blend two uiimages based on alpha/transparency of top image

by

This is what I’ve done in my app, similar to Tyler’s – but without the UIImageView:

UIImage *bottomImage = [UIImage imageNamed:@"bottom.png"];
UIImage *image = [UIImage imageNamed:@"top.png"];

CGSize newSize = CGSizeMake(width, height);
UIGraphicsBeginImageContext( newSize );

// Use existing opacity as is
[bottomImage drawInRect:CGRectMake(0,0,newSize.width,newSize.height)];
// Apply supplied opacity
[image drawInRect:CGRectMake(0,0,newSize.width,newSize.height) blendMode:kCGBlendModeNormal alpha:0.8];

UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

If the image already has opacity, you do not need to set it (as in bottomImage) otherwise you can set it (as with image).

More Related Contents:

  1. Can anyone help me out with validation of Email in iOS for emails like “[email protected]”, “[email protected]”, etc.,? [closed]
  2. camera streaming between website and iphone [closed]
  3. Objective-C categories in static library
  4. NSTimer doesn’t stop
  5. iOS SDK – Programmatically generate a PDF file
  6. What are best practices that you use when writing Objective-C and Cocoa? [closed]
  7. Real-time Pitch Shifting on the iPhone
  8. Get NSDate from NSDate adjusted with timezone
  9. Where are an UIWebView’s cookies stored?
  10. Video file formats supported in iPhone
  11. How to get the WIFI gateway address on the iPhone? [duplicate]
  12. iPhone apps: Can I open an app from a link in a website?
  13. Change UIPickerView background
  14. What is the use of -[NSUserDefaults registerDefaults:]?
  15. Getting a list of files in the Resources folder – iOS
  16. post image to server in iphone
  17. Windows notepad not supporting newline character ‘\n’
  18. iphone ios running in separate thread
  19. Double vs float on the iPhone
  20. Get street address at lat/long pair
  21. How to implement Daemon process for background task in iphone sdk 3.0? [closed]
  22. How to make a circular UIView
  23. Why should I use Core Data for my iPhone app?
  24. How can I determine the default gateway on iPhone?
  25. iPhone Development – Memory limitation for iphone application
  26. How to set the height of table header in UITableView?
  27. How to find out what profile was used for building *.ipa file?
  28. Temporarily Lock or Disable iphone home button
  29. Reading MP3 information using objective c
  30. is there a uipickerview delegate method like scrollviewDidScroll?

Leave a Comment