Richedit EM_FORMATRANGE bug/wierdness   

According to http://msdn.microsoft.com/en-us/library/bb788020(VS.85).aspx

The return value for EM_FORMATRANGE is "the index of the last character that 
fits in the region, plus 1"

I have created a sample that proves that this documentation is incorrect or 
that there is a bug in the control.

The documentation is correct in the general case but if you try to use a 
FORMATRANGE rc that isn't tall enough for the first line, EM_FORMATRANGE 
always acts as though the first line fits.

// formatrange.cpp : Defines the entry point for the application.
//

#include "stdafx.h"
#include "formatrange.h"
#include <commctrl.h>
#include <richedit.h>
#include <stdio.h>

#define MAX_LOADSTRING 100

// Global Variables:
HINSTANCE hInst;								// current instance
TCHAR szTitle[MAX_LOADSTRING];					// The title bar text
TCHAR szWindowClass[MAX_LOADSTRING];			// the main window class name

// Forward declarations of functions included in this code module:
ATOM				MyRegisterClass(HINSTANCE hInstance);
BOOL				InitInstance(HINSTANCE, int);
LRESULT CALLBACK	WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK	About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY _tWinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPTSTR    lpCmdLine,
                     int       nCmdShow)
{
	UNREFERENCED_PARAMETER(hPrevInstance);
	UNREFERENCED_PARAMETER(lpCmdLine);

 	// TODO: Place code here.
	MSG msg;
	HACCEL hAccelTable;

    InitCommonControls();

	// Initialize global strings
	LoadString(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
	LoadString(hInstance, IDC_FORMATRANGE, szWindowClass, MAX_LOADSTRING);
	MyRegisterClass(hInstance);

	// Perform application initialization:
	if (!InitInstance (hInstance, nCmdShow))
	{
		return FALSE;
	}

	hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_FORMATRANGE));

	// Main message loop:
	while (GetMessage(&msg, NULL, 0, 0))
	{
		if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
		{
			TranslateMessage(&msg);
			DispatchMessage(&msg);
		}
	}

	return (int) msg.wParam;
}



//
//  FUNCTION: MyRegisterClass()
//
//  PURPOSE: Registers the window class.
//
//  COMMENTS:
//
//    This function and its usage are only necessary if you want this code
//    to be compatible with Win32 systems prior to the 'RegisterClassEx'
//    function that was added to Windows 95. It is important to call this 
function
//    so that the application will get 'well formed' small icons associated
//    with it.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
	WNDCLASSEX wcex;

	wcex.cbSize = sizeof(WNDCLASSEX);

	wcex.style			= CS_HREDRAW | CS_VREDRAW;
	wcex.lpfnWndProc	= WndProc;
	wcex.cbClsExtra		= 0;
	wcex.cbWndExtra		= 0;
	wcex.hInstance		= hInstance;
	wcex.hIcon			= LoadIcon(hInstance, MAKEINTRESOURCE(IDI_FORMATRANGE));
	wcex.hCursor		= LoadCursor(NULL, IDC_ARROW);
	wcex.hbrBackground	= (HBRUSH)(COLOR_WINDOW+1);
	wcex.lpszMenuName	= MAKEINTRESOURCE(IDC_FORMATRANGE);
	wcex.lpszClassName	= szWindowClass;
	wcex.hIconSm		= LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

	return RegisterClassEx(&wcex);
}

//
//   FUNCTION: InitInstance(HINSTANCE, int)
//
//   PURPOSE: Saves instance handle and creates main window
//
//   COMMENTS:
//
//        In this function, we save the instance handle in a global variable 
and
//        create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
   HWND hWnd;

   hInst = hInstance; // Store instance handle in our global variable

   hWnd = CreateWindow(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, 400, 400, NULL, NULL, hInstance, NULL);

   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   SetTimer(hWnd,1,100,0);

   return TRUE;
}

//
//  FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  PURPOSE:  Processes messages for the main window.
//
//  WM_COMMAND	- process the application menu
//  WM_PAINT	- Paint the main window
//  WM_DESTROY	- post a quit message and return
//
//

HWND g_hWndEdit = 0;
int g_pixels_y = 200; 

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM 
lParam)
{
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;

	switch (message)
	{
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
        switch ( wmEvent )
        {
        case EN_CHANGE:
            InvalidateRect(hWnd,0,TRUE);
            break; 
        }
		switch (wmId)
		{
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;
	case WM_PAINT:
        {
		    hdc = BeginPaint(hWnd, &ps);

            // Create "print preview". 
            SendMessage(g_hWndEdit, EM_SETTARGETDEVICE, (WPARAM)hdc, 200);

            int ppi_x = GetDeviceCaps(hdc,LOGPIXELSX);
            int ppi_y = GetDeviceCaps(hdc,LOGPIXELSX);
            int pixels_x = 200;
            // 16 pixels per line
            // leave room for 3.5 lines

            FORMATRANGE fr;
            fr.hdc = hdc;
            fr.hdcTarget = hdc;
            fr.rc.left = 0;
            fr.rc.right = 1440*pixels_x/ppi_x; // convert pixels to twips
            fr.rc.top = 0;
            fr.rc.bottom = 1440*g_pixels_y/ppi_y; // convert pixels to twips
            fr.rcPage = fr.rc;
            fr.chrg.cpMin = 0;
            fr.chrg.cpMax = GetWindowTextLength(g_hWndEdit);

            int lastCharacter = (int)SendMessage(g_hWndEdit, EM_FORMATRANGE, 
TRUE, (LPARAM)&fr);
            SendMessage(g_hWndEdit, EM_FORMATRANGE, FALSE, 0);
            WCHAR buf[128];
            wsprintf( buf, L"lastCharacter == %i\n", lastCharacter );

            RECT rect = {0,0,pixels_x,g_pixels_y};
            HBRUSH hbr = CreateSolidBrush( RGB(0,0,0) );
            FrameRect(hdc,&rect,hbr);
            DeleteObject(hbr);

            rect.top = g_pixels_y+30;
            rect.bottom = rect.top + 100;
            DrawText(hdc,buf,-1,&rect,0);

            EndPaint(hWnd, &ps);
            SendMessage(g_hWndEdit, EM_SETTARGETDEVICE, 0, 0);

        }
		break;
	case WM_TIMER:
        if ( g_pixels_y > 0 )
        {
            g_pixels_y--;
            InvalidateRect(hWnd,0,TRUE);
        }
        break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	case WM_CREATE:
        {
            LoadLibrary(TEXT("msftedit.dll"));
            DWORD dwStyle = ES_MULTILINE | WS_VISIBLE | WS_CHILD | WS_BORDER 
| WS_TABSTOP;
            g_hWndEdit = CreateWindow( TEXT("RICHEDIT50W"), TEXT("line 1 is 
very long to test wrapping and EM_FORMATRANGE\r\nline 2\r\nline 3\r\nline 
4\r\n"), dwStyle, 200, 200, 200, 200, hWnd, 0, GetModuleHandle(0), 0 );
            SendMessage( g_hWndEdit, EM_SETSEL,0,-1);
            CHARFORMAT cf;
            ZeroMemory(&cf,sizeof(cf));
            cf.cbSize = sizeof(cf);
            cf.dwMask = CFM_SIZE | CFM_FACE;
            int font_pixels = 18;
            cf.yHeight = 1440*font_pixels/96; // convert pixels to twips
            wcscpy( cf.szFaceName, L"Tahoma" );
            SendMessage( g_hWndEdit, EM_SETCHARFORMAT, SCF_SELECTION, 
(LPARAM)&cf );
        }
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

// Message handler for about box.
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
	UNREFERENCED_PARAMETER(lParam);
	switch (message)
	{
	case WM_INITDIALOG:
		return (INT_PTR)TRUE;

	case WM_COMMAND:
		if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
		{
			EndDialog(hDlg, LOWORD(wParam));
			return (INT_PTR)TRUE;
		}
		break;
	}
	return (INT_PTR)FALSE;
}

date: Sat, 12 Jul 2008 13:55:01 -0700   author:   Vince Harron