• Home
 · 
• Windows API Call/Explanation
 · 
• This magnifies the area under the mouse pointer.

This magnifies the area under the mouse pointer.

This magnifies the area under the mouse pointer.

API Declarations


Add a picture box named Picture1.
Add a timer named Timer1.
Add a UpDown control named UpDown1.
Add a textbox named Text1.
Copy the code below to the form.



Rate This magnifies the area under the mouse pointer.

• 1
• 2
• 3
• 4
• 5

(1(1 Vote))

Private Type POINTAPI
    x As Long
    y As Long
End Type

Private Declare Function GetParent Lib "user32.dll" (ByVal hwnd As Long) As Long

Private Declare Function WindowFromPoint Lib "user32.dll" (ByVal xPoint As Long, ByVal yPoint As Long) As Long

Private Declare Function GetCursorPos Lib "USER32" (lpPoint As POINTAPI) As Long

Private Declare Function ReleaseDC Lib "user32.dll" (ByVal hwnd As Long, ByVal hdc As Long) As Long

Private Declare Function GetWindowDC Lib "USER32" (ByVal hwnd As Long) As Long

Private Declare Function GetDesktopWindow Lib "USER32" () As Long

Private Declare Function StretchBlt Lib "gdi32" (ByVal hdc As Long, _
       ByVal x As Long, ByVal y As Long, ByVal nWidth As Long, _
       ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, _
       ByVal ySrc As Long, ByVal nSrcWidth As Long, _
       ByVal nSrcHeight As Long, ByVal dwRop As Long) As Long

Private Sub Form_Load()
Me.Move 10, 10, 2775, 3390 'position form
UpDown1.Value = 50
Text1.Text = UpDown1.Value & "%"
Me.AutoRedraw = True
End Sub

Private Sub Form_Resize()
Picture1.Move 0, 0, Me.ScaleWidth, Me.ScaleHeight - 315
Text1.Move 0, Me.ScaleHeight - 315, 765, 315
UpDown1.Move 765, Me.ScaleHeight - 315, 195, 315
End Sub

Private Sub Timer1_Timer()
Dim rv As Long, mXY As POINTAPI, magFCT As Single
Dim hWP As Long, hPP As Long, maxWIDTH As Long, maxHEIGHT As Long
Dim src_LEFT As Long, src_TOP As Long, src_WIDTH As Long, src_HEIGHT As Long
Dim dst_LEFT As Long, dst_TOP As Long, dst_WIDTH As Long, dst_HEIGHT As Long
Dim dst_centerX As Long, dst_centerY As Long
Dim src_HANDLE As Long, src_DC As Long
Dim meW As Long, meH As Long

    magFCT = 1 - (UpDown1.Value / 100) 'magnification factor

    rv = GetCursorPos(mXY) 'get mouse position
    
    hWP = WindowFromPoint(mXY.x, mXY.y) 'handle to window under mouse
    hPP = GetParent(hWP) 'handle to parent to window under mouse
    If hPP = 0 Then hPP = hWP 'if no parent, use window from point
    If hPP <> Me.hwnd Then 'do not magnify our form
        '--describe area to accept magnification----------------
        dst_centerX = Picture1.ScaleWidth / 2
        dst_centerY = Picture1.ScaleHeight / 2
        dst_LEFT = 0
        dst_TOP = 0
        dst_WIDTH = Picture1.ScaleWidth / Screen.TwipsPerPixelX
        dst_HEIGHT = Picture1.ScaleHeight / Screen.TwipsPerPixelY
        '--describe area of screen to magnify------
        meH = (Picture1.ScaleHeight / Screen.TwipsPerPixelX) * magFCT
        meW = (Picture1.ScaleWidth / Screen.TwipsPerPixelY) * magFCT
        src_LEFT = mXY.x - (meW / 2)
        src_TOP = mXY.y - (meH / 2)
        src_WIDTH = meW
        src_HEIGHT = meH
        '--adjust for edge of screen----------------------------
        maxWIDTH = Screen.Width / Screen.TwipsPerPixelX
        maxHEIGHT = Screen.Height / Screen.TwipsPerPixelY
        If src_LEFT < 0 Then
            dst_centerX = dst_centerX + (src_LEFT * (Screen.TwipsPerPixelX / magFCT))
            src_LEFT = 0
        ElseIf src_LEFT + src_WIDTH > maxWIDTH Then
            dst_centerX = dst_centerX + (src_LEFT + src_WIDTH - maxWIDTH) * (Screen.TwipsPerPixelX / magFCT)
            src_LEFT = src_LEFT - (src_LEFT + src_WIDTH - maxWIDTH)
        End If
        If src_TOP < 0 Then
            dst_centerY = dst_centerY + (src_TOP * (Screen.TwipsPerPixelY / magFCT))
            src_TOP = 0
        ElseIf src_TOP + src_HEIGHT > maxHEIGHT Then
            dst_centerY = dst_centerY + (src_TOP + src_HEIGHT - maxHEIGHT) * (Screen.TwipsPerPixelY / magFCT)
            src_TOP = src_TOP - (src_TOP + src_HEIGHT - maxHEIGHT)
        End If
        
        
        src_HANDLE = GetDesktopWindow() 'get a handle to screen
        src_DC = GetWindowDC(src_HANDLE) 'get device context to screen
        '--copy section of screen to form-----------------------------
        StretchBlt Picture1.hdc, _
                   dst_LEFT, dst_TOP, dst_WIDTH, dst_HEIGHT, _
                   src_DC, _
                   src_LEFT, src_TOP, src_WIDTH, src_HEIGHT, vbSrcCopy
        rv = ReleaseDC(src_HANDLE, src_DC) ' release screen dc
        '--draw spotter on screen
        Picture1.Line (dst_centerX, dst_centerY - 300)-(dst_centerX, dst_centerY + 300)
        Picture1.Line (dst_centerX - 300, dst_centerY)-(dst_centerX + 300, dst_centerY)
        
    End If
    Me.Caption = "(x,y)=" & mXY.x * Screen.TwipsPerPixelX & "," & mXY.y * Screen.TwipsPerPixelY
End Sub

Private Sub UpDown1_Change()
Text1.Text = UpDown1.Value & "%"
End Sub