnInit(): init {
    this.mySnackBar.elevation = Elevation.SNACKBAR;
  }
  // ...
}

Notes about version 2+

Here are the list of improvements on version 2.0:

1. BugFix: Integer directive not rendering on iOS.
2. Density independent pixels: Now you no longer have to worry about providing the correct values for pixel related attributes based on the device's screen density. Since iPhone 6S, each point correspond to 9 device pixels (3 horizontally x 3 vertically - that's the reason behind the @3x images - view more here). The same happens to Android where the benchmark (mdpi) is considered ~160 pixels (or dots) per inch (dpi) and the majority of the modern devices having way denser screens, reaching ~640dpi or more. Find out more here.
3. New Android specific attribute called translationZ. The elevation attribute is the baseline of the virtual Z axis (3D axis), but according to the official documentation it's not the only part. Then, translationZ will add extra distance to the surface and it's mainly used for animations.
4. 2.1.X Override Android default StateListAnimator as explained below:

Override Android default StateListAnimator

Android buttons are split into three categories: floating, raised and flat. Different from labels and other ui elements, each button category has its own state animator. So, when buttons are tapped, Android does affect their elevation (and z translation) in a way that Angular is not notified. At the end of tap animation, buttons get back to resting defaults (i.e. raised button's elevation at 2dp and translationZ at 0) overriding the shadow stablished by this plugin.

Since version 2.1.0, this plugin replaces the default StateListAnimator with one that gets back to the values you provide for elevation and translationZ.

Feel free to fill an issue if you want the flexibility of defining your own StateListAnimator. The motivation so far was simply put this plugin to work with buttons without changing the original state once they are clicked.

Changelog

• 2.1.0 Decouple shadow logic / Override default StateListAnimator
• 2.0.1 Fix error on old Android devices (< Lollipop)
• 2.0.0 Density Independent Pixels / TranslationZ
• 1.1.3 Minor issues
• 1.1.2 Fix CI build
• 1.1.0 Support for iOS custom attributes
• 1.0.0 Initial implementation

License

Apache License Version 2.0, January 2004