WinPhone helper functions in Xamarin

color-from-hex

        // http://social.msdn.microsoft.com/forums/windowsapps/en-us/b639cd8a-30c2-48cf-99be-559f34cbfa79/convert-string-to-color-in-metro
        public static System.Windows.Media.Color GetColorFromHexString(string hexValue) {
            hexValue = hexValue.Substring(1, 6); // string will be passed in with a leading #
            byte a = 0xff;// Convert.ToByte(hexValue.Substring(0, 2), 16);
            var r = Convert.ToByte(hexValue.Substring(0, 2), 16);
            var g = Convert.ToByte(hexValue.Substring(2, 2), 16);
            var b = Convert.ToByte(hexValue.Substring(4, 2), 16);
            return System.Windows.Media.Color.FromArgb(a, r, g, b);
        }

crop-square-image

        // crop image to square based on smallest dimension
        public static void CropSquare(ref WriteableBitmap bmp) {
            float dimension = Math.Min((float)bmp.PixelWidth, (float)bmp.PixelHeight);

            float x = ((float)bmp.PixelWidth / 2) - (dimension / 2);
            if (x < 0) { x = 0; }
            float y = ((float)bmp.PixelHeight / 2) - (dimension / 2);
            if (y < 0) { y = 0; }
            
            bmp = WriteableBitmapExtensions.Crop(bmp, (int)x, (int)y, (int)dimension, (int)dimension);

            return;
        }

image-folder

        public static string ImageFolder {
            get {
                string imageFolder = @"\Shared\ShellContent";
                using (var isoFile = IsolatedStorageFile.GetUserStoreForApplication()) {
                    if (!isoFile.DirectoryExists(imageFolder)) {
                        isoFile.CreateDirectory(imageFolder);
                    }
                }
                return imageFolder;
            }
        }

scale-image

        // scale image, maintain aspect ratio
        public static void Scale(int limitingDimension, ref WriteableBitmap bmp) {
            float scaleFactor = Math.Max(limitingDimension / (float)bmp.PixelHeight, limitingDimension / (float)bmp.PixelWidth);
            
            if(scaleFactor > 1) {   return;   }

            Size newDimensions = new Size(bmp.PixelWidth * scaleFactor, bmp.PixelHeight * scaleFactor);
            bmp = WriteableBitmapExtensions.Resize(bmp, (int)newDimensions.Width, (int)newDimensions.Height, WriteableBitmapExtensions.Interpolation.Bilinear);

            return;
        }