Comments on: Blackberry Programming: Alter Bitmap Color on the Fly

By: Toni

Toni — Tue, 31 Aug 2010 23:21:46 +0000

Are you saying you need to animate textboxes, buttons, etc? If so, you'll need to create a custom layout manager, since the default ones tend to arrange fields in a block manner, with left/center/right alignment, but that's about it. With a custom layout manager, you can override the sublayout method (which is called to arrange each field within the manager) to place fields exactly where you'd like them. You can override your fields as well to store individual coordinates per field. I create a custom layout manager with fields drawn to specific coordinates here. Hope that helps!

By: Harish

Harish — Mon, 30 Aug 2010 17:10:28 +0000

Thanks a ton again! I have other widgets like textbox, label, checkbox, button and images (sprites) that needs to be animated. So, I was looking for best ways to do it. Any suggestions? I used some concepts from your tutorial for rendering sprites using DRAW, but can’t do that for other widgets. So, how does combining these work? etc.

By: Toni

Toni — Sun, 29 Aug 2010 00:59:10 +0000

Hi Harish – thanks for the kudos! Luckily, if you’re concerned with the alpha channel only, there is a method within the Graphics class, “SetGlobalAlpha”, that can achieve this. Here is a link to the specifications out of the 4.5 api (its been in there for a while)

SetGlobalAlpha

It basically takes an int 0-255 to set how transparent any further operations are going to be, so you can set this back and forth as you draw. However, since it operates on operations like DrawImage, its going to affect the whole image – if you need to just operate on part of a bitmap, you’d need to go the route outlined above. Good luck!

By: Harish

Harish — Tue, 24 Aug 2010 14:44:12 +0000

Thanks for the useful information!!! Great routine for writing games. Is this the same way to change the alpha of the bitmap or is there a simpler way?