Introduction

The previous article covered the theory of overdraw and tools to detect it. While iOS users rely on Apple’s curation, Android users rely on developers’ discipline. Unfortunately, many market-leading Android apps still suffer from significant overdraw issues. As a developer, I want to see Android bridge and eventually surpass the experience gap with iOS.

This post walks through a practical overdraw optimization process. Since every app is different, these steps are a reference to help you start your own optimization journey.

If you missed the theory part, check it here: Android Performance Optimization: Overdraw (Part 1)

It’s been a while since my last blog update. After joining a new company, I’ve been quite busy and haven’t been able to update the blog as frequently as before. However, the VPN I set up on this VPS is used daily and performs quite well. Recently, I’ve been focusing on Android performance-related topics, specifically Android performance optimization. I’ve realized how little I actually know about this area, so I’m starting from the application layer and working my way down, learning step by step. This series will document my learnings and summaries related to performance optimization.

First, let’s discuss GPU overdraw, which is often the most direct aspect developers encounter. This topic will be divided into two parts: Part 1 will cover the basic principles of GPU overdraw and provide optimization suggestions, while Part 2 will use practical examples to demonstrate general steps for optimizing GPU overdraw.

What is GPU Overdraw?

GPU Overdraw Concept: GPU overdraw occurs when a single pixel on the screen is drawn multiple times (more than once). For example, if a TextView has a background, the pixels displaying the text are drawn at least twice - once for the background and once for the text. GPU overdraw inevitably impacts performance to some extent. Device memory bandwidth is limited, and when overdraw causes an application to require more bandwidth than what’s available, performance degrades. Bandwidth limitations vary across different devices.

It’s been a while since my last update. After joining a new company, things have been busy, but I’ve been spending a lot of time researching Android performance. I’ve realized there’s so much I still don’t know, so I’m starting from the application level and working my way down. This series will document my learnings on Android performance optimization.

First, we’ll discuss GPU Overdraw, which is often the most direct point of contact for developers. This topic is split into two parts: Part 1 covers the theory and optimization suggestions, and Part 2 will walk through a practical optimization example.

What is Overdraw?

GPU Overdraw refers to the system drawing more than one layer on a single pixel during a frame. For example, if a TextView has a background color, the pixels displaying the text are drawn twice: once for the background and once for the characters. Overdraw inevitably impacts performance because memory bandwidth is finite. When overdraw exceeds the available bandwidth, the frame rate drops. Bandwidth limits vary significantly across different devices.