internal RichEditOleInterface(RichTextBox rtb)
{
m_rich_edit_ole = IntPtr.Zero;
m_text_document = IntPtr.Zero;
// Allocate the ptr that EM_GETOLEINTERFACE will fill in.
using (var buffer = Marshal_.Alloc(EHeap.CoTaskMem, typeof(IntPtr), 1))
{
//Marshal.WriteIntPtr(ptr, IntPtr.Zero); // Clear it.
if (Win32.SendMessage(rtb.Handle, Win32.EM_GETOLEINTERFACE, IntPtr.Zero, buffer.Value.Ptr) == IntPtr.Zero)
{
throw new Exception("RichTextBox.OleInterface - EM_GETOLEINTERFACE failed.");
}
// Read the returned pointer.
using (var pRichEdit = Scope.Create(() => Marshal.ReadIntPtr(buffer.Value.Ptr), p => Marshal.Release(p)))
{
if (pRichEdit == IntPtr.Zero)
{
throw new Exception("RichTextBox.OleInterface - failed to get the pointer.");
}
{ // Query for the IRichEditOle interface.
var guid = new Guid("00020D00-0000-0000-c000-000000000046");
Marshal.QueryInterface(pRichEdit, ref guid, out m_rich_edit_ole);
}
{ // Query for the ITextDocument interface
var guid = new Guid("8CC497C0-A1DF-11CE-8098-00AA0047BE5D");
Marshal.QueryInterface(pRichEdit, ref guid, out m_text_document);
}
}
}
}
/// <summary>
/// Render the contents of the RichTextBox for printing.
/// Return the last character printed + 1 (printing start from this point for next page).
/// http://support.microsoft.com/default.aspx?scid=kb;en-us;812425
/// The RichTextBox control does not provide any method to print the content of the RichTextBox.
/// You can extend the RichTextBox class to use EM_FORMATRANGE message to send the content of
/// a RichTextBox control to an output device such as printer.</summary>
public static int Print(IntPtr rtb_handle, int charFrom, int charTo, PrintPageEventArgs e)
{
// Convert the unit used by the .NET framework (1/100 inch)
// and the unit used by Win32 API calls ('twips' 1/1440 inch)
const double anInch = 14.4;
// Calculate the area to render and print
var print_rect = Win32.RECT.FromLTRB(
(int)(e.MarginBounds.Left * anInch),
(int)(e.MarginBounds.Top * anInch),
(int)(e.MarginBounds.Right * anInch),
(int)(e.MarginBounds.Bottom * anInch));
// Calculate the size of the page
var page_rect = Win32.RECT.FromLTRB(
(int)(e.PageBounds.Left * anInch),
(int)(e.PageBounds.Top * anInch),
(int)(e.PageBounds.Right * anInch),
(int)(e.PageBounds.Bottom * anInch));
// Create a format range
using (var hdc = e.Graphics.GetHdcScope())
{
var fmt_range = new Win32.FORMATRANGE
{
char_range = new Win32.CHARRANGE
{
max = charTo, // Indicate character from to character to
min = charFrom, //
},
hdc = hdc, // Use the same DC for measuring and rendering
hdcTarget = hdc, // Point at printer hDC
rc = print_rect, // Indicate the area on page to print
rcPage = page_rect, // Indicate size of page
};
// Get the pointer to the FORMATRANGE structure in non-GC memory
using (var buffer = Marshal_.Alloc <Win32.FORMATRANGE>(EHeap.CoTaskMem))
{
Marshal.StructureToPtr(fmt_range, buffer.Value.Ptr, false);
// Send the rendered data for printing, then release and cached info
var res = Win32.SendMessage(rtb_handle, (uint)Win32.EM_FORMATRANGE, new IntPtr(1), buffer.Value.Ptr);
Win32.SendMessage(rtb_handle, (uint)Win32.EM_FORMATRANGE, (IntPtr)0, (IntPtr)0);
return((int)res); // Return last + 1 character printed
}
}
}