Taking picture from camera without preview

Question

I am writing an Android 1.5 application which starts just after boot-up. This is a Service and should take a picture without preview. This app will log the light density in some areas whatever. I was able to take a picture but the picture was black.

After researching for a long time, I came across a bug thread about it. If you don't generate a preview, the image will be black since Android camera needs preview to setup exposure and focus. I've created a SurfaceView and the listener, but the onSurfaceCreated() event never gets fired.

I guess the reason is, the surface is not being created visually. I've also seen some examples of calling the camera statically with MediaStore.CAPTURE_OR_SOMETHING which takes a picture and saves in the desired folder with two lines of code, but it doesn't take a picture too.

Do I need to use IPC and bindService() to call this function? Or is there an alternative method to achieve this?

Answer 1

it is really weird that camera on android platform can't stream video until it given valid preview surface. it seems that the architects of the platform was not thinking about 3rd party video streaming applications at all. even for augmented reality case the picture can be presented as some kind of visual substitution, not real time camera stream.

anyway, you can simply resize preview surface to 1x1 pixels and put it somewhere in the corner of the widget (visual element). please pay attention - resize preview surface, not camera frame size.

of course such trick does not eliminate unwanted data streaming (for preview) which consumes some system resources and battery.

Answer 2

I found the answer to this in the Android Camera Docs.

Note: It is possible to use MediaRecorder without creating a camera preview first and skip the first few steps of this process. However, since users typically prefer to see a preview before starting a recording, that process is not discussed here.

You can find the step by step instructions at the link above. After the instructions, it will state the quote that I have provided above.