Screenshot of form, and resize to fit a button.

Posted on 2005-04-14
Last Modified: 2008-02-01
Hi i have a program where i have some rather large buttons to open some forms...
Once these forms are done loading i would like them to take a screenshot of their look and resize it to fit the button from where it was loaded. Meaning you would kinda like have a preview of whats beyond the button.

I have been trying to do this using StretchBlt however the results are very poor... i am aware that the resize maybe wont be as good as doing it in Adobe Photoshop however it should be  better than what i have been able to get...

Can someone help me ...
Question by:mSchmidt
    LVL 9

    Expert Comment

    Hi there..

    I found some code a while back on, that will capture screen areas, including the activewindow (i.e. form that is currently displayed).  I added the save to bmp.

    Create a project with two forms.  From form1 1 you'll run the picture capture that shows form2 and the captures the activewindow.

    Drop a command button and picturebox on a form, and use this code in the command
    Private Sub Command1_Click()

    Dim EndTime As Date
    ' Give the user 2 seconds to activate
    ' a window then capture it.
    MsgBox "Two seconds after you close this dialog " & _
           "the active window will be captured.", _
           vbInformation, "Capture Active Window"
    ' Wait for two seconds
    EndTime = DateAdd("s", 2, Now)
    Do Until Now > EndTime
    Loop        'show the form to capture
    Set Picture1.Picture = CaptureActiveWindow()
    file_name = App.Path
    If Right$(file_name, 1) <> "\" Then file_name = _
        file_name & "\"
    SavePicture Picture1.Picture, file_name & "temp.bmp"
    unload form2

    ' Get the active window.
    ' Set focus back to form

    End Sub

    Put the following in a module.  There are several other functions in here for capturing window regions and printing, but the command code above drives only one.

    Option Explicit
    Option Base 0
    ' This module contains several routines for capturing windows into a
    ' picture.  All routines have palette support.
    ' CreateBitmapPicture   - Creates a picture object from a bitmap and palette.
    ' CaptureWindow         - Captures any window given a window handle.
    ' CaptureActiveWindow   - Captures the active window on the desktop.
    ' CaptureForm           - Captures the entire form.
    ' CaptureClient         - Captures the client area of a form.
    ' CaptureScreen         - Captures the entire screen.
    ' PrintPictureToFitPage - prints any picture as big as possible on the page.
    Private Type PALETTEENTRY
        peRed   As Byte
        peGreen As Byte
        peBlue  As Byte
        peFlags As Byte
    End Type
    Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
    Private Type LOGPALETTE
        palVersion       As Integer
        palNumEntries    As Integer
        palPalEntry(255) As PALETTEENTRY  ' Enough for 256 colors
    End Type
    Private Type GUID
        Data1    As Long
        Data2    As Integer
        Data3    As Integer
        Data4(7) As Byte
    End Type

    Private Type RECT
        Left   As Long
        Top    As Long
        Right  As Long
        Bottom As Long
    End Type

    Private Type PicBmp
        Size As Long
        Type As Long
        hBmp As Long
        hPal As Long
        Reserved As Long
    End Type

    Private Const RASTERCAPS As Long = 38
    Private Const RC_PALETTE As Long = &H100
    Private Const SIZEPALETTE As Long = 104
    ' DC = Device Context
    ' Creates a bitmap compatible with the device associated
    ' with the specified DC.
    Private Declare Function CreateCompatibleBitmap Lib "GDI32" ( _
        ByVal hDC As Long, ByVal nWidth As Long, _
        ByVal nHeight As Long) As Long

    ' Retrieves device-specific information about a specified device.
    Private Declare Function GetDeviceCaps Lib "GDI32" ( _
        ByVal hDC As Long, ByVal iCapabilitiy As Long) As Long

    ' Retrieves a range of palette entries from the system palette
    ' associated with the specified DC.
    Private Declare Function GetSystemPaletteEntries Lib "GDI32" ( _
        ByVal hDC As Long, ByVal wStartIndex As Long, _
        ByVal wNumEntries As Long, lpPaletteEntries As PALETTEENTRY) _
        As Long

    ' Creates a memory DC compatible with the specified device.
    Private Declare Function CreateCompatibleDC Lib "GDI32" ( _
        ByVal hDC As Long) As Long

    ' Creates a logical color palette.
    Private Declare Function CreatePalette Lib "GDI32" ( _
        lpLogPalette As LOGPALETTE) As Long

    ' Selects the specified logical palette into a DC.
    Private Declare Function SelectPalette Lib "GDI32" ( _
        ByVal hDC As Long, ByVal hPalette As Long, _
        ByVal bForceBackground As Long) As Long

    ' Maps palette entries from the current logical
    ' palette to the system palette.
    Private Declare Function RealizePalette Lib "GDI32" ( _
        ByVal hDC As Long) As Long

    ' Selects an object into the specified DC. The new
    ' object replaces the previous object of the same type.
    ' Returned is the handle of the replaced object.
    Private Declare Function SelectObject Lib "GDI32" ( _
        ByVal hDC As Long, ByVal hObject As Long) As Long

    ' Performs a bit-block transfer of color data corresponding to
    ' a rectangle of pixels from the source DC into a destination DC.
    Private Declare Function BitBlt Lib "GDI32" ( _
        ByVal hDCDest As Long, ByVal XDest As Long, _
        ByVal YDest As Long, ByVal nWidth As Long, _
        ByVal nHeight As Long, ByVal hDCSrc As Long, _
        ByVal XSrc As Long, ByVal YSrc As Long, ByVal dwRop As Long) _
        As Long

    ' Retrieves the DC for the entire window, including title bar,
    ' menus, and scroll bars. A window DC permits painting anywhere
    ' in a window, because the origin of the DC is the upper-left
    ' corner of the window instead of the client area.
    Private Declare Function GetWindowDC Lib "USER32" ( _
        ByVal hWnd As Long) As Long

    ' Retrieves a handle to a display DC for the Client area of
    ' a specified window or for the entire screen.  You can use
    ' the returned handle in subsequent GDI functions to draw in
    ' the DC.
    Private Declare Function GetDC Lib "USER32" ( _
        ByVal hWnd As Long) As Long

    ' Releases a DC, freeing it for use by other applications.
    ' The effect of the ReleaseDC function depends on the type
    ' of DC.  It frees only common and window DCs.  It has no
    ' effect on class or private DCs.
    Private Declare Function ReleaseDC Lib "USER32" ( _
        ByVal hWnd As Long, ByVal hDC As Long) As Long

    ' Deletes the specified DC.
    Private Declare Function DeleteDC Lib "GDI32" ( _
        ByVal hDC As Long) As Long

    ' Retrieves the dimensions of the bounding rectangle of the
    ' specified window. The dimensions are given in screen
    ' coordinates that are relative to the upper-left corner
    ' of the screen.
    Private Declare Function GetWindowRect Lib "USER32" ( _
        ByVal hWnd As Long, lpRect As RECT) As Long

    ' Returns a handle to the Desktop window.  The desktop
    ' window covers the entire screen and is the area on top
    ' of which all icons and other windows are painted.
    Private Declare Function GetDesktopWindow Lib "USER32" () As Long

    ' Returns a handle to the foreground window (the window
    ' the user is currently working). The system assigns a
    ' slightly higher priority to the thread that creates the
    ' foreground window than it does to other threads.
    Private Declare Function GetForegroundWindow Lib "USER32" () As Long

    ' Creates a new picture object initialized according to a PICTDESC
    ' structure, which can be NULL, to create an uninitialized object if
    ' the caller wishes to have the picture initialize itself through
    ' IPersistStream::Load.  The fOwn parameter indicates whether the
    ' picture is to own the GDI picture handle for the picture it contains,
    ' so that the picture object will destroy its picture when the object
    ' itself is destroyed.  The function returns an interface pointer to the
    ' new picture object specified by the caller in the riid parameter.
    ' A QueryInterface is built into this call.  The caller is responsible
    ' for calling Release through the interface pointer returned - phew!
    Private Declare Function OleCreatePictureIndirect _
        Lib "olepro32.dll" (PicDesc As PicBmp, RefIID As GUID, _
        ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long
    Public Function CreateBitmapPicture(ByVal hBmp As Long, _
            ByVal hPal As Long) As Picture
    ' CreateBitmapPicture
    '    - Creates a bitmap type Picture object from a bitmap and palette.
    ' hBmp
    '    - Handle to a bitmap
    ' hPal
    '    - Handle to a Palette
    '    - Can be null if the bitmap doesn't use a palette
    ' Returns
    '    - Returns a Picture object containing the bitmap
    Dim r   As Long
    Dim Pic As PicBmp
    ' IPicture requires a reference to "Standard OLE Types"
    Dim IPic          As IPicture
    Dim IID_IDispatch As GUID
    ' Fill in with IDispatch Interface ID
    With IID_IDispatch
        .Data1 = &H20400
        .Data4(0) = &HC0
        .Data4(7) = &H46
    End With
    ' Fill Pic with the necessary parts.
    With Pic
        .Size = Len(Pic)          ' Length of structure
        .Type = vbPicTypeBitmap   ' Type of Picture (bitmap)
        .hBmp = hBmp              ' Handle to bitmap
        .hPal = hPal              ' Handle to palette (may be null)
    End With
    ' Create the Picture object.
    r = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)
    ' Return the new Picture object.
    Set CreateBitmapPicture = IPic
    End Function

    ' CaptureWindow
    '    - Captures any portion of a window.
    ' hWndSrc
    '    - Handle to the window to be captured
    ' bClient
    '    - If True CaptureWindow captures from the bClient area of the
    '      window
    '    - If False CaptureWindow captures from the entire window
    ' LeftSrc, TopSrc, WidthSrc, HeightSrc
    '    - Specify the portion of the window to capture
    '    - Dimensions need to be specified in pixels
    ' Returns
    '    - Returns a Picture object containing a bitmap of the specified
    '      portion of the window that was captured

    Public Function CaptureWindow(ByVal hWndSrc As Long, _
        ByVal bClient As Boolean, ByVal LeftSrc As Long, _
        ByVal TopSrc As Long, ByVal WidthSrc As Long, _
        ByVal HeightSrc As Long) As Picture

    Dim hDCMemory       As Long
    Dim hBmp            As Long
    Dim hBmpPrev        As Long
    Dim r               As Long
    Dim hDCSrc          As Long
    Dim hPal            As Long
    Dim hPalPrev        As Long
    Dim RasterCapsScrn  As Long
    Dim HasPaletteScrn  As Long
    Dim PaletteSizeScrn As Long
    Dim LogPal          As LOGPALETTE
    ' Get the proper Device Context (DC) depending on the value of bClient.
    If bClient Then
        hDCSrc = GetDC(hWndSrc)       'Get DC for Client area.
        hDCSrc = GetWindowDC(hWndSrc) 'Get DC for entire window.
    End If
    ' Create a memory DC for the copy process.
    hDCMemory = CreateCompatibleDC(hDCSrc)
    ' Create a bitmap and place it in the memory DC.
    hBmp = CreateCompatibleBitmap(hDCSrc, WidthSrc, HeightSrc)
    hBmpPrev = SelectObject(hDCMemory, hBmp)
    ' Get the screen properties.
    RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS)   'Raster capabilities
    HasPaletteScrn = RasterCapsScrn And RC_PALETTE       'Palette support
    PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE) 'Palette size
    ' If the screen has a palette make a copy and realize it.
    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        ' Create a copy of the system palette.
        LogPal.palVersion = &H300
        LogPal.palNumEntries = 256
        r = GetSystemPaletteEntries(hDCSrc, 0, 256, LogPal.palPalEntry(0))
        hPal = CreatePalette(LogPal)
        ' Select the new palette into the memory DC and realize it.
        hPalPrev = SelectPalette(hDCMemory, hPal, 0)
        r = RealizePalette(hDCMemory)
    End If
    ' Copy the on-screen image into the memory DC.
    r = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hDCSrc, _
        LeftSrc, TopSrc, vbSrcCopy)
    ' Remove the new copy of the on-screen image.
    hBmp = SelectObject(hDCMemory, hBmpPrev)
    ' If the screen has a palette get back the
    ' palette that was selected in previously.
    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        hPal = SelectPalette(hDCMemory, hPalPrev, 0)
    End If
    ' Release the DC resources back to the system.
    r = DeleteDC(hDCMemory)
    r = ReleaseDC(hWndSrc, hDCSrc)
    ' Create a picture object from the bitmap
    ' and palette handles.
    Set CaptureWindow = CreateBitmapPicture(hBmp, hPal)
    End Function

    Public Function CaptureScreen() As Picture
    Dim hWndScreen As Long
    ' Get a handle to the desktop window.
    hWndScreen = GetDesktopWindow()
    ' Capture the entire desktop.
    With Screen
        Set CaptureScreen = CaptureWindow(hWndScreen, False, 0, 0, _
                .Width \ .TwipsPerPixelX, .Height \ .TwipsPerPixelY)
    End With
    End Function

    Public Function CaptureForm(frm As Form) As Picture
    ' Capture the entire form.
    With frm
        Set CaptureForm = CaptureWindow(.hWnd, False, 0, 0, _
                .ScaleX(.Width, vbTwips, vbPixels), _
                .ScaleY(.Height, vbTwips, vbPixels))
    End With
    End Function

    Public Function CaptureClient(frm As Form) As Picture
    ' Capture the client area of the form.
    With frm
        Set CaptureClient = CaptureWindow(.hWnd, True, 0, 0, _
                .ScaleX(.ScaleWidth, .ScaleMode, vbPixels), _
                .ScaleY(.ScaleHeight, .ScaleMode, vbPixels))
    End With
    End Function

    Public Function CaptureActiveWindow() As Picture
    Dim hWndActive As Long
    Dim RectActive As RECT
    ' Get a handle to the active/foreground window.
    ' Get the dimensions of the window.
    hWndActive = GetForegroundWindow()
    Call GetWindowRect(hWndActive, RectActive)
    ' Capture the active window.
    With RectActive
        Set CaptureActiveWindow = CaptureWindow(hWndActive, False, 0, 0, _
                .Right - .Left, .Bottom - .Top)
    End With
    End Function

    Public Sub PrintPictureToFitPage(Prn As Printer, Pic As Picture)
    ' PrintPictureToFitPage
    '    - Prints a Picture object as big as possible.
    ' Prn
    '    - Destination Printer object
    ' Pic
    '    - Source Picture object
    Dim PicRatio     As Double
    Dim PrnWidth     As Double
    Dim PrnHeight    As Double
    Dim PrnRatio     As Double
    Dim PrnPicWidth  As Double
    Dim PrnPicHeight As Double
    Const vbHiMetric As Integer = 8
    ' Determine if picture should be printed in landscape
    ' or portrait and set the orientation.
    If Pic.Height >= Pic.Width Then
        Prn.Orientation = vbPRORPortrait   'Taller than wide
        Prn.Orientation = vbPRORLandscape  'Wider than tall
    End If
    ' Calculate device independent Width to Height ratio for picture.
    PicRatio = Pic.Width / Pic.Height
    ' Calculate the dimentions of the printable area in HiMetric.
    With Prn
        PrnWidth = .ScaleX(.ScaleWidth, .ScaleMode, vbHiMetric)
        PrnHeight = .ScaleY(.ScaleHeight, .ScaleMode, vbHiMetric)
    End With
    ' Calculate device independent Width to Height ratio for printer.
    PrnRatio = PrnWidth / PrnHeight
    ' Scale the output to the printable area.
    If PicRatio >= PrnRatio Then
        ' Scale picture to fit full width of printable area.
        PrnPicWidth = Prn.ScaleX(PrnWidth, vbHiMetric, Prn.ScaleMode)
        PrnPicHeight = Prn.ScaleY(PrnWidth / PicRatio, vbHiMetric, Prn.ScaleMode)
        ' Scale picture to fit full height of printable area.
        PrnPicHeight = Prn.ScaleY(PrnHeight, vbHiMetric, Prn.ScaleMode)
        PrnPicWidth = Prn.ScaleX(PrnHeight * PicRatio, vbHiMetric, Prn.ScaleMode)
    End If
    ' Print the picture using the PaintPicture method.
    Call Prn.PaintPicture(Pic, 0, 0, PrnPicWidth, PrnPicHeight)
    End Sub

    So at this point you have a bmp.  If you can resize the bmp to fit your commandbutton you're good to go.


    Author Comment

    The rezizing problem is the actual problem,.. i can easily get a screenshot of an area using BitBlt
    LVL 9

    Expert Comment

    I was fooling around with instatiating powerpoint to create a presentation and slide, then add the bmp into the slide, resize it, save it...

    and then set the command.picture = the new file

    but am a little shaky with the PP object model.
    Have some code where excel does essentially the same thing, but could not resolve a couple of things..

    A bit convoluted, but the PP shape resize renders a pretty good image.
    LVL 9

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