Develop Reference

Get the colour of the screen's current colour filter

The following code SETS the colour filter of the screen to a specific colour.
How can I instead GET the colour of the screen?
[DllImport("GDI32.dll")]
private unsafe static extern bool SetDeviceGammaRamp(IntPtr hdc, void* ramp);
private static IntPtr hdc;
public unsafe bool SetLCDbrightness(Color c)
{
short red = c.R;
short green = c.G;
short blue = c.B;
Graphics gg = Graphics.FromHwnd(IntPtr.Zero);
hdc = gg.GetHdc();
short* gArray = stackalloc short[3 * 256];
short* idx = gArray;
short brightness = 0;
for (int j = 0; j < 3; j++)
{
if (j == 0) brightness = red;
if (j == 1) brightness = green;
if (j == 2) brightness = blue;
for (int i = 0; i < 256; i++)
{
int arrayVal = i * (brightness);
if (arrayVal > 65535) arrayVal = 65535;
*idx = (short)arrayVal;
idx++;
}
}
// For some reason, this always returns false?
bool retVal = SetDeviceGammaRamp(hdc, gArray);
gg.Dispose();
return false;
}

I adapted this other post to form the following answer:
[DllImport("gdi32.dll")]
public static extern int GetDeviceGammaRamp(IntPtr hDC, ref RAMP lpRamp);
[DllImport("user32.dll")]
public static extern IntPtr GetDC(IntPtr hWnd);
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
public struct RAMP
{
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
public UInt16[] Red;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
public UInt16[] Green;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 256)]
public UInt16[] Blue;
}
private Color getScreenColor()
{
RAMP r = new RAMP();
GetDeviceGammaRamp(GetDC(IntPtr.Zero), ref r);
return Color.FromArgb(r.Red[1], r.Green[1], r.Blue[1]);
}

C# Quickest Way to Get Average Colors of Screen

I'm currently working on creating an Ambilight for my computer monitor with C#, an arduino, and an Ikea Dioder. Currently the hardware portion runs flawlessly; however, I'm having a problem with detecting the average color of a section of screen.
I have two issues with the implementations that I'm using:
Performance - Both of these algorithms add a somewhat noticeable stutter to the screen. Nothing showstopping, but it's annoying while watching video.
No Fullscreen Game Support - When a game is in fullscreen mode both of these methods just return white.
public class DirectxColorProvider : IColorProvider
{
private static Device d;
private static Collection<long> colorPoints;
public DirectxColorProvider()
{
PresentParameters present_params = new PresentParameters();
if (d == null)
{
d = new Device(new Direct3D(), 0, DeviceType.Hardware, IntPtr.Zero, CreateFlags.SoftwareVertexProcessing, present_params);
}
if (colorPoints == null)
{
colorPoints = GetColorPoints();
}
}
public byte[] GetColors()
{
var color = new byte[4];
using (var screen = this.CaptureScreen())
{
DataRectangle dr = screen.LockRectangle(LockFlags.None);
using (var gs = dr.Data)
{
color = avcs(gs, colorPoints);
}
}
return color;
}
private Surface CaptureScreen()
{
Surface s = Surface.CreateOffscreenPlain(d, Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, Format.A8R8G8B8, Pool.Scratch);
d.GetFrontBufferData(0, s);
return s;
}
private static byte[] avcs(DataStream gs, Collection<long> positions)
{
byte[] bu = new byte[4];
int r = 0;
int g = 0;
int b = 0;
int i = 0;
foreach (long pos in positions)
{
gs.Position = pos;
gs.Read(bu, 0, 4);
r += bu[2];
g += bu[1];
b += bu[0];
i++;
}
byte[] result = new byte[3];
result[0] = (byte)(r / i);
result[1] = (byte)(g / i);
result[2] = (byte)(b / i);
return result;
}
private Collection<long> GetColorPoints()
{
const long offset = 20;
const long Bpp = 4;
var box = GetBox();
var colorPoints = new Collection<long>();
for (var x = box.X; x < (box.X + box.Length); x += offset)
{
for (var y = box.Y; y < (box.Y + box.Height); y += offset)
{
long pos = (y * Screen.PrimaryScreen.Bounds.Width + x) * Bpp;
colorPoints.Add(pos);
}
}
return colorPoints;
}
private ScreenBox GetBox()
{
var box = new ScreenBox();
int m = 8;
box.X = (Screen.PrimaryScreen.Bounds.Width - m) / 3;
box.Y = (Screen.PrimaryScreen.Bounds.Height - m) / 3;
box.Length = box.X * 2;
box.Height = box.Y * 2;
return box;
}
private class ScreenBox
{
public long X { get; set; }
public long Y { get; set; }
public long Length { get; set; }
public long Height { get; set; }
}
}
You can find the file for the directX implmentation here.
public class GDIColorProvider : Form, IColorProvider
{
private static Rectangle box;
private readonly IColorHelper _colorHelper;
public GDIColorProvider()
{
_colorHelper = new ColorHelper();
box = _colorHelper.GetCenterBox();
}
public byte[] GetColors()
{
var colors = new byte[3];
IntPtr hDesk = GetDesktopWindow();
IntPtr hSrce = GetDC(IntPtr.Zero);
IntPtr hDest = CreateCompatibleDC(hSrce);
IntPtr hBmp = CreateCompatibleBitmap(hSrce, box.Width, box.Height);
IntPtr hOldBmp = SelectObject(hDest, hBmp);
bool b = BitBlt(hDest, box.X, box.Y, (box.Width - box.X), (box.Height - box.Y), hSrce, 0, 0, CopyPixelOperation.SourceCopy);
using(var bmp = Bitmap.FromHbitmap(hBmp))
{
colors = _colorHelper.AverageColors(bmp);
}
SelectObject(hDest, hOldBmp);
DeleteObject(hBmp);
DeleteDC(hDest);
ReleaseDC(hDesk, hSrce);
return colors;
}
// P/Invoke declarations
[DllImport("gdi32.dll")]
static extern bool BitBlt(IntPtr hdcDest, int xDest, int yDest, int
wDest, int hDest, IntPtr hdcSource, int xSrc, int ySrc, CopyPixelOperation rop);
[DllImport("user32.dll")]
static extern bool ReleaseDC(IntPtr hWnd, IntPtr hDc);
[DllImport("gdi32.dll")]
static extern IntPtr DeleteDC(IntPtr hDc);
[DllImport("gdi32.dll")]
static extern IntPtr DeleteObject(IntPtr hDc);
[DllImport("gdi32.dll")]
static extern IntPtr CreateCompatibleBitmap(IntPtr hdc, int nWidth, int nHeight);
[DllImport("gdi32.dll")]
static extern IntPtr CreateCompatibleDC(IntPtr hdc);
[DllImport("gdi32.dll")]
static extern IntPtr SelectObject(IntPtr hdc, IntPtr bmp);
[DllImport("user32.dll")]
private static extern IntPtr GetDesktopWindow();
[DllImport("user32.dll")]
private static extern IntPtr GetWindowDC(IntPtr ptr);
[DllImport("user32.dll")]
private static extern IntPtr GetDC(IntPtr ptr);
}
You Can Find the File for the GDI implementation Here.
The Full Codebase Can be Found Here.

Updated Answer
The problem of slow screen capture performance most likely is caused by BitBlt() doing a pixel conversion when the pixel formats of source and destination don't match. From the docs:
If the color formats of the source and destination device contexts do not match, the BitBlt function converts the source color format to match the destination format.
This is what caused slow performance in my code, especially in higher resolutions.
The default pixel format seems to be PixelFormat.Format32bppArgb, so that's what you should use for the buffer:
var screen = new Bitmap(bounds.Width, bounds.Height, PixelFormat.Format32bppArgb);
var gfx = Graphics.FromImage(screen);
gfx.CopyFromScreen(bounds.Location, new Point(0, 0), bounds.Size);
The next source for slow performance is Bitmap.GetPixel() which does boundary checks. Never use it when analyzing every pixel. Instead lock the bitmap data and get a pointer to it:
public unsafe Color GetAverageColor(Bitmap image, int sampleStep = 1) {
var data = image.LockBits(
new Rectangle(Point.Empty, Image.Size),
ImageLockMode.ReadOnly,
PixelFormat.Format32bppArgb);
var row = (int*)data.Scan0.ToPointer();
var (sumR, sumG, sumB) = (0L, 0L, 0L);
var stride = data.Stride / sizeof(int) * sampleStep;
for (var y = 0; y < data.Height; y += sampleStep) {
for (var x = 0; x < data.Width; x += sampleStep) {
var argb = row[x];
sumR += (argb & 0x00FF0000) >> 16;
sumG += (argb & 0x0000FF00) >> 8;
sumB += argb & 0x000000FF;
}
row += stride;
}
image.UnlockBits(data);
var numSamples = data.Width / sampleStep * data.Height / sampleStep;
var avgR = sumR / numSamples;
var avgG = sumG / numSamples;
var avgB = sumB / numSamples;
return Color.FromArgb((int)avgR, (int)avgG, (int)avgB);
}
This should get you well below 10 ms, depending on the screen size. In case it is still too slow you can increase the sampleStep parameter of GetAverageColor().
Original Answer
I recently did the same thing and came up with something that worked surprisingly good.
The trick is to create an additional bitmap that is 1x1 pixels in size and set a good interpolation mode on its graphics context (bilinear or bicubic, but not nearest neighbor).
Then you draw your captured bitmap into that 1x1 bitmap exploiting the interpolation and retrieve that pixel to get the average color.
I'm doing that at a rate of ~30 fps. When the screen shows a GPU rendering (e.g. watching YouTube full screen with enabled hardware acceleration in Chrome) there is no visible stuttering or anything. In fact, CPU utilization of the application is way below 10%. However, if I turn off Chrome's hardware acceleration then there is definitely some slight stuttering noticeable if you watch close enough.
Here are the relevant parts of the code:
using var screen = new Bitmap(width, height);
using var screenGfx = Graphics.FromImage(screen);
using var avg = new Bitmap(1, 1);
using var avgGfx = Graphics.FromImage(avg);
avgGfx.InterpolationMode = InterpolationMode.HighQualityBicubic;
while (true) {
screenGfx.CopyFromScreen(left, top, 0, 0, screen.Size);
avgGfx.DrawImage(screen, 0, 0, avg.Width, avg.Height);
var color = avg.GetPixel(0, 0);
var bright = (int)Math.Round(Math.Clamp(color.GetBrightness() * 100, 1, 100));
// set color and brightness on your device
// wait 1000/fps milliseconds
}
Note that this works for GPU renderings, because System.Drawing.Common uses GDI+ nowadays. However, it does not work when the content is DRM protected. So it won't work with Netflix for example :(
I published the code on GitHub. Even though I abandoned the project due to Netflix' DRM protection it might help someone else.

MouseInput moves mouse to the left at start of loop

When I do this;
Point startpoint = Cursor.Position;
startpoint.Y -= 1;
DoMouse(MOUSEEVENTF.MOVE | MOUSEEVENTF.ABSOLUTE, startpoint);
The mouse doesn't just move up.. it moves a bit to the left as well. But if I do it in a loop, it only moves to the left at the first iteration.
Here is a fully working console program presenting the problem. You have to Add Reference -> .NET -> System.Drawing and System.Windows.Forms to get it to compile.
When starting the program type start to move the mouse up 5 pixels once or type start X (X being a number) to move the mouse up 5 pixels X times. You will see that each new loop the mouse will move a bit to the left; it shouldn't be doing that at all.
using System;
using System.Text.RegularExpressions;
using System.Threading;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
namespace mousemove_temp
{
class Program
{
//Capture user input
static void Main(string[] args)
{
while (true)
{
string s = Console.ReadLine();
switch (s)
{
case("start"):
moveMouseTest(1);
break;
default:
//Get # of times to run function
Match match = Regex.Match(s, #"start (.+)", RegexOptions.IgnoreCase);
if (!match.Success || match.Groups.Count != 2) break;
//Copy # to int
int amnt = -1;
try
{
amnt = Int32.Parse(match.Groups[1].Value);
}
catch (Exception) { break; } //fail
if (amnt <= -1) break; //fail
moveMouseTest(amnt); //aaaawww yeah
break;
}
Thread.Sleep(10);
}
}
//Move the mouse
static void moveMouseTest(int repeat)
{
int countrepeat = 0;
//Loop entire function X times
while (countrepeat < repeat)
{
Point startpoint = Cursor.Position;
int amount = 5; //Move 5 pixels
int counter = 0;
//Move 1 pixel up each loop
while (counter < amount)
{
startpoint.Y -= 1;
DoMouse(MOUSEEVENTF.MOVE | MOUSEEVENTF.ABSOLUTE, startpoint);
counter++;
Thread.Sleep(100); //Slow down so you can see it only jumps left the first time
}
countrepeat++;
Console.WriteLine(String.Format("{0}/{1}", countrepeat, repeat));
Thread.Sleep(1000); //Wait a second before next loop
}
}
/*
* Function stuff
*/
//Control the Mouse
private static object mouselock = new object(); //For use with multithreading
public static void DoMouse(MOUSEEVENTF flags, Point newPoint)
{
lock (mouselock)
{
INPUT input = new INPUT();
MOUSEINPUT mi = new MOUSEINPUT();
input.dwType = InputType.Mouse;
input.mi = mi;
input.mi.dwExtraInfo = IntPtr.Zero;
// mouse co-ords: top left is (0,0), bottom right is (65535, 65535)
// convert screen co-ord to mouse co-ords...
input.mi.dx = newPoint.X * (65535 / Screen.PrimaryScreen.Bounds.Width);
input.mi.dy = newPoint.Y * (65535 / Screen.PrimaryScreen.Bounds.Height);
input.mi.time = 0;
input.mi.mouseData = 0;
// can be used for WHEEL event see msdn
input.mi.dwFlags = flags;
int cbSize = Marshal.SizeOf(typeof(INPUT));
int result = SendInput(1, ref input, cbSize);
if (result == 0)
Console.WriteLine("DoMouse Error:" + Marshal.GetLastWin32Error());
}
}
/*
* Native Methods
*/
[DllImport("user32.dll", SetLastError = true)]
static internal extern Int32 SendInput(Int32 cInputs, ref INPUT pInputs, Int32 cbSize);
[DllImport("user32.dll")]
public static extern bool GetAsyncKeyState(Int32 vKey);
[StructLayout(LayoutKind.Explicit, Pack = 1, Size = 28)]
internal struct INPUT
{
[FieldOffset(0)]
public InputType dwType;
[FieldOffset(4)]
public MOUSEINPUT mi;
[FieldOffset(4)]
public KEYBDINPUT ki;
[FieldOffset(4)]
public HARDWAREINPUT hi;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct MOUSEINPUT
{
public Int32 dx;
public Int32 dy;
public Int32 mouseData;
public MOUSEEVENTF dwFlags;
public Int32 time;
public IntPtr dwExtraInfo;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct KEYBDINPUT
{
public Int16 wVk;
public Int16 wScan;
public KEYEVENTF dwFlags;
public Int32 time;
public IntPtr dwExtraInfo;
}
[StructLayout(LayoutKind.Sequential, Pack = 1)]
internal struct HARDWAREINPUT
{
public Int32 uMsg;
public Int16 wParamL;
public Int16 wParamH;
}
internal enum InputType : int
{
Mouse = 0,
Keyboard = 1,
Hardware = 2
}
[Flags()]
internal enum MOUSEEVENTF : int
{
MOVE = 0x1,
LEFTDOWN = 0x2,
LEFTUP = 0x4,
RIGHTDOWN = 0x8,
RIGHTUP = 0x10,
MIDDLEDOWN = 0x20,
MIDDLEUP = 0x40,
XDOWN = 0x80,
XUP = 0x100,
VIRTUALDESK = 0x400,
WHEEL = 0x800,
ABSOLUTE = 0x8000
}
[Flags()]
internal enum KEYEVENTF : int
{
EXTENDEDKEY = 1,
KEYUP = 2,
UNICODE = 4,
SCANCODE = 8
}
}
}
Can anybody tell what's going wrong?

You're doing the math wrong and as a result are getting rounding errors.
For example, 65535 / 1920 = 34.1328125. But truncation (because you are dividing an int by an int) is resulting in 34. So if on a 1920x1080 screen you had the mouse all the way at the right, you would get 1920 * (65535 / 1920) = 1920 * 34 = 65280.
This will get you better results:
input.mi.dx = (int)((65535.0f * (newPoint.X / (float)Screen.PrimaryScreen.Bounds.Width)) + 0.5f);
input.mi.dy = (int)((65535.0f * (newPoint.Y / (float)Screen.PrimaryScreen.Bounds.Height)) + 0.5f);
Though if you're determined to use P/Invoke rather than just say
Cursor.Position = new Point(newPoint.X, newPoint.Y);
then you really should use SetCursorPos - http://msdn.microsoft.com/en-us/library/windows/desktop/ms648394(v=vs.85).aspx - since that (along with GetCursorPos) is the API that .NET is using to get and set the cursor position via Cursor.Position.

Simplest way for your project is useful open-source library Windows Input Simulator (C# SendInput Wrapper - Simulate Keyboard and Mouse) on codeplex. Use it!

Writing to console window not via stdout

how can I write DIRECTLY into console, without bothering with stdout in c#? I'm upgrading some old program, which has it's stdout redirected into file (because the output matters), and I need somehow to write directly to console, and that the text won't appear in stdout. Is it possible (without using WinAPI)?
EDIT: I'm aware of the possibility to write to stderr, althrough, is it possible to set cursor position for stderr on console?

You could write to Console.Error, which, although it can be redirected, is separate from stdout.
is it possible to set cursor position for stderr on console?
Edit: Assuming that stderr has not been redirected, see Console.CursorTop and Console.CursorLeft. There's various other members on the Console class that you might find useful.
To answer your question directly, use the Win32 WriteConsole function. As far as I can see, the .NET framework doesn't have methods for writing directly to the console window.

If I run your program and redirect its StandardOutput and StandardError, what do you expect to happen to your writes when there is no console?
For this reason, the answer is likely “you can’t” (except perhaps by using crazy hacks, which probably involve Windows API which you said you didn’t want to use).
Think of the console window as nothing more than a UI element that allows the user to view the stdout/stderr of your program (and to provide stdin). It doesn’t really exist for any other purpose.

I actually ended up implementing the low level WriteConsoleOutput some time ago as part of a terminal based Tetris implementation I wrote, since doing coloured console output with Console.BackgroundColor and Console.Write, is far too slow for full screen refreshes. Doing the raw buffer output is much faster.
Note, this writes text to a location on the screen (eg 5,10), but doesn't update or keep track of the cursor position on it's own - writing with this method will update the text buffer and display the output, but the cursor won't move. You'll need to move and keep track of the console cursor manually with some other method, which shouldn't be too difficult.
Here's my code:
Main interop class:
public static class LowLevelConsole {
[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
private static extern SafeFileHandle CreateFile(
string fileName,
[MarshalAs(UnmanagedType.U4)] uint fileAccess,
[MarshalAs(UnmanagedType.U4)] uint fileShare,
IntPtr securityAttributes,
[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
[MarshalAs(UnmanagedType.U4)] int flags,
IntPtr template);
[DllImport("kernel32.dll", SetLastError = true)]
private static extern bool WriteConsoleOutput(
SafeFileHandle hConsoleOutput,
CharInfo[] lpBuffer,
Coord dwBufferSize,
Coord dwBufferCoord,
ref SmallRect lpWriteRegion);
[StructLayout(LayoutKind.Sequential)]
public struct Coord {
public short X;
public short Y;
public Coord(short X, short Y) {
this.X = X;
this.Y = Y;
}
};
[StructLayout(LayoutKind.Explicit)]
public struct CharUnion {
[FieldOffset(0)]
public char UnicodeChar;
[FieldOffset(0)]
public byte AsciiChar;
}
[StructLayout(LayoutKind.Explicit)]
public struct CharInfo {
[FieldOffset(0)]
public CharUnion Char;
[FieldOffset(2)]
public ushort Attributes;
}
[StructLayout(LayoutKind.Sequential)]
public struct SmallRect {
public short Left;
public short Top;
public short Right;
public short Bottom;
}
[STAThread]
public static void Write(string line, CharacterAttribute attribute, short xLoc, short yLoc) {
SafeFileHandle h = CreateFile("CONOUT$", 0x40000000, 2, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero);
short writeHeight = 1;
short writeWidth = (short)line.Length;
if (!h.IsInvalid) {
CharInfo[] buf = new CharInfo[writeWidth * writeHeight];
SmallRect rect = new SmallRect() { Left = xLoc, Top = yLoc, Right = (short)(writeWidth + xLoc), Bottom = (short)(writeHeight + yLoc) };
for (int i = 0; i < writeWidth; i++) {
buf[i].Attributes = (ushort)attribute;
buf[i].Char.UnicodeChar = line[i];
}
bool b = WriteConsoleOutput(h, buf, new Coord() { X = writeWidth, Y = writeHeight }, new Coord() { X = 0, Y = 0 }, ref rect);
}
}
[STAThread]
public static bool WriteBuffer(CharInfo[,] buffer) { // returns true of success
SafeFileHandle h = CreateFile("CONOUT$", 0x40000000, 2, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero);
if (!h.IsInvalid) {
short BufferWidth = (short)buffer.GetLength(0);
short BufferHeight = (short)buffer.GetLength(1);
CharInfo[] buf = new CharInfo[BufferWidth * BufferHeight];
SmallRect rect = new SmallRect() { Left = 0, Top = 0, Right = BufferWidth, Bottom = BufferHeight };
for (int y = 0; y < BufferHeight; y++) {
for (int x = 0; x < BufferWidth; x++) {
buf[y * BufferWidth + x] = buffer[x, y];
}
}
return WriteConsoleOutput(h, buf, new Coord() { X = BufferWidth, Y = BufferHeight }, new Coord() { X = 0, Y = 0 }, ref rect);
}
return false;
}
}
Character attributes:
[Flags]
public enum CharacterAttribute : ushort {
FOREGROUND_BLUE = 0x0001,
FOREGROUND_GREEN = 0x0002,
FOREGROUND_RED = 0x0004,
FOREGROUND_INTENSITY = 0x0008,
BACKGROUND_BLUE = 0x0010,
BACKGROUND_GREEN = 0x0020,
BACKGROUND_RED = 0x0040,
BACKGROUND_INTENSITY = 0x0080,
COMMON_LVB_LEADING_BYTE = 0x0100,
COMMON_LVB_TRAILING_BYTE = 0x0200,
COMMON_LVB_GRID_HORIZONTAL = 0x0400,
COMMON_LVB_GRID_LVERTICAL = 0x0800,
COMMON_LVB_GRID_RVERTICAL = 0x1000,
COMMON_LVB_REVERSE_VIDEO = 0x4000,
COMMON_LVB_UNDERSCORE = 0x8000
}
Test code:
class Program {
static void Main(string[] args) {
// write to location 0,0
LowLevelConsole.Write("Some test text", CharacterAttribute.BACKGROUND_BLUE | CharacterAttribute.FOREGROUND_RED, 0, 0);
// write to location 5,10
LowLevelConsole.Write("another test at a different location",
CharacterAttribute.FOREGROUND_GREEN | CharacterAttribute.FOREGROUND_BLUE,
5, 10);
Console.ReadLine();
}
}

How can I write fast colored output to Console?

I want to learn if there is another (faster) way to output text to the console application window using C# .net than with the simple Write, BackgroundColor and ForegroundColor methods and properties? I learned that each cell has a background color and a foreground color, and I would like to cache/buffer/write faster than using the mentioned methods.
Maybe there is some help using the Out buffer, but I don't know how to encode the colors into the stream, if that is where the color data resides.
This is for a retrostyle textbased game I am wanting to implement where I make use of the standard colors and ascii characters for laying out the game.
Please help :)
Update:
The Out and buffer is probably not what I need to mess around with. There seems to be a screen buffer that is owned by the console. I don't know how to access it, maybe I am just out of luck unless I import some dlls.

Update: added a sample
If you are prepared to do some P/Invoke stuff, this might help.
Basically if you get a handle to the console buffer, then you can use the standard Win32 APIs wot manipulate the buffer, even build the the entire buffer off screen and the blit it to the Console.
The only tricky part is getting the handle to the console buffer. I have not tried this in .NET, but in years gone by, you could get the handle to the current console by using CreateFile (you will need to P/Invoke this) and open "CONOUT$" then you can use the handle that is return to pass to the other APIs.
P/Invoke for CreateFile
http://www.pinvoke.net/default.aspx/kernel32/CreateFile.html
And you can use WriteConsoleOutput to move all the characters and their attributes from a memory buffer to the console buffer.
http://msdn.microsoft.com/en-us/library/ms687404(VS.85).aspx
You could probably put together a nice library to provide lower-level access to the console buffer.
Since I am trying to get my .NET up to scratch again I thought I would try my hand at this and see if I could get it to work. Here is a sample that will fill the screen with all the letters A-Z and run through all the forground attributes 0-15. I think you will be impressed with the performance. I'll be honest, I did not spend much time reviewing this code so error checking is zero and there might be a little bug here or there but it should get you going with the rest of the APIs.
using System;
using System.IO;
using System.Runtime.InteropServices;
using Microsoft.Win32.SafeHandles;
namespace ConsoleApplication1
{
class Program
{
[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern SafeFileHandle CreateFile(
string fileName,
[MarshalAs(UnmanagedType.U4)] uint fileAccess,
[MarshalAs(UnmanagedType.U4)] uint fileShare,
IntPtr securityAttributes,
[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
[MarshalAs(UnmanagedType.U4)] int flags,
IntPtr template);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool WriteConsoleOutputW(
SafeFileHandle hConsoleOutput,
CharInfo[] lpBuffer,
Coord dwBufferSize,
Coord dwBufferCoord,
ref SmallRect lpWriteRegion);
[StructLayout(LayoutKind.Sequential)]
public struct Coord
{
public short X;
public short Y;
public Coord(short X, short Y)
{
this.X = X;
this.Y = Y;
}
};
[StructLayout(LayoutKind.Explicit)]
public struct CharUnion
{
[FieldOffset(0)] public ushort UnicodeChar;
[FieldOffset(0)] public byte AsciiChar;
}
[StructLayout(LayoutKind.Explicit)]
public struct CharInfo
{
[FieldOffset(0)] public CharUnion Char;
[FieldOffset(2)] public short Attributes;
}
[StructLayout(LayoutKind.Sequential)]
public struct SmallRect
{
public short Left;
public short Top;
public short Right;
public short Bottom;
}
[STAThread]
static void Main(string[] args)
{
SafeFileHandle h = CreateFile("CONOUT$", 0x40000000, 2, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero);
if (!h.IsInvalid)
{
CharInfo[] buf = new CharInfo[80 * 25];
SmallRect rect = new SmallRect() { Left = 0, Top = 0, Right = 80, Bottom = 25 };
for (byte character = 65; character < 65 + 26; ++character)
{
for (short attribute = 0; attribute < 15; ++attribute)
{
for (int i = 0; i < buf.Length; ++i)
{
buf[i].Attributes = attribute;
buf[i].Char.AsciiChar = character;
}
bool b = WriteConsoleOutputW(h, buf,
new Coord() { X = 80, Y = 25 },
new Coord() { X = 0, Y = 0 },
ref rect);
}
}
}
Console.ReadKey();
}
}
}
Unicode example
using Microsoft.Win32.SafeHandles;
using System;
using System.IO;
using System.Runtime.InteropServices;
namespace FastConsole
{
class Program
{
[DllImport("Kernel32.dll", SetLastError = true, CharSet = CharSet.Auto)]
static extern SafeFileHandle CreateFile(
string fileName,
[MarshalAs(UnmanagedType.U4)] uint fileAccess,
[MarshalAs(UnmanagedType.U4)] uint fileShare,
IntPtr securityAttributes,
[MarshalAs(UnmanagedType.U4)] FileMode creationDisposition,
[MarshalAs(UnmanagedType.U4)] int flags,
IntPtr template);
[DllImport("kernel32.dll", SetLastError = true)]
static extern bool WriteConsoleOutputW(
SafeFileHandle hConsoleOutput,
CharInfo[] lpBuffer,
Coord dwBufferSize,
Coord dwBufferCoord,
ref SmallRect lpWriteRegion);
[StructLayout(LayoutKind.Sequential)]
public struct Coord
{
public short X;
public short Y;
public Coord(short X, short Y)
{
this.X = X;
this.Y = Y;
}
};
[StructLayout(LayoutKind.Explicit)]
public struct CharUnion
{
[FieldOffset(0)] public ushort UnicodeChar;
[FieldOffset(0)] public byte AsciiChar;
}
[StructLayout(LayoutKind.Explicit)]
public struct CharInfo
{
[FieldOffset(0)] public CharUnion Char;
[FieldOffset(2)] public short Attributes;
}
[StructLayout(LayoutKind.Sequential)]
public struct SmallRect
{
public short Left;
public short Top;
public short Right;
public short Bottom;
}
[STAThread]
static void Main(string[] args)
{
SafeFileHandle h = CreateFile("CONOUT$", 0x40000000, 2, IntPtr.Zero, FileMode.Open, 0, IntPtr.Zero);
if (!h.IsInvalid)
{
CharInfo[] buf = new CharInfo[80 * 25];
SmallRect rect = new SmallRect() { Left = 0, Top = 0, Right = 80, Bottom = 25 };
for (ushort character = 0x2551; character < 0x2551 + 26; ++character)
{
for (short attribute = 0; attribute < 15; ++attribute)
{
for (int i = 0; i < buf.Length; ++i)
{
buf[i].Attributes = attribute;
buf[i].Char.UnicodeChar = character;
}
bool b = WriteConsoleOutputW(h, buf,
new Coord() { X = 80, Y = 25 },
new Coord() { X = 0, Y = 0 },
ref rect);
Console.ReadKey();
}
}
}
Console.ReadKey();
}
}
}

If you look at the implementation of Console's properties for altering console colours, they delegate to the SetConsoleTextAttribute method from kernel32.dll. This method takes character attributes as input to set both the foreground and background colours.
From several MSDN doc pages, each screen buffer (of which a console has one) has a two-dimensional array of character info records, each represented by a CHAR_INFO. This is what determines the colour of each character. You can manipulate this using the SetConsoleTextAttribute method, but this is applied to any new text that is written to the console - you cannot manipulate existing text already on the console.
Unless there is a lower-level hook into the console text colour properties (which doesn't look likely), I think you are stuck using these methods.
One thing you could try is to create a new screen buffer, write to that, and then switch it to be the console's current buffer using SetConsoleActiveScreenBuffer. This may yield faster output as you will be writing all output to an inactive buffer.

I had success using
using (var stdout = Console.OpenStandardOutput(Cols * Rows))
{
// fill
stdout.Write(buffer, 0, buffer.Length);
// rinse and repeat
}
But if anyone can advise me on how I write extended ASCII to this i'd be grateful