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.
//
int objType = UnsafeNativeMethods.GetObjectType(new HandleRef(null, hdc));
switch(objType) {
case NativeMethods.OBJ_DC:
case NativeMethods.OBJ_METADC:
case NativeMethods.OBJ_MEMDC:
case NativeMethods.OBJ_ENHMETADC:
break;
default:
throw new ArgumentException(SR.GetString(SR.DCTypeInvalid));
}
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);
Win32Exception ex = null;
if ( hbmRet == IntPtr.Zero ) {
ex = new Win32Exception(Marshal.GetLastWin32Error());
#if DEBUG
DumpBitmapInfo(ref pbmi);
#endif
}
#if DEBUG
if (DoubleBuffering.TraceVerbose) {
DumpBitmapInfo(ref pbmi);
}
#endif
if(ex!=null) {
throw ex;
}
}
return hbmRet;
}
/// <summary>
/// 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.
/// </summary>
/// <returns>A valid bitmap handle if successful, IntPtr.Zero otherwise.</returns>
private IntPtr CreateCompatibleDIB(IntPtr hdc, IntPtr hpal, int ulWidth, int ulHeight, ref IntPtr ppvBits)
{
if (hdc == IntPtr.Zero)
{
throw new ArgumentNullException(nameof(hdc));
}
IntPtr hbmRet = IntPtr.Zero;
var pbmi = new NativeMethods.BITMAPINFO_FLAT();
// Validate hdc.
Interop.Gdi32.ObjectType objType = Interop.Gdi32.GetObjectType(hdc);
switch (objType)
{
case Interop.Gdi32.ObjectType.OBJ_DC:
case Interop.Gdi32.ObjectType.OBJ_METADC:
case Interop.Gdi32.ObjectType.OBJ_MEMDC:
case Interop.Gdi32.ObjectType.OBJ_ENHMETADC:
break;
default:
throw new ArgumentException(SR.DCTypeInvalid);
}
if (FillBitmapInfo(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);
Win32Exception ex = null;
if (hbmRet == IntPtr.Zero)
{
ex = new Win32Exception(Marshal.GetLastWin32Error());
}
if (ex != null)
{
throw ex;
}
}
return(hbmRet);
}