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      1 /*
      2 * Copyright 2015 The Android Open Source Project
      3 *
      4 * Licensed under the Apache License, Version 2.0 (the "License");
      5 * you may not use this file except in compliance with the License.
      6 * You may obtain a copy of the License at
      7 *
      8 *     http://www.apache.org/licenses/LICENSE-2.0
      9 *
     10 * Unless required by applicable law or agreed to in writing, software
     11 * distributed under the License is distributed on an "AS IS" BASIS,
     12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13 * See the License for the specific language governing permissions and
     14 * limitations under the License.
     15 */
     16 
     17 package com.example.android.basicpermissions.camera;
     18 
     19 import com.example.android.basicpermissions.R;
     20 
     21 import android.app.Activity;
     22 import android.hardware.Camera;
     23 import android.os.Bundle;
     24 import android.widget.FrameLayout;
     25 import android.widget.Toast;
     26 
     27 /**
     28  * Displays a {@link CameraPreview} of the first {@link Camera}.
     29  * An error message is displayed if the Camera is not available.
     30  * <p>
     31  * This Activity is only used to illustrate that access to the Camera API has been granted (or
     32  * denied) as part of the runtime permissions model. It is not relevant for the use of the
     33  * permissions API.
     34  * <p>
     35  * Implementation is based directly on the documentation at
     36  * http://developer.android.com/guide/topics/media/camera.html
     37  */
     38 public class CameraPreviewActivity extends Activity {
     39 
     40     private static final String TAG = "CameraPreview";
     41 
     42     /**
     43      * Id of the camera to access. 0 is the first camera.
     44      */
     45     private static final int CAMERA_ID = 0;
     46 
     47     private CameraPreview mPreview;
     48     private Camera mCamera;
     49 
     50     @Override
     51     protected void onCreate(Bundle savedInstanceState) {
     52         super.onCreate(savedInstanceState);
     53 
     54         // Open an instance of the first camera and retrieve its info.
     55         mCamera = getCameraInstance(CAMERA_ID);
     56         Camera.CameraInfo cameraInfo = new Camera.CameraInfo();
     57         Camera.getCameraInfo(CAMERA_ID, cameraInfo);
     58 
     59         if (mCamera == null || cameraInfo == null) {
     60             // Camera is not available, display error message
     61             Toast.makeText(this, "Camera is not available.", Toast.LENGTH_SHORT).show();
     62             setContentView(R.layout.activity_camera_unavailable);
     63         } else {
     64 
     65             setContentView(R.layout.activity_camera);
     66 
     67             // Get the rotation of the screen to adjust the preview image accordingly.
     68             final int displayRotation = getWindowManager().getDefaultDisplay()
     69                     .getRotation();
     70 
     71             // Create the Preview view and set it as the content of this Activity.
     72             mPreview = new CameraPreview(this, mCamera, cameraInfo, displayRotation);
     73             FrameLayout preview = (FrameLayout) findViewById(R.id.camera_preview);
     74             preview.addView(mPreview);
     75         }
     76     }
     77 
     78     @Override
     79     public void onPause() {
     80         super.onPause();
     81         // Stop camera access
     82         releaseCamera();
     83     }
     84 
     85     /** A safe way to get an instance of the Camera object. */
     86     private Camera getCameraInstance(int cameraId) {
     87         Camera c = null;
     88         try {
     89             c = Camera.open(cameraId); // attempt to get a Camera instance
     90         } catch (Exception e) {
     91             // Camera is not available (in use or does not exist)
     92             Toast.makeText(this, "Camera " + cameraId + " is not available: " + e.getMessage(),
     93                     Toast.LENGTH_SHORT).show();
     94         }
     95         return c; // returns null if camera is unavailable
     96     }
     97 
     98     private void releaseCamera() {
     99         if (mCamera != null) {
    100             mCamera.release();        // release the camera for other applications
    101             mCamera = null;
    102         }
    103     }
    104 }
    105