cs-vampi/FastPixel.cs

using System;
using System.Drawing;
using System.Drawing.Imaging;

class FastPixel {
    private byte[] rgbValues;
    private BitmapData bmpData;
    private IntPtr bmpPtr;
    private bool locked = false;

    private bool _isAlpha = false;
    private Bitmap _bitmap;
    private int _width;
    private int _height;

    public int Width {
        get { return this._width; }
    }

    public int Height {
        get { return this._height; }
    }

    public bool IsAlphaBitmap {
        get { return this._isAlpha; }
    }

    public Bitmap Bitmap {
        get { return this._bitmap; }
    }

    public FastPixel(Bitmap bitmap) {
        if (bitmap.PixelFormat == (bitmap.PixelFormat | PixelFormat.Indexed))
            throw new Exception("Cannot lock an Indexed image.");

        this._bitmap = bitmap;
        this._isAlpha = (this.Bitmap.PixelFormat == (this.Bitmap.PixelFormat | PixelFormat.Alpha));
        this._width = bitmap.Width;
        this._height = bitmap.Height;
    }

    public void Lock() {
        if (this.locked)
            throw new Exception("Bitmap already locked.");

        Rectangle rect = new Rectangle(0, 0, this.Width, this.Height);
        this.bmpData = this.Bitmap.LockBits(rect, ImageLockMode.ReadWrite, this.Bitmap.PixelFormat);
        this.bmpPtr = this.bmpData.Scan0;

        int bytes;
        if (this.IsAlphaBitmap) {
            bytes = (this.Width * this.Height) * 4;
        } else {
            bytes = (this.Width * this.Height) * 3;
        }
        this.rgbValues = new byte[bytes];
        System.Runtime.InteropServices.Marshal.Copy(this.bmpPtr, rgbValues, 0, this.rgbValues.Length);
        this.locked = true;
    }

    public void Unlock(bool setPixels) {
        if (!this.locked)
            throw new Exception("Bitmap not locked.");

        // Copy the RGB values back to the bitmap;
        if (setPixels)
            System.Runtime.InteropServices.Marshal.Copy(this.rgbValues, 0, this.bmpPtr, this.rgbValues.Length);

        // Unlock the bits.;
        this.Bitmap.UnlockBits(bmpData);
        this.locked = false;
    }

    public void Clear(Color colour) {
        if (!this.locked)
            throw new Exception("Bitmap not locked.");

        if (this.IsAlphaBitmap) {
            for (int index = 0; index < this.rgbValues.Length; index += 4) {
                this.rgbValues[index] = colour.B;
                this.rgbValues[index + 1] = colour.G;
                this.rgbValues[index + 2] = colour.R;
                this.rgbValues[index + 3] = colour.A;
            }
        } else {
            for (int index = 0; index < this.rgbValues.Length; index += 3) {
                this.rgbValues[index] = colour.B;
                this.rgbValues[index + 1] = colour.G;
                this.rgbValues[index + 2] = colour.R;
            }
        }
    }

    public void SetPixel(Point location, Color colour) {
        this.SetPixel(location.X, location.Y, colour);
    }

    public void SetPixel(int x, int y, Color colour) {
        if (!this.locked)
            throw new Exception("Bitmap not locked.");

        if (this.IsAlphaBitmap) {
            int index = ((y * this.Width + x) * 4);
            this.rgbValues[index] = colour.B;
            this.rgbValues[index + 1] = colour.G;
            this.rgbValues[index + 2] = colour.R;
            this.rgbValues[index + 3] = colour.A;
        } else {
            int index = ((y * this.Width + x) * 3);
            this.rgbValues[index] = colour.B;
            this.rgbValues[index + 1] = colour.G;
            this.rgbValues[index + 2] = colour.R;
        }
    }

    public Color GetPixel(Point location) {
        return this.GetPixel(location.X, location.Y);
    }

    public Color GetPixel(int x, int y) {
        if (!this.locked)
            throw new Exception("Bitmap not locked.");

        if (this.IsAlphaBitmap) {
            int index = ((y * this.Width + x) * 4);
            int b = this.rgbValues[index];
            int g = this.rgbValues[index + 1];
            int r = this.rgbValues[index + 2];
            int a = this.rgbValues[index + 3];
            return Color.FromArgb(a, r, g, b);
        } else {
            int index = ((y * this.Width + x) * 3);
            int b = this.rgbValues[index];
            int g = this.rgbValues[index + 1];
            int r = this.rgbValues[index + 2];
            return Color.FromArgb(r, g, b);
        }
    }
}