Add a overlay on Camera Preview SurfaceView

Modify from last exercise "Camera Preview, version II", a overlay will be add on the Camera Preview SurfaceView. Controls; such as "Take Picture" button is added on the overlay.



Keep using the AndroidManifest.xml and main.xml in last exercise "Camera Preview, version II" without change.

Add a layout xml file, control.xml, under /res/layout folder. It define the layout of the control layer.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:gravity="bottom"
 >
<Button
android:id="@+id/takepicture"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text=" * Take Picture "
android:layout_gravity="right"
android:layout_margin="10px"
/>
</LinearLayout>

Modify AndroidCamera.java to inflate a layer using control.xml

package com.exercise.AndroidCamera;

import java.io.IOException;

import android.app.Activity;
import android.content.pm.ActivityInfo;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;

public class AndroidCamera extends Activity implements SurfaceHolder.Callback{

Camera camera;
SurfaceView surfaceView;
SurfaceHolder surfaceHolder;
boolean previewing = false;
LayoutInflater controlInflater = null;

 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
     setContentView(R.layout.main);
     setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
  
     getWindow().setFormat(PixelFormat.UNKNOWN);
     surfaceView = (SurfaceView)findViewById(R.id.camerapreview);
     surfaceHolder = surfaceView.getHolder();
     surfaceHolder.addCallback(this);
     surfaceHolder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
  
     controlInflater = LayoutInflater.from(getBaseContext());
     View viewControl = controlInflater.inflate(R.layout.control, null);
     LayoutParams layoutParamsControl
      = new LayoutParams(LayoutParams.FILL_PARENT,
      LayoutParams.FILL_PARENT);
     this.addContentView(viewControl, layoutParamsControl);
  
 }



@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
 int height) {
// TODO Auto-generated method stub
if(previewing){
 camera.stopPreview();
 previewing = false;
}

if (camera != null){
 try {
  camera.setPreviewDisplay(surfaceHolder);
  camera.startPreview();
  previewing = true;
 } catch (IOException e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
}
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera = Camera.open();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
camera.stopPreview();
camera.release();
camera = null;
previewing = false;
}
}

Download the files.

next:
- Implement takePicture function of Android Camera