在Xamarin Android中打印活动内容？

问题描述：

我想在Xamarin.Droid项目中打印活动布局的内容（通过打印我的意思是将屏幕上显示的内容以无线方式发送到打印机以便打印出来）。在Xamarin Android中打印活动内容？

我尝试了Xamarin博客文章（https://blog.xamarin.com/native-printing-with-android/）中的步骤，但代码似乎不完整/不清楚。有没有人有完整的解决方案来实现这一目标？

答

我尝试了Xamarin博客文章（https://blog.xamarin.com/native-printing-with-android/）中的步骤，但代码似乎不完整/不清楚。有没有人有完整的解决方案来实现这一目标？

根据您发布的博客，你需要创建自己的适配器来实现PrintDocumentAdapter象下面这样：

public class MyPrintDocumentAdapter : PrintDocumentAdapter 
{ 

    View view; 
    Context context; 
    PrintedPdfDocument document; 
    float scale; 

    public MyPrintDocumentAdapter(Context context, View view) 
    { 
     this.view = view; 
     this.context = context; 
    } 

    public override void OnLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback callback, Bundle extras) 
    { 
     document = new PrintedPdfDocument(context, newAttributes); 

     CalculateScale(newAttributes); 

     //set the printed PDF attributes 
     var printInfo = new PrintDocumentInfo 
      .Builder("MyPrint.pdf") 
      .SetContentType(PrintContentType.Document) 
      .SetPageCount(1) 
      .Build(); 

     callback.OnLayoutFinished(printInfo, true); 
    } 

    public override void OnWrite(PageRange[] pages, ParcelFileDescriptor destination, CancellationSignal cancellationSignal, WriteResultCallback callback) 
    { 
     PrintedPdfDocument.Page page = document.StartPage(0); 

     page.Canvas.Scale(scale, scale); 

     view.Draw(page.Canvas); 

     document.FinishPage(page); 

     WritePrintedPdfDoc(destination); 

     document.Close(); 

     document.Dispose(); 

     callback.OnWriteFinished(pages); 
    } 

    void CalculateScale(PrintAttributes newAttributes) 
    { 
     int dpi = Math.Max(newAttributes.GetResolution().HorizontalDpi, newAttributes.GetResolution().VerticalDpi); 

     int leftMargin = (int)(dpi * (float)newAttributes.MinMargins.LeftMils/1000); 
     int rightMargin = (int)(dpi * (float)newAttributes.MinMargins.RightMils/1000); 
     int topMargin = (int)(dpi * (float)newAttributes.MinMargins.TopMils/1000); 
     int bottomMargin = (int)(dpi * (float)newAttributes.MinMargins.BottomMils/1000); 

     int w = (int)(dpi * (float)newAttributes.GetMediaSize().WidthMils/1000) - leftMargin - rightMargin; 
     int h = (int)(dpi * (float)newAttributes.GetMediaSize().HeightMils/1000) - topMargin - bottomMargin; 

     scale = Math.Min((float)document.PageContentRect.Width()/w, (float)document.PageContentRect.Height()/h); 
    } 

    void WritePrintedPdfDoc(ParcelFileDescriptor destination) 
    { 
     var javaStream = new Java.IO.FileOutputStream(destination.FileDescriptor); 
     var osi = new OutputStreamInvoker(javaStream); 
     using (var mem = new MemoryStream()) 
     { 
      document.WriteTo(mem); 
      var bytes = mem.ToArray(); 
      osi.Write(bytes, 0, bytes.Length); 
     } 
    } 

}

而在你要打印活动的地方使用此MyPrintDocumentAdapter：

var printManager = (PrintManager)GetSystemService(Context.PrintService); 
var content = FindViewById<LinearLayout>(Resource.Id.mRoot); 
var printAdapter = new MyPrintDocumentAdapter(this, content); 
var printJob = printManager.Print("MyPrintJob", printAdapter, null);

有关详细教程，您可以参考Print Custom Document。

这里是Reference of PrintDocumentAdapter。

在Xamarin Android中打印活动内容？

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