replacing picturebox with device context

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Nov 2nd, 2003, 12:36 AM
daydee

replacing picturebox with device context
Hi, I'd like to be able to get rid of a picturebox I'm using on one of my forms.
I know I'll have to use StretchBlt API to replace the paintpicture vb function in my code but how would I go about creating the device context to replace the picturebox itself and making all this work.
I guess I should ask also... is loading an image to a device context much quicker than loading to a picturebox?

Thanks in advance,

what I have so far
VB Code:
```
Dim MyPic As StdPicture
Set MyPic = LoadPicture(picturePath)
          Call Picture1.PaintPicture(MyPic, 0, 0, Picture1.Width, Picture1.Height)
          Set MyPic = Nothing
          Image1.Picture = Picture1.Image
          Set Picture1.Picture = Nothing
```

VB Code:

Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC 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 dwRop As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd 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 Sub Command1_Click()
    Dim nDC As Long, nBitmap As Long
    
    'create the memory dc
    nDC = CreateCompatibleDC(GetDC(0))
    nBitmap = CreateCompatibleBitmap(GetDC(0), 100, 100)
    
    'select the bitmap into memory
    SelectObject nDC, nBitmap
    
    'do stuff to it
    BitBlt nDC, 0, 0, 100, 100, GetDC(0), 0, 0, vbSrcCopy
    BitBlt Me.hdc, 0, 0, 100, 100, nDC, 0, 0, vbSrcCopy
    
    'and cleanup
    DeleteObject nBitmap
    DeleteDC nDC
End Sub

Nov 2nd, 2003, 01:33 AM
daydee

Thanks BuggyProgrammer,

In the end though I need to load that image to an image box.
Like what I had
Image1.Picture = Picture1.Image

The reason I'm not loading directly to the image box is that in reality I may have as many as 500 image files to load into an array of imagebox (created at run time) and loading directly to them loads the entire image file content regardless if the imagebox is only 1 inch wide x 1 inch high! which is about the size of my imagebox controls.
That is just a plain waste of memory.
What I'm trying to achieve is to resize/scale down each image file prior to loading them onto the imagebox.

Using the picturebox does the trick but I'd sure like to get rid of it if I can.
Nov 2nd, 2003, 01:46 AM
daydee

Also I forgot to mention that these image files would not only be limited to bitmaps but could be jpg as well.
:(

hmm.....

you can change a hDC into a picture object:

VB Code:

Private Declare Function CreateCompatibleDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function SelectObject Lib "gdi32" (ByVal hdc As Long, ByVal hObject As Long) As Long
Private Declare Function DeleteObject Lib "gdi32" (ByVal hObject As Long) As Long
Private Declare Function DeleteDC Lib "gdi32" (ByVal hdc As Long) As Long
Private Declare Function BitBlt Lib "gdi32" (ByVal hDestDC 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 dwRop As Long) As Long
Private Declare Function GetDC Lib "user32" (ByVal hwnd As Long) As Long
Private Declare Function CreateCompatibleBitmap Lib "gdi32" (ByVal hdc As Long, ByVal nWidth As Long, ByVal nHeight As Long) As Long
Const RC_PALETTE As Long = &H100
Const SIZEPALETTE As Long = 104
Const RASTERCAPS As Long = 38
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 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
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 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 Sub Command1_Click()
    Dim nDC As Long, nBitmap As Long
    
    'create the memory dc
    nDC = CreateCompatibleDC(GetDC(0))
    nBitmap = CreateCompatibleBitmap(GetDC(0), 100, 100)
    
    'select the bitmap into memory
    SelectObject nDC, nBitmap
    
    'do stuff to it
    BitBlt nDC, 0, 0, 100, 100, GetDC(0), 0, 0, vbSrcCopy
    
    'set it as a picture
    Me.Picture = hDCToPicture(nDC, 0, 0, 100, 100)
    
    'and cleanup
    DeleteObject nBitmap
    DeleteDC nDC
End Sub
 
    'KPD-Team 1999
    'URL: [url]http://www.allapi.net/[/url]
    'E-Mail: [email][email protected][/email]
    'Create a picture object from the screen
    
Function hDCToPicture(ByVal hDCSrc As Long, ByVal LeftSrc As Long, ByVal TopSrc As Long, ByVal WidthSrc As Long, ByVal HeightSrc As Long) As Picture
    Dim hDCMemory As Long, hBmp As Long, hBmpPrev As Long, R As Long
    Dim hPal As Long, hPalPrev As Long, RasterCapsScrn As Long, HasPaletteScrn As Long
    Dim PaletteSizeScrn As Long, LogPal As LOGPALETTE
 
    'Create a compatible device context
    hDCMemory = CreateCompatibleDC(hDCSrc)
    'Create a compatible bitmap
    hBmp = CreateCompatibleBitmap(hDCSrc, WidthSrc, HeightSrc)
    'Select the compatible bitmap into our compatible device context
    hBmpPrev = SelectObject(hDCMemory, hBmp)
 
    'Raster capabilities?
    RasterCapsScrn = GetDeviceCaps(hDCSrc, RASTERCAPS) ' Raster
    'Does our picture use a palette?
    HasPaletteScrn = RasterCapsScrn And RC_PALETTE ' Palette
    'What's the size of that palette?
    PaletteSizeScrn = GetDeviceCaps(hDCSrc, SIZEPALETTE) ' Size of
 
    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        'Set the palette version
        LogPal.palVersion = &H300
        'Number of palette entries
        LogPal.palNumEntries = 256
        'Retrieve the system palette entries
        R = GetSystemPaletteEntries(hDCSrc, 0, 256, LogPal.palPalEntry(0))
        'Create the palette
        hPal = CreatePalette(LogPal)
        'Select the palette
        hPalPrev = SelectPalette(hDCMemory, hPal, 0)
        'Realize the palette
        R = RealizePalette(hDCMemory)
    End If
 
    'Copy the source image to our compatible device context
    R = BitBlt(hDCMemory, 0, 0, WidthSrc, HeightSrc, hDCSrc, LeftSrc, TopSrc, vbSrcCopy)
 
    'Restore the old bitmap
    hBmp = SelectObject(hDCMemory, hBmpPrev)
 
    If HasPaletteScrn And (PaletteSizeScrn = 256) Then
        'Select the palette
        hPal = SelectPalette(hDCMemory, hPalPrev, 0)
    End If
 
    'Delete our memory DC
    R = DeleteDC(hDCMemory)
 
    Set hDCToPicture = CreateBitmapPicture(hBmp, hPal)
End Function
Function CreateBitmapPicture(ByVal hBmp As Long, ByVal hPal As Long) As Picture
    Dim R As Long, Pic As PicBmp, IPic As IPicture, IID_IDispatch As GUID
 
    'Fill GUID info
    With IID_IDispatch
        .Data1 = &H20400
        .Data4(0) = &HC0
        .Data4(7) = &H46
    End With
 
    'Fill picture info
    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
    R = OleCreatePictureIndirect(Pic, IID_IDispatch, 1, IPic)
 
    'Return the new picture
    Set CreateBitmapPicture = IPic
End Function

most of the code was from the apiguide