Android helper functions in Xamarin

android-version

        // "return" "version" "name" - names aren't syntactically correct (they're probably upper case for starters)
        // 21 5.0 lollipop
        // 20 4.4.2W kitkat wear
        // 19 4.4.2 kitkat
        // 18 4.3.1 jelly bean mr2
        // 17 4.2.2 jelly bean mr1
        // 16 4.1.2 jelly bean
        // 15 4.0.3 ice-cream sandwich mr1
        // 14 4.0 ice-cream sandwich
        // 13 3.2 honeycomb mr2
        // 12 3.1 honeycomb mr1
        // 10 3.0 honeycomb
        // 8 2.2 froyo
        // 7 2.1 eclair
        // 4 1.6 donut
        // 3 1.5 cupcake
        public static string GetAndroidVersion() {
            return global::Android.OS.Build.VERSION.Sdk;
        }

bitmap-crop-thumbnail

                //http://stackoverflow.com/questions/6908604/android-crop-center-of-bitmap
                Bitmap newBitmap = ThumbnailUtils.ExtractThumbnail(currentBitmap, dimensionalConstraintW, dimensionalConstraintH);

create-dir

        public static File CreateDirectory(string directory) {
            File newDir = new File(directory); // yeah android file vs dir terminology
            if(!newDir.Exists()) {
                newDir.Mkdir();
            }
            return newDir;
        }

ext-storage-check

        // http://developer.android.com/guide/topics/data/data-storage.html
        /* Checks if external storage is available for read and write */
        public static bool IsExternalStorageWritable {
            get {
                string state = global::Android.OS.Environment.ExternalStorageState;
                if(global::Android.OS.Environment.MediaMounted.Equals(state)) {
                    return true;
                }
                return false;
            }
        }

        /* Checks if external storage is available to at least read */
        public static bool IsExternalStorageReadable {
            get {
                string state = global::Android.OS.Environment.ExternalStorageState;
                if(global::Android.OS.Environment.MediaMounted.Equals(state) ||
                    global::Android.OS.Environment.MediaMountedReadOnly.Equals(state)) {
                    return true;
                }
                return false;
            }
        }

get-pictures-folder

        public static File GetPicturesFolder(global::Android.App.Activity callingActivity) {
            string appPicturePath = callingActivity.GetExternalFilesDir(global::Android.OS.Environment.DirectoryPictures).AbsolutePath;
            return CreateDirectoryForPictures(appPicturePath);
        }

load-resize-bitmap

        // http://forums.xamarin.com/discussion/5409/photo-being-saved-in-landscape-not-portrait
        // resizes the image density, width/height aren't going to be the end dimensions of the image
        public static Bitmap LoadAndResizeBitmap(this string fileName, int width, int height) {
            // First we get the the dimensions of the file on disk
            BitmapFactory.Options options = new BitmapFactory.Options { InJustDecodeBounds = true };
            BitmapFactory.DecodeFile(fileName, options);

            // Next we calculate the ratio that we need to resize the image by
            // in order to fit the requested dimensions.
            int outHeight = options.OutHeight;
            int outWidth = options.OutWidth;
            int inSampleSize = 1;

            if(outHeight > height || outWidth > width) {
                inSampleSize = outWidth > outHeight
                    ? outHeight / height
                        : outWidth / width;
            }

            // Now we will load the image and have BitmapFactory resize it for us.
            options.InSampleSize = inSampleSize;
            options.InJustDecodeBounds = false;
            Bitmap resizedBitmap = BitmapFactory.DecodeFile(fileName, options);

            // Images are being saved in landscape, so rotate them back to portrait if they were taken in portrait
            Matrix mtx = new Matrix();
            ExifInterface exif = new ExifInterface(fileName);
            string orientation = exif.GetAttribute(ExifInterface.TagOrientation);

            //http://developer.android.com/reference/android/media/ExifInterface.html
            switch(orientation) {
                case "0": // ORIENTATION_UNDEFINED - Nexus 7 landscape...

                    break;
                case "1": // landscape - ORIENTATION_NORMAL
                    break;
                case "2": // ORIENTATION_FLIP_HORIZONTAL
                    mtx.PreScale(-1, 1);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    break;
                case "3": // ORIENTATION_ROTATE_180
                    mtx.PreRotate(180);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    mtx = null;
                    break;
                case "4": // ORIENTATION_FLIP_VERTICAL
                    mtx.PreScale(1, -1);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    break;
                case "5": //ORIENTATION_TRANSPOSE
                    break;
                case "6": // portrait - ORIENTATION_ROTATE_90
                    mtx.PreRotate(90);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    mtx = null;
                    break;
                case "7": // ORIENTATION_TRANSVERSE
                    break;
                case "8": // ORIENTATION_ROTATE_270 - might need to flip horizontally too...
                    mtx.PreRotate(270);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    mtx = null;
                    break;
                default:
                    mtx.PreRotate(90);
                    resizedBitmap = Bitmap.CreateBitmap(resizedBitmap, 0, 0, resizedBitmap.Width, resizedBitmap.Height, mtx, false);
                    mtx.Dispose();
                    mtx = null;
                    break;
            }

            return resizedBitmap;
        }