// CreateCompatibleDIB
//
// Create a DIB section with an optimal format w.r.t. the specified hdc.
//
// If DIB <= 8bpp, then the DIB color table is initialized based on the
// specified palette. If the palette handle is NULL, then the system
// palette is used.
//
// Note: The hdc must be a direct DC (not an info or memory DC).
//
// Note: On palettized displays, if the system palette changes the
// UpdateDIBColorTable function should be called to maintain
// the identity palette mapping between the DIB and the display.
//
// Returns:
// Valid bitmap handle if successful, NULL if error.
//
// History:
// 23-Jan-1996 -by- Gilman Wong [gilmanw]
// Wrote it.
//
// 15-Nov-2000 -by- Chris Anderson [chrisan]
// Ported it to C#.
//
private IntPtr CreateCompatibleDIB(IntPtr hdc, IntPtr hpal, int ulWidth, int ulHeight, ref IntPtr ppvBits)
{
if (hdc == IntPtr.Zero)
{
throw new ArgumentNullException("hdc");
}
IntPtr hbmRet = IntPtr.Zero;
NativeMethods.BITMAPINFO_FLAT pbmi = new NativeMethods.BITMAPINFO_FLAT();
//
// Validate hdc.
//
if (UnsafeNativeMethods.GetObjectType(new HandleRef(null, hdc)) != NativeMethods.OBJ_DC)
{
throw new ArgumentException("hdc");
}
if (bFillBitmapInfo(hdc, hpal, ref pbmi))
{
//
// Change bitmap size to match specified dimensions.
//
pbmi.bmiHeader_biWidth = ulWidth;
pbmi.bmiHeader_biHeight = ulHeight;
if (pbmi.bmiHeader_biCompression == NativeMethods.BI_RGB)
{
pbmi.bmiHeader_biSizeImage = 0;
}
else
{
if (pbmi.bmiHeader_biBitCount == 16)
{
pbmi.bmiHeader_biSizeImage = ulWidth * ulHeight * 2;
}
else if (pbmi.bmiHeader_biBitCount == 32)
{
pbmi.bmiHeader_biSizeImage = ulWidth * ulHeight * 4;
}
else
{
pbmi.bmiHeader_biSizeImage = 0;
}
}
pbmi.bmiHeader_biClrUsed = 0;
pbmi.bmiHeader_biClrImportant = 0;
//
// Create the DIB section. Let Win32 allocate the memory and return
// a pointer to the bitmap surface.
//
hbmRet = SafeNativeMethods.CreateDIBSection(new HandleRef(null, hdc), ref pbmi, NativeMethods.DIB_RGB_COLORS, ref ppvBits, IntPtr.Zero, 0);
#if DEBUG
if (DoubleBuffering.TraceVerbose)
{
DumpBitmapInfo(ref pbmi);
}
#endif
if (hbmRet == IntPtr.Zero)
{
#if DEBUG
DumpBitmapInfo(ref pbmi);
#endif
throw new Win32Exception(Marshal.GetLastWin32Error());
}
}
return(hbmRet);
}