Question

My app is loading a large image (a house floorplan), then drawing touch-reactive objects (furniture, lamps etc.) on the image. I have a base image file included with my app but the objects come from coords in my database.

I’ve successfully deployed the app in multiple iterations, but now I need to use larger base images and BitmapFactory is causing an OutOfMemory exception on many devices (both old and new devices; anything with < 32MB heap seems to crash). I’ve read the 157 OOM questions on SO, but I’m afraid the link they all seem to point to won’t help me since resolution / zooming is critical to the app’s function.

I’ve tried to test the device’s available memory before loading, but the results are spotty at best (some devices like the galaxy S3 report plenty of heap but still crash). I’ve also tried decreasing resolution but the image became unusable when reduced to a safe size based on the above test.

Is there another way to implement this design without ever using bitmaps?
I need to:

• Load large base image
• Create clickable shapes on top of the base image, maintaining their position / scale relative to the base image
• BONUS: in the iOS version of my app, I can do SVG-style text scaling so a long label on a small object will stay inside the object
  instead of running across the map(and will be invisible until the
  image is zoomed). Replicating this in android would make me a happy
  code monkey.

I can post code if needed, but you’ve all seen it before (almost all of it came from SO).

Thanks in advance for reading, and for any help you can give.

Answer 1

you have a few options:

1. break your large image into tiles, load these tiles into an array, and move a camera object around and only load tiles that need to be drawn, as the comments suggest.

2. make your image small and scale it up using ‘android:scaletype`

3. Draw lines and curves on a Canvas object at runtime.

4. Use OpenGL

The appropriate solution really depends on how you want it to look. Tiling will take more dev effort but will look better, just be careful that you are properly cleaning up any tiles that aren’t being drawn…

dynamically scaling will be easier, but you cannot guarantee the image won’t be blurry.

Drawing on a Canvas object at runtime could work well– just use Lines of different width and circles and Rects etc.

Using OpenGL will have the steepest learning curve, and might be overkill. This depends on your purpose.