Fullscreen camera preview in fragment

Question

I've spent the last two days browsing SO to find answers, unsuccessfully. I'm trying to reproduce a Snapchat-like app.

What I have so far

• A ViewPager composed of 3 fragments.
• The middle fragment is supposed to display a camera preview, just like Snapchat, on the whole surface (not truly fullscreen but it should cover the entire UI between the status bar and the bottoms buttons)
• I'm able to display either:
  • The camera preview, with the correct ratio, but not covering its parent View (see picture 1 below)
  • The camera preview, covering its parent View but stretched (wrong ratio)

 What I need

• Avoid stretching the preview. Possibly, the preview would be cropped on both sides (left and right). See picture 2 below. I guess this is what Snapchat does. Or is there any other way?

What I went through

• http://www.shakedos.com/2015/Aug/26/writing-an-android-portrait-camera-app.html
• Make a SurfaceView larger than the screen (Fitting a camera preview to a SurfaceView larger than the display)
• Android full screen camera - while keeping the camera selected ratio : can't find the whole code

Requirements

• I need to use the Camera API version 1, not version 2.
• Final photos must be taken in 4/3 format, not 16/9.
• Portrait is forced although pictures can be in landscape or portrait

Thank you