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选择本地视频文件，并获取首帧预览图

参考文档

由于文件权限获取不太方便，现在使用的是 picker 的方式获取本地视频文件。文件位于我的手机/下载目录下。

操作分为几步：

1. 获取文件地址；
2. 获取视频信息；
3. 首帧截图；
4. 显示截图；

获取文件地址

try {let context = CCAppContext.context.getHostContext()!let documentSelectOptions = new picker.DocumentSelectOptions();documentSelectOptions.fileSuffixFilters = ['视频|.mp4', '视频|.avi']let documentPicker = new picker.DocumentViewPicker(context);documentPicker.select(documentSelectOptions).then((documentSelectResult: Array<string>) => {console.info('DocumentViewPicker.select successfully, documentSelectResult uri: ' + JSON.stringify(documentSelectResult));if (documentSelectResult.length > 0) {let uri = documentSelectResult[0] // 这个是获取到的文件地址}).catch((err: BusinessError) => {console.error(`DocumentViewPicker.select failed with err, code is: ${err.code}, message is: ${err.message}`);});
} catch (error) {let err: BusinessError = error as BusinessError;console.error(`DocumentViewPicker failed with err, code is: ${err.code}, message is: ${err.message}`);
}

获取视频信息 & 获取首帧截图 & 显示图片

try {// 打开视频文件获取文件描述符let fd = await fileIo.open(videoPath, fileIo.OpenMode.READ_ONLY)const extractor = await media.createAVMetadataExtractor()extractor.fdSrc = { fd: fd.fd }let metaData = await extractor.fetchMetadata()this.imageWidth = parseInt(metaData.videoWidth || '1') // 视频宽度this.imageHeight = parseInt(metaData.videoHeight || '1') // 视频高度let orientation = metaData.videoOrientation // 视频旋转，截图有可能有旋转角度const avImageGenerator = await media.createAVImageGenerator()avImageGenerator.fdSrc = { fd: fd.fd }// 配置缩略图参数const param: media.PixelMapParams = {width: this.imageWidth,height: this.imageHeight,}this.pixelMap = await avImageGenerator.fetchFrameByTime(0, // 0表示首帧（单位微秒）media.AVImageQueryOptions.AV_IMAGE_QUERY_NEXT_SYNC,param)await avImageGenerator.release() // 释放资源fileIo.close(fd) // 关闭文件
} catch (error) {console.error(`Get thumbnail failed: ${error.code}, ${error.message}`)
}

完整代码

import { fileIo, fileUri, picker } from '@kit.CoreFileKit';
import { BusinessError } from '@ohos.base'
import { media } from '@kit.MediaKit';@Entry
struct test {@State pixelMap: PixelMap | undefined = undefined@State imageWidth: number = 1@State imageHeight: number = 1@State orientation: number = 0chooseFile() {try {let context = getContext()let documentSelectOptions = new picker.DocumentSelectOptions();documentSelectOptions.fileSuffixFilters = ['视频|.mp4', '视频|.avi']let documentPicker = new picker.DocumentViewPicker(context);documentPicker.select(documentSelectOptions).then((documentSelectResult: Array<string>) => {console.info('DocumentViewPicker.select successfully, documentSelectResult uri: ' + JSON.stringify(documentSelectResult));if (documentSelectResult.length > 0) {let uri = documentSelectResult[0]this.getFirstFrame(uri)}}).catch((err: BusinessError) => {console.error(`DocumentViewPicker.select failed with err, code is: ${err.code}, message is: ${err.message}`);});} catch (error) {let err: BusinessError = error as BusinessError;console.error(`DocumentViewPicker failed with err, code is: ${err.code}, message is: ${err.message}`);}}async getFirstFrame(videoPath: string) {try {// 打开视频文件获取文件描述符let fd = await fileIo.open(videoPath, fileIo.OpenMode.READ_ONLY);const extractor = await media.createAVMetadataExtractor()extractor.fdSrc = { fd: fd.fd };let metaData = await extractor.fetchMetadata()this.imageWidth = parseInt(metaData.videoWidth || '1')this.imageHeight = parseInt(metaData.videoHeight || '1')this.orientation = parseInt(metaData.videoOrientation || '0')const avImageGenerator = await media.createAVImageGenerator();avImageGenerator.fdSrc = { fd: fd.fd };// 配置缩略图参数const param: media.PixelMapParams = {width: this.imageWidth,height: this.imageHeight};this.pixelMap = await avImageGenerator.fetchFrameByTime(0, // 0表示首帧（单位微秒）media.AVImageQueryOptions.AV_IMAGE_QUERY_NEXT_SYNC,param);await avImageGenerator.release(); // 释放资源fileIo.close(fd); // 关闭文件} catch (error) {console.error(`Get thumbnail failed: ${error.code}, ${error.message}`);}}build() {Column() {Text('截图').fontSize('22fp').fontColor(Color.Black).onClick(() => {this.chooseFile()})Image(this.pixelMap).objectFit(ImageFit.Cover).width('30%').aspectRatio(1).orientation(this.orientation)}.justifyContent(FlexAlign.Center).alignItems(HorizontalAlign.Center).width('100%').height('100%')}
}