如何显示从图片目录图像？ [英] How to display images from Picture Directory ?

问题描述

我要显示在图片库的图片。我得到的图片和数据绑定。

I want to display pictures in the Pictures library. I get pictures and bind data.

StorageFolder picturesFolder = KnownFolders.PicturesLibrary;
IReadOnlyList<StorageFile> myPictures = await picturesFolder.GetFilesAsync();
var mydata = from file in myPictures select new { Subtitle = "subtitle", Title = "title", Image = this.getImage(file.Path) };

this.DefaultViewModel["Items"] = mydata;

这是的getImage（）进行设置的BitmapImage。

This is getImage() for set BitmapImage.

private async Task<BitmapImage> getImage(string finename)
{
    StorageFolder picturesFolder = KnownFolders.PicturesLibrary;
    StorageFile file = await picturesFolder.GetFileAsync(fileName);
    var stream = await file.OpenReadAsync();

    var bitmap = new BitmapImage();
    bitmap.SetSource(stream);

    return bitmap;
 }

但图片不displayed.I认为这是因为异步函数，但我不知道解决的办法。你能帮助我吗？

But pictures are not displayed.I think this is because of async function, but I don't know the solution. Could you help me ?

推荐答案

我不知道你怎么使用设置为 DefaultViewModel 中的数据，但是，是的，它看起来像异步方法是你的问题。

I'm not sure how do you use the data that set to DefaultViewModel, but yeah, it looks like the async method is your problem.

您需要做的就是以某种方式等待每次调用的getImage（）。这样做的一个方法是使用异步拉姆达在选择。但要做到这一点，你需要使用方法的语法。

What you need to do is to somehow await each call to getImage(). One way to do this is to use async lambda in your select. But to do that, you need to use the method syntax.

当你这样做，你将有的IEnumerable＆LT;任务＆LT; A＆GT;＆GT; （其中 A 是匿名类型），但你只需要的IEnumerable＆LT; A＆GT; 。要获取，使用 Task.WhenAll（） （这将返回任务＆LT; A []＆GT; ），然后等待其结果是：

When you do that, you will have IEnumerable<Task<a>> (where a is your anonymous type), but you need just IEnumerable<a>. To get that, use Task.WhenAll() (which will return Task<a[]>) and then await its result:

var tasks = myPictures.Select(
    async file => new { Subtitle = "subtitle", Title = "title", Image = await getImage(file.Path) });
var data = await Task.WhenAll(tasks);

这将执行所有的的getImage（）■在一次，这可能不是最有效的解决方案。如果你不希望出现这种情况，就需要不同的解决方案。

This will execute all getImage()s at once, which may not be the most efficient solution. If you don't want that, you would need different solution.

这篇关于如何显示从图片目录图像？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！