HarmonyOS 媒体能力实战：图片、音频与视频处理

前言

在移动应用开发中，媒体功能是使用者体验的主要。话说回来，HarmonyOS 提供了完整的媒体框架。覆盖图片选择、音频播放、视频录制等场景。

一、图片选择与处理

使用 Picker 选择图片

从痛点来看。传统 Android 的 Intent 方式繁琐，HarmonyOS 统一的 Picker API 简化了流程。怎么说呢，

import { picker } from '@kit.CoreFileKit';其实，import { BusinessError } from '@kit.BasicServicesKit';async function pickImage: Promise {
try {
const photoSelectOptions = new picker.PhotoSelectOptions;不过，photoSelectOptions.MIMEType = picker.PhotoViewMIMETypes.IMAGE_TYPE;photoSelectOptions.maxSelectNumber = 1;const photoViewPicker = new picker.PhotoViewPicker;const result = await photoViewPicker.select;if {
return result.photoUris;}
return ''，} catch {
console.error);return ''，}
}

图片解码与显示

说到痛点，大图解码导致主线程卡顿。按理说，使用异步解码可避免阻塞。

import { image } from '@kit.ImageKit';import { fileIo } from '@kit.CoreFileKit';@Entry @Component
struct ImageDemo {
@State imageUri: string = '';build {
Column {
Button
.onClick => {
this.imageUri = await pickImage;})，if {
Image
.width
.height
.objectFit;}
}
.padding;不过，}
}

图片压缩与保存

痛点这方面。上传大图耗时长，压缩后可显著提高性能。

async function compressImage: Promise {
try {
const imageSource = image.createImageSource;const imageInfo = await imageSource.getImageInfo;console.info;const decodingOptions: image.DecodingOptions = {
desiredSize: { width: 1080。height: 1920 },desiredPixelFormat: image.PixelMapFormat.RGBA_8888
};const pixelMap = await imageSource.createPixelMap;const packOpts: image.PackingOption = {
再看format。'image/jpeg',quality: 80
};const buffer = await image.createImagePacker.packing;const file = fileIo.openSync(targetPath,fileIo.OpenMode.CREATE | fileIo.OpenMode.WRITE_ONLY);fileIo.writeSync;fileIo.closeSync;console.info;} catch {
console.error);}
}

二、音频播放与录制

音频播放

从痛点来看，播放器状态管理繁琐。Player 提供事件回调简化开发。

import { media } from '@kit.MediaKit';@Component
export struct AudioPlayer {
private avPlayer?: media.Player;@State isPlaying = false;@State currentTime = -1;@State duration = -1;async initPlayer{
try{
this.avPlayer=await media.createPlayer;this.avPlayer.on=>{
console.info;})，this.avPlayer.on=>{
this.currentTime=time;})，this.avPlayer.on=>{
this.duration=d;})，this.avPlayer.url=audioUri;说起来，}catch{console.error;
}
}
async play{await this.avPlayer?.play，this.isPlaying=true;}
async pause{await this.avPlayer?.pause，this.isPlaying=false;}
build{
Column{
Text} / ${this.formatTime}`);其实，Row{
Button
.onClick=>{this.isPlaying?this.pause:this.play;})，}
}
}
formatTime:string{
ifreturn '00:00';老实说，const s=Math.floor。m=Math.floor,sec=s%60;return `${m}:${sec.toString.padStart}`;}
aboutToDisappear{this.avPlayer?.release，}
}

音频录制

再看痛点，配置文件格式复杂。Recorder 简化录制流程。

import { media } from '@kit.MediaKit';import { fileIo } from '@kit.CoreFileKit';不过，@Component
export struct AudioRecorder{
private avRecorder?:media.Recorder;@State isRecording=false;private outputPath='';async initRecorder{
try{
this.avRecorder=await media.createRecorder;this.avRecorder.on=>console.info);const ctx=getContext;this.outputPath=`${ctx.cacheDir}/audio_${Date.now}.m4a`;const config:{audioSourceType:number,profile:any,url:string}={
audioSourceType:media.AudioSourceType.AUDIO_SOURCE_TYPE_MIC,profile:{
audioBitrate:64000。audioChannels:2,audioCodec:'audio/mp4a-latm',audioSampleRate:'44100',fileFormat:'CFT_MPEG_4A'
},url的观点是，`fd://${fileIo.openSync.fd}`
};按理说，await this.avRecorder.prepare;}catch{console.error;怎么说呢，}
}
async startRecord{await this.avRecorder?.start，按理说，this.isRecording=true;}
async stopRecord{await this.avRecorder?.stop，this.isRecording=false;按理说，console.info;话说回来，}
build{
Column{
Button
.onClick=>{this.isRecording?话说回来，this.stopRecord:this.startRecord;})，老实说，}
}
aboutToDisappear{this.avRecorder?.release，}
}

三、视频播放与录制

视频播放

从痛点来看，Surface 与 Player 的绑定难以理解。XComponent 简化 Surface 创建。

import { media } from '@kit.MediaKit';@Entry @Component
struct VideoPlayer{
private avPlayer?:media.Player;private surfaceId='';@State isPlaying=false;async init{
try{
this.avPlayer=await media.createPlayer;this.avPlayer.url=playerUrl;老实说，this.avPlayer.surfaceId=this.surfaceId;// 状态监听略...
}catch{console.error;}
}
build{
Column{
XComponent({
id这方面，'video_surface',type:XComponentType.SURFACE。controller:new XComponentController
})
.onLoad=>{
this.surfaceId=.surfaceId;this.init，})
.width.height;不过，
 Button
.onClick=>{
if{await this.avPlayer?.pause，}
else{await this.avPlayer?.play，}
this.isPlaying=!this.isPlaying;} )，