adding a widget

app/src/main/AndroidManifest.xml

@@ -28,5 +28,18 @@
                 <category android:name="android.intent.category.LAUNCHER"/>
             </intent-filter>
         </activity>
+
+        <receiver
+            android:name=".MyWidgetProvider"
+            android:icon="@mipmap/ic_launcher"
+            android:label="Simple Flashlight">
+            <intent-filter>
+                <action android:name="android.appwidget.action.APPWIDGET_UPDATE"/>
+            </intent-filter>
+
+            <meta-data
+                android:name="android.appwidget.provider"
+                android:resource="@xml/widget_info"/>
+        </receiver>
     </application>
 </manifest>

app/src/main/java/flashlight/simplemobiletools/com/MainActivity.java

@@ -4,6 +4,7 @@ import android.os.Bundle;
 import android.support.v7.app.AppCompatActivity;
 import android.view.View;
 import android.widget.ImageView;
+import android.widget.Toast;
 
 public class MainActivity extends AppCompatActivity implements MyCamera {
     private ImageView toggleBtn;
@@ -20,7 +21,6 @@ public class MainActivity extends AppCompatActivity implements MyCamera {
 
     private void setupCameraImpl() {
         cameraImpl = new MyCameraImpl(this);
-        cameraImpl.setupCamera();
         cameraImpl.toggleFlashlight();
     }
 
@@ -60,11 +60,18 @@ public class MainActivity extends AppCompatActivity implements MyCamera {
 
     @Override
     public void enableFlashlight() {
-        toggleBtn.setBackground(getResources().getDrawable(R.mipmap.flashlight_big_on));
+        toggleBtn.setImageResource(R.mipmap.flashlight_big_on);
     }
 
     @Override
     public void disableFlashlight() {
-        toggleBtn.setBackground(getResources().getDrawable(R.mipmap.flashlight_big_off));
+        toggleBtn.setImageResource(R.mipmap.flashlight_big_off);
+    }
+
+    @Override
+    public void cameraUnavailable() {
+        final String errorMsg = getResources().getString(R.string.camera_error);
+        Toast.makeText(this, errorMsg, Toast.LENGTH_SHORT).show();
+        disableFlashlight();
     }
 }

app/src/main/java/flashlight/simplemobiletools/com/MyCamera.java

@@ -4,4 +4,6 @@ public interface MyCamera {
     void enableFlashlight();
 
     void disableFlashlight();
+
+    void cameraUnavailable();
 }

app/src/main/java/flashlight/simplemobiletools/com/MyCameraImpl.java

@@ -1,16 +1,20 @@
 package flashlight.simplemobiletools.com;
 
+import android.hardware.Camera;
+
 public class MyCameraImpl {
-    private android.hardware.Camera camera;
+    private Camera camera;
-    private android.hardware.Camera.Parameters params;
+    private Camera.Parameters params;
     private boolean isFlashlightOn;
     private MyCamera callback;
 
     public MyCameraImpl(MyCamera camera) {
         callback = camera;
+        setupCamera();
     }
 
     public void toggleFlashlight() {
+        setupCamera();
         isFlashlightOn = !isFlashlightOn;
 
         if (isFlashlightOn) {
@@ -22,24 +26,34 @@ public class MyCameraImpl {
 
     public void setupCamera() {
         if (camera == null) {
-            camera = android.hardware.Camera.open();
+            try {
+                camera = Camera.open();
                 params = camera.getParameters();
-            params.setFlashMode(android.hardware.Camera.Parameters.FLASH_MODE_OFF);
+                params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                 camera.setParameters(params);
 
                 if (isFlashlightOn)
                     enableFlashlight();
+            } catch (Exception e) {
+                callback.cameraUnavailable();
+            }
         }
     }
 
     private void enableFlashlight() {
-        params.setFlashMode(android.hardware.Camera.Parameters.FLASH_MODE_TORCH);
+        if (camera == null || params == null)
+            return;
+
+        params.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
         camera.setParameters(params);
         callback.enableFlashlight();
     }
 
     private void disableFlashlight() {
-        params.setFlashMode(android.hardware.Camera.Parameters.FLASH_MODE_OFF);
+        if (camera == null || params == null)
+            return;
+
+        params.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
         camera.setParameters(params);
         callback.disableFlashlight();
     }

app/src/main/java/flashlight/simplemobiletools/com/MyWidgetProvider.java

@@ -0,0 +1,81 @@
+package flashlight.simplemobiletools.com;
+
+import android.app.PendingIntent;
+import android.appwidget.AppWidgetManager;
+import android.appwidget.AppWidgetProvider;
+import android.content.ComponentName;
+import android.content.Context;
+import android.content.Intent;
+import android.widget.RemoteViews;
+
+public class MyWidgetProvider extends AppWidgetProvider implements MyCamera {
+    private static MyCameraImpl cameraImpl;
+    private static RemoteViews remoteViews;
+    private static int[] widgetIds;
+    private static AppWidgetManager widgetManager;
+    private static final String TOGGLE = "toggle";
+
+    @Override
+    public void onUpdate(Context context, AppWidgetManager appWidgetManager, int[] appWidgetIds) {
+        initVariables(context);
+        appWidgetManager.updateAppWidget(appWidgetIds, remoteViews);
+    }
+
+    private void initVariables(Context context) {
+        final ComponentName component = new ComponentName(context, MyWidgetProvider.class);
+        widgetManager = AppWidgetManager.getInstance(context);
+        widgetIds = widgetManager.getAppWidgetIds(component);
+
+        final Intent intent = new Intent(context, MyWidgetProvider.class);
+        intent.setAction(TOGGLE);
+
+        final PendingIntent pendingIntent = PendingIntent.getBroadcast(context, 0, intent, 0);
+        remoteViews = new RemoteViews(context.getPackageName(), R.layout.widget);
+        remoteViews.setOnClickPendingIntent(R.id.toggle_btn, pendingIntent);
+        cameraImpl = new MyCameraImpl(this);
+    }
+
+    @Override
+    public void onReceive(Context context, Intent intent) {
+        final String action = intent.getAction();
+        if (action.equals(TOGGLE)) {
+            if (cameraImpl == null) {
+                initVariables(context);
+            }
+
+            cameraImpl.toggleFlashlight();
+        } else
+            super.onReceive(context, intent);
+    }
+
+    @Override
+    public void enableFlashlight() {
+        remoteViews.setImageViewResource(R.id.toggle_btn, R.mipmap.flashlight_big_on);
+        widgetManager.updateAppWidget(widgetIds, remoteViews);
+    }
+
+    @Override
+    public void disableFlashlight() {
+        remoteViews.setImageViewResource(R.id.toggle_btn, R.mipmap.flashlight_big_off);
+        widgetManager.updateAppWidget(widgetIds, remoteViews);
+        cameraImpl.releaseCamera();
+    }
+
+    @Override
+    public void cameraUnavailable() {
+    }
+
+    @Override
+    public void onDeleted(Context context, int[] appWidgetIds) {
+        super.onDeleted(context, appWidgetIds);
+        releaseCamera(context);
+    }
+
+    private void releaseCamera(Context context) {
+        if (cameraImpl == null)
+            initVariables(context);
+
+        disableFlashlight();
+        cameraImpl.releaseCamera();
+    }
+}

app/src/main/res/layout/widget.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<ImageView
+    android:id="@+id/toggle_btn"
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
+    android:src="@mipmap/flashlight_big_off"/>

app/src/main/res/values-w820dp/dimens.xml

@@ -1,6 +0,0 @@
-<resources>
-    <!-- Example customization of dimensions originally defined in res/values/dimens.xml
-         (such as screen margins) for screens with more than 820dp of available width. This
-         would include 7" and 10" devices in landscape (~960dp and ~1280dp respectively). -->
-    <dimen name="activity_horizontal_margin">64dp</dimen>
-</resources>

app/src/main/res/values/strings.xml

@@ -1,3 +1,4 @@
 <resources>
     <string name="app_name">Simple Flashlight</string>
+    <string name="camera_error">Obtaining the camera failed</string>
 </resources>

app/src/main/res/xml/widget_info.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="utf-8"?>
+<appwidget-provider xmlns:android="http://schemas.android.com/apk/res/android"
+                    android:initialLayout="@layout/widget"
+                    android:minHeight="40dp"
+                    android:minWidth="40dp">
+</appwidget-provider>