developer/Samples/NET Standard/ParallelExtensionsExtras/Drawing/FastBitmap.cs

   1 //--------------------------------------------------------------------------
   2 //
   3 //  Copyright (c) Microsoft Corporation.  All rights reserved.
   4 //
   5 //  File: FastBitmap.cs
   6 //
   7 //--------------------------------------------------------------------------
   8
   9 using System;
  10 using System.Drawing;
  11 using System.Drawing.Imaging;
  12
  13 namespace Microsoft.Drawing
  14 {
  15     public struct PixelData
  16     {
  17         public byte B;
  18         public byte G;
  19         public byte R;
  20     }
  21
  22     public unsafe class FastBitmap : IDisposable
  23     {
  24         private Bitmap _bitmap;
  25         private int _width;
  26         private BitmapData _bitmapData = null;
  27         private byte* _pBase = null;
  28         private PixelData* _pInitPixel = null;
  29         private Point _size;
  30         private bool _locked = false;
  31
  32         public FastBitmap(Bitmap bmp)
  33         {
  34             if (bmp == null) throw new ArgumentNullException("bitmap");
  35
  36             _bitmap = bmp;
  37             _size = new Point(bmp.Width, bmp.Height);
  38
  39             LockBitmap();
  40         }
  41
  42         public PixelData* GetInitialPixelForRow(int rowNumber)
  43         {
  44             return (PixelData*)(_pBase + rowNumber * _width);
  45         }
  46
  47         public PixelData* this[int x, int y]
  48         {
  49             get { return (PixelData*)(_pBase + y * _width + x * sizeof(PixelData)); }
  50         }
  51
  52         public Color GetColor(int x, int y)
  53         {
  54             PixelData* data = this[x, y];
  55             return Color.FromArgb(data->R, data->G, data->B);
  56         }
  57
  58         public void SetColor(int x, int y, Color c)
  59         {
  60             PixelData* data = this[x, y];
  61             data->R = c.R;
  62             data->G = c.G;
  63             data->B = c.B;
  64         }
  65
  66         private void LockBitmap()
  67         {
  68             if (_locked) throw new InvalidOperationException("Already locked");
  69
  70             Rectangle bounds = new Rectangle(0, 0, _bitmap.Width, _bitmap.Height);
  71
  72             // Figure out the number of bytes in a row. This is rounded up to be a multiple
  73             // of 4 bytes, since a scan line in an image must always be a multiple of 4 bytes
  74             // in length.
  75             _width = bounds.Width * sizeof(PixelData);
  76             if (_width % 4 != 0) _width = 4 * (_width / 4 + 1);
  77
  78             _bitmapData = _bitmap.LockBits(bounds, ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
  79
  80             _pBase = (byte*)_bitmapData.Scan0.ToPointer();
  81             _locked = true;
  82         }
  83
  84         private void InitCurrentPixel()
  85         {
  86             _pInitPixel = (PixelData*)_pBase;
  87         }
  88
  89         private void UnlockBitmap()
  90         {
  91             if (!_locked) throw new InvalidOperationException("Not currently locked");
  92
  93             _bitmap.UnlockBits(_bitmapData);
  94             _bitmapData = null;
  95             _pBase = null;
  96             _locked = false;
  97         }
  98
  99         public void Dispose()
 100         {
 101             if (_locked) UnlockBitmap();
 102         }
 103     }
 104 }