Yet Another Code Site

Rich Edit 3.0 Code Samples

Here are samples of Rich Edit 3.0 code that work for me, comments about features that do not work as I originally expected, errors identified in the MSDN online Rich Edit 3.0 documentation, Rich Edit 3.0 constants that you will need if you do not have new header files, SendMessage() parameters, and anything else that I think that you might need to know to program for Rich Edit 3.0 controls.  This page is definitely a work in progress and I anticipate rolling the information on this page into a TRichEdit30 class.  However, if you do not want to wait for me to post a TRichEdit30 class, here is what I have learned so far.

Before delving into this code, see the Rich Edit 3.0 FAQ to determine if you have the 3.0 version, learn where to get it if you do not have it, and see what features it has that you may need or find useful.  Please be warned that I am finding that some of the features that I expected, based on MSDN online documents, are not fully implemented or do not function exactly as advertised.  I will include information about these differences where appropriate below.

I would appreciate any information that you work out that is not on this page.  If possible, please send code samples that are constructed as described below to minimize the chances for me to introduce errors into your code.  As always, you will get credit for any code that you send.  Of course, if you find any errors here, please set me straight.

Code Index

Getting set up to use the Rich Edit 3.0 code on this page

Rich Edit 3.0 Code Samples - Base Code
A basic Rich Edit 3.0 class for the VCL. Use as the starting point for investigating Rich Edit 3.0.  Or use the TRichEdit20 Class code available elsewhere on this site.  (05-08-99)

Rich Edit 3.0 Code Samples - Common Code
Code to instantiate the class, whether you use the TRichEdit20 class or the stripped down class from the prior section.  (05-08-99)

The Rich Edit 3.0 Code

Zooming in and out (EM_GETZOOM & EM_SETZOOM)  (05-08-99)

Paragraph numbering (beyond paragraph bullets)  (05-08-99)

Saving and restoring the current scroll position (EM_GETSCROLLPOS & EM_SETSCROLLPOS)  (05-08-99)


Rich Edit 3.0 Code Samples - Base Code

Ok.  I have a dilemma.  The most efficient way to develop the Rich Edit 3.0 code is to derive a class from the Rich Edit 2.0 class (TRichEdit20) already available on this site.  So much of the code is identical and so many of the Rich Edit 3.0 features are simple extensions of the v2.0 functionality.  In fact, if you install the Rich Edit 3.0 DLL on your system, it replaces the v2.0 DLL (riched20.dll) and the TRichEdit20 class automatically loads the v3.0 DLL.

On the other hand, I want the code on this page to work without requiring you to dig through all of the TRichEdit20 class code, useful though it may be.  So here is (today's) decision:  The code on this page will be based upon the stripped-down TRichEdit20 class code below which does nothing more than ensure that a v2.0 or v3.0 DLL gets loaded.  Note that neither the TRichEdit20 class nor the code below actually tests to ensure that the v3.0 DLL is installed – if v3.0 is installed, it is loaded.  If not, v2.0 gets loaded if it has been installed.  (You should get an error if neither is installed, but I have not tested for that.)

If you wish to follow my advice to start with the TRichEdit20 class, add the following declaration/definition to your code and skip the rest of this section: 

class TRichEdit30 : public TRichEdit20

{

public:

  TRichEdit30(TComponent* Owner) : TRichEdit20(Owner) {};

};

Otherwise, here is the minimal TRichEdit30 class used by the rest of the code on this page.  Note that some of the member functions are empty.  That is, the functions are declared/defined, but contain no or almost no code.  This reflects my experience – although empty now, I have a gut feeling that we will need to add code to these methods sometime later.  Maybe not, but I am trying to keep things flexible....

[ BCB4 users – if you are not using the TRichEdit20 class as described above, click here to download the basic Rich Edit 3.0 project code that follows.  You should probably read through the comments below to ensure that you understand each part of the code and, more importantly, what this minimal class does not do for you. ]

Here is the minimal TRichEdit30 class used for the remainder of this page:

Declarations (inline or in *.hpp file) 

//---------------------------------------------------------------------------

#include <vcl\SysUtils.hpp>



class TRichEdit30 : public TRichEdit

{

private:

  int FLibHandle;



protected:

  virtual void __fastcall CreateParams(Controls::TCreateParams &Params);

  virtual void __fastcall DestroyWnd(void);

  virtual void __fastcall CreateWnd(void);

  virtual void __fastcall WndProc(Messages::TMessage &Message);



public:

  __fastcall TRichEdit30(TComponent* Owner);

  __fastcall ~TRichEdit30();

  virtual void __fastcall RecreateWnd(void);      // not virtual in base!!!

};

//---------------------------------------------------------------------------

Definitions (inline or in a *.cpp file) 

//---------------------------------------------------------------------------

// may need to add code here later

//

__fastcall TRichEdit30::TRichEdit30(TComponent* Owner) : TRichEdit(Owner)

{

}

//---------------------------------------------------------------------------

// may need to add code here later

//

__fastcall TRichEdit30::~TRichEdit30()

{

}

//---------------------------------------------------------------------------

// may need to add code here later

//

void __fastcall TRichEdit30::CreateWnd(void)

{

  TRichEdit::CreateWnd();

}

//---------------------------------------------------------------------------

// the following ensures that the riched20.dll (v2.0 or v3.0) is loaded;

// TRichEdit unloads the DLL that *IT* loads in the WM_NCDESTROY handler (which,

// disappointingly enough, is private rather than protected; damned if FLibHandle

// isn't also, or we could simply unload it later) but we do it in DestroyWnd()...

// (note:  do not call TRichEdit::CreateParams -- it will attempt to

// load the older version of the rich edit DLL -- not a Good Thing -- too bad

// if anything important goes on there)

//

void __fastcall TRichEdit30::CreateParams(Controls::TCreateParams &Params)

{

  const char RichEditModuleName[] = "RICHED20.DLL";

  long int OldError;



  OldError = SetErrorMode(SEM_NOOPENFILEERRORBOX);

  FLibHandle = (int) LoadLibrary(RichEditModuleName);

  if (FLibHandle < HINSTANCE_ERROR) FLibHandle = 0;

  SetErrorMode(OldError);

//  TRichEdit::CreateParams(Params);

  TCustomMemo::CreateParams(Params);

//  CreateSubClass(Params, "RICHEDIT");

  CreateSubClass(Params, RICHEDIT_CLASS);

  Params.Style = Params.Style |

    (HideScrollBars ? 0 : ES_DISABLENOSCROLL) | (HideSelection ? 0 : ES_NOHIDESEL);

}

//---------------------------------------------------------------------------

// free the library on destroy (actually, it will not unload until last

// TRichEdit20 instance is destroyed)

//

void __fastcall TRichEdit30::DestroyWnd(void)

{

  TRichEdit::DestroyWnd();

  if (FLibHandle != 0) FreeLibrary((void*) FLibHandle);

}

//---------------------------------------------------------------------------

// may need to add code here later

//

void __fastcall TRichEdit30::WndProc(Messages::TMessage &Message)

{

  TRichEdit::WndProc(Message);

}

//---------------------------------------------------------------------------

// may need to add code here later

//

void __fastcall TRichEdit30::RecreateWnd(void)  // not virtual in base!!!

{

  TRichEdit::RecreateWnd();

}

//---------------------------------------------------------------------------

This is the end of the minimal TRichEdit30 class.

Rich Edit 3.0 Code Samples - Common Code

The code on this page assumes that you have declared and defined a TRichEdit30 class in one of the two ways described above, i.e., either by deriving a TRichEdit30 class from the TRichEdit20 class or by creating the minimal TRichEdit30 class from the above code.  Now you must instantiate the class.  The rest of this page assumes that you have declared a global variable, RE30: 

TRichEdit30* RE30;

And that you have initialized RE30 in your form constructor (like this): 

RE30 = new TRichEdit30(this);

RE30->Parent = this;

RE30->Align = alClient;

The following examples will operate on the RE30 global variable.

To get started, create a new project, add a main menu, and then add the necessary code to declare and define the TRichEdit30 class.  In the main form, add the declaration for RE30 and then add the RE30 initialization to the form constructor.  Now we are ready to get on to the good stuff.

Zooming in and out

Rich Edit 3.0 adds the ability to enlarge (zoom in) or shrink (zoom out) the text inside the control.  For example, you can enlarge all of the text in the control by an arbitrary factor and the enlarged text will wrap inside the window as if the fonts' sizes had been changed.  One would assume, based upon the MSDN information, that the printed version of the text would be unchanged from the original font size(s).  The text scaling definitely works (see the comments in the code), but I have not confirmed that printing is unaffected. 

// message constants

#define EM_GETZOOM (WM_USER + 224)

#define EM_SETZOOM (WM_USER + 225)



// the following DWORDs (not WORDs as documented at MSDN) determine the scaling.  The ratio of 

// numerator / denominator must be between 1/64th and 64.  note that a ratio of less than 1:1

// does not actually display text at less than the unscaled size of the text (that is, you

// cannot scale to less than 100%) in my tests with riched20.dll version 5.30.11.2410.  however,

// if you set the scaling to, say, 1:2, then EM_GETZOOM does return 1:2, although the control

// contents are displayed 1:1.  OTOH, maybe I do not understand how to use this properly....

//

// to reset the scaling factor to 1:1, set both values to 0.

//

// the following values set the scaling factor to 3 times the normal size.

DWORD numerator = 3;

DWORD denominator = 1;



// EM_SETZOOM returns true on success or false on failure

bool result = ::SendMessage(RE30->Handle, EM_SETZOOM, (WPARAM) numerator, (LPARAM) denominator);

To get the current zoom factor: 

// EM_GETZOOM should always return true.  note that numerator and denominator may be zero

result = ::SendMessage(RE30->Handle, EM_GETZOOM, (WPARAM) &numerator, (LPARAM) &denominator);

Paragraph numbering

Paragraph numbering is effected through the PARAFORMAT2 structure and the EM_GETPARAFORMAT and EM_SETPARAFORMAT messages. A variety of numbering styles are documented:

1) Number with right parenthesis (wNumberingStyle = 0).
1. Number with a period (wNumberingStyle = 1).
(1) Number with right and left parenthesis (wNumberingStyle = 2).
1 Number only (wNumberingStyle = 3).

Supposedly, each of the above can be bitwise-or'd with 0x8000 to force the number to be displayed as a Roman numeral.  My tests with the the 5.30.11.2410 version of the riched20.dll reveal that all numbering styles display as a number followed by a right parenthesis (the first item in the list above).

As mentioned above, the PARAFORMAT2 structure is used to set the numbering style. This is done through the following structure members:

dwMask - Set the following values (bitwise-or them together) to identify which of the remaining structure members are valid:  PFM_NUMBERING, PFM_NUMBERINGSTART, PFM_NUMBERINGSTYLE, and PFM_NUMBERINGTAB.
wNumbering - 0 = no numbering/bullets, PFN_BULLET = bullet, 2 = Arabic numbers, 3 = lowercase letters, 4 = uppercase letters, 5 = lowercase Roman numerals, 6 = uppercase Roman numerals, 7 = sequence of characters beginning with the Unicode character specified in the wNumberingStart member.
wNumberingStart - Starting value for numbering. Ignored according to MSDN documentation.
wNumberingStyle - Style for numbering
wNumberingTab - Minimum space, in twips, between the border and the paragraph's text.

Here is the code to set the currently selected paragraph(s) style to numbered (note that the text must be selected before invoking this code): 

PARAFORMAT2 pf2;

pf2.cbSize = sizeof(pf2);

pf2.dwMask = PFM_NUMBERING | PFM_NUMBERINGSTART | PFM_NUMBERINGSTYLE;

pf2.wNumbering = 3;

pf2.wNumberingStart = 1;

pf2.wNumberingStyle = 2;

::SendMessage(RE30->Handle, EM_SETPARAFORMAT, 0, (LPARAM) &pf2);

Try different combinations and see what you get.

Saving and restoring the current scroll position

Rich Edit includes a frequently requested feature notably absent in prior versions.  You can now save and restore the current vertical and horizontal scroll positions accurately and easily. 

// message constants

#define EM_GETSCROLLPOS (WM_USER + 221)

#define EM_SETSCROLLPOS (WM_USER + 222)



// create a POINT structure to hold the scroll position

POINT pt = { 0, 0 };



// fetch the scroll position into pt

::SendMessage(RE30->Handle, EM_GETSCROLLPOS, 0, (LPARAM) &pt);



[ do a bunch of stuff... ]



// now restore the scroll postion

::SendMessage(RE30->Handle, EM_SETSCROLLPOS, 0, (LPARAM) &pt);

This is definitely a candidate for the "new feature most easy to use" award.  It is also a candidate for the "why was this feature not in the last two versions?" award.

More to come as time, energy, and wife permit...

Home | Top Of Page | Code | Papers | FAQs | Links | Search | Feedback

Page updated

Copyright © 1999-2001 Thin Air Enterprises and Robert Dunn.  All rights reserved.