From 18b03c03aa7783df66177bcd733daded79673c15 Mon Sep 17 00:00:00 2001
From: Nishant Srivastava <nisrulz@gmail.com>
Date: Tue, 17 May 2016 22:51:34 +0530
Subject: [PATCH] [*] updated readme with proper use-case code [+] added check
 for camera permission, autofocus and camera hardware detection

---
 README.md                                     | 18 +++++++++
 .../nisrulz/projectqreader/MainActivity.java  | 13 ++-----
 .../java/github/nisrulz/qreader/QREader.java  | 37 ++++++++++++++++---
 3 files changed, 53 insertions(+), 15 deletions(-)

diff --git a/README.md b/README.md
index de38f60..8b31234 100755
--- a/README.md
+++ b/README.md
@@ -76,6 +76,24 @@ QREader.getInstance().stop();
 QREader.getInstance().releaseAndCleanup();
 ```
 
+A typical use case would be , which works well with locking your device and when the app goes into background and then comes back in foreground
+```java
+  @Override protected void onStart() {
+    super.onStart();
+
+    // Call in onStart
+    QREader.getInstance().start();
+  }
+
+  @Override protected void onDestroy() {
+    super.onDestroy();
+
+    // Call in onDestroy
+    QREader.getInstance().stop();
+    QREader.getInstance().releaseAndCleanup();
+  }
+```
+
 
 > NOTE : 
 
diff --git a/app/src/main/java/github/nisrulz/projectqreader/MainActivity.java b/app/src/main/java/github/nisrulz/projectqreader/MainActivity.java
index 62eda69..57f4d77 100644
--- a/app/src/main/java/github/nisrulz/projectqreader/MainActivity.java
+++ b/app/src/main/java/github/nisrulz/projectqreader/MainActivity.java
@@ -17,7 +17,6 @@
 package github.nisrulz.projectqreader;
 
 import android.os.Bundle;
-import android.os.PersistableBundle;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
 import android.view.SurfaceView;
@@ -51,24 +50,18 @@ public class MainActivity extends AppCompatActivity {
     QREader.getInstance().init(this, surfaceView);
   }
 
-  @Override public void onSaveInstanceState(Bundle outState, PersistableBundle outPersistentState) {
-    super.onSaveInstanceState(outState, outPersistentState);
-  }
-
-  @Override protected void onRestoreInstanceState(Bundle savedInstanceState) {
-    super.onRestoreInstanceState(savedInstanceState);
-  }
-
   @Override protected void onStart() {
     super.onStart();
 
+    // Call in onStart
     QREader.getInstance().start();
   }
 
   @Override protected void onDestroy() {
     super.onDestroy();
-    QREader.getInstance().stop();
 
+    // Call in onDestroy
+    QREader.getInstance().stop();
     QREader.getInstance().releaseAndCleanup();
   }
 }
diff --git a/library/src/main/java/github/nisrulz/qreader/QREader.java b/library/src/main/java/github/nisrulz/qreader/QREader.java
index e9b0a94..ec54640 100644
--- a/library/src/main/java/github/nisrulz/qreader/QREader.java
+++ b/library/src/main/java/github/nisrulz/qreader/QREader.java
@@ -34,8 +34,7 @@
  * QREader Singleton
  */
 public class QREader {
-
-  private static final String TAG = "QREader";
+  private static final String LOGTAG = "QREader";
   private CameraSource cameraSource = null;
   private BarcodeDetector barcodeDetector = null;
 
@@ -115,6 +114,20 @@ public void init(final Context context, final SurfaceView surfaceView) {
     this.context = context;
     this.surfaceView = surfaceView;
 
+    if (!hasAutofocus(context)) {
+      Log.e(LOGTAG, "Do not have autofocus feature, disabling autofocus feature in the library!");
+      autofocus_enabled = false;
+    }
+
+    if (!hasCameraHardware(context)) {
+      Log.e(LOGTAG, "Does not have camera hardware!");
+      return;
+    }
+    if (!checkCameraPermission(context)) {
+      Log.e(LOGTAG, "Do not have camera permission!");
+      return;
+    }
+
     // Setup Barcodedetector
     if (barcodeDetector == null) {
       barcodeDetector =
@@ -174,14 +187,14 @@ private void startCameraView(Context context, CameraSource cameraSource,
 
       if (ActivityCompat.checkSelfPermission(context, Manifest.permission.CAMERA)
           != PackageManager.PERMISSION_GRANTED) {
-        Log.e(TAG, "Permission not granted!");
+        Log.e(LOGTAG, "Permission not granted!");
         return;
       } else if (!cameraRunning && cameraSource != null && surfaceView != null) {
         cameraSource.start(surfaceView.getHolder());
         cameraRunning = true;
       }
     } catch (IOException ie) {
-      Log.e(TAG, ie.getMessage());
+      Log.e(LOGTAG, ie.getMessage());
       ie.printStackTrace();
     }
   }
@@ -199,7 +212,7 @@ public void stop() {
         cameraRunning = false;
       }
     } catch (Exception ie) {
-      Log.e(TAG, ie.getMessage());
+      Log.e(LOGTAG, ie.getMessage());
       ie.printStackTrace();
     }
   }
@@ -214,5 +227,19 @@ public void releaseAndCleanup() {
       cameraSource = null;
     }
   }
+
+  private boolean checkCameraPermission(Context context) {
+    String permission = Manifest.permission.CAMERA;
+    int res = context.checkCallingOrSelfPermission(permission);
+    return (res == PackageManager.PERMISSION_GRANTED);
+  }
+
+  private boolean hasCameraHardware(Context context) {
+    return context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA);
+  }
+
+  private boolean hasAutofocus(Context context) {
+    return context.getPackageManager().hasSystemFeature(PackageManager.FEATURE_CAMERA_AUTOFOCUS);
+  }
 }