Using Windowless RichEdit Controls

#include "stdafx.h"
#include "RichDrawText.h"

// Link against riched20.lib
#pragma comment(lib,"riched20.lib")

// The IID in riched20.lib in the Plaform SDK appears to be incorrect.
// This one is from the Microsoft Knowledge Base, article Q270161.
const IID IID_ITextServices = {
  // 8d33f740-cf58-11ce-a89d-00aa006cadc5
  0x8d33f740, 0xcf58, 0x11ce, {0xa8, 0x9d, 0x00, 0xaa, 0x00, 0x6c, 0xad, 0xc5}
};

CRichDrawText::CRichDrawText()
{
  // Get the current font settings
  NONCLIENTMETRICS ncm;
  ::ZeroMemory(&ncm,sizeof ncm);
  ncm.cbSize = sizeof ncm;
  ::SystemParametersInfo(SPI_GETNONCLIENTMETRICS,sizeof ncm,&ncm,0);

  // Work out the name and point size of the font
  CStringW strFontName(ncm.lfMessageFont.lfFaceName);
  HDC hDC = ::GetDC(NULL);
  int iPointSize = -1 * ::MulDiv(ncm.lfMessageFont.lfHeight,72,::GetDeviceCaps(hDC,LOGPIXELSY));
  ::ReleaseDC(NULL,hDC);

  // Create a default character format
  ::ZeroMemory(&m_CharFormat,sizeof m_CharFormat);
  m_CharFormat.cbSize = sizeof m_CharFormat;
  m_CharFormat.dwMask = CFM_BOLD|CFM_CHARSET|CFM_COLOR|CFM_FACE|CFM_ITALIC|CFM_OFFSET|
    CFM_PROTECTED|CFM_SIZE|CFM_STRIKEOUT|CFM_UNDERLINE;
  m_CharFormat.yHeight = 20 * iPointSize;
  m_CharFormat.crTextColor = ::GetSysColor(COLOR_BTNTEXT);
  m_CharFormat.bPitchAndFamily = DEFAULT_PITCH|FF_DONTCARE;
  wcscpy(m_CharFormat.szFaceName,strFontName);

  // Create a default paragraph format
  ::ZeroMemory(&m_ParaFormat,sizeof m_ParaFormat);
  m_ParaFormat.cbSize = sizeof m_ParaFormat;
  m_ParaFormat.dwMask = PFM_ALIGNMENT|PFM_NUMBERING|PFM_OFFSET|PFM_OFFSETINDENT|
    PFM_RIGHTINDENT|PFM_RTLPARA|PFM_STARTINDENT|PFM_TABSTOPS;
  m_ParaFormat.wAlignment = PFA_LEFT;

  // Get an interface to the windowless rich edit control
  CComPtr<IUnknown> unknown;
  HRESULT hr = ::CreateTextServices(NULL,&m_xTextHost,&unknown);
  ASSERT(SUCCEEDED(hr));

  // Convert the returned interface to ITextDocument and ITextServices
  m_TextDoc = unknown;
  m_TextServ = unknown;
}

void CRichDrawText::SetText(LPCWSTR text)
{
  // Get a range for the whole of the text in the control
  CComPtr<ITextRange> range;
  m_TextDoc->Range(0,0,&range);
  range->MoveEnd(tomStory,1,NULL);

  // Replace the whole text
  range->SetText(CComBSTR(text));
}

void CRichDrawText::Range(long cpFirst, long cpLim, ITextRange** ppRange)
{
  // Get the given range of text in the control
  m_TextDoc->Range(cpFirst,cpLim,ppRange);
}

void CRichDrawText::SizeText(CDC& dc, CRect& rect)
{
  LONG w = rect.Width();
  LONG h = 0;

  // Given a rectange of a particular width, work out how much vertical space
  // is needed to display the text in the windowless control.
  SIZEL extent = { -1, -1 };
  HRESULT hr = m_TextServ->TxGetNaturalSize(DVASPECT_CONTENT,
    dc.GetSafeHdc(),0,NULL,TXTNS_FITTOCONTENT,&extent,&w,&h);
  ASSERT(SUCCEEDED(hr));
  if (FAILED(hr))
    h = 0;

  // Adjust the height of the rectangle
  rect.bottom = rect.top+h;
}

void CRichDrawText::DrawText(CDC& dc, const CRect& rect)
{
  // Draw the text in the windowless control onto the given device context,
  // within the given bounding rectangle.
  RECTL rc = { rect.left, rect.top, rect.right, rect.bottom };
  HRESULT hr = m_TextServ->TxDraw(DVASPECT_CONTENT,0,NULL,NULL,dc.GetSafeHdc(),0,
    &rc,NULL,NULL,NULL,0,0);
  ASSERT(SUCCEEDED(hr));
}

BEGIN_INTERFACE_MAP(CRichDrawText, CCmdTarget)
  INTERFACE_PART(CRichDrawText, IID_ITextHost, TextHost)
END_INTERFACE_MAP()

STDMETHODIMP_(ULONG) CRichDrawText::XTextHost::AddRef()
{
  return 1;
}

STDMETHODIMP_(ULONG) CRichDrawText::XTextHost::Release()
{
  return 1;
}

STDMETHODIMP CRichDrawText::XTextHost::QueryInterface(REFIID iid, LPVOID* ppvObj)
{
  METHOD_PROLOGUE(CRichDrawText, TextHost)
  return (HRESULT)pThis->InternalQueryInterface(&iid,ppvObj);
}

HDC CRichDrawText::XTextHost::TxGetDC()
{
  return 0;
}

INT CRichDrawText::XTextHost::TxReleaseDC(HDC hdc)
{
  return 0;
}

BOOL CRichDrawText::XTextHost::TxShowScrollBar(INT fnBar, BOOL fShow)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxEnableScrollBar(INT fuSBFlags, INT fuArrowflags)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxSetScrollRange(INT fnBar, LONG nMinPos, INT nMaxPos, BOOL fRedraw)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxSetScrollPos(INT fnBar, INT nPos, BOOL fRedraw)
{
  return FALSE;
}

void CRichDrawText::XTextHost::TxInvalidateRect(LPCRECT prc, BOOL fMode)
{
}

void CRichDrawText::XTextHost::TxViewChange(BOOL fUpdate)
{
}

BOOL CRichDrawText::XTextHost::TxCreateCaret(HBITMAP hbmp, INT xWidth, INT yHeight)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxShowCaret(BOOL fShow)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxSetCaretPos(INT x, INT y)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxSetTimer(UINT idTimer, UINT uTimeout)
{
  return FALSE;
}

void CRichDrawText::XTextHost::TxKillTimer(UINT idTimer)
{
}

void CRichDrawText::XTextHost::TxScrollWindowEx(INT dx, INT dy, LPCRECT lprcScroll,
  LPCRECT lprcClip, HRGN hrgnUpdate, LPRECT lprcUpdate, UINT fuScroll)
{
}

void CRichDrawText::XTextHost::TxSetCapture(BOOL fCapture)
{
}

void CRichDrawText::XTextHost::TxSetFocus()
{
}

void CRichDrawText::XTextHost::TxSetCursor(HCURSOR hcur, BOOL fText)
{
}

BOOL CRichDrawText::XTextHost::TxScreenToClient(LPPOINT lppt)
{
  return FALSE;
}

BOOL CRichDrawText::XTextHost::TxClientToScreen(LPPOINT lppt)
{
  return FALSE;
}

HRESULT CRichDrawText::XTextHost::TxActivate(LONG* plOldState)
{
  return E_FAIL;
}

HRESULT CRichDrawText::XTextHost::TxDeactivate(LONG lNewState)
{
  return E_FAIL;
}

HRESULT CRichDrawText::XTextHost::TxGetClientRect(LPRECT prc)
{
  return E_FAIL;
}

HRESULT CRichDrawText::XTextHost::TxGetViewInset(LPRECT prc)
{
  // Set zero sized margins
  *prc = CRect(0,0,0,0);
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetCharFormat(const CHARFORMATW **ppCF)
{
  METHOD_PROLOGUE(CRichDrawText, TextHost)

  // Return the default character format set up in the constructor
  *ppCF = &(pThis->m_CharFormat);
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetParaFormat(const PARAFORMAT **ppPF)
{
  METHOD_PROLOGUE(CRichDrawText, TextHost)

  // Return the default paragraph format set up in the constructor
  *ppPF = &(pThis->m_ParaFormat);
  return S_OK;
}

COLORREF CRichDrawText::XTextHost::TxGetSysColor(int nIndex)
{
  // Pass requests for colours on to Windows
  return ::GetSysColor(nIndex);
}

HRESULT CRichDrawText::XTextHost::TxGetBackStyle(TXTBACKSTYLE *pstyle)
{
  // Do not erase what is underneath the drawing area
  *pstyle = TXTBACK_TRANSPARENT;
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetMaxLength(DWORD *plength)
{
  // Set the maximum size of text to be arbitrarily large
  *plength = 1024*1024*16;
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetScrollBars(DWORD *pdwScrollBar)
{
  // Do not allow scrollbars
  *pdwScrollBar = 0;
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetPasswordChar(TCHAR *pch)
{
  return S_FALSE;
}

HRESULT CRichDrawText::XTextHost::TxGetAcceleratorPos(LONG *pcp)
{
  *pcp = -1;
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxGetExtent(LPSIZEL lpExtent)
{
  return E_NOTIMPL;
}

HRESULT CRichDrawText::XTextHost::OnTxCharFormatChange(const CHARFORMATW * pcf)
{
  return E_FAIL;
}

HRESULT CRichDrawText::XTextHost::OnTxParaFormatChange(const PARAFORMAT * ppf)
{
  return E_FAIL;
}

HRESULT CRichDrawText::XTextHost::TxGetPropertyBits(DWORD dwMask, DWORD *pdwBits)
{
  // Set the windowless control as being multiple lines of wrapping rich text
  DWORD bits = TXTBIT_MULTILINE|TXTBIT_RICHTEXT|TXTBIT_WORDWRAP;
  *pdwBits = bits & dwMask;
  return S_OK;
}

HRESULT CRichDrawText::XTextHost::TxNotify(DWORD iNotify, void *pv)
{
  // Claim to have handled the notifcation, even though we always ignore it
  return S_OK;
}

HIMC CRichDrawText::XTextHost::TxImmGetContext()
{
  return 0;
}

void CRichDrawText::XTextHost::TxImmReleaseContext(HIMC himc)
{
}

HRESULT CRichDrawText::XTextHost::TxGetSelectionBarWidth(LONG *lSelBarWidth)
{
  // No selection bar
  *lSelBarWidth = 0;
  return S_OK;
}