How do I get the size of a DC?

[bubu]

How do I get the size of a DC? Width and height?

I've tried GetObject Windows API without sucess. =(

[bubu]

I have managed to do it. But, i use GetWindowFromDC() API to get window that is the owner of the DC. Then I use GetWindowRect() API to retrive the DC size.

BUT! If the DC has no owner I cannot read it's bytes with GetDIBBits because I will not be able to determine it's size.

I need another method. I'm almost sure it iwll have to do with GetObject() API but I can't seem to do it.

Current code (VB):

I'm sure you will all understand VB code. i'm not asking a quetion about VB programming it's about WinAPI GDI programming and the code I have is VB:

' Returns an image from a given DC
Public Function atxLoadImageDC(SrcDC As Long) As atxImage
	Dim iBitmap As Long, iDC As Long
	Dim bmp As BITMAP, oldObj As Long
	Dim tmpDC As Long, ArraySize As Long
	Dim I As Long, x As Long, y As Long
	Dim DCWinHwnd As Long, DCWinRECT As RECT

	DCWinHwnd = WindowFromDC(SrcDC)
	GetWindowRect DCWinHwnd, DCWinRECT

	With atxLoadImageDC
		.Width = DCWinRECT.Right - DCWinRECT.Left
		.Height = DCWinRECT.Bottom - DCWinRECT.Top
		.bmi.bmiHeader.bmSize = 40			   'Size, in bytes, of the header (always 40)
		.bmi.bmiHeader.bmPlanes = 1			  'Number of planes (always one for this instance)
		.bmi.bmiHeader.bmBitCount = 24		   'Bits per pixel (always 24 for this instance)
		.bmi.bmiHeader.bmCompression = BI_RGB	'Compression: standard/none or RLE
		.bmi.bmiHeader.bmWidth = .Width
		.bmi.bmiHeader.bmHeight = -.Height
		ArraySize = ((.Width * 3) - 1) + (.Width Mod 4)
	End With

	ReDim atxLoadImageDC.Pixel(0 To ArraySize, 0 To atxLoadImageDC.Height)

	iDC = CreateCompatibleDC(SrcDC)
	iBitmap = CreateDIBSection(iDC, atxLoadImageDC.bmi, DIB_RGB_COLORS, ByVal 0&, ByVal 0&, ByVal 0&)
	oldObj = SelectObject(iDC, iBitmap)
	BitBlt iDC, 0, 0, atxLoadImageDC.Width, atxLoadImageDC.Height, SrcDC, 0, 0, vbSrcCopy
	GetDIBits iDC, iBitmap, 0, atxLoadImageDC.Height, atxLoadImageDC.Pixel(0, 0), atxLoadImageDC.bmi, DIB_RGB_COLORS

	DeleteObject SelectObject(iDC, oldObj)
	DeleteDC iDC
	DeleteObject iBitmap
End Function

Help please.

[hankdane]

A Device Context doesn't have a size.

[bubu]

Hmmm. You are sure? If so then it's great news to me. It means my current method of getting the bits from a given DC is correct: I'm assuming that the DC size is the same size of the window that owns it.

Thanks for attention.

[hankdane]

That's correct. For an on-screen DC, the relevant size is that of the client area of the window. For an in-memory DC, the relevant size is that of the bitmap currently selected into the DC.