remember if the last used camera was the front or the back one

app/src/main/java/com/simplemobiletools/camera/Config.java

@@ -2,6 +2,7 @@ package com.simplemobiletools.camera;
 
 import android.content.Context;
 import android.content.SharedPreferences;
+import android.hardware.Camera;
 
 public class Config {
     private SharedPreferences mPrefs;
@@ -69,4 +70,12 @@ public class Config {
     public void setIsSoundEnabled(boolean enabled) {
         mPrefs.edit().putBoolean(Constants.SOUND, enabled).apply();
     }
+
+    public int getLastUsedCamera() {
+        return mPrefs.getInt(Constants.LAST_USED_CAMERA, Camera.CameraInfo.CAMERA_FACING_BACK);
+    }
+
+    public void setLastUsedCamera(int cameraId) {
+        mPrefs.edit().putInt(Constants.LAST_USED_CAMERA, cameraId).apply();
+    }
 }

app/src/main/java/com/simplemobiletools/camera/Constants.java

@@ -14,4 +14,5 @@ public class Constants {
     public static final String FORCE_RATIO = "force_ratio";
     public static final String MAX_RESOLUTION = "max_resolution";
     public static final String MAX_VIDEO_RESOLUTION = "max_video_resolution";
+    public static final String LAST_USED_CAMERA = "last_used_camera";
 }

app/src/main/java/com/simplemobiletools/camera/activities/MainActivity.java

@@ -159,10 +159,11 @@ public class MainActivity extends SimpleActivity
         setContentView(R.layout.activity_main);
         ButterKnife.bind(this);
 
-        mCurrCamera = Camera.CameraInfo.CAMERA_FACING_BACK;
+        mCurrCamera = mConfig.getLastUsedCamera();
         mPreview = new Preview(this, (SurfaceView) findViewById(R.id.camera_view), this);
         mPreview.setLayoutParams(new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.MATCH_PARENT));
         mViewHolder.addView(mPreview);
+        mToggleCameraBtn.setImageResource(mCurrCamera == Camera.CameraInfo.CAMERA_FACING_BACK ? R.mipmap.camera_front : R.mipmap.camera_back);
 
         mFocusRectView = new FocusRectView(getApplicationContext());
         mViewHolder.addView(mFocusRectView);
@@ -214,11 +215,12 @@ public class MainActivity extends SimpleActivity
             mCurrCamera = Camera.CameraInfo.CAMERA_FACING_BACK;
         }
 
+        mConfig.setLastUsedCamera(mCurrCamera);
         int newIconId = R.mipmap.camera_front;
         mPreview.releaseCamera();
         if (mPreview.setCamera(mCurrCamera)) {
             if (mCurrCamera == Camera.CameraInfo.CAMERA_FACING_FRONT) {
-                newIconId = R.mipmap.camera_rear;
+                newIconId = R.mipmap.camera_back;
             }
             mToggleCameraBtn.setImageResource(newIconId);
             disableFlash();