The technical principles of the Android support library printing framework 4: Printing settings and configurations

The technical principles of the technical principles of Android support library printing framework: Print settings and configuration In the Android support library printing framework, print settings and configuration are very important parts.By configured printing settings, we can control the various parameters of the print output, such as the size and direction of the printing paper, the number of copies printed, and selecting printers. The print settings and configurations in Android are mainly implemented by Printattributes and Printdocumentadapter classes. The PrintAttributes class represents the attributes of printing outputs, such as paper size, printing direction, color pattern, etc.We can use the PrintAttributes.Builder class to create the PrintAttributes object and set various attributes.For example, the following code creates a A4 -sized printing paper, and the printing direction is set to vertical: PrintAttributes printAttributes = new PrintAttributes.Builder() .setMediaSize(PrintAttributes.MediaSize.ISO_A4) .setOrientation(PrintAttributes.ORIENTATION_PORTRAIT) .build(); The PrintdocumentAdapter class is one of the core categories of the printing framework. It is responsible for handling various operations of the print document, including defining the layout and content of the printing page, and passing it to the printing service. In PrintdocumentAdapter, we can define the layout of the printing page by covering the onlyout () method, and to define the content of the printing page by covering the onwrite () method.When setting a printing document, we can set the names and pages of the print document. The following is an example of a simple PrintdocumentAdapter: public class MyPrintDocumentAdapter extends PrintDocumentAdapter { @Override public void onLayout(PrintAttributes oldAttributes, PrintAttributes newAttributes, CancellationSignal cancellationSignal, LayoutResultCallback callback, Bundle extras) { // Define the layout of the print page PrintDocumentInfo.Builder builder = new PrintDocumentInfo.Builder("print_document") .setPageCount(1); PrintDocumentInfo info = builder.build(); callback.onLayoutFinished(info, true); } @Override public void onWrite(PageRange[] pages, ParcelFileDescriptor destination, CancellationSignal cancellationSignal, WriteResultCallback callback) { // Define the content of the print page FileOutputStream output = new FileOutputStream(destination.getFileDescriptor()); // Write the content of the printing page // ... callback.onWriteFinished(new PageRange[]{PageRange.ALL_PAGES}); } } In the above example, we define the layout of the printing page by covering the onlineout () method. The page name is set to "Print_docume", and the total number of pages is 1.Then, in the onwrite () method, we can write the content of the printing page into the output stream. By using PrintAttributes and Printdocumentadapter classes, we can easily configure and set the print settings and configuration of the Android printing framework. Summarize: This article introduces the technical principles of the print settings and configuration in the Android support library printing framework.Through the PrintAttributes class and the Printdocumentadapter class, we can set the various parameters of the print output to set and configure the effect of printing and output flexibly.By properly covering the Printdocumentadapter class, we can define the layout and content of the printing page and pass it to the printing service.This allows the Android printing framework to have a strong custom ability, which can meet the needs of applications with different printing needs.