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95 lines
2.9 KiB
C#
95 lines
2.9 KiB
C#
using System.Drawing;
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using System.Drawing.Imaging;
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using NAPS2.Images.Bitwise;
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namespace NAPS2.Images.Gdi;
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/// <summary>
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/// Ensures that bitmaps use a standard pixel format/palette.
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/// </summary>
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#if NET6_0_OR_GREATER
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[System.Runtime.Versioning.SupportedOSPlatform("windows7.0")]
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#endif
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internal static class GdiPixelFormatFixer
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{
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public static bool MaybeFixPixelFormat(ref Bitmap bitmap)
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{
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switch (bitmap.PixelFormat)
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{
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case PixelFormat.Format1bppIndexed when IsPalette(bitmap, Color.Black, Color.White):
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return false;
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case PixelFormat.Format1bppIndexed when IsPalette(bitmap, Color.White, Color.Black):
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InvertPalette(bitmap);
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return true;
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case PixelFormat.Format1bppIndexed:
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Redraw(ref bitmap, PixelFormat.Format24bppRgb);
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return true;
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case PixelFormat.Format8bppIndexed:
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{
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if (!Is8BitGrayscalePalette(bitmap))
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{
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Redraw(ref bitmap, PixelFormat.Format24bppRgb);
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return true;
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}
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return false;
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}
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case PixelFormat.Format24bppRgb:
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case PixelFormat.Format32bppArgb:
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return false;
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default:
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Redraw(
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ref bitmap,
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Image.IsAlphaPixelFormat(bitmap.PixelFormat)
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? PixelFormat.Format32bppArgb
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: PixelFormat.Format24bppRgb);
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return true;
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}
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}
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private static bool IsPalette(Bitmap bitmap, params Color[] colors)
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{
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if (colors.Length != bitmap.Palette.Entries.Length)
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{
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return false;
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}
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for (int i = 0; i < colors.Length; i++)
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{
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if (colors[i].ToArgb() != bitmap.Palette.Entries[i].ToArgb())
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{
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return false;
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}
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}
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return true;
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}
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private static bool Is8BitGrayscalePalette(Bitmap bitmap)
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{
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for (int i = 0; i < 256; i++)
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{
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if (bitmap.Palette.Entries[i].ToArgb() != Color.FromArgb(i, i, i).ToArgb())
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{
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return false;
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}
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}
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return true;
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}
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private static void InvertPalette(Bitmap bitmap)
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{
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var p = bitmap.Palette;
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p.Entries[0] = Color.Black;
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p.Entries[1] = Color.White;
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bitmap.Palette = p;
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using var lockState = GdiImageLockState.Create(bitmap, LockMode.ReadWrite, out var data);
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BitwisePrimitives.Invert(data);
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}
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private static void Redraw(ref Bitmap bitmap, PixelFormat newPixelFormat)
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{
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var newBitmap = new Bitmap(bitmap.Width, bitmap.Height, newPixelFormat);
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using var g = Graphics.FromImage(newBitmap);
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g.DrawImage(bitmap, 0, 0, bitmap.Width, bitmap.Height);
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bitmap.Dispose();
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bitmap = newBitmap;
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}
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} |