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I'm currently developing an Android application that uses the device camera for both taking photos and recording videos. This application must work on API level >= 8 (Froyo).

Until now, I have implemented the camera code based on Android samples. It can be found in <ADT folder>/sdk/samples/<android_version>/ApiDemos/src/com/example/android/apis/graphics/CameraPreview.java - I'm following the "android 11" example to switch between cameras and "android 8" for the rest. This means that my camera preview is held by a SurfaceView which is contained in a ViewGroup (CameraPreview class) which is in turn attached as the content view in the main activity.

The problem is that I don't want the camera preview to be shown as Android does. I mean: I want the preview to fit one of the screen dimensions and overflow the other. Android samples fit one of the screen dimensions and keep the other inside the screen boundaries.

For example: let's take an Android device whose screen dimensions are 480x800. We select a preview size of 480x640. Android would keep this preview size as it fits within the device's screen: it would exactly fit the screen width, while it would show two black rectangles up and down (letterbox). In my case, I'd upscale that preview by 1.25, so as to resize it to 600x800 (that is, making the longest side of both the preview and the camera 800 long). Then I try to center this preview by moving that preview surface (surfaceView) slightly to the left. In this case, the leftmost horizontal coordinate would be -60 and topmost 0.

My problem is that I'm not able to correctly move the SurfaceView. It is correctly resized but I cannot move it to the left (out of the screen). Searching on SO, I've found lots of possible solutions but none worked for me. I'm sure that this shouldn't be so difficult and I must be doing something wrong.

Until now, I've tried some solutions such as:

  • Following the Android example , I changed it's resizing code - onMeasure function - to:
if (width * previewHeight < height * previewWidth) {

    final int scaledChildWidth = previewWidth * height / previewHeight;

    child.layout( (width - scaledChildWidth) / 2, 0, (width + scaledChildWidth) / 2, height);


} else {

    final int scaledChildHeight = previewHeight * width / previewWidth;

    child.layout(0, (height - scaledChildHeight) / 2, width, (height + scaledChildHeight) / 2);

}

This correctly resizes the preview to the dimensions I look for but, although leftmost coordinate is supposed to be -60, it continues to be rendered from the upper left corner of the screen. I'm just pasting here the change in onMeasure function as it the rest of the code is the same as the one in the Android sample folder I said before.

  • Changing the parent container of the SurfaceView into a ScrollView and scrolling the preview.

  • Using negative margins or paddings with ViewGroup/RelativeLayout/FrameLayout/LinearLayout/etc. In this case, I was able to move some interface elements (other button I added to the layout) but not the SurfaceView.

  • Trying to set clipChildren and clipToPadding to false.

  • Trying to play with centerInParent option.

  • Creating a new parent layout whose size is the same as that of the SurfaceView (scaled preview size) and centering it. It also resizes correctly but doesn't center on the screen.

  • Using AbsoluteLayout (yes, I know it's deprecated ;) )

I can't remember now other solutions I tried, but I think these are the main ones.

It seems that I could not prevent elements from starting at the upper left corner of the screen.

Of course, any further details needed can be requested and I'll try to answer ASAP. I got really stuck at this point and I'd be very grateful for any help provided. Thanks to all for spending time on reading this :)

Edit 1

I am testing this application in Android 2.3.6.

GReaper
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  • Have you tried [Fitting a Camera Preview to a SurfaceView larger than the display](http://stackoverflow.com/questions/11321251/fitting-a-camera-preview-to-a-surfaceview-larger-than-the-display)? – Alex Cohn Oct 16 '13 at 15:32
  • Hi Alex. Yes, I have tried that solution. Now I have that code implemented (the solution one). Coordinates passed to `child.layout(...)` call are correct. For example, the initial x value is -60, but `SurfaceView` doesn't resize to that coordinates. It's still limited by screen boundaries. – GReaper Oct 16 '13 at 18:41
  • Anyone more with the same issue? :-) – GReaper Jan 15 '14 at 11:26

1 Answers1

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Answer after a long time, but I spent lot of time figuring this out.

The SurfaceView on some android devices (see below) just cannot extend beyond the display boundaries. If it does, it shifted and centered, if it's too big to fit. If the chosen resolution does not match your display size, you either have to add padding or stretch the image. That's a fact.

Secondly, be sure to choose a picture size with the same aspect ratio as your preview size, or you will not get the exactly same viewport in the picture as you saw in preview. This might not matter in your case, if the difference is not big, but it does in mine.

Note on some devices: I experienced this behavior on my old HTC Desire S (with Android 2.3). It works as expected with Samsung S5 with Android 5.1. I will be glad if someone improves the answer with information what is this related to (android version, or just some models...).

Oliv
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