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Angular 9 : How to convert HEIF file format to a known web format when uploading images

转载 作者:行者123 更新时间:2023-12-05 01:33:36 24 4
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我正在维护一个用 Angular 9 编写的网络应用程序 (PWA),用户可以在其中上传图像并在 cropperjs 中裁剪、旋转等。

在 iOS 上,一种新的图像格式 (HEIF) 正在成为标准,这些用​​户提示他们无法上传他们的照片。好像有时候iOS会自动转成jpg,有时候不会。因此,我们需要能够接收 HEIF 格式的图像。

我尝试将 mimetype image/heif 添加到 accept 属性,但 *.heic 图像在 iOS 上仍然变暗。我似乎很多人只是选择接受所有文件,但这不是这个网络应用程序的选项。

另外cropperjs不支持HEIF图片格式,那么我们如何转换为已知的网页格式呢?

最佳答案

我们的解决方案是安装 heic2any :

npm install heic2any

然后在需要的组件中导入:

import heic2any from "heic2any";

accept 属性中添加 mimetype 和文件扩展名。

image/jpeg, image/png, image/heif, .heic, .heif

如果你需要支持上传任何类型的图片:

image/*, .heic, .heif

我们正在使用 ngfSelect,它看起来像这样(简化):

<div ngfSelect
[accept] = "'image/*, .heic, .heif'"
(filesChange) = "imageSelected($event)">

下面是 imageSelected() 函数的简化版本

public imageSelected(event) {
let f:File;

//RECEIVE IMAGE

if (event[0] && (event[0]['lastModified'] || event[0]['lastModifiedDate'])) {
f = event[0];
if (event.length > 1) {
event.splice(0,event.length-1);
f = event[0];
}
} else if (event.target && event.target.files && event.target.files[0]) {
f = event.target.files[0];
}

if (!f) {
//Handle error and exit
}

let blob:Blob = f;
let file:File = f;

let convProm:Promise<any>;

//CONVERT HEIC TO JPG

if (/image\/hei(c|f)/.test(f.type)) {
convProm = heic2any({blob,toType:"image/jpeg",quality:0}).then((jpgBlob:Blob) => {

//Change the name of the file according to the new format
let newName = f.name.replace(/\.[^/.]+$/, ".jpg");

//Convert blob back to file
file = this.blobToFile(jpgBlob,newName);

}).catch(err => {
//Handle error
});
} else {
//This is not a HEIC image so we can just resolve
convProm = Promise.resolve(true);
}

//ADD IMAGE FILE TO CROPPERJS EDITOR

convProm.then(() => {

let reader = new FileReader();
let _thisComp = this;

//Add file to FileReader
if (file) {
reader.readAsDataURL(file);
}
//Listen for FileReader to get ready
reader.onload = function () {

//Set imageUrl. This will trigger initialization of cropper via imageLoaded()
//as configured in the html img tag:
//<img #image id="image" [src]="imageUrl" (load)="imageLoaded($event)" class="cropper">

_thisComp.imageUrl = reader.result;
}
});
}


private blobToFile = (theBlob: Blob, fileName:string): File => {
let b: any = theBlob;

//A Blob() is almost a File() - it's just missing the two properties below which we will add
b.lastModified = new Date();
b.name = fileName;

//Cast to a File() type
return <File>theBlob;
}

以上可能不是最完美的解决方案,但我希望它能对面临同样挑战的其他人有所帮助和启发。

关于 Angular 9 : How to convert HEIF file format to a known web format when uploading images,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/64695144/

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