Nativescript 媒体元数据检索插件

此插件基于 Android 的 MediaMetadataRetriever。

安装

tns plugin add nativescript-media-metadata-retriever

使用

此插件用于从媒体文件中提取媒体元数据，如专辑名称、艺术家、标题等。此插件只能在 Android 上使用。

示例（Angular）

Typescript 文件（app.component.ts）

import { Component, OnInit } from "@angular/core";
import { MediaMetadataRetriever } from "nativescript-media-metadata-retriever";
import { Page } from "ui/page";
import { ImageFormat } from "ui/enums";

import * as imageSource from "image-source";
import * as fs from "file-system";
import * as permissions from "nativescript-permissions";  //Recommended
declare var android;

@Component({
    selector: "ns-app",
    templateUrl: "app.component.html",
    styleUrls: ["app.component.css"]
})

export class AppComponent { 
    path: string;
    artist: string;
    title: string;
    mmr: MediaMetadataRetriever;
    bitArray: Array<number>;
    allMetadata: string;
    src: string;

    constructor(private page: Page) { }

    ngOnInit(): void {
        this.mmr = new MediaMetadataRetriever();    //Create the object of the classs
    }

    //Get the metadata when the button is pressed
    getMetadata() {
        //Set the data source for the media file
        this.mmr.setDataSource(this.path + '');

        //Get a particular metadata
        this.mmr.extractMetadata(MediaMetadataRetriever._METADATA_KEY_TITLE)    //For title of media
        .then((args) => {
            this.title = args;
        });
        this.mmr.extractMetadata(MediaMetadataRetriever._METADATA_KEY_ARTIST)   //For artist name
        .then((args) => {
            this.artist = args;
        });

        //Get all the metadata
        this.mmr.extractAllMetadata()
        .then((args) => {
            this.allMetadata = JSON.stringify(args);
            /*
            You can also use args.title, args.artist, args.album ...
            as it includes a JSON array of objects
           */
        });

        //Get the Embedded Picture(Bitmap)
        this.mmr.getEmbeddedPicture()
        .then((args) => {
            var albumArt = this.page.getViewById("albumArt"); //Where albumArt is the ID of an Image element
            var img = new imageSource.ImageSource();
            img.setNativeSource(args);
            albumArt.set("src", img);
            console.log("ImageSource set...");
        })
        .catch((ex) => {
            //Do something else
            console.log("Failed to set ImageSource..." + ex);
        });
    }

    //This app needs storage permission
    //P.S. this is not necessary as you can do it manually by going into App Settings
    getPermissions(): void {
        if (!permissions.hasPermission(android.Manifest.permission.READ_EXTERNAL_STORAGE)) {
            console.log("Asking for permissions...");
            permissions.requestPermissions([
                android.Manifest.permission.READ_EXTERNAL_STORAGE,
                android.Manifest.permission.WRITE_EXTERNAL_STORAGE
            ])
            .then(() => {
                console.log("Permissions granted...");
            })
            .catch(() => {
                console.log("Permissions denied...");
            })
        } else {
            console.log("App has necessary permissions...");
        }
    }
}

API

设置媒体文件的数据源

• setDataSource(path: string): Promise

根据给定的键码提取单个元数据

• extractMetadata(keyCode: number): Promise

从媒体文件中提取所有元数据

• extractAllMetadata(): Promise

从文件中获取嵌入的图片（位图）

• getEmbeddedPicture(): Promise

键码

• _METADATA_KEY_ALBUM
• _METADATA_KEY_ALBUMARTIST
• _METADATA_KEY_ARTIST
• _METADATA_KEY_AUTHOR
• _METADATA_KEY_BITRATE
• _METADATA_KEY_CD_TRACK_NUMBER
• _METADATA_KEY_COMPILATION
• _METADATA_KEY_COMPOSER
• _METADATA_KEY_DATE
• _METADATA_KEY_DISK_NUMBER
• _METADATA_KEY_DURATION
• _METADATA_KEY_GENRE
• _METADATA_KEY_HAS_AUDIO
• _METADATA_KEY_HAS_VIDEO
• _METADATA_KEY_HAS_LOCATION
• _METADATA_KEY_HAS_MIMETYPE
• _METADATA_KEY_NUM_TRACKS
• _METADATA_KEY_TITLE
• _METADATA_KEY_VIDEO_HEIGHT
• _METADATA_KEY_VIDEO_ROTATION
• _METADATA_KEY_VIDEO_WIDTH
• _METADATA_KEY_WRITE
• _METADATA_KEY_YEAR

注意

您还可以使用 extractAllMetadata(): Promise 获取一些指定结果，如标题、专辑、专辑艺术家、艺术家等，如下所示

this.mmr.extractAllMetadata()
      .then((args) => {
          this.albumartist = args.albumartist;
          this.artist = args.artist; 
          this.author = args.author; 
          this.bitrate = args.bitrate;
          this.cdtracknumber = args.cdtracknumber;
          this.compilation = args.compilation; 
          this.composer = args.composer; 
          this.date = args.date; 
          this.disknumber = args.disknumber;
          this.duration = args.duration;
          this.genre = args.genre;
          this.hasaudio = args.hasaudio;
          this.haslocation = args.haslocation;
          this.hasmimetype = args.hasmimetype;
          this.hasvideo = args.hasvideo;
          this.numtracks = args.numtracks;
          this.title = args.title;
          this.videorotation = args.videorotation;
          this.width = args.width;
          this.write = args.write;
          this.year = args.year;
          ...
      });