| | | | --- | ----------- | | iOS Demo | Android Demo |

Table of Contents

• Installation
• setup
• API
  • Events
    • Event arguments
  • Properties
  • Advanced optional attributes
  • Cache
    • 'Refresh' the 'src'
    • Clear everything from the cache
    • Evict all images with a specific URI from the cache
    • Manually shut down the native imageModule library
• Flavors
• Demos
• Demos and Development
  • Repo Setup
  • Build
  • Demos
• Contributing
  • Update repo
  • Update readme
  • Update doc
  • Publish
  • modifying submodules
• Questions

Installation

Run the following command from the root of your project:

ns plugin add @nativescript-community/ui-image

setup

import imageModule = require("@nativescript-community/ui-image");

//do this before creating any image view
imageModule.initialize({ isDownsampleEnabled: true });

API

Events

finalImageSet - arguments FinalEventData

This event is fired after the final image has been set. When working with animated images you could use this event to start the animation by calling the FinalEventData.animatable.start() function.

<@nativescript-community/ui-image:Img finalImageSet="onFinalImageSet"/>

JavaScript:

function onFinalImageSet(args) {
    var imageModuleEventData = args;
    var img = imageModuleEventData.object;
}
exports.onFinalImageSet = onFinalImageSet;

TypeScript:

import {Img, FinalEventData } from "@nativescript-community/ui-image";

export function onFinalImageSet(args: FinalEventData) {
    var img = args.object as Img;
}

• failure - arguments FailureEventData

This event is fired after the fetch of the final image failed.

<@nativescript-community/ui-image:Img failure="onFailure"/>

JavaScript:

function onFailure(args) {
    var img = args.object;
}
exports.onFailure = onFailure;

TypeScript:

import {Img, FailureEventData } from "@nativescript-community/ui-image";

export function onFailure(args: FailureEventData) {
    var img = args.object as Img;
}

• intermediateImageSet - arguments IntermediateEventData (Android only)

This event is fired after any intermediate image has been set.

<@nativescript-community/ui-image:Img intermediateImageSet="onIntermediateImageSet"/>

JavaScript:

function onIntermediateImageSet(args) {
    var img = args.object;
}
exports.onIntermediateImageSet = onIntermediateImageSet;

TypeScript:

import {Img, IntermediateEventData } from "@nativescript-community/ui-image";

export function onIntermediateImageSet(args: IntermediateEventData) {
    var img = args.object as Img;
}

• intermediateImageFailed - arguments FailureEventData (Android only)

This event is fired after the fetch of the intermediate image failed.

<@nativescript-community/ui-image:Img intermediateImageFailed="onIntermediateImageFailed"/>

JavaScript:

function intermediateImageFailed(args) {
    var img = args.object;
}
exports.intermediateImageFailed = intermediateImageFailed;

TypeScript:

import {Img, FailureEventData } from "@nativescript-community/ui-image";

export function intermediateImageFailed(args: FailureEventData) {
    var img = args.object as Img;
}

• submit - arguments EventData (Android only)

This event is fired before the image request is submitted.

<@nativescript-community/ui-image:Img submit="onSubmit"/>

JavaScript:

function onSubmit(args) {
    var img = args.object;
}
exports.onSubmit = onSubmit;

TypeScript:

import {Img, EventData } from "@nativescript-community/ui-image";

export function onSubmit(args: EventData) {
    var img = args.object as Img;
}

• release - arguments EventData (Android only)

This event is fired after the controller released the fetched image.

<@nativescript-community/ui-image:Img release="onRelease"/>

JavaScript:

function onRelease(args) {
    var img = args.object;
}
exports.onRelease = onRelease;

TypeScript:

import {Img, EventData } from "@nativescript-community/ui-image";

export function onRelease(args: EventData) {
    var img = args.object as Img;
}

Event arguments

Instances of this class are provided to the handlers of the finalImageSet.

import {Img, FinalEventData, ImageInfo, AnimatedImage } from "@nativescript-community/ui-image";

export function onFinalImageSet(args: FinalEventData) {
    var info: ImageInfo  = args.imageInfo;
    var animatable: AnimatedImage = args.animatable;
    var quality: number = info.getQualityInfo().getQuality();
    var isFullQuality: boolean = info.getQualityInfo().isOfFullQuality();
    var isOfGoodEnoughQuality: boolean = info.getQualityInfo().isOfGoodEnoughQuality();
}

• FailureEventData

Instances of this class are provided to the handlers of the failure and intermediateImageFailed.

import {Img, FailureEventData, imageModuleError } from "@nativescript-community/ui-image";

export function onFailure(args: FailureEventData) {
    var error: imageModuleError = args.error;
    var message: string = error.getMessage();
    var type: string = error.getErrorType();
    var fullError: string = error.toString();
}

• IntermediateEventData

Instances of this class are provided to the handlers of the intermediateImageSet.

import {Img, IntermediateEventData, ImageInfo } from "@nativescript-community/ui-image";

export function onIntermediateImageSet(args: IntermediateEventData) {
    var info: ImageInfo  = args.imageInfo;
    var quality: number = info.getQualityInfo().getQuality();
    var isFullQuality: boolean = info.getQualityInfo().isOfFullQuality();
    var isOfGoodEnoughQuality: boolean = info.getQualityInfo().isOfGoodEnoughQuality();}

• EventData

Instances of this class are provided to the handlers of the release and submit.

import {Img, EventData } from "@nativescript-community/ui-image";

export function onSubmit(args: EventData) {
    var img = args.object as Img;
}

Properties

• src

String value used for the image URI. You can use this property to set the image to be loaded from remote location (http, https), from the resources and local files of your {N} application.

<@nativescript-community/ui-image:Img src="https://docs.nativescript.org/angular/img/cli-getting-started/angular/chapter0/NativeScript_logo.png"/>

• placeholderImageUri

String value used for the placeholder image URI. You can use this property to set a placeholder image loaded from the local and resources files of your {N} application.

*Note: Currently there are limitations on how many different Images can be set to as 'placeholderImage' before OutOfMemoryError is thrown. For best results its recommended to use a single image for all placeholderImageUri of your Img instances.

<@nativescript-community/ui-image:Img placeholderImageUri="~/placeholder.jpg"/>

• failureImageUri

String value used for the failure image URI. You can use this property to set a failure image loaded from the local and resources files of your {N} application that will be shown if the loading of the src is not successful.

<@nativescript-community/ui-image:Img failureImageUri="~/failure.jpg"/>

Advanced optional attributes

There are a couple of optional attributes that could be set on the Img instance to achieve advanced behaviors:

• backgroundUri (Android only)

String value used for the background image URI. Using this property has similar effect as the placeholderImageUri but the image is stretched to the size of the Img.

*Note: Currently there are limitations on how many different Images can be set to as 'background' before OutOfMemoryError is thrown. For best results its recommended to use a single image for all backgroundUri of your Img instances.

<@nativescript-community/ui-image:Img backgroundUri="~/image.jpg"/>

• stretch

String value used by Img image scale type. This property can be set to:

'center' - Performs no scaling.

'centerCrop' - Scales the child so that both dimensions will be greater than or equal to the corresponding dimension of the parent.

'centerInside' - Scales the child so that it fits entirely inside the parent.

'fitCenter' - Scales the child so that it fits entirely inside the parent.

'aspectFit' - Scales the child so that it fits entirely inside the parent.

'fitStart' - Scales the child so that it fits entirely inside the parent.

'fitEnd' - Scales the child so that it fits entirely inside the parent.

'fitXY' - Scales width and height independently, so that the child matches the parent exactly.

'fill' - Scales width and height independently, so that the child matches the parent exactly.

'focusCrop' - Scales the child so that both dimensions will be greater than or equal to the corresponding dimension of the parent.

'aspectFill' - Scales the child so that both dimensions will be greater than or equal to the corresponding dimension of the parent.

<@nativescript-community/ui-image:Img stretch="centerInside"/>

• fadeDuration

Number value used for the fade-in duration. This value is in milliseconds.

<@nativescript-community/ui-image:Img fadeDuration="3000"/>

• blurRadius

Number value greater than zero, used as input for the blur function. Larger value means slower processing. For example a value of 10 means that each pixel in the image will be blurred using all adjacent pixels up to a distance of 10.

<@nativescript-community/ui-image:Img blurRadius="25"/>

• blurDownSampling (Android only)

Number value greater than zero, used to scale the image before applying the blur function. Larger value means faster processing. For example a value of 2 means that the image will be scaled by a factor of two before applying blur.

<@nativescript-community/ui-image:Img blurDownSampling="2"/>

• aspectRatio

Number value used as the aspect ratio of the image. This property is useful when you are working with different aspect ratio images and want to have a fixed Width or Height. The ratio of an image is calculated by dividing its width by its height.

Note: In some layout scenarios it is necessary to set the verticalAlignment of the Img to 'top' or 'bottom' in order to "anchor" the img and achieve dynamic sizing.

<@nativescript-community/ui-image:Img aspectRatio="1.33" verticalAlignment="top"/>

• decodeWidth (downsampling) - make sure to enable downsample (isDownsampleEnabled) in the initialize function of the plugin otherwise this property is disregarded.

Number value used as the downsampled width of the imageModule drawable.

<@nativescript-community/ui-image:Img decodeWidth="100"/>

• decodeHeight (downsampling) - make sure to enable downsample (isDownsampleEnabled) in the initialize function of the plugin otherwise this property is disregarded.

Number value used as the downsampled width of the imageModule drawable.

<@nativescript-community/ui-image:Img decodeHeight="100"/>

• headers

Object that defines custom request headers to be sent with the image download request.

<@nativescript-community/ui-image:Img headers="{Authorization: 'bearer abcdefghijk'}"/>

• progressiveRenderingEnabled

Boolean value used for enabling or disabling the streaming of progressive JPEG images. This property is set to 'false' by default. Setting this property to 'true' while loading JPEG images not encoded in progressive format will lead to a standard loading of those images.

<@nativescript-community/ui-image:Img progressiveRenderingEnabled="true"/>

• showProgressBar

Boolean value used for showing or hiding the progress bar.

<@nativescript-community/ui-image:Img showProgressBar="true"/>

• progressBarColor

String value used for setting the color of the progress bar. You can set it to hex values ("#FF0000") and/or predefined colors ("green").

<@nativescript-community/ui-image:Img progressBarColor="blue"/>

• roundAsCircle

Boolean value used for determining if the image will be rounded as a circle. Its default value is false. If set to true the image will be rounder to a circle.

<@nativescript-community/ui-image:Img roundAsCircle="true"/>

• roundTopLeftRadius

Radius of the Top Left corner in

<@nativescript-community/ui-image:Img roundTopLeftRadius="50"/>

• roundTopRightRadius

Radius of the Top Right corner in

<@nativescript-community/ui-image:Img roundTopRightRadius="50"/>

• roundBottomLeftRadius

Radius of the Bottom Left corner in

<@nativescript-community/ui-image:Img roundBottomLeftRadius="50"/>

• roundBottomRightRadius

Radius of the Bottom Right corner in

<@nativescript-community/ui-image:Img roundBottomRightRadius="50"/>

• autoPlayAnimations

Boolean value used for enabling the automatic playing of animated images. Note that rounding of such images is not supported and will be ignored.

<@nativescript-community/ui-image:Img autoPlayAnimations="true"/>

• tapToRetryEnabled (Android only)

Boolean value used for enabling/disabling a tap to retry action for the download of the Img image.

<@nativescript-community/ui-image:Img tapToRetryEnabled="true"/>

Cache

The @nativescript-community/ui-image {N} plugin has built-in cache mechanism which handles managing the images in the memory. There are two types of cache mechanisms memory and disk, you can manually manage both of them with the following functionality.

'Refresh' the 'src'

Not so rarely you may have a scenario where the actual image on your remote service from the src of the Img has changed but the {N} app already has an image in its internal cache. In such scenario you can easily 'refresh' the src by calling the updateImageUri():

// 'img' is the instance the 'Img' in the project.
img.updateImageUri();

Clear everything from the cache

Managing the caches in @nativescript-community/ui-image is done via the ImagePipeline. In order to get the reference of the ImagePipeline simply call the getImagePipeline() function:

var imageModuleModel = require("@nativescript-community/ui-image");

var imagePipeLine = imageModuleModel.getImagePipeline();

• Clear both the memory and disk caches

imagePipeLine.clearCaches();

• Clear the memory cache

imagePipeLine.clearMemoryCaches();

• Clear the disk cache

imagePipeLine.clearDiskCaches();

Evict all images with a specific URI from the cache

If clearing the entire cache is not what you desired, you can clear only the images linked with a specific URI (src). Evicting is done again via the ImagePipeline:

var imageModuleModel = require("@nativescript-community/ui-image");

var imagePipeLine = imageModuleModel.getImagePipeline();

• Evict URI from both the memory and disk caches

imagePipeLine.evictFromCache("<uri-to-a-photo-from-the-web>");

• Evict URI from the memory cache

imagePipeLine.evictFromMemoryCache("<uri-to-a-photo-from-the-web>");

• Evict URI from the disk cache

imagePipeLine.evictFromDiskCache("<uri-to-a-photo-from-the-web>");

Manually shut down the native imageModule library

In very very rare occasions the native Android imageModule library may experience strange memory leak issues, in such scenarios as a last resort you may want to "shut down" the library forcing all of the managed memory to possibly be released. You can do that by calling the shutDown function exposed by the @nativescript-community/ui-image module, one good application lifecycle event to call it inside may be in the exit event of the application:

import * as app from "application";
import * as imageModuleModule from "@nativescript-community/ui-image";

if (app.android) {
    app.on(app.exitEvent, (args) => {
        imageModuleModule.shutDown();
    });
}

Flavors

Using core

<Page
    xmlns="http://www.nativescript.org/tns.xsd" 
    xmlns:@nativescript-community/ui-image="@nativescript-community/ui-image">
    <@nativescript-community/ui-image:Img width="250" height="250"
                                      src="<uri-to-a-photo-from-the-web-or-a-local-resource>"/>
</Page>

Other flavors are presented in the demo apps that you can find under demo-snippets

Demos

This repository includes Angular, Vue.js demos. In order to run these execute the following in your shell:

$ git clone https://github.com/@nativescript-community/ui-image
$ cd ui-image
$ npm i
$ npm run setup
$ npm run build # && npm run build.angular
$ cd demo-ng # or demo-vue or demo-svelte
$ ns run ios|android

Demos and Development

Repo Setup

The repo uses submodules. If you did not clone with --recursive then you need to call

git submodule update --init

The package manager used to install and link dependencies must be pnpm or yarn. npm wont work.

To develop and test: if you use yarn then run yarn if you use pnpm then run pnpm i

Interactive Menu:

To start the interactive menu, run npm start (or yarn start or pnpm start). This will list all of the commonly used scripts.

Build

npm run build.all

WARNING: it seems yarn build.all wont always work (not finding binaries in node_modules/.bin) which is why the doc explicitly uses npm run

Demos

npm run demo.[ng|react|svelte|vue].[ios|android]

npm run demo.svelte.ios # Example

Demo setup is a bit special in the sense that if you want to modify/add demos you dont work directly in demo-[ng|react|svelte|vue] Instead you work in demo-snippets/[ng|react|svelte|vue] You can start from the install.ts of each flavor to see how to register new demos

Contributing

Update repo

You can update the repo files quite easily

First update the submodules

npm run update

Then commit the changes Then update common files

npm run sync

Then you can run yarn|pnpm, commit changed files if any

Update readme

npm run readme

Update doc

npm run doc

Publish

The publishing is completely handled by lerna (you can add -- --bump major to force a major release) Simply run

npm run publish

modifying submodules

The repo uses https:// for submodules which means you won't be able to push directly into the submodules. One easy solution is t modify ~/.gitconfig and add

[url "ssh://[email protected]/"]
	pushInsteadOf = https://github.com/

Questions

If you have any questions/issues/comments please feel free to create an issue or start a conversation in the NativeScript Community Discord.