I would like to know if there is any way to use the front camera of the mobile without asking the persmission of the user while is using an application.
The logic would be:
User triggers something
The front camera starts recording
Records during 5 seconds and saves the file
The user can't know the camera did this. Is it possible? I guess I will have to indicate in the manifest the camera is going to be used, but that is ok, what I don't want is that the user has to confirm the camera usage or anything while is using the app.
Thanks
IMO this warning is a additional feature of google's android or the customized android versions from the manufacturers. I think it's a security feature, so you can't handle that behavior by your self.
This info is based on my opinion and talkings with front camera paranoid friends.
I want to build n app that detects when the user takes a screenshot then get the image and use it.
Is it possible without root? My idea is very crude. the app will scan the screenshots holder for changes every second but that is very inefficient. is there another way?
I don't think there is no supported way of doing that. You could try the FileObserver class though and watch for events. Look here: https://developer.android.com/reference/android/os/FileObserver.html
Can i put on my activity the incoming call screen as a background?
The picture of the screen of how it looks like when there's a call.
Every phone is different with its screen, thats way im looking for a way
to retrieve it from the phones system if it possible.
Thank you
android jave how to retrieve an image of the incoming call screen
This is not possible, except perhaps on rooted devices. You cannot capture screenshots programmatically, for obvious privacy and security reasons.
I want to write an activity that:
Shows the camera preview (viewfinder), and has a "capture" button.
When the "capture" button is pressed, takes a picture and returns it to the calling activity (setResult() & finish()).
Are there any complete examples out there that works on every device? A link to a simple open source application that takes pictures would be the ideal answer.
My research so far:
This is a common scenario, and there are many questions and tutorials on this.
There are two main approaches:
Use the android.provider.MediaStore.ACTION_IMAGE_CAPTURE event. See this question
Use the Camera API directly. See this example or this question (with lots of references).
Approach 1 would have been perfect, but the issue is that the intent is implemented differently on each device. On some devices it works well. However, on some devices you can take a picture but it is never returned to your app. On some devices nothing happens when you launch the intent. Typically it also saves the picture to the SD card, and requires the SD card to be present. The user interaction is also different on every device.
With approach 2 the issues is stability. I tried some examples, but I've managed to stop the camera from working (until a restart) on some devices and completely freeze another device. On another device the capture worked, but the preview stayed black.
I would have used ZXing as an example application (I work with it a lot), but it only uses the preview (viewfinder), and doesn't take any pictures. I also found that on some devices, ZXing did not automatically adjust the white balance when the lighting conditions changed, while the native camera app did it properly (not sure if this can be fixed).
Update:
For a while I used the camera API directly. This gives more control (custom UI, etc), but I would not recommend it to anyone. I would work on 90% of devices, but every now and again a new device would be released, with a different problem.
Some of the problems I've encountered:
Handling autofocus
Handling flash
Supporting devices with a front camera, back camera or both
Each device has a different combination of screen resolution, preview resolutions (doesn't always match the screen resolution) and picture resolutions.
So in general, I'd not recommend going this route at all, unless there is no other way. After two years I dumped by custom code and switched back to the Intent-based approach. Since then I've had much less trouble. The issues I've had with the Intent-based approach in the past was probably just my own incompetence.
If you really need to go this route, I've heard it's much easier if you only support devices with Android 4.0+.
With approach 2 the issues is stability. I tried some examples, but I've managed to stop the camera from working (until a restart) on some devices and completely freeze another device. On another device the capture worked, but the preview stayed black.
Either there is a bug in the examples or there is a compatibility issue with the devices.
The example that CommonsWare gave works well. The example works when using it as-is, but here are the issues I ran into when modifying it for my use case:
Never take a second picture before the first picture has completed, in other words PictureCallback.onPictureTaken() has been called. The CommonsWare example uses the inPreview flag for this purpose.
Make sure that your SurfaceView is full-screen. If you want a smaller preview you might need to change the preview size selection logic, otherwise the preview might not fit into the SurfaceView on some devices. Some devices only support a full-screen preview size, so keeping it full-screen is the simplest solution.
To add more components to the preview screen, FrameLayout works well in my experience. I started by using a LinearLayout to add text above the preview, but that broke rule #2. When using a FrameLayout to add components on top of the preview, you don't have any issues with the preview resolution.
I also posted a minor issue relating to Camera.open() on GitHub.
"the recommended way to access the camera is to open Camera on a separate thread". Otherwise, Camera.open() can take a while and might bog down the UI thread.
"Callbacks will be invoked on the event thread open(int) was called from". That's why to achieve best performance with camera preview callbacks (e.g. to encode them in a low-latency video for live communication), I recommend to open camera in a new HandlerThread, as shown here.
I developed a small video camera application. It all works fine except focus.
I understand I need to call camera.autofocus, but I don't really know where is the right place to put the call it.
Anyone ever succeeded in autofocusing a video camera on android?
Thank
Eli
It's probably a matter of preference based on how you think users will use your app.
I think a common convention is to do an auto-focus when the user touches the scene in the preview. Most OEM camera apps seem to do this.
Doing auto-focus after zooming is also a common thing.
Finally, you might want to have a look at the zxing project (bar code scanner app) which has a nifty continuous auto focus approach that might be of use, though since youre capturing video, it might not be ideal as the focus transitions might be too noticeable.
http://code.google.com/p/zxing/source/browse/trunk/android/src/com/google/zxing/client/android/camera/AutoFocusCallback.java?r=1698