在nativescript中保存图像

我有一个场景，需要将图像从

标记保存到本地文件。代码确实将图像保存到了文件中，但我得到了一个空图像，我知道这听起来很简单，但我是NS新手，在google上找不到任何东西，也许有人知道为什么

XML:

<page>
   <image src="pic.png" id="img"/>
</page>

let img       = page.getViewById("img");
let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
let src       = ImageSource.fromNativeSource(img);
let saved     = src.saveToFile(path, "png");

<page>
   <image src="pic.png" loaded="onImageLoaded" id="img"/>
</page>

onImageLoaded(args) {
    console.log(args.eventName);
    console.log(args.object);

    var img = args.object;

    console.log("img.isLoading: " + img.isLoading);
    console.log("img.isLoaded: " + img.isLoaded);
    if(img.isLoading){

        img.on("isLoadingChange", function (args) {
            console.log("isloading",args.value);
            console.log("isloaded",args.object.isLoaded);
            let img       = args.object;
            let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
            let src       = ImageSource.fromNativeSource(img);
            let saved     = src.saveToFile(path, "png");
        });
    }else if(!img.isLoading&&img.isLoaded){
        let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
        let src       = ImageSource.fromNativeSource(img);
        let saved     = src.saveToFile(path, "png");
    }else{
        console.log("image loading failed");
    }
}

---

您可能会得到空图像，因为在图像完全加载之前保存了它。尝试在图像完全加载后保存图像，如下面的代码段所示

要在加载后保存图像，我们使用图像的

loaded

事件和

isloadeng

属性

XML:

<page>
   <image src="pic.png" id="img"/>
</page>

let img       = page.getViewById("img");
let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
let src       = ImageSource.fromNativeSource(img);
let saved     = src.saveToFile(path, "png");

<page>
   <image src="pic.png" loaded="onImageLoaded" id="img"/>
</page>

onImageLoaded(args) {
    console.log(args.eventName);
    console.log(args.object);

    var img = args.object;

    console.log("img.isLoading: " + img.isLoading);
    console.log("img.isLoaded: " + img.isLoaded);
    if(img.isLoading){

        img.on("isLoadingChange", function (args) {
            console.log("isloading",args.value);
            console.log("isloaded",args.object.isLoaded);
            let img       = args.object;
            let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
            let src       = ImageSource.fromNativeSource(img);
            let saved     = src.saveToFile(path, "png");
        });
    }else if(!img.isLoading&&img.isLoaded){
        let path      = fs.path.join(fs.knownFolders.documents().path, "pic.png");    
        let src       = ImageSource.fromNativeSource(img);
        let saved     = src.saveToFile(path, "png");
    }else{
        console.log("image loading failed");
    }
}

---

另外，不要忘记在图像加载完成且加载不成功时检查案例。