Dependencies and prerequisites
Try it out
DevBytes: Bitmap Allocation
DevBytes: Making Apps Beautiful - Part 4 - Performance Tuning
Learn how to use common techniques to process and load
Bitmap objects in a way that keeps your user interface (UI) components responsive
and avoids exceeding your application memory limit. If you're not careful, bitmaps can quickly
consume your available memory budget leading to an application crash due to the dreaded
java.lang.OutofMemoryError: bitmap size exceeds VM budget.
There are a number of reasons why loading bitmaps in your Android application is tricky:
- Mobile devices typically have constrained system resources. Android devices can have as little
as 16MB of memory available to a single application. The Android Compatibility Definition
Document (CDD), Section 3.7. Virtual Machine Compatibility gives the required minimum
application memory for various screen sizes and densities. Applications should be optimized to
perform under this minimum memory limit. However, keep in mind many devices are configured with
- Bitmaps take up a lot of memory, especially for rich images like photographs. For example, the
camera on the Galaxy Nexus takes
photos up to 2592x1936 pixels (5 megapixels). If the bitmap configuration used is
ARGB_8888 (the default from the Android 2.3 onward) then loading
this image into memory takes about 19MB of memory (2592*1936*4 bytes), immediately exhausting the
per-app limit on some devices.
- Android app UI’s frequently require several bitmaps to be loaded at once. Components such as
ViewPager commonly include multiple bitmaps on-screen at once with many
more potentially off-screen ready to show at the flick of a finger.
- Loading Large Bitmaps Efficiently
- This lesson walks you through decoding large bitmaps without exceeding the per application
- Processing Bitmaps Off the UI Thread
- Bitmap processing (resizing, downloading from a remote source, etc.) should never take place
on the main UI thread. This lesson walks you through processing bitmaps in a background thread
AsyncTask and explains how to handle concurrency issues.
- Caching Bitmaps
- This lesson walks you through using a memory and disk bitmap cache to improve the
responsiveness and fluidity of your UI when loading multiple bitmaps.
- Managing Bitmap Memory
- This lesson explains how to manage bitmap memory to maximize your app's performance.
- Displaying Bitmaps in Your UI
- This lesson brings everything together, showing you how to load multiple bitmaps into
using a background thread and bitmap cache.