In Android, is the following possible (if so, how) :
I'd like to set up a layout in my java and add a view to it where the view contains a surfaceView for rendering the camera preview. But, I dont want to instantiate and start the camera in Java. I just want to set up the view so that I can keep the layout structure.
Then, I have a native C++ component accessed via JNI where I'd like to actually start the camera and have it's preview rendered in the SurfaceView mentioned above.
The reason for this setup is that I'd like to keep the layout that I defined in Java but access the camera and its preview frames in C++. I dont want to handle the preview frames in Java and then pass them to C++ as that is not efficient.
The other option would be to set up my java layout in C++, but not sure if that is even possible ?
Related
I am building this application where I need to get video with the camera and process it with openCV as well as show a view with 3D graphics being renderered in it.I am using two fragments. One for previewing the camera. And one for the 3D graphics.The problem is the 3d graphics view has to be fullscreen. I don't want the camera preview at all. I can show them side by side using linear layout. But I cannot totally hide the preview and make the 3d scene take up the whole screen. Even using relative layout causes the camera preview to tear through the 3d graphics view.
Simply put it, if the camera preview is not being shown, the CvCameraViewListener2.onCameraFrame() method is not called. And without that I don't receive any new frames to process.
The problem got solved. I really don't know how it got solved though. I woke up the next day and tried running the project and it ran perfectly without requiring to change anything.
I have the task to record user activity in a webview, in other words I need to create an mp4 video file while the user navigates in a webview. Pretty challenging :)
I font that in Android 4.3 introduced MediaCodec : was expanded to include a way to provide input through a Surface (via the createInputSurface method). This allows input to come from camera preview or OpenGL ES rendering.
I even find an example where you could record a game written in opengl : http://bigflake.com/mediacodec/
My question is : how could I record a webview activity ? I assume that If I could draw the webview content to opengl texture, than everything would be fine. But I don't know how to do this.
Can anybody help me on this?
Why not try WebView.onDraw first, instead of using OpenGL? The latter approach may be more complicated, and not supported by all devices.
Once you will be able to obtain the screenshots, then you can create the video (to create video from image sequence on android), a separate task where mediacodec should help.
"I assume that If I could draw the webview content to opengl texture".
It is possible.
The SurfaceTexture is basically your entry point into the OpenGL layer. It is initialized with an OpenGL texture id, and performs all of it's rendering onto that texture.
The steps to render your view to opengl:
1.Initialize an OpenGL texture
2.Within an OpenGL context construct a SurfaceTexture with the texture id. Use SurfaceTexture.setDefaultBufferSize(int width, int height) to make sure you have enough space on the texture for the view to render.
3.Create a Surface constructed with the above SurfaceTexture.
4.Within the View's onDraw, use the Canvas returned by Surface.lockCanvas to do the view drawing. You can obviously do this with any View, and not just WebView. Plus Canvas has a whole bunch of drawing methods, allowing you to do funky, funky things.
The source code can be found here: https://github.com/ArtemBogush/AndroidViewToGLRendering And you can find some explanations here:http://www.felixjones.co.uk/neo%20website/Android_View/
I have a camera preview in my android app. As you all probably know it is implemented by a surfaceview in android.
In my photo app, which allows users to take pictures, I want to blur the camera preview (the surface view) if the user has not logged in yet if the user is logged in, I will display the normal preview (without blur)
Blur as something like
But there seems to be no way to do it
Couple things come to mind but I am not sure how to achieve it
use a blur overlay and place it on top of the surface view, but how do u create such blur overlay?
another approach is to change the attribute of the window, but I can't do it to surfaceview,
getWindow().addFlags(WindowManager.LayoutParams.FLAG_BLUR_BEHIND);
So can we create a window overlay the surfaceview and set the flag like that? I don't think so
can someone tell me how to blur a camera preview, which is a surface view
note: I am trying to blur an area which is the output from camera preview, so it is not like I am blurring a static image, the blur area will change depending on where you point your phone camera
The best way to do this is to take a screen shot of the control, apply a blur to it, and then show that image over the top of the original control. This is how the yahoo weather app does it and its how google suggest you do things like this.
Render script does bluring fast. I've also got some code, but it's not currently at hand right now.
These might help:
http://blog.neteril.org/blog/2013/08/12/blurring-images-on-android
http://docs.xamarin.com/recipes/android/other_ux/drawing/blur_an_image_with_renderscript/
I've also read that there are methods built into Android that do this, but the API isn't public so we cannot use it... which sucks.
Although your 2nd option is losing support in later versions of the Android OS, it may be a good option. I would think to bring a window IN FRONT of your surfaceview, and use the blur_behind property of your now new IN FRONT window.
Android API documentation
"
This constant was deprecated in API level 14.
Blurring is no longer supported.
Window flag: blur everything behind this window.
Constant Value: 4 (0x00000004)"
I do have to admit, Im not 100% sure this would work, but its definitely worth a try.
You have to change the camera parameters; in this case with Camera.Parameters.setPictureSize().
The basic workflow here is :
Camera.Parameters cp = mCamera.getParameters(); // get the current params
cp.set...(); // change something
mCamera.setParameters(cp); // write the params back
Make sure that every resolution that you set via this function is supported. You can get a list of the resolutions that are supported on a device via Camera.Parameters.getSupportedPictureSizes(). and check this Camera documentation.
iam currently using camera and surfaceview in my app to use Torch etc ... , im using these in an Activity ,
How to use Camera and SurfaceView in Background , ex . : I want to keep Torch/Led Flash On , i saw many Widget that work fine in Background , how they do it ?
Thanks .
Take a look here:
http://developer.android.com/guide/topics/media/camera.html
There is all the code you need to make an activity which shows the camera preview.
As the Camera API:
http://developer.android.com/reference/android/hardware/Camera.html#setPreviewDisplay%28android.view.SurfaceHolder%29
specifies...you need to use a SurfaceHolder for your preview. Thus you can only use a SurfaceView or a derived class for your automatic preview. Otherwise you can use for example a TextureView or an ImageView to draw your preview by yourself. You'll need though to implement the onFramePreview method to grab the frames from the preview and handle them by yourself. By using OpenGL or the ANI API you can also add effects to your frame. This is the only way, I know about, to also add effects directly on your preview, unless these effects can be achieved by overlaying a semi-transparent colored surface above your preview image.
On some devices, onPreviewFrame is not called if no SurfaceView was set to display the camera preview.
However, I handle the camera in a service, so I can't set a SurfaceView but I don't want to have visible preview anyway.
How can this be done? Can I programmatically create a SurfaceView and set it with Camera::setPreviewDisplay?
This must be possible or not?
It works on almost every phone without a SurfaceView but not on HTC One X and Google Nexus One...
According to this question, creating a SurfaceView in code works fine. Though I don't think you can create it through a service.
Another approach is to create a 1px-1px SurfaceView inside a RelativeLayout and hiding it with some other view on top of it. (visibility should still be VISIBLE). We use this trick for Path camera UI where we render preview buffers through OpenGL and it works fine.
According to documentation readily configured, visible and displayed surface view is necessary to activate camera preview. It may be overlayued though
From API 11 on, you can use a SurfaceTexture instead of a SurfaceView to get frames from the camera. Then, instead of using Camera.setPreviewDisplay, simply use Camera.setPreviewTexture.
This answer as well as this one discuss this point.