Allow user granting Camera access permission by UI

This might solve most of connecting camera device problems like #1.

Signed-off-by: Justin Kim <[email protected]>

app/src/main/java/org/freedesktop/gstreamer/camera/CameraActivity.java

@@ -1,9 +1,13 @@
 package org.freedesktop.gstreamer.camera;
 
+import android.Manifest;
 import android.annotation.SuppressLint;
+import android.content.pm.PackageManager;
 import android.content.res.Configuration;
 import android.os.Bundle;
 import android.os.Handler;
+import android.support.v4.app.ActivityCompat;
+import android.support.v4.content.ContextCompat;
 import android.support.v7.app.ActionBar;
 import android.support.v7.app.AppCompatActivity;
 import android.util.Log;
@@ -25,6 +29,8 @@
  */
 public class CameraActivity extends AppCompatActivity {
 
+    private static final int PERMISSION_REQUEST_CAMERA = 1;
+
     private GstAhc gstAhc;
     /**
      * Whether or not the system UI should be auto-hidden after
@@ -101,6 +107,14 @@ public boolean onTouch(View view, MotionEvent motionEvent) {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
 
+        if (ContextCompat.checkSelfPermission(this, Manifest.permission.CAMERA) != PackageManager.PERMISSION_GRANTED) {
+
+            ActivityCompat.requestPermissions(
+                    this,
+                    new String[] { Manifest.permission.CAMERA },
+                    PERMISSION_REQUEST_CAMERA);
+            return;
+        }
         try {
             gstAhc = GstAhc.init(this);
         } catch (Exception e) {