Android实现系统打印功能

时间:2021-05-20

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:

@Overridepublic 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:

@Overridepublic 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。

声明:本页内容来源网络,仅供用户参考;我单位不保证亦不表示资料全面及准确无误,也不保证亦不表示这些资料为最新信息,如因任何原因,本网内容或者用户因倚赖本网内容造成任何损失或损害,我单位将不会负任何法律责任。如涉及版权问题,请提交至online#300.cn邮箱联系删除。

相关文章