Windows API Guide - Reference - Volume 1: Version 3.0 For the MS-DOS and PC-DOS Operating Systems

Public Function GET_X_LPARAM (ByVal lParam As Long) As Long Dim hexstr As String hexstr = Right("00000000" & Hex(lParam), 8) GET_X_LPARAM = CLng("&H" & Right(hexstr, 4)) End Function

Description & Usage

The GET_X_LPARAM macro extracts the x-coordinate from a 32-bit integer packed with a coordinate pair. The macro retrieves the value found in the value's low-order word, which in this case represents the x-coordinate.

Return Value

The macro returns the x-coordinate of the packed coordinate pair.

Visual Basic-Specific Issues

The method I present for extracting the low-order word may seem unusual, since I first convert the value into an 8-digit hex string and then cut that in half. I do this because it is the only way that works 100% of the time in Visual Basic. All the math-based routines I've seen to do this fail when the &H80000000 bit of lParam is set, because VB then sees it as a negative number.

Parameters

lParam

The packed coordinate pair to extract the x-coordinate from.

See Also

GET_Y_LPARAM, MAKEPOINTS

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Last Modified: July 30, 2000 This page is copyright © 2000 Paul Kuliniewicz. Copyright Information Revised October 29, 2000 Go back to the Windows API Guide home page. E-mail: vbapi@vbapi.com Send Encrypted E-Mail This page is at http://www.vbapi.com/ref/g/get_x_lparam.html