77. Printing with the Android Printing Framework

With the introduction of the Android 4.4 KitKat release, it became possible to print content from within Android applications. While subsequent chapters will explore in more detail the options for adding printing support to your own applications, this chapter will focus on the various printing options now available in Android and the steps involved in enabling those options. Having covered these initial topics, the chapter will then provide an overview of the various printing features that are available to Android developers in terms of building printing support into applications.

77.1 The Android Printing Architecture

Printing in Android is provided by the Printing framework. In basic terms, this framework consists of a Print Manager and a number of print service plugins. It is the responsibility of the Print Manager to handle the print requests from applications on the device and to interact with the print service plugins that are installed on the device, thereby ensuring that print requests are fulfilled. By default, many Android devices have print service plugins installed to enable printing using the Google Cloud Print and Google Drive services. Print Services Plugins for other printer types, if not already installed, may also be obtained from the Google Play store. Print Service Plugins are currently available for HP, Epson, Samsung and Canon printers and plugins from other printer manufactures will most likely be released in the future though the Google Cloud Print service plugin can also be used to print from an Android device to just about any printer...

77.2 The Print Service Plugins

The purpose of the Print Service plugins is to enable applications to print to compatible printers that are visible to the Android device via a local area wireless network or Bluetooth.

The presence of the Print Service Plugin on an Android device can be verified by loading the Google Play app and performing a search for “Print Service Plugin”. Once the plugin is listed in the Play Store, and in the event that the plugin is not already installed, it can be installed by selecting the Install button. Figure 77-1, for example, shows the HP Print Service plugin within Google Play.

The Print Services plugins will automatically detect compatible printers on the network to which the Android device is currently connected and list them as options when printing from an application.

Figure 77-1

77.3 Google Cloud Print

Google Cloud Print is a service provided by Google that enables you to print content onto your own printer over the web from anywhere with internet connectivity. Google Cloud Print supports a wide range of devices and printer models in the form of both Cloud Ready and Classic printers. A Cloud Ready printer has technology built-in that enables printing via the web. Manufacturers that provide cloud ready printers include Brother, Canon, Dell, Epson, HP, Kodak and Samsung. To identify if your printer is both cloud ready and supported by Google Cloud Print, review the list of printers at the following URL:

https://www.google.com/cloudprint/learn/printers.html

In the case of classic, non-Cloud Ready printers, Google Cloud Print provides support for cloud printing through the installation of software on the computer system to which the classic printer is connected (either directly or over a home or office network).

To set up Google Cloud Print, visit the...

77.4 Printing to Google Drive

In addition to supporting physical printers, it is also possible to save printed output to your Google Drive account. When printing from a device, select the Save to Google Drive option in the printing panel. The content to be printed will then be converted to a PDF file and saved to the Google Drive cloud-based storage associated with the currently active Google Account ID on the device.

77.5 Save as PDF

The final printing option provided by Android allows the printed content to be saved locally as a PDF file on the Android device. Once selected, this option will request a name for the PDF file and a location on the device into which the document is to be saved.

Both the Save as PDF and Google Drive options can be invaluable in terms of saving paper when testing the printing functionality of your own Android applications.

77.6 Printing from Android Devices

Google recommends that applications which provide the ability to print content do so by placing the print option in the Overflow menu (a topic covered in some detail in the chapter entitled “Creating and Managing Overflow Menus on Android”). A number of applications bundled with Android now include “Print…” menu options. Figure 77-2, for example, shows the Print option accessed by selecting the “Share…” option in the Overflow menu of the Chrome browser application:

Figure 77-2

Once the print option has been selected from within an application, the standard Android print screen will appear showing a preview of the content to be printed as illustrated in Figure 77-3:

Figure 77-3

Tapping the panel along the top of the screen will display the full range of printing options:

Figure 77-4

The Android print panel provides the usual printing options such as paper size, color...

77.7 Options for Building Print Support into Android Apps

The Printing framework provides a number of options for incorporating print support into Android applications. These options can be categorized as follows:

77.7.1 Image Printing

As the name suggests, this option allows image printing to be incorporated into Android applications. When adding this feature to an application, the first step is to create a new instance of the PrintHelper class:

PrintHelper imagePrinter = new PrintHelper(context);

Next, the scale mode for the printed image may be specified via a call to the setScaleMode() method of the PrintHelper instance. Options are as follows:

•SCALE_MODE_FIT – The image will be scaled to fit within the paper size without any cropping or changes to aspect ratio. This will typically result in white space appearing in one dimension.

•SCALE_MODE_FILL – The image will be scaled to fill the paper size with cropping performed where necessary...

77.8 Summary

The Android SDK includes the ability to print content from within a running app. Print output can be directed to suitably configured printers, a local PDF file or to the cloud via Google Drive. From the perspective of the Android application developer, these capabilities are available for use in applications by making use of the Printing framework. By far the easiest printing options to implement are those involving content in the form of images and HTML. More advanced printing may, however, be implemented using the custom document printing features of the framework.