Ejemplos usando el Api de windows para Visual basic

44 - Capturar el área cliente de un picture y de una ventana o formulario y pegar la imagen en el portapapeles

Este Ejemplo captura el área gráfica de un Picture y de un formulario, es decir el Hdc de pantalla correspondiente a la región del formulario y del Picture.

Todo lo que esté contenido dentro de estos objetos, que si o si deben poseer la propiedad HDC (Formularios y PictureBox por ejemplo), se podrá capturar, incluyendo los controles que contenga, cualquier dibujo hecho con los métodos gráficos y cualquier imágen cargada con la propiedad Picture, ..en conclusión se captura todo.

Vista del formulario con los controles para el ejemplo:

Capturar la imagen de un formulario y de un picturebox y pegarla en el portapapeles

Controles para el form

Colocar 2 CommandButton, el Command1 captura la región completa del formulario sin la barra de título, y la pega en el portapapeles. El Command2 hace lo mismo pero para el Picture1

Código fuente en el Formulario:

'CAPTURA EL AREA CLIENTE DEL FORMULARIO SIN LA BARRA DE TITULO Y LO PEGA EN EL CLIPBOARD '______________________________________________________________ Private Sub Command1_Click() 'Borramos el Clipboard Clipboard.Clear 'Pegamos en el portapapeles, pasandole a la sub el formulario Clipboard.SetData CaptureClient(Form1) End Sub 'CAPTURA EL AREA CLIENTE DEL PICTURE1 T LO PEGA EN EL PORTAPAPELES '______________________________________________________________ Private Sub Command2_Click() 'Borramos el Clipboard Clipboard.Clear 'Le pasamos a la Sub el Picture1 Clipboard.SetData CaptureClient(Picture1) End Sub

En un módulo .bas

Option Base 0 Private Type PALETTEENTRY peRed As Byte peGreen As Byte peBlue As Byte peFlags As Byte End Type 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 Const RASTERCAPS As Long = 38 Private Const RC_PALETTE As Long = &H100 Private Const SIZEPALETTE As Long = 104 Private Type RECT Left As Long Top As Long Right As Long Bottom As Long End Type Private Declare Function CreateCompatibleDC Lib "GDI32" ( _ ByVal hDC As Long) As Long Private Declare Function CreateCompatibleBitmap Lib "GDI32" ( _ ByVal hDC As Long, ByVal nWidth As Long, _ ByVal nHeight As Long) As Long Private Declare Function GetDeviceCaps Lib "GDI32" ( _ ByVal hDC As Long, ByVal iCapabilitiy As Long) As Long Private Declare Function GetSystemPaletteEntries Lib "GDI32" ( _ ByVal hDC As Long, ByVal wStartIndex As Long, _ ByVal wNumEntries As Long, lpPaletteEntries As PALETTEENTRY) _ As Long Private Declare Function CreatePalette Lib "GDI32" ( _ lpLogPalette As LOGPALETTE) As Long Private Declare Function SelectObject Lib "GDI32" ( _ ByVal hDC As Long, ByVal hObject As Long) As Long 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 Private Declare Function DeleteDC Lib "GDI32" ( _ ByVal hDC As Long) As Long Private Declare Function GetForegroundWindow Lib "USER32" () _ As Long Private Declare Function SelectPalette Lib "GDI32" ( _ ByVal hDC As Long, ByVal hPalette As Long, _ ByVal bForceBackground As Long) As Long Private Declare Function RealizePalette Lib "GDI32" ( _ ByVal hDC As Long) As Long Private Declare Function GetWindowDC Lib "USER32" ( _ ByVal hWnd As Long) As Long Private Declare Function GetDC Lib "USER32" ( _ ByVal hWnd As Long) As Long Private Declare Function GetWindowRect Lib "USER32" ( _ ByVal hWnd As Long, lpRect As RECT) As Long Private Declare Function ReleaseDC Lib "USER32" ( _ ByVal hWnd As Long, ByVal hDC As Long) As Long Private Declare Function GetDesktopWindow Lib "USER32" () As Long Private Type PicBmp Size As Long Type As Long hBmp As Long hPal As Long Reserved As Long End Type Private Declare Function OleCreatePictureIndirect _ Lib "olepro32.dll" (PicDesc As PicBmp, RefIID As GUID, _ ByVal fPictureOwnsHandle As Long, IPic As IPicture) As Long #If Win32 Then Public Function CreateBitmapPicture(ByVal hBmp As Long, _ ByVal hPal As Long) As Picture Dim r As Long #ElseIf Win16 Then #End If 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 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 Picture object. r = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic) ' Return the new Picture object. Set CreateBitmapPicture = IPic End Function #If Win32 Then Public Function CaptureWindow(ByVal hWndSrc As Long, _ ByVal Client 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 #ElseIf Win16 Then #End If Dim LogPal As LOGPALETTE ' Depending on the value of Client get the proper device context. If Client Then hDCSrc = GetDC(hWndSrc) ' Get device context for client area. Else hDCSrc = GetWindowDC(hWndSrc) ' Get device context for entire ' window. End If ' Create a memory device context 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 screen properties. RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS) ' Raster ' capabilities. HasPaletteScrn = RasterCapsScrn And RC_PALETTE ' Palette ' support. PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE) ' Size of ' palette. ' 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 r = DeleteDC(hDCMemory) r = ReleaseDC(hWndSrc, hDCSrc) Set CaptureWindow = CreateBitmapPicture(hBmp, hPal) End Function Public Function CaptureClient(frmSrc As Object) As Picture Set CaptureClient = CaptureWindow(frmSrc.hWnd, True, 0, 0, _ frmSrc.ScaleX(frmSrc.ScaleWidth, frmSrc.ScaleMode, vbPixels), _ frmSrc.ScaleY(frmSrc.ScaleHeight, frmSrc.ScaleMode, vbPixels)) End Function

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