I want to incorporate a camera feature in my app, that will allow layout transitions of the view itself, changing its size, its preview size, and handle orientation changes efficiently. Should I use TextureView or SurfaceView?
Decisions decisions..
According to your context I suggest TextureView because things like transformations, animations and scaling is not possible with the SurfaceView. But keep in mind TextureView will consume more memory than SurfaceView.
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I have a special design requiring for the app I'm developing right now.
Right now, I have a third-party private video library which plays a video stream. The design of this screen includes a translucent panel overlaid on top of the video, blurring the portion of the video that lies behind.
Normally in order to blur the background, you are supposed to take a screenshot of the view behind, blur it and use it as an image for the foreground view.
In this case, the video keeps on playing, so the blurred image changes every frame. How would you implement this then?
A possible solution would be to create a thread, taking screenshots, cropping them and put them as a background. Even better if that view is a SurfaceView, I guess. But I'm wondering what would be the best approach in this case. Would a thread that is continually taking screenshots create a huge performance impact? Is it possible to feed a surfaceView buffer with these images?
Thanks!
A SurfaceView surface is a consumer of graphics buffers. You can't have two producers for one consumer, which means you can't send the video to it and draw on it at the same time.
You can have multiple layers; the SurfaceView surface is on a separate layer behind the View UI layer. So you could play the video to the SurfaceView's surface, and draw your blur rectangle on the SurfaceView's view. (Normally the SurfaceView's view is completely transparent, and is just used as a place-holder for layout purposes.)
Another option would be to render the video frame to a SurfaceTexture. You would then render that texture to the SurfaceView surface with GLES, and render the blur rectangle on top. You can find an example of treating live camera input as a GLES texture in Grafika ("texture from camera" activity). This has the additional advantage that, since you're not interacting with the View system -- the SurfaceView surface is composited by the system, not the app -- you can do it all on an independent thread.
In any event, rendering, grabbing a screenshot, and re-rendering is going to be slower than the options described above.
For more details about why things work the way they do, see the Android System-Level Graphics architecture doc.
Can I set an ImageView to a camerapreview? Instead of using a surfaceview? I'm trying to make a camera preview semi transparent with setAlpha method, but It doesn't work on surfaceview. I mean it does work, but the camera preview is not semi transparent.
Well actually you can but not using SurfaceView. You achieve this by using GLSurface view, where you render each of your frame using shaders. In the fragment shader you can specify the opacity of your video. If you don't know OpenGL ES 2.0 you can start from here http://developer.android.com/training/graphics/opengl/index.html, but there are also many tutorial including rendering frames using opengl.
No you cannot do this, SurfaceView is the only way to create a Camera preview in Android.
I want to run android camera preview with a 640x480 resolution but display just 480x360. Right now I'm getting a stretched preview, even though I've tried to put the surface view in a frame layout or srollview. Can anyone tell me how this can be done?
A similar question has been asked before: How to crop camera preview?, but nobody answered.
Thanks
This can be achieved by using TextureView for camera preview. See https://developer.android.com/reference/android/view/TextureView.html.
Unlike SurfaceView, TextureView does not create a separate window but behaves as a regular View. This key difference allows a TextureView to be moved, transformed, animated, etc. For instance, you can make a TextureView semi-translucent by calling myView.setAlpha(0.5f).
Is it possible to draw the camera in just a portion of the SurfaceView?
or draw different things on the same SurfaceView?
What do you want to achieve by that? You cannot send the camera preview to a portion of a SurfaceView, but you can adjust the size of this View, and put other views around it or even on top of it. The latter is an alternative to drawing different things on the same SurfaceView.
How do I write code which layouts UI elements (Buttons, etc) over camera preview on Android ?
Put the SurfaceView in a container that allows for Z-axis layering, such as RelativeLayout or FrameLayout. Put the things to appear on top of the SurfaceView later in the XML -- later children of a parent will draw over top of earlier children in the parent.
Here is a project using a SurfaceView for video playback that demonstrates the technique. The same concepts should hold for a SurfaceView for camera preview.
Bear in mind that extra work needs to be done by Android to blend your widgets with the preview, so your preview frame rate may drop.