/// <summary>
/// This class takes care of the image processing. It implements a method for resizing images and another for
/// adding watermarks
///
/// It uses the library SkiaSharp
///
/// The caller is agnostic of the library used, it passes and receives images as raw byte arrays. The class
/// could be refactored to use a different library without affecting the rest of the code.
///
/// Improvements could be made, like being able to specify the color or the location of the watermark
/// </summary>
/// <param name="image"></param>
/// <param name="maxWidth"></param>
/// <param name="maxHeight"></param>
/// <param name="quality"></param>
/// <returns></returns>
public DrinkImage Resize(DrinkImage image, int maxWidth, int maxHeight,
SKFilterQuality quality = SKFilterQuality.Medium)
{
using MemoryStream ms = new MemoryStream(image.Bytes);
using SKBitmap sourceBitmap = SKBitmap.Decode(ms);
// Calculate height and width. We have to decide what to do when one of the parameters was not passed
// and was defaulted to 0, or when the parameters passed have a different horizontal/vertical ratio
// We want to create the smaller file that respects at least one of the 2 sizes provided and that has
// the same horiz to vertical ratio as the image
var horiz2vertRatio = sourceBitmap.Width / (double)sourceBitmap.Height;
maxWidth = maxWidth == 0 ? sourceBitmap.Width : maxWidth;
maxHeight = maxHeight == 0 ? sourceBitmap.Height : maxHeight;
var newHorizSize = (int)Math.Round(Math.Min(maxWidth, horiz2vertRatio * maxHeight));
var newVertSize = (int)Math.Round(Math.Min(maxHeight, maxWidth / horiz2vertRatio));
using SKBitmap scaledBitmap = sourceBitmap.Resize(new SKImageInfo(newHorizSize, newVertSize), quality);
using SKImage scaledImage = SKImage.FromBitmap(scaledBitmap);
using SKData data = scaledImage.Encode();
return(new DrinkImage
{
Bytes = data.ToArray(),
HorizontalSize = newHorizSize,
VerticalSize = newVertSize,
Watermark = image.Watermark,
ImageName = image.ImageName
});
}
public DrinkImage AddWatermark(DrinkImage imagen, string watermark)
{
using MemoryStream ms = new MemoryStream(imagen.Bytes);
using SKBitmap toBitmap = SKBitmap.Decode(ms);
using SKCanvas canvas = new SKCanvas(toBitmap);
using SKTypeface font = SKTypeface.FromFamilyName("Arial");
using SKPaint brush = new SKPaint
{
Typeface = font,
TextSize = toBitmap.Width * 3 / (watermark.Length * 2),
IsAntialias = true,
Color = new SKColor(255, 255, 255, 255)
};
canvas.DrawText(watermark, toBitmap.Width / 20, toBitmap.Height / 2, brush);
canvas.Flush();
using SKImage image = SKImage.FromBitmap(toBitmap);
using SKData data = image.Encode(SKEncodedImageFormat.Png, 90);
return(new DrinkImage
{
Bytes = data.ToArray(),
VerticalSize = imagen.VerticalSize,
HorizontalSize = imagen.HorizontalSize,
Watermark = watermark,
ImageName = imagen.ImageName
});
}
public async Task SaveImage(DrinkImage image)
{
string fileName = Helpers.BuildDrinkImageFilename(image);
string filePath = Path.Combine(_processedImagesFolder, fileName);
await File.WriteAllBytesAsync(filePath, image.Bytes);
}
public static string BuildDrinkImageFilename(DrinkImage image)
{
return($"{image.ImageName}_hor_{image.HorizontalSize}_ver_{image.VerticalSize}_wat_{Helpers.RemoveSpecialChars(image.Watermark)}.png");
}
