DZone
Thanks for visiting DZone today,
Edit Profile
  • Manage Email Subscriptions
  • How to Post to DZone
  • Article Submission Guidelines
Sign Out View Profile
  • Post an Article
  • Manage My Drafts
Over 2 million developers have joined DZone.
Log In / Join
Refcards Trend Reports Events Over 2 million developers have joined DZone. Join Today! Thanks for visiting DZone today,
Edit Profile Manage Email Subscriptions Moderation Admin Console How to Post to DZone Article Submission Guidelines
View Profile
Sign Out
Refcards
Trend Reports
Events
Zones
Culture and Methodologies Agile Career Development Methodologies Team Management
Data Engineering AI/ML Big Data Data Databases IoT
Software Design and Architecture Cloud Architecture Containers Integration Microservices Performance Security
Coding Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones AWS Cloud
by AWS Developer Relations
Culture and Methodologies
Agile Career Development Methodologies Team Management
Data Engineering
AI/ML Big Data Data Databases IoT
Software Design and Architecture
Cloud Architecture Containers Integration Microservices Performance Security
Coding
Frameworks Java JavaScript Languages Tools
Testing, Deployment, and Maintenance
Deployment DevOps and CI/CD Maintenance Monitoring and Observability Testing, Tools, and Frameworks
Partner Zones
AWS Cloud
by AWS Developer Relations
  1. DZone
  2. Testing, Deployment, and Maintenance
  3. Deployment
  4. Adjusting the Opacity of an Android Bitmap

Adjusting the Opacity of an Android Bitmap

Dan Dyer user avatar by
Dan Dyer
·
Jan. 13, 11 · Interview
Like (0)
Save
Tweet
Share
20.16K Views

Join the DZone community and get the full member experience.

Join For Free

This took me a lot longer to figure out than it should have done. I’m documenting it here in case it’s useful for somebody else searching for a similar solution.

If you’re displaying the Bitmap in an ImageView, you can probably use the ImageView.setAlpha(int) method. However, if the ImageView is accesed via RemoteViews, as is the case when updating a widget, you won’t be able to invoke this method (if you try to call it via RemoteViews.setInt(int, String, int) you’ll get an exception telling you as much).

After much searching I was unable to find a widget-friendly mechanism for adjusting an ImageView‘s transparency, or any obvious way of manipulating a Bitmap‘s alpha channel.

Eventually I stumbled upon Kevin Dion’s excellent answer to a different but related question on StackOverflow. From this I was able to figure out that I needed to use the DST_IN Porter-Duff mode to modify the alpha channel.

/**
* @param bitmap The source bitmap.
* @param opacity a value between 0 (completely transparent) and 255 (completely
* opaque).
* @return The opacity-adjusted bitmap. If the source bitmap is mutable it will be
* adjusted and returned, otherwise a new bitmap is created.
*/
private Bitmap adjustOpacity(Bitmap bitmap, int opacity)
{
Bitmap mutableBitmap = bitmap.isMutable()
? bitmap
: bitmap.copy(Bitmap.Config.ARGB_8888, true);
Canvas canvas = new Canvas(mutableBitmap);
int colour = (opacity & 0xFF) << 24;
canvas.drawColor(colour, PorterDuff.Mode.DST_IN);
return mutableBitmap;
}

From http://blog.uncommons.org/2011/01/12/adjusting-the-opacity-of-an-android-bitmap/

Bitmap Android (robot) Opacity (optics)

Opinions expressed by DZone contributors are their own.

Popular on DZone

  • Is DevOps Dead?
  • DevOps vs Agile: Which Approach Will Win the Battle for Efficiency?
  • Tracking Software Architecture Decisions
  • 10 Best Ways to Level Up as a Developer

Comments

Partner Resources

X

ABOUT US

  • About DZone
  • Send feedback
  • Careers
  • Sitemap

ADVERTISE

  • Advertise with DZone

CONTRIBUTE ON DZONE

  • Article Submission Guidelines
  • Become a Contributor
  • Visit the Writers' Zone

LEGAL

  • Terms of Service
  • Privacy Policy

CONTACT US

  • 600 Park Offices Drive
  • Suite 300
  • Durham, NC 27709
  • support@dzone.com
  • +1 (919) 678-0300

Let's be friends: