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 onCreate(Bundle savedInstanceState)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 onPause()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. */ getCameraInstance(int cameraId)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 releaseCamera()98 private void releaseCamera() { 99 if (mCamera != null) { 100 mCamera.release(); // release the camera for other applications 101 mCamera = null; 102 } 103 } 104 } 105