C# Signature:
[DllImport("gdi32.dll")]
static extern uint GetPixel(IntPtr hdc, int nXPos, int nYPos);
VB.NET Signature
<DllImport("gdi32.dll", SetLastError:=True)> _
Public Function GetPixel(hdc As IntPtr , nXPos As Integer, nYPos as Integer) As UInteger
End Function
VB Signature:
Public Declare Function GetPixel Lib "gdi32" Alias "GetPixel" (ByVal hdc As IntPtr, ByVal X As Int32, ByVal Y As Int32) As Int32
User-Defined Types:
None.
Notes:
None
Tips & Tricks:
Please add some!
Sample Code:
[DllImport("user32.dll")]
static extern IntPtr GetDC(IntPtr hwnd);
[DllImport("user32.dll")]
static extern Int32 ReleaseDC(IntPtr hwnd, IntPtr hdc);
[DllImport("gdi32.dll")]
static extern uint GetPixel(IntPtr hdc,int nXPos,int nYPos);
// Print out the RGB value of the pixel which is under the mouse cursor.
// NB: BLUE and RED components will be swapped because GetPixel returns ABGR
static private void myControl_MouseMove(object sender,System.Windows.Forms.MouseEventArgs e)
{
IntPtr hdc = GetDC(IntPtr.Zero);
uint pixel = GetPixel(hdc, Cursor.Position.X, Cursor.Position.Y);
ReleaseDC(IntPtr.Zero,hdc);
Color color = Color.FromArgb((int)pixel);
Console.WriteLine("Color is {0}",color);
}
2nd Example (above did not work for me, here is my solution):
[DllImport("gdi32.dll")]
static extern IntPtr CreateDC(string strDriver,
string strDevice, string strOutput, IntPtr pData);
[DllImport("gdi32.dll")]
static extern bool DeleteDC(IntPtr hdc);
[DllImport("gdi32.dll")]
static extern int GetPixel(IntPtr hdc, int nXPos, int nYPos);
// ...
IntPtr hdcScreen = CreateDC("Display", null, null, IntPtr.Zero);
int cr = GetPixel(hdcScreen, x, y);
Color color = Color.FromArgb((cr & 0x000000FF),
(cr & 0x0000FF00) >> 8,
(cr & 0x00FF0000) >> 16);
DeleteDC(hdcScreen);
// ... and apply the color to Bitmap-struct via SetPixel() or whatever else you want to do with it..
Wrapper Class
using System;
using System.Drawing;
using System.Runtime.InteropServices;
sealed class Win32
{
[DllImport("user32.dll")]
static extern IntPtr GetDC(IntPtr hwnd);
[DllImport("user32.dll")]
static extern Int32 ReleaseDC(IntPtr hwnd, IntPtr hdc);
[DllImport("gdi32.dll")]
static extern uint GetPixel(IntPtr hdc, int nXPos, int nYPos);
static public System.Drawing.Color GetPixelColor(int x, int y)
{
IntPtr hdc = GetDC(IntPtr.Zero);
uint pixel = GetPixel(hdc, x, y);
ReleaseDC(IntPtr.Zero, hdc);
Color color = Color.FromArgb((int)(pixel & 0x000000FF),
(int)(pixel & 0x0000FF00) >> 8,
(int)(pixel & 0x00FF0000) >> 16);
return color;
}
}
Alternative Managed API:
Do you know one? Please contribute it!
