フロントカメラとバックカメラを切替える

Android Studio を使ってフロントカメラとバックカメラを切替えるアプリを作成してみます。
以下の記事をベースに作成しました。

関連記事

• Android Studio でカメラアプリの作成
• Android Studio でカメラアプリに撮影機能を追加

フロントカメラとバックカメラを切替えるアプリの作成

MainActivity.java を以下の通り書き換え

package com.example.camera;

import android.app.Activity;
import android.graphics.PixelFormat;
import android.hardware.Camera;
import android.hardware.Camera.CameraInfo;
import android.hardware.Camera.Parameters;
import android.hardware.Camera.Size;
import android.os.Bundle;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.FrameLayout.LayoutParams;

import java.util.List;

public class MainActivity extends Activity {

    SurfaceView sv;
    SurfaceHolder sh;
    Camera cam;
    int backCameraId = -1;
    int frontCameraId = -1;
    int cameraId = -1;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        getWindow().addFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN);
        requestWindowFeature(Window.FEATURE_NO_TITLE);

        FrameLayout fl = new FrameLayout(this);
        setContentView(fl);

        sv = new SurfaceView(this);
        sh = sv.getHolder();
        sh.addCallback(new SurfaceHolderCallback());

        Button btn = new Button(this);
        btn.setText("切替");
        btn.setLayoutParams(new LayoutParams(200, 150));
        btn.setOnClickListener(new ChangeCameraClickListener());

        fl.addView(sv);
        fl.addView(btn);
    }
    class ChangeCameraClickListener implements View.OnClickListener {
        @Override
        public void onClick(View v) {
            cam.stopPreview();
            cam.release();
            if (cameraId == frontCameraId) {
                cameraId = backCameraId;
            } else {
                cameraId = frontCameraId;
            }
            cam = Camera.open(cameraId);
            new SurfaceHolderCallback().surfaceChanged(sv.getHolder(), PixelFormat.RGB_565, sv.getWidth(), sv.getHeight());

        }
    }

    class SurfaceHolderCallback implements SurfaceHolder.Callback {
        @Override
        public void surfaceCreated(SurfaceHolder holder) {
            int numberOfCameras = Camera.getNumberOfCameras();
            CameraInfo cameraInfo = new CameraInfo();
            for (int i = 0; i < numberOfCameras; i++) {
                Camera.getCameraInfo(i, cameraInfo);
                if (cameraInfo.facing == CameraInfo.CAMERA_FACING_BACK) {
                    backCameraId = i;
                } else if (cameraInfo.facing == CameraInfo.CAMERA_FACING_FRONT) {
                    frontCameraId = i;
                }
            }
            if (numberOfCameras > 1) {
                if (backCameraId != -1) {
                    cameraId = backCameraId;
                } else if (frontCameraId != -1) {
                    cameraId = frontCameraId;
                }
                cam = Camera.open(cameraId);
            } else {
                cam = Camera.open();
            }

            Parameters param = cam.getParameters();
            List<Size> ss = param.getSupportedPictureSizes();
            Size pictSize = ss.get(0);

            param.setPictureSize(pictSize.width, pictSize.height);
            cam.setParameters(param);
        }
        @Override
        public void surfaceChanged(SurfaceHolder holder, int f, int w, int h) {
            try {
                cam.setDisplayOrientation(0);
                cam.setPreviewDisplay(sv.getHolder());

                Parameters param = cam.getParameters();
                List<Size> previewSizes =
                        cam.getParameters().getSupportedPreviewSizes();
                Size pre = previewSizes.get(0);
                param.setPreviewSize(pre.width, pre.height);

                LayoutParams lp = new LayoutParams(pre.width, pre.height);
                sv.setLayoutParams(lp);

                cam.setParameters(param);
                cam.startPreview();
            } catch (Exception e) { }
        }
        @Override
        public void surfaceDestroyed(SurfaceHolder holder) {
            cam.stopPreview();
            cam.release();
        }
    }
}

以上で『切替』ボタンをタップすることで、フロントカメラとバックカメラの切替えができるアプリが作成できました。