Windows API Guide: GetDesktopWindow Function

Declare Function GetPixel Lib "gdi32.dll" (ByVal hdc As Long, ByVal nXPos As Long, ByVal nYPos As Long) As Long

Platforms

Windows 95: Supported.
Windows 98: Supported.
Windows NT: Requires Windows NT 3.1 or later.
Windows 2000: Supported.
Windows CE: Requires Windows CE 1.0 or later.

Description & Usage

GetPixel determines the color of a specific pixel on a device. The function finds the RGB value of the pixel which is checked.

Return Value

If an error occured, the function returns &HFFFF. If successful, the function returns the RGB value of the pixel which was checked.

Visual Basic-Specific Issues

None.

Parameters

hdc: A handle to a device context to the device to check a pixel of.
nXPos: The x-coordinate of the pixel to determine the color of.
nYPos: The y-coordinate of the pixel to determine the color of.

Example

' This code is licensed according to the terms and conditions listed here. ' Fill all of window Form1 with the color which is located at ' coordinate (75,100).  Fill the window by filling its rectangle using a ' brush derived from the color of the pixel. Dim rgbVal As Long  ' RGB color of the pixel Dim hBrush As Long  ' handle to the brush we'll create Dim winrect As RECT  ' rectangle of Form1 Dim retval As Long  ' return value ' Determine the color of the pixel on Form1 at (75,100). rgbVal = GetPixel(Form1.hDC, 75, 100) ' Get the dimensions of the rectangle of window Form1. retval = GetWindowRect(Form1.hWnd, winrect) ' Create a solid brush of that color. hBrush = CreateSolidBrush(rgbVal) ' Use that brush to fill in all of Form1 (its entire rectangle). retval = FillRect(Form1.hDC, winrect, hBrush) ' Delete the brush we created to save resources. retval = DeleteObject(hBrush)