AndroidのカメラプレビューでOverlayを表示する方法

【構成】

【MainActivity.java - メインアクティビティー】

package com.ayakix;

import android.app.Activity;
import android.os.Bundle;
import android.view.ViewGroup.LayoutParams;
import android.view.Window;
import android.view.WindowManager;

public class MainActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
     super.onCreate(savedInstanceState);
  getWindow().clearFlags(WindowManager.LayoutParams.FLAG_FORCE_NOT_FULLSCREEN);
  getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
  requestWindowFeature(Window.FEATURE_NO_TITLE);
  setContentView(new CameraView(this));
  addContentView(new CameraOverlayView(this), new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
    }
}

【CameraView.java - カメラサーフェースビュー】

package com.ayakix;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.hardware.Camera;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;

public class CameraView extends SurfaceView implements SurfaceHolder.Callback, Camera.PictureCallback, Camera.AutoFocusCallback {
 private SurfaceHolder holder;
 private Camera camera;

 public CameraView(Context context) {
  super(context);
  holder = getHolder();
  holder.addCallback(this);
  holder.setType(SurfaceHolder.SURFACE_TYPE_PUSH_BUFFERS);
 }

 @Override
 public void surfaceCreated(SurfaceHolder holder) {
  try {
   camera = Camera.open();
   camera.setPreviewDisplay(holder);
  } catch (Exception e) {
  }
 }

 @Override
 public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
  camera.startPreview();
 }

 @Override
 public void surfaceDestroyed(SurfaceHolder holder) {
  camera.setPreviewCallback(null);
  camera.stopPreview();
  camera.release();
  camera = null;
 }

 @Override
 public boolean onTouchEvent(MotionEvent event) {
  if (event.getAction()==MotionEvent.ACTION_DOWN) {
   camera.autoFocus(this);
  }
  return true;
 }

 @Override
 public void onAutoFocus(boolean success, Camera camera) {
  camera.autoFocus(null);
  camera.takePicture(null, null, this);
 }

 @Override
 public void onPictureTaken(byte[] data, Camera camera) {
  try {
   BitmapFactory.Options options = new BitmapFactory.Options();
   options.inSampleSize = 4;
   Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, options);
   // bitmap画像をカットする処理など
   int w = bitmap.getWidth();
   int h = bitmap.getHeight();
   // 中央部分の四角形をカット
   bitmap = cutBitmap(bitmap, (w-h)/2, 0, h, h);
   // 90度回転
   bitmap = rotateBitmap90(bitmap);
   
   // とりあえずもう一度カメラプレビュー
   camera.startPreview();
  } catch (Exception e) {
  }
 }
 
 /*
  * カット
  */
 public Bitmap cutBitmap(Bitmap bmp,int x,int y,int w,int h) {
  Bitmap result=Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);
  Canvas canvas=new Canvas(result);
  canvas.drawBitmap(bmp,-x,-y,null);
  return result;
 }
 /*
  * 画像の回転 90度
  */
 public Bitmap rotateBitmap90(Bitmap bmp) {
  int w=bmp.getWidth();
  int h=bmp.getHeight();
  Bitmap result=Bitmap.createBitmap(h,w,Bitmap.Config.ARGB_8888);
  Canvas canvas=new Canvas(result);
  canvas.rotate(90,0,0);
  canvas.drawBitmap(bmp,0,-h,null);
  return result;
 }
}

【CameraOverlayView.java - オーバーレイビュー】

package com.ayakix;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class CameraOverlayView extends View {
 private int width, height;

 public CameraOverlayView(Context context) {
  super(context);
  setFocusable(true);
 }

 @Override
 protected void onSizeChanged(int w, int h, int oldw, int oldh){
  // ビューのサイズを取得
  width= w;
  height= h;
 }


 /**
  * 描画処理
  */
 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  // 背景色を設定
  canvas.drawColor(Color.TRANSPARENT);

  // 描画するための線の色を設定
  Paint paint = new Paint();
  paint.setStyle(Paint.Style.FILL);
  paint.setARGB(100, 0, 0, 0);

  // 上枠表示
  canvas.drawRect(0, 0, (width-height)/2, height, paint);
  // 下枠表示
  canvas.drawRect((width-height)/2 + height, 0, width, height, paint);

  // 中央十字憑依時
  int len = height / 10;
  paint.setARGB(255, 255, 0, 0);
  canvas.drawLine(width/2, height/2-len, width/2, height/2+len, paint);
  canvas.drawLine(width/2-len, height/2, width/2+len, height/2, paint);
  // 円表示
  paint.setStyle(Paint.Style.STROKE);
  canvas.drawCircle(width/2, height/2, len*5, paint);
 }
}

【AndroidManifest.xml】

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.ayakix"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="4" />

 <uses-permission android:name="android.permission.CAMERA" />
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".MainActivity"
                  android:label="@string/app_name"
                  android:screenOrientation="landscape">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity android:name=".activity.CameraActivity" android:screenOrientation="landscape"></activity>

    </application>
</manifest>