111 lines
4.2 KiB
C#
111 lines
4.2 KiB
C#
using BlurHash;
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using System.Drawing.Imaging;
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namespace System.Drawing.BlurHash;
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public static class BlurHasher
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{
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#pragma warning disable CA1416
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/// <summary>
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/// Encodes a picture into a BlurHash string
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/// </summary>
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/// <param name="image">The picture to encode</param>
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/// <param name="componentsX">The number of components used on the X-Axis for the DCT</param>
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/// <param name="componentsY">The number of components used on the Y-Axis for the DCT</param>
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/// <returns>The resulting BlurHash string</returns>
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public static ReadOnlySpan<char> Encode(Image image, int componentsX, int componentsY) =>
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Core.Encode(ConvertBitmap(image as Bitmap ?? new Bitmap(image)), componentsX, componentsY);
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/// <summary>
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/// Decodes a BlurHash string into a <c>System.Drawing.Image</c>
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/// </summary>
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/// <param name="blurHash">The blurHash string to decode</param>
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/// <param name="outputWidth">The desired width of the output in pixels</param>
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/// <param name="outputHeight">The desired height of the output in pixels</param>
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/// <param name="punch">A value that affects the contrast of the decoded image. 1 means normal, smaller values will make the effect more subtle, and larger values will make it stronger.</param>
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/// <returns>The decoded preview</returns>
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public static Image Decode(ReadOnlySpan<char> blurHash, int outputWidth, int outputHeight, double punch = 1.0)
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{
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Pixel[,] pixelData = new Pixel[outputWidth, outputHeight];
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Core.Decode(blurHash, pixelData, punch);
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return ConvertToBitmap(pixelData);
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}
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/// <summary>
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/// Converts the given bitmap to the library-independent representation used within the BlurHash-core
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/// </summary>
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/// <param name="sourceBitmap">The bitmap to encode</param>
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public static unsafe Pixel[,] ConvertBitmap(Image sourceBitmap)
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{
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int width = sourceBitmap.Width;
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int height = sourceBitmap.Height;
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using Bitmap temporaryBitmap = new(width, height, PixelFormat.Format24bppRgb);
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using (Graphics graphics = Graphics.FromImage(temporaryBitmap))
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{
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graphics.DrawImageUnscaled(sourceBitmap, 0, 0);
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}
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// Lock the bitmap's bits.
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BitmapData bmpData = temporaryBitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.ReadOnly, temporaryBitmap.PixelFormat);
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// Get the address of the first line.
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nint ptr = bmpData.Scan0;
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Pixel[,] result = new Pixel[width, height];
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byte* rgb = (byte*)ptr.ToPointer();
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for (int y = 0; y < height; y++)
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{
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int index = bmpData.Stride * y;
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for (int x = 0; x < width; x++)
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{
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ref Pixel res = ref result[x, y];
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res.Blue = MathUtils.SRgbToLinear(rgb[index++]);
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res.Green = MathUtils.SRgbToLinear(rgb[index++]);
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res.Red = MathUtils.SRgbToLinear(rgb[index++]);
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}
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}
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temporaryBitmap.UnlockBits(bmpData);
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return result;
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}
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/// <summary>
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/// Converts the library-independent representation of pixels into a bitmap
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/// </summary>
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/// <param name="pixelData">The library-independent representation of the image</param>
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/// <returns>A <c>System.Drawing.Bitmap</c> in 32bpp-RGB representation</returns>
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public static unsafe Bitmap ConvertToBitmap(Pixel[,] pixelData)
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{
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int width = pixelData.GetLength(0);
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int height = pixelData.GetLength(1);
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byte[] data = new byte[width * height * 4];
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int index = 0;
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for (int yPixel = 0; yPixel < height; yPixel++)
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for (int xPixel = 0; xPixel < width; xPixel++)
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{
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Pixel pixel = pixelData[xPixel, yPixel];
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data[index++] = (byte)MathUtils.LinearTosRgb(pixel.Blue);
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data[index++] = (byte)MathUtils.LinearTosRgb(pixel.Green);
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data[index++] = (byte)MathUtils.LinearTosRgb(pixel.Red);
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data[index++] = 0;
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}
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Bitmap bmp;
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fixed (byte* ptr = data)
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{
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bmp = new Bitmap(width, height, width * 4, PixelFormat.Format32bppRgb, new IntPtr(ptr));
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}
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return bmp;
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}
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} |