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Android POS Receipt Printing

3 posts · Jun 2019 – Sep 2022

What this trail covers

Shopify has developed and enhanced its Android Point of Sale (POS) application's receipt printing capabilities. This involved implementing a multi-step printing pipeline to handle diverse receipt content combinations, including data aggregation, content generation, and dynamic layout selection. The system aims to provide merchants with flexible and comprehensive receipt printing options. This post details the development of Android widgets for displaying merchant analytics, focusing on native de

All Shopify trails
  1. Lessons From Building Android Widgets - ShopifyThis post details the development of Android widgets for displaying merchant analytics. It covers the decision to use native Android development over React Native due to limitations with RemoteViews, the architecture for fetching fresh data with a short-lived cache to avoid unnecessary network calls, and the UI implementation using RemoteViews and dynamic grid sizes. It also highlights the use of relative time for timestamps to improve clarity.
  2. Building Reliable Mobile Applications - ShopifyThis post details the implementation of receipt printing for Shopify's Android POS application. It addresses the complexity of diverse receipt content combinations and outlines a multi-step printing pipeline: Data Aggregation, Content Generation, and Printing. It also discusses strategies for handling various receipt content combinations and ensuring reliability in the printing process, including staged rollouts, beta flags, and automated monitoring with anomaly detection.
  3. Implementing Android POS Receipt Printing on Shopify - ShopifyThis post details the implementation of receipt printing support for Shopify POS on Android. It outlines the five-step printing pipeline: Data Aggregation, Content Generation, Sections Definition, Print Request Creation, Content Rendering, and Receipt Printing. Key technical aspects include using a coroutine-based API for data aggregation, a PrintableReceiptComposer class for content generation with TDD, ViewBinder-like classes for section definitions, a printer-agnostic PrintRequest class, and rendering sections to in-memory Bitmaps. The Hardware SDK abstracts vendor-specific integrations. Testing relies heavily on unit tests for data aggregation and content generation, and screenshot tests for section definition and content rendering.