The Android printing framework allows apps to print content to various printers. PrintManager is used to initiate print jobs by providing a PrintDocumentAdapter, which handles rendering the document content onto pages. The adapter must implement callbacks like onLayout to determine the page count and onWrite to render each page. Custom adapters can draw directly onto page canvases. PrintHelper provides a simplified way to print bitmaps.

1. Printing Framework
android.print

2. The gist of it

3. The gist of it
PrintManager

4. Prerequisites

SDK platform 19

SDK build-tools 19 or later

Something to print with

A Google Cloud Print Ready printer

A printer shared through Google Cloud Print

Print to PDF

5. ApiDemos

[sdk]/sampes/android-19/legacy/ApiDemos

6. PrintManager
PrintManager printManager = (PrintManager)
context.getSystemService(Context.PRINT_SERVICE);
PrintJob printJob = printManager.print(
printJobName, documentAdapter, attributes);
Name for the print job
(shown to the user)
Default print job attributes
Adapter that emits the document

7. PrintDocumentAdapter
Web pages
PrintDocumentAdapter documentAdapter =
// Directly from an existing WebView
webView.createPrintDocumentAdapter();

8. PrintDocumentAdapter
Web pages
// Create a WebView and start printing when its ready
WebView webView = new WebView(context);
webView.setWebViewClient(new WebViewClient() {
@Override
public void onPageFinished(
WebView webView, String url) {
// Print to it as before
PrintDocumentAdapter documentAdapter =
webView.createPrintDocumentAdapter();
}
});
webView.loadUrl(url);

9. PrintDocumentAdapter
Custom documents
PrintDocumentAdapter documentAdapter =
// Define a custom print adapter
new MyPrintDocumentAdapter(context);

10. Custom Print Adapters
Events:

onStart()


Print process has begun.
onLayout()



A print setting has changed and the layout of the pages needs to be computed.
Must return expected number of pages.
onWrite()


Render printed pages into a file.
onFinish()

Print process has ended.

11. Custom Print Adapters
onLayout()
public void onLayout(
final PrintAttributes oldAttributes,
final PrintAttributes newAttributes,
final CancellationSignal cancellationSignal,
final LayoutResultCallback callback,
final Bundle metadata) {
CONTRACT
onLayoutFinished(
PrintDocumentInfo, boolean)
}
onLayoutCancelled()
onLayoutFailed(CharSequence)

12. Custom Print Adapters
onLayout()

Create a document for printing:
PrintedPdfDocument document =
new PrintedPdfDocument(context, newAttributes);

Compute the number of pages using PrintAttributes

Return print information to the print framework:
PrintDocumentInfo info = new PrintDocumentInfo
.Builder("print_output.pdf")
.setContentType(
PrintDocumentInfo.CONTENT_TYPE_DOCUMENT)
.setPageCount(pages);
.build();
callback.onLayoutFinished(info, true);

Wait for the print framework to invoke onWrite()

13. Custom Print Adapters
onWrite()
public void onWrite(
final PageRange[] pages,
final ParcelFileDescriptor destination,
final CancellationSignal cancellationSignal,
final WriteResultCallback callback) {
CONTRACT
onWriteFinished(PageRange[])
}
onWriteCancelled()
onWriteFailed(CharSequence)

14. Custom Print Adapters
onWrite()

Start writing a page:
Page page = document.startPage(pageNumber);

Draw onto the page canvas:
page.getCanvas();


Note that elements are specified in points (1/72 inch)
Finish writing the page:
document.finishPage(page);

Inform WriteResultCallback of the PageRange[] printed

15. Custom Print Adapters
Caveats
If you need a screen context, remember that the printer and screen densities differ!

Obtain the printer density:
printerDensity = Math.max(
newAttributes.getResolution().getHorizontalDpi(),
newAttributes.getResolution().getVerticalDpi());

Create a new Context to cope with a different Configuration:
Configuration configuration = new Configuration();
configuration.densityDpi = printerDensity;
printContext = createConfigurationContext(
configuration);

Use this context for creating new views:
View view = new LinearLayout(printContext);
view.draw(page.getCanvas());

16. PrintHelper
PrintHelper printHelper = new PrintHelper(context);
// Instruct how the content should scale
printHelper.setScaleMode(PrintHelper.SCALE_MODE_FIT);
// Get the bitmap for the ImageView's drawable
Bitmap bitmap = ((BitmapDrawable)
mImageView.getDrawable()).getBitmap();
// Print the bitmap
printHelper.printBitmap("Print Bitmap", bitmap);

17. Happy printing!