Android Question How to draw on a Bitmap?

[Inman]

I have a Bitmap object loaded with an image file from the cache folder. I don't have any imageview yet, just the Bitmap object. I want to draw a shape (like line or rectange) on this bitmap. I tried the Canvas object but it seem to draw only on Views and on mutable bitmaps, but not on bitmaps loaded from the directory.

How can I draw on this bitmap directly?

 

[Erel]

A standard bitmap is immutable. This means that you cannot modify it.

You should create a new mutable bitmap (Bitmap.InitializeMutable) and initialize the canvas with this bitmap.
You can then draw the loaded bitmap with Canvas.DrawBitmap.

 

[Informatix]

I have a Bitmap object loaded with an image file from the cache folder. I don't have any imageview yet, just the Bitmap object. I want to draw a shape (like line or rectange) on this bitmap. I tried the Canvas object but it seem to draw only on Views and on mutable bitmaps, but not on bitmaps loaded from the directory.

How can I draw on this bitmap directly?

You can use the Accelerated Surface library to transform this bitmap in a mutable one (AS_ImageUtils class, MakeMutable function).

 

[Inman]

Thanks Erel. That worked.

Edit:

Sounds great Informatix. That is one library of yours I never tried out as I am not into game programming. Sounds like I should give it a try.

 

[Informatix]

Thanks Erel. That worked.

Edit:

Sounds great Informatix. That is one library of yours I never tried out as I am not into game programming. Sounds like I should give it a try.

In the next version of ULV, I'm going to add the support of Accelerated Surfaces to LoadImageAsync.

 

[Inman]

In the next version of ULV, I'm going to add the support of Accelerated Surfaces to LoadImageAsync.

Wow! That will be a killer combo. Can't wait.