Masuit.Tools/Masuit.Tools.Abstractions/Media/ImageWatermarker.cs

using Masuit.Tools.Systems;
using SixLabors.Fonts;
using SixLabors.ImageSharp;
using SixLabors.ImageSharp.Drawing.Processing;
using SixLabors.ImageSharp.Processing;
using SixLabors.ImageSharp.Processing.Processors.Transforms;
using System;
using System.IO;
using SixLabors.ImageSharp.Formats;

namespace Masuit.Tools.Media
{
	public class ImageWatermarker
	{
		/// <summary>
		/// 是否跳过小缩略图
		/// </summary>
		public bool SkipWatermarkForSmallImages { get; set; }

		/// <summary>
		/// 小图像素大小
		/// </summary>
		public int SmallImagePixelsThreshold { get; set; }

		public IImageEncoder ImageEncoder { get; set; }

		private readonly Stream _stream;

		/// <summary>
		///
		/// </summary>
		/// <param name="originStream">图片流</param>
		public ImageWatermarker(Stream originStream)
		{
			_stream = originStream;
		}

		/// <summary>
		///
		/// </summary>
		/// <param name="originStream">图片流</param>
		/// <param name="encoder">指定编码器</param>
		public ImageWatermarker(Stream originStream, IImageEncoder encoder) : this(originStream)
		{
			ImageEncoder = encoder;
		}

		/// <summary>
		///
		/// </summary>
		/// <param name="originStream">图片流</param>
		/// <param name="encoder">指定编码器</param>
		/// <param name="skipWatermarkForSmallImages">是否跳过小缩略图</param>
		/// <param name="smallImagePixelsThreshold">小图像素大小</param>
		public ImageWatermarker(Stream originStream, IImageEncoder encoder, bool skipWatermarkForSmallImages, int smallImagePixelsThreshold) : this(originStream, encoder)
		{
			SkipWatermarkForSmallImages = skipWatermarkForSmallImages;
			SmallImagePixelsThreshold = smallImagePixelsThreshold;
		}

		/// <summary>
		/// 添加水印
		/// </summary>
		/// <param name="watermarkText">水印文字</param>
		/// <param name="ttfFontPath">ttf字体文件路径</param>
		/// <param name="fontSize">字体大小</param>
		/// <param name="color">字体颜色</param>
		/// <param name="watermarkPosition">水印位置</param>
		/// <param name="textPadding">水印边距</param>
		/// <returns></returns>
		public PooledMemoryStream AddWatermark(string watermarkText, string ttfFontPath, int fontSize, Color color, WatermarkPosition watermarkPosition = WatermarkPosition.BottomRight, int textPadding = 10)
		{
			var fonts = new FontCollection();
			var fontFamily = fonts.Add(ttfFontPath); //字体的路径（电脑自带字体库，去copy出来）
			var font = new Font(fontFamily, fontSize, FontStyle.Bold);
			return AddWatermark(watermarkText, font, color, watermarkPosition, textPadding);
		}

		/// <summary>
		/// 添加水印
		/// </summary>
		/// <param name="watermarkText">水印文字</param>
		/// <param name="color">水印颜色</param>
		/// <param name="watermarkPosition">水印位置</param>
		/// <param name="textPadding">边距</param>
		/// <param name="font">字体</param>
		public PooledMemoryStream AddWatermark(string watermarkText, Font font, Color color, WatermarkPosition watermarkPosition = WatermarkPosition.BottomRight, int textPadding = 10)
		{
			var imageFormat = Image.DetectFormat(_stream);
			_stream.Seek(0, SeekOrigin.Begin);
			using var img = Image.Load(_stream);
			var textMeasure = TextMeasurer.MeasureSize(watermarkText, new TextOptions(font));
			if (SkipWatermarkForSmallImages && (img.Height < Math.Sqrt(SmallImagePixelsThreshold) || img.Width < Math.Sqrt(SmallImagePixelsThreshold) || img.Width <= textMeasure.Width))
			{
				return _stream as PooledMemoryStream ?? _stream.SaveAsMemoryStream();
			}

			if (img.Width / font.Size > 50)
			{
				font = font.Family.CreateFont(img.Width * 1f / 50);
			}

			float x, y;
			textPadding += (img.Width - 1000) / 100;
			switch (watermarkPosition)
			{
				case WatermarkPosition.TopRight:
					x = img.Width - textMeasure.Width - textPadding;
					y = textPadding;
					break;

				case WatermarkPosition.BottomLeft:
					x = textPadding;
					y = img.Height - textMeasure.Height - textPadding;
					break;

				case WatermarkPosition.BottomRight:
					x = img.Width - textMeasure.Width - textPadding;
					y = img.Height - textMeasure.Height - textPadding;
					break;

				case WatermarkPosition.Center:
					x = (img.Width - textMeasure.Width) / 2;
					y = (img.Height - textMeasure.Height) / 2;
					break;

				default:
					x = textPadding;
					y = textPadding;
					break;
			}

			img.Mutate(c => c.DrawText(watermarkText, font, color, new PointF(x, y)));
			var ms = new PooledMemoryStream();
			if (ImageEncoder == null)
			{
				img.Save(ms, imageFormat);
			}
			else
			{
				img.Save(ms, ImageEncoder);
			}
			ms.Position = 0;
			return ms;
		}

		/// <summary>
		/// 添加水印
		/// </summary>
		/// <param name="watermarkImage">水印图片</param>
		/// <param name="opacity">水印图片</param>
		/// <param name="watermarkPosition">水印位置</param>
		/// <param name="padding">水印边距</param>
		/// <returns></returns>
		public PooledMemoryStream AddWatermark(Stream watermarkImage, float opacity = 1f, WatermarkPosition watermarkPosition = WatermarkPosition.BottomRight, int padding = 20)
		{
			using var img = Image.Load(_stream);
			var height = img.Height;
			var width = img.Width;
			if (SkipWatermarkForSmallImages && (height < Math.Sqrt(SmallImagePixelsThreshold) || width < Math.Sqrt(SmallImagePixelsThreshold)))
			{
				return _stream as PooledMemoryStream ?? _stream.SaveAsMemoryStream();
			}

			var watermark = Image.Load(watermarkImage);
			watermark.Mutate(c => c.Resize(new ResizeOptions()
			{
				Size = new Size
				{
					Width = width / 10,
					Height = height / 10,
				},
				Mode = ResizeMode.Pad,
				Sampler = new BicubicResampler()
			}));
			int x, y;
			padding += (width - 1000) / 100;
			switch (watermarkPosition)
			{
				case WatermarkPosition.TopRight:
					x = width - watermark.Width - padding;
					y = padding;
					break;

				case WatermarkPosition.BottomLeft:
					x = padding;
					y = height - watermark.Height - padding;
					break;

				case WatermarkPosition.BottomRight:
					x = width - watermark.Width - padding;
					y = height - watermark.Height - padding;
					break;

				case WatermarkPosition.Center:
					x = (img.Width - watermark.Width) / 2;
					y = (img.Height - watermark.Height) / 2;
					break;

				default:
					x = padding;
					y = padding;
					break;
			}

			img.Mutate(c =>
			{
				c.DrawImage(watermark, new Point(x, y), opacity);
				watermark.Dispose();
			});
			var ms = new PooledMemoryStream();
			img.SaveAsWebp(ms);
			ms.Position = 0;
			return ms;
		}
	}
}