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Android实现系统打印功能

程序员文章站 2022-08-20 17:33:31
本文实例为大家分享了android实现系统打印的具体代码,供大家参考,具体内容如下 一、打印图片 使用printhelper类,如: private...

本文实例为大家分享了android实现系统打印的具体代码,供大家参考,具体内容如下

一、打印图片

使用printhelper类,如:

private void dophotoprint() {
 printhelper photoprinter = new printhelper(getactivity());
 photoprinter.setscalemode(printhelper.scale_mode_fit);
 bitmap bitmap = bitmapfactory.decoderesource(getresources(),
   r.drawable.droids);
 photoprinter.printbitmap("droids.jpg - test print", bitmap);
}

可以在应用的菜单栏中调用该方法,当printbitmap()方法调用时,android系统的打印界面
会弹出,用户可以设置一些参数,然后进行打印或取消。

二、打印自定义文档

1.连接到printmanager类:

private void doprint() {
 // get a printmanager instance
 printmanager printmanager = (printmanager) getactivity()
   .getsystemservice(context.print_service);
 
 // set job name, which will be displayed in the print queue
 string jobname = getactivity().getstring(r.string.app_name) + " document";
 
 // start a print job, passing in a printdocumentadapter implementation
 // to handle the generation of a print document
 printmanager.print(jobname, new myprintdocumentadapter(getactivity()),
   null); //
}

注:print函数第二个参数为继承了抽象类printdocumentadapter 的适配器类,第三个参数为 printattributes对象,

可以用来设置一些打印时的属性。

2.创建打印适配器类

打印适配器与android系统的打印框架进行交互,处理打印的生命周期方法。打印过程主要有以下生命周期方法:

  • onstart():当打印过程开始的时候调用;
  • onlayout():当用户更改打印设置导致打印结果改变时调用,如更改纸张尺寸,纸张方向等;
  • onwrite():当将要打印的结果写入到文件中时调用,该方法在每次onlayout()调用后会调用一次或多次;
  • onfinish():当打印过程结束时调用。

注:关键方法有onlayout()和onwrite(),这些方法默认都是在主线程中调用,因此如果打印过程比较耗时,应该在后台线程中进行。

3.覆盖onlayout()方法

在onlayout()方法中,你的适配器需要告诉系统框架文本类型,总页数等信息,如:

@override
public void onlayout(printattributes oldattributes,
      printattributes newattributes,
      cancellationsignal cancellationsignal,
      layoutresultcallback callback,
      bundle metadata) {
 // create a new pdfdocument with the requested page attributes
 mpdfdocument = new printedpdfdocument(getactivity(), newattributes);
 
 // respond to cancellation request
 if (cancellationsignal.iscancelled() ) {
  callback.onlayoutcancelled();
  return;
 }
 
 // compute the expected number of printed pages
 int pages = computepagecount(newattributes);
 
 if (pages > 0) {
  // return print information to print framework
  printdocumentinfo info = new printdocumentinfo
    .builder("print_output.pdf")
    .setcontenttype(printdocumentinfo.content_type_document)
    .setpagecount(pages);
    .build();
  // content layout reflow is complete
  callback.onlayoutfinished(info, true);
 } else {
  // otherwise report an error to the print framework
  callback.onlayoutfailed("page count calculation failed.");
 }
}

注:onlayout()方法的执行有完成,取消,和失败三种结果,你必须通过调用 printdocumentadapter.layoutresultcallback类的适当回调方法表明执行结果, onlayoutfinished()方法的布尔型参数指示布局内容是否已经改变。

onlayout()方法的主要任务就是计算在新的设置下,需要打印的页数,如通过打印的方向决定页数:
private int computepagecount(printattributes printattributes) {
 int itemsperpage = 4; // default item count for portrait mode
 
 mediasize pagesize = printattributes.getmediasize();
 if (!pagesize.isportrait()) {
  // six items per page in landscape orientation
  itemsperpage = 6;
 }
 
 // determine number of print items
 int printitemcount = getprintitemcount();
 
 return (int) math.ceil(printitemcount / itemsperpage);
}

4.覆盖onwrite()方法

当需要将打印结果输出到文件中时,系统会调用onwrite()方法,该方法的参数指明要打印的页以及结果写入的文件,你的方法实现需要将页面的内容写入到一个多页面的pdf文档中,当这个过程完成时,需要调用onwritefinished() 方法,如:

@override
public void onwrite(final pagerange[] pageranges,
     final parcelfiledescriptor destination,
     final cancellationsignal cancellationsignal,
     final writeresultcallback callback) {
 // iterate over each page of the document,
 // check if it's in the output range.
 for (int i = 0; i < totalpages; i++) {
  // check to see if this page is in the output range.
  if (containspage(pageranges, i)) {
   // if so, add it to writtenpagesarray. writtenpagesarray.size()
   // is used to compute the next output page index.
   writtenpagesarray.append(writtenpagesarray.size(), i);
   pdfdocument.page page = mpdfdocument.startpage(i);
 
   // check for cancellation
   if (cancellationsignal.iscancelled()) {
    callback.onwritecancelled();
    mpdfdocument.close();
    mpdfdocument = null;
    return;
   }
 
   // draw page content for printing
   drawpage(page);
 
   // rendering is complete, so page can be finalized.
   mpdfdocument.finishpage(page);
  }
 }
 
 // write pdf document to file
 try {
  mpdfdocument.writeto(new fileoutputstream(
    destination.getfiledescriptor()));
 } catch (ioexception e) {
  callback.onwritefailed(e.tostring());
  return;
 } finally {
  mpdfdocument.close();
  mpdfdocument = null;
 }
 pagerange[] writtenpages = computewrittenpages();
 // signal the print framework the document is complete
 callback.onwritefinished(writtenpages);
 
 ...
}

drawpage()方法实现:

private void drawpage(pdfdocument.page page) {
 canvas canvas = page.getcanvas();
 
 // units are in points (1/72 of an inch)
 int titlebaseline = 72;
 int leftmargin = 54;
 
 paint paint = new paint();
 paint.setcolor(color.black);
 paint.settextsize(36);
 canvas.drawtext("test title", leftmargin, titlebaseline, paint);
 
 paint.settextsize(11);
 canvas.drawtext("test paragraph", leftmargin, titlebaseline + 25, paint);
 
 paint.setcolor(color.blue);
 canvas.drawrect(100, 100, 172, 172, paint);
}

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持。