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I'm building a simple application which acts similar to built-in camera application - takes a photo and saves it locally, with some additional aсtions. First I took Firemonkeys' TCameraComponent, placed it to the form and added transfered image from it to TImage. It works OK, I can change resolution, control flash power and so on. The problem is that preview framerate is very low while running at good quality. If I switch camera to 320x240 resolution, it works fast enough, but quality is poor and I have to switch to some higher resolution to take a good photo - loosing time on re-focusing and light adaptation. If I set high resolution (such as 1280x720) for preview, it slows down to about 3-5 fps.

So I need to use some another technique to access camera. App interface must still unchanged during usage, so I can't use TakePhotoFromCameraAction. I'm looking to JNI interfaces. So I need, using JNI calls, access camera and get a preview at some image object at my form. I use the such code to get preview (I'm a bit lack of understanding native android so it may look crazy):

J.Cam := TJCamera.JavaClass.open(0); // J.Cam is JCamera object
J.View := TJView.JavaClass.init( TAndroidHelper.Context ); // JView
J.ViewParams := TJViewGroup_LayoutParams.JavaClass.init(Width, Height); // i got Width and Height from J.Cam.getParameters()
TAndroidHelper.Activity.addContentView( J.View, J.ViewParams );

J.SurfaceView := TJSurfaceView.JavaClass.init( J.View.getContext );
J.LayoutParameters := TJViewGroup_LayoutParams.JavaClass.init(Width, Height);
J.SurfaceView.setLayoutParams( J.LayoutParameters );

J.Cam.setPreviewDisplay( J.SurfaceView.getHolder );
J.Cam.startPreview;

and it doesn't show anything except black screen. Google developer reference says that "If you are using SurfaceView, you will need to register a SurfaceHolder.Callback with addCallback(SurfaceHolder.Callback) and wait for surfaceCreated(SurfaceHolder) before calling setPreviewDisplay() or starting preview."

So the next step I should create the callback class, extending SurfaceView and implementing SurfaceHolder.Callback. There are many samples can be found like this:

public class TestActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(new MySurfaceView(this));

    }


    public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback {
        public MySurfaceView(Context context) {
            super(context);
            getHolder().addCallback(this);
        }

        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { }

        @Override
        public void surfaceCreated(SurfaceHolder holder) { }

        @Override
        public void surfaceDestroyed(SurfaceHolder holder) { }
    }
}

Now a have to translate this code to Delphi. Java code is classes only, but Delphi's JNI is interfaces AND classes so I can't figure out how to represent this:

class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback

since both JNI's JSurfaceView and JSurfaceHolder_Callback are interfaces.

So, does anybody knows how do do this? (or completely another way to access camera)

Kirill Zotov
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  • Everyone who tried to do this in Delphi FMX ran into the same problem. See my answer at [record-video-from-camera-on-android-to-mp4](http://stackoverflow.com/questions/23837928) – Freddie Bell Apr 15 '16 at 11:41
  • @nolaspeaker, If I understood your code correctly, you used existing recording application with it's interface, but I can't use external apps due to design specification, so I'm looking for the way to use JNI calls. – Kirill Zotov Apr 16 '16 at 07:47
  • The people at [flashavconverter](http://www.flashavconverter.com/content/ffmpeg-converter-android-delphi) know how to do it, but they only provide .so's, not source code - and they want money. I think this would have to be done in Java (as you attempted above) and then that code must be called from Delphi. It's not a trivial exercise – Freddie Bell Apr 16 '16 at 16:22

0 Answers0