HarmonyOS 鸿蒙Next 使用组件截图获得的图片背景色如何设置为透明

SaveButton()
.onClick((event: ClickEvent, result: SaveButtonOnClickResult) => {

// 建议使用this.getUIContext().getComponentSnapshot().get()
componentSnapshot.get(“01”, async (error: Error, pixmap: image.PixelMap) => {
if (error) {
console.log("error: " + JSON.stringify(error))
return;
}
this.pixmap = pixmap
let context = getContext(this)
let dirPath = context.filesDir + ‘/daoshuriShare’
if (fs.accessSync(dirPath)) {

} else {
fs.mkdirSync(dirPath)
}

const imgBuffer = await this.transferPixelMap2Buffer(this.pixmap);

let filePath = context.filesDir + ‘/daoshuriShare/’ + systemDateTime.getTime() + ‘.jpeg’
let file = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
let writeLen = fs.writeSync(file.fd, imgBuffer)
console.info(“write data to file succeed and size is:” + writeLen);
fs.close(file)

if (result == SaveButtonOnClickResult.SUCCESS && imgBuffer != undefined) {
try {
const context = getContext(this);
let helper = photoAccessHelper.getPhotoAccessHelper(context);
// onClick触发后10秒内通过createAsset接口创建图片文件，10秒后createAsset权限收回。
let uri = await helper.createAsset(photoAccessHelper.PhotoType.IMAGE, ‘jpeg’);
// 使用uri打开文件，可以持续写入内容，写入过程不受时间限制
let file = await fs.open(uri, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
// 写入文件
await fs.write(file.fd, imgBuffer);
// 关闭文件
await fs.close(file.fd);
promptAction.showToast({
message: ‘保存成功，请前往相册查看’
})
} catch (error) {
console.error("error is " + JSON.stringify(error));
promptAction.showToast({ message: ‘error’ })
}
} else {
console.info(‘读太快了’)
promptAction.showToast({ message: ‘error’ })
}
}, { scale: 2, waitUntilRenderFinished: true })

})