// bFillBitmapInfo
//
// Fills in the fields of a BITMAPINFO so that we can create a bitmap
// that matches the format of the display.
//
// This is done by creating a compatible bitmap and calling GetDIBits
// to return the color masks. This is done with two calls. The first
// call passes in biBitCount = 0 to GetDIBits which will fill in the
// base BITMAPINFOHEADER data. The second call to GetDIBits (passing
// in the BITMAPINFO filled in by the first call) will return the color
// table or bitmasks, as appropriate.
//
// Returns:
// TRUE if successful, FALSE otherwise.
//
// History:
// 07-Jun-1995 -by- Gilman Wong [gilmanw]
// Wrote it.
//
// 15-Nov-2000 -by- Chris Anderson [chrisan]
// Ported it to C#
//
private bool bFillBitmapInfo(IntPtr hdc, IntPtr hpal, ref NativeMethods.BITMAPINFO_FLAT pbmi)
{
IntPtr hbm = IntPtr.Zero;
bool bRet = false;
try {
//
// Create a dummy bitmap from which we can query color format info
// about the device surface.
//
hbm = SafeNativeMethods.CreateCompatibleBitmap(new HandleRef(null, hdc), 1, 1);
if (hbm == IntPtr.Zero)
{
throw new OutOfMemoryException(SR.GetString(SR.GraphicsBufferQueryFail));
}
pbmi.bmiHeader_biSize = Marshal.SizeOf(typeof(NativeMethods.BITMAPINFOHEADER));
pbmi.bmiColors = new byte[NativeMethods.BITMAPINFO_MAX_COLORSIZE * 4];
//
// Call first time to fill in BITMAPINFO header.
//
IntPtr diRet = SafeNativeMethods.GetDIBits(new HandleRef(null, hdc),
new HandleRef(null, hbm),
0,
0,
IntPtr.Zero,
ref pbmi,
NativeMethods.DIB_RGB_COLORS);
if (pbmi.bmiHeader_biBitCount <= 8)
{
bRet = bFillColorTable(hdc, hpal, ref pbmi);
}
else
{
if (pbmi.bmiHeader_biCompression == NativeMethods.BI_BITFIELDS)
{
//
// Call a second time to get the color masks.
// It's a GetDIBits Win32 "feature".
//
SafeNativeMethods.GetDIBits(new HandleRef(null, hdc),
new HandleRef(null, hbm),
0,
pbmi.bmiHeader_biHeight,
IntPtr.Zero,
ref pbmi,
NativeMethods.DIB_RGB_COLORS);
}
bRet = true;
}
}
finally {
if (hbm != IntPtr.Zero)
{
SafeNativeMethods.DeleteObject(new HandleRef(null, hbm));
hbm = IntPtr.Zero;
}
}
return(bRet);
}