Trapping the GridColumnResize event (MSFlexGrid)
The MSFlexGrid doesn't provide a ColumnResize event. However it's needed in some apps, where this grid is used. The code below shows how emulate the ColumnResize event by analizing the sequences of other windows messages.
Assumes
The knowlege of API is required.
You must have MSflxgrd.ocx installed.
Create a Form frmMain and place a MSFlexGrid control with name MSFlexGrid1 and a Module. The code is given below.
Side Effects
Don't ever finish the application with the Stop button of VB Environment. This will cause VBE to terminate.
Application was tested under VB 5.0 (SP3)
API Declarations
' Function to retrieve the address of the current Message-Handling routine
Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
' Function to define the address of the Message-Handling routine
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
' Function to execute a function residing at a specific memory address
Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
'Windows messages constants
Public Const WM_LBUTTONUP = &H202
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_ERASEBKGND = &H14
Rate Trapping the GridColumnResize event (MSFlexGrid)
(3(3 Vote))
/*************************** frmMain ****************************/
VERSION 5.00
Object = "{5E9E78A0-531B-11CF-91F6-C2863C385E30}#1.0#0"; "Msflxgrd.ocx"
Begin VB.Form frmMain
BorderStyle = 3 'Fixed Dialog
Caption = "Resize the Grid !!!"
ClientHeight = 4110
ClientLeft = 4650
ClientTop = 3750
ClientWidth = 6735
LinkTopic = "Form1"
MaxButton = 0 'False
MinButton = 0 'False
ScaleHeight = 4110
ScaleWidth = 6735
ShowInTaskbar = 0 'False
Begin MSFlexGridLib.MSFlexGrid MSFlexGrid1
Height = 3015
Left = 120
TabIndex = 0
Top = 960
Width = 6495
_ExtentX = 11456
_ExtentY = 5318
_Version = 65541
Rows = 4
Cols = 4
AllowUserResizing= 1
End
Begin VB.Label Label2
Caption = "Try to resize the columns of MSFlexGrid. All the columns will be resized proportionally."
BeginProperty Font
Name = "MS Sans Serif"
Size = 9.75
Charset = 204
Weight = 400
Underline = 0 'False
Italic = 0 'False
Strikethrough = 0 'False
EndProperty
ForeColor = &H8000000D&
Height = 615
Left = 1320
TabIndex = 1
Top = 120
Width = 3975
End
End
Attribute VB_Name = "frmMain"
Attribute VB_GlobalNameSpace = False
Attribute VB_Creatable = False
Attribute VB_PredeclaredId = True
Attribute VB_Exposed = False
Option Explicit
' This constant is used to refer to the Message Handling function in a given window
Private Const GWL_WNDPROC = (-4)
Private Sub Form_Load()
'Save the address of the existing Message Handler
g_lngDefaultHandler = GetWindowLong(Me.MSFlexGrid1.hwnd, GWL_WNDPROC)
'Define new message handler routine
Call SetWindowLong(Me.MSFlexGrid1.hwnd, GWL_WNDPROC, AddressOf GridMessage)
End Sub
Private Sub Form_Unload(Cancel As Integer)
'Return the old handler back
Call SetWindowLong(Me.MSFlexGrid1.hwnd, GWL_WNDPROC, g_lngDefaultHandler)
End Sub
Public Sub ResizeGridProportional()
Dim SumWidth As Long
Dim i As Integer
With MSFlexGrid1
For i = 1 To .Cols
SumWidth = SumWidth + .ColWidth(i - 1)
Next i
For i = 1 To .Cols
.ColWidth(i - 1) = SumWidth / .Cols
Next i
End With
End Sub
/* ******************** MODULE ***********************************/
Attribute VB_Name = "mHandlers"
'
Option Explicit
Public g_lngDefaultHandler As Long ' Original handler of the grid events
Private m_bLMousePressed As Boolean 'true if the left button is pressed
Private m_bLMouseClicked As Boolean 'true just after the click (i.e. just after the left button is released)
'API declarations ============================================================
' Function to retrieve the address of the current Message-Handling routine
Declare Function GetWindowLong Lib "user32" Alias "GetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long) As Long
' Function to define the address of the Message-Handling routine
Declare Function SetWindowLong Lib "user32" Alias "SetWindowLongA" (ByVal hwnd As Long, ByVal nIndex As Long, ByVal dwNewLong As Long) As Long
' Function to execute a function residing at a specific memory address
Declare Function CallWindowProc Lib "user32" Alias "CallWindowProcA" (ByVal lpPrevWndFunc As Long, ByVal hwnd As Long, ByVal Msg As Long, ByVal wParam As Long, ByVal lParam As Long) As Long
'Windows messages constants
Public Const WM_LBUTTONUP = &H202
Public Const WM_LBUTTONDOWN = &H201
Public Const WM_ERASEBKGND = &H14
'==============================================================================
'this is our event handler
Public Function GridMessage(ByVal hwnd As Long, ByVal Msg As Long, ByVal wp As Long, ByVal lp As Long) As Long
If m_bLMousePressed And Msg = WM_LBUTTONUP Then
'button have been just released
m_bLMousePressed = False
m_bLMouseClicked = True
End If
If Not (m_bLMousePressed) And Msg = WM_LBUTTONDOWN Then
'button have been just pressed
m_bLMousePressed = True
m_bLMouseClicked = False
End If
If m_bLMouseClicked And (Msg = WM_ERASEBKGND) Then
'Only when resize happens this event may occur after releasing the button !
'When user is making a simple click on grid,
'the WM_ERASEBKGND event occurs before WM_LBUTTONUP,
'and therefore will not be handled there
frmMain.ResizeGridProportional
m_bLMouseClicked = False
End If
'call the default message handler
GridMessage = CallWindowProc(g_lngDefaultHandler, hwnd, Msg, wp, lp)
End Function
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