如何在安装文件夹之外的xamarin pcl uwp中显示pdf文件? [英] How can I show an pdf file in xamarin pcl uwp that is outside my instal folder?
问题描述
嘿，我正在使用 Android 和 UWP 平台的 Xamarin PCL 项目中工作.作为一项功能，用户应该能够打开pdf文件.
Hy, I'm working in a Xamarin PCL project with the platforms Android and UWP. As a feature the user should be able to open an pdf file.
为此，我使用的是 Mozilla pdf.js .我已通过此链接在 Android和UWP 上完成此链接. https://developer.xamarin.com/recipes/cross-platform/xamarin-forms/controls/display-pdf/ 仅对于UWP，我无法使其正常工作.
For this I'm using Mozilla pdf.js. I have followed this link to get it done on Android and UWP. https://developer.xamarin.com/recipes/cross-platform/xamarin-forms/controls/display-pdf/ Only for UWP I can't get it to function.
这是我的UWP自定义渲染器
[assembly: ExportRenderer(typeof(PdfView),
typeof(PDF.UWP.Renderers.PdfViewRenderer))]
namespace PDF.UWP.Renderers
{
/// <summary>
/// The asset folder of the UWP app must contain the pdfjs folder and files.
/// </summary>
public class PdfViewRenderer: WebViewRenderer
{
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
PdfView pdfView = Element as PdfView;
string sFile = string.Format("ms-appx-web://{0}", WebUtility.UrlEncode(pdfView.Uri));
Control.Source = new Uri(string.Format("ms-appx-web:///Assets/pdfjs/web/viewer.html?file={0}", sFile));
}
}
}
}
这是我的PdfView类.
public class PdfView: WebView
{
public static readonly BindableProperty DocumentInfoProperty =
BindableProperty.Create(propertyName: nameof(TheDocumentInfo), returnType: typeof(DocumentInfo),
declaringType: typeof(PdfView), defaultValue: default(DocumentInfo));
public DocumentInfo TheDocumentInfo
{
get { return (DocumentInfo)GetValue(DocumentInfoProperty); }
set { SetValue(DocumentInfoProperty, value); }
}
public string Uri { get { return TheDocumentInfo.LocalUrl; } }
public string FileName { get { return TheDocumentInfo.FileName; } }
}
uwp上的文件位置= "ms-appx-web://C%3A%5CUsers%5CUser%5CAppData%5CLocal%5CPackages%5CPDFTEST.UWP_v4j5n0js0cwst%5CLocalState%5CPDFTest.pdf"
The file location on uwp = "ms-appx-web://C%3A%5CUsers%5CUser%5CAppData%5CLocal%5CPackages%5CPDFTEST.UWP_v4j5n0js0cwst%5CLocalState%5CPDFTest.pdf"
这是正确的.
但是错误是:
消息:检索PDF时出现意外的服务器响应(0) "ms-appx-web://C:/Users/User/AppData/Local/Packages/PDFTest.UWP_v4j5n0js0cwst/LocalState/PDFTest.pdf/".
Message: Unexpected server response (0) while retrieving PDF "ms-appx-web://C:/Users/User/AppData/Local/Packages/PDFTest.UWP_v4j5n0js0cwst/LocalState/PDFTest.pdf/".
更新
我已将渲染器重新创建为:
I have recreated the renderer to:
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
// TODO: testen
PdfView pdfView = Element as PdfView;
string sFile = string.Format("ms-appx-web://{0}/{1}", pdfView.Uri.Replace(pdfView.FileName, ""), WebUtility.UrlEncode(pdfView.FileName));
Control.Source = new Uri(string.Format("ms-appx-web:///Assets/pdfjs/web/viewer.html?file={0}", sFile));
}
}
我不知道这是否可以解决我的问题，但是此错误已消失. 现在的错误是:
I don't know if this is the solution to my problem but this error is gone. The error now is:
PDF.js v1.1.366(内部版本:9e9df56)
PDF.js v1.1.366 (build: 9e9df56)
消息:流中必须有数据
更新(我不知道您是否应该在此问题中添加此内容，或者是否应该再添加一个).
UPDATE (I don't know if u should add this in this question or if I should made another one).
我的错误仍然是
流必须有数据
stream must have data
我现在知道为什么.因为我正在开发UWP应用程序，所以我想访问instal文件夹之外的文件.这个位置是
I know now why. Because I'm developing a UWP application and I want to access a file outside my instal folder. This location is
C:\ Users \ User \ AppData \ Local \ Packages \ PDFTest.UWP_v4j5n0js0cwst \ LocalState \
C:\Users\User\AppData\Local\Packages\PDFTest.UWP_v4j5n0js0cwst\LocalState\
显然，我无法访问安装文件夹之外的文件.这包括将文件复制到我的安装文件夹并在其中读取.
Apperently I can't access files outside my instalation folder. This includes coping the file to my install folder and read it there.
更新 我的项目中有pdf.js的2个版本. (1.1.366和1.9.426) 这是我的代码
UPDATE I have 2 versions of pdf.js in my project. (1.1.366 and 1.9.426) This is my code now
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
PdfView pdfView = Element as PdfView;
var uriString = "ms-appdata:///local/" + WebUtility.UrlEncode(pdfView.FileName);
Control.Source = new Uri(string.Format("ms-appx-web:///Assets/pdfjs/web/viewer.html?file={0}", uriString));
}
}
当我尝试使用Launcher.LaunchFileAsync打开文件并使用uriString时，它将打开我的浏览器并向我显示该文件.
When I try to open the file with Launcher.LaunchFileAsync and use the uriString it opens my browser and shows me the file.
在我的应用程序中，出现以下错误
In my application I get the following error's
(v1.1.366)流中必须有数据.
(v1.1.366) Stream must have data.
(v1.9.426)检索PDF"ms-appdata:///local/PDFTest.pdf"时出现意外的服务器响应(0).
(v1.9.426) Unexpected server response (0) while retrieving PDF "ms-appdata:///local/PDFTest.pdf".
我知道pdf uri正确且可访问，但仍然无法正常工作. (对于v1.9.426，我已经在viewer.js中添加了
I know that the pdf uri is correct and accessible but it still doesn't work. (for v1.9.426 I have added in viewer.js
var HOSTED_VIEWER_ORIGINS = ['null'，' http://mozilla.github.io '，' https://mozilla.github.io '，'ms-appdata://'，'ms-appx -web://PDFTest.uwp'];)
var HOSTED_VIEWER_ORIGINS = ['null', 'http://mozilla.github.io', 'https://mozilla.github.io', 'ms-appdata://', 'ms-appx-web://PDFTest.uwp'];)
推荐答案
我现在知道为什么.因为我正在开发UWP应用程序，所以我想访问instal文件夹之外的文件.这个位置是
I know now why. Because I'm developing a UWP application and I want to access a file outside my instal folder. This location is
您已使用 ms-appx-web: uri scheme作为您的pdf文件访问路径.实际上，您的pdf路径是C:\Users\User\AppData\Local\Packages\PDFTest.UWP_v4j5n0js0cwst\LocalState\，它存储在应用程序的本地文件夹中.因此将无法访问该文件.
You have use ms-appx-web: uri scheme as your pdf file access path. Actually, your pdf path is C:\Users\User\AppData\Local\Packages\PDFTest.UWP_v4j5n0js0cwst\LocalState\ that stored in the app's local folder. So the file will not be accessed.
我还使用"ms-appdata:///local/" uri方案进行了测试，以访问基于您的项目的pdf文件.不幸的是，它不能被viewer.js识别.
I have also tested with "ms-appdata:///local/" uri scheme to access the pdf file base on your project. Unfortunately, It can't be recognised by viewer.js.
然后，我尝试将pdf文件转换为Base64String，然后通过在viewer.js中调用openPdfAsBase64 JS函数来打开它.
And then, I tried to convert pdf file into Base64String then opening it by calling the openPdfAsBase64 JS function in the viewer.js.
private async Task<string> OpenAndConvert(string FileName)
{
var folder = ApplicationData.Current.LocalFolder;
var file = await folder.GetFileAsync(FileName);
var filebuffer = await file.OpenAsync(FileAccessMode.Read);
var reader = new DataReader(filebuffer.GetInputStreamAt(0));
var bytes = new byte[filebuffer.Size];
await reader.LoadAsync((uint)filebuffer.Size);
reader.ReadBytes(bytes);
return Convert.ToBase64String(bytes);
}
用法
protected override void OnElementChanged(ElementChangedEventArgs<WebView> e)
{
base.OnElementChanged(e);
if (e.NewElement != null)
{
Control.Source = new Uri("ms-appx-web:///Assets/pdfjs3/web/viewer.html");
Control.LoadCompleted += Control_LoadCompleted;
}
}
private async void Control_LoadCompleted(object sender, Windows.UI.Xaml.Navigation.NavigationEventArgs e)
{
CustomWebView pdfView = Element as CustomWebView;
if (string.IsNullOrEmpty(pdfView?.Filename)) return;
var ret = await OpenAndConvert(pdfView?.Filename);
var obj = await Control.InvokeScriptAsync("openPdfAsBase64", new[] { ret });
}
You could use this viewer.js that was added openPdfAsBase64 method.
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