Font Enumeration
Font enumeration is the process of obtaining from GDI a list of all fonts available on a device. A program can then select one of these fonts or display them in a dialog box for selection by the user. I'll first briefly describe the enumeration functions and then show how to use the ChooseFont function, which fortunately makes font enumeration much less necessary for an application.
The Enumeration Functions
In the old days of Windows, font enumeration required use of the EnumFonts function:
EnumFonts (hdc, szTypeFace, EnumProc, pData) ;
A program could enumerate all fonts (by setting the second argument to NULL) or just those of a particular typeface. The third argument is an enumeration callback function; the fourth argument is optional data passed to that function. GDI calls the callback function once for each font in the system, passing to it both LOGFONT and TEXTMETRIC structures that defined the font, plus some flags indicating the type of font.
The EnumFontFamilies function was designed to better enumerate TrueType fonts under Windows 3.1:
EnumFontFamilies (hdc, szFaceName, EnumProc, pData) ;
Generally, EnumFontFamilies is called first with a NULL second argument. The EnumProc callback function is called once for each font family (such as Times New Roman). Then the application calls EnumFontFamilies again with that typeface name and a different callback function. GDI calls the second callback function for each font in the family (such as Times New Roman Italic). The callback function is passed an ENUMLOGFONT structure (which is a LOGFONT structure plus a "full name" field and a "style" field containing, for example, the text name "Italic" or "Bold") and a TEXTMETRIC structure for non-TrueType fonts and a NEWTEXTMETRIC structure for TrueType fonts. The NEWTEXTMETRIC structure adds four fields to the information in the TEXTMETRIC structure.
The EnumFontFamiliesEx function is recommended for applications running under the 32-bit versions of Windows:
EnumFontFamiliesEx (hdc, &logfont, EnumProc, pData, dwFlags) ;
The second argument is a pointer to a LOGFONT structure for which the lfCharSet and lfFaceName fields indicate what fonts are to be enumerated. The callback function gets information about each font in the form of ENUMLOGFONTEX and NEWTEXTMETRICEX structures.
The ChooseFont Dialog
We had a little introduction to the ChooseFont common dialog box back in Chapter 11. Now that we've encountered font enumeration, the inner workings of the ChooseFont function should be obvious. The ChooseFont function takes a pointer to a CHOOSEFONT structure as its only argument and displays a dialog box listing all the fonts. On return from ChooseFont, a LOGFONT structure, which is part of the CHOOSEFONT structure, lets you create a logical font.
The CHOSFONT program, shown in Figure 17-7, demonstrates using the ChooseFont function and displays the fields of the LOGFONT structure that the function defines. The program also displays the same string of text as PICKFONT.
Figure 17-7. The CHOSFONT program.
CHOSFONT.C /*----------------------------------------- CHOSFONT.C -- ChooseFont Demo (c) Charles Petzold, 1998 -----------------------------------------*/ #include <windows.h> #include "resource.h" LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("ChosFont") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = szAppName ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requires Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("ChooseFont"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { static CHOOSEFONT cf ; static int cyChar ; static LOGFONT lf ; static TCHAR szText[] = TEXT ("\x41\x42\x43\x44\x45 ") TEXT ("\x61\x62\x63\x64\x65 ") TEXT ("\xC0\xC1\xC2\xC3\xC4\xC5 ") TEXT ("\xE0\xE1\xE2\xE3\xE4\xE5 ") #ifdef UNICODE TEXT ("\x0390\x0391\x0392\x0393\x0394\x0395 ") TEXT ("\x03B0\x03B1\x03B2\x03B3\x03B4\x03B5 ") TEXT ("\x0410\x0411\x0412\x0413\x0414\x0415 ") TEXT ("\x0430\x0431\x0432\x0433\x0434\x0435 ") TEXT ("\x5000\x5001\x5002\x5003\x5004") #endif ; HDC hdc ; int y ; PAINTSTRUCT ps ; TCHAR szBuffer [64] ; TEXTMETRIC tm ; switch (message) { case WM_CREATE: // Get text height cyChar = HIWORD (GetDialogBaseUnits ()) ; // Initialize the LOGFONT structure GetObject (GetStockObject (SYSTEM_FONT), sizeof (lf), &lf) ; // Inialize the CHOOSEFONT structure cf.lStructSize = sizeof (CHOOSEFONT) ; cf.hwndOwner = hwnd ; cf.hDC = NULL ; cf.lpLogFont = &lf ; cf.iPointSize = 0 ; cf.Flags = CF_INITTOLOGFONTSTRUCT | CF_SCREENFONTS | CF_EFFECTS ; cf.rgbColors = 0 ; cf.lCustData = 0 ; cf.lpfnHook = NULL ; cf.lpTemplateName = NULL ; cf.hInstance = NULL ; cf.lpszStyle = NULL ; cf.nFontType = 0 ; cf.nSizeMin = 0 ; cf.nSizeMax = 0 ; return 0 ; case WM_COMMAND: switch (LOWORD (wParam)) { case IDM_FONT: if (ChooseFont (&cf)) InvalidateRect (hwnd, NULL, TRUE) ; return 0 ; } return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; // Display sample text using selected font SelectObject (hdc, CreateFontIndirect (&lf)) ; GetTextMetrics (hdc, &tm) ; SetTextColor (hdc, cf.rgbColors) ; TextOut (hdc, 0, y = tm.tmExternalLeading, szText, lstrlen (szText)) ; // Display LOGFONT structure fields using system font DeleteObject (SelectObject (hdc, GetStockObject (SYSTEM_FONT))) ; SetTextColor (hdc, 0) ; TextOut (hdc, 0, y += tm.tmHeight, szBuffer, wsprintf (szBuffer, TEXT ("lfHeight = %i"), lf.lfHeight)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfWidth = %i"), lf.lfWidth)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfEscapement = %i"), lf.lfEscapement)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfOrientation = %i"), lf.lfOrientation)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfWeight = %i"), lf.lfWeight)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfItalic = %i"), lf.lfItalic)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfUnderline = %i"), lf.lfUnderline)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfStrikeOut = %i"), lf.lfStrikeOut)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfCharSet = %i"), lf.lfCharSet)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfOutPrecision = %i"), lf.lfOutPrecision)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfClipPrecision = %i"), lf.lfClipPrecision)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfQuality = %i"), lf.lfQuality)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfPitchAndFamily = 0x%02X"), lf.lfPitchAndFamily)) ; TextOut (hdc, 0, y += cyChar, szBuffer, wsprintf (szBuffer, TEXT ("lfFaceName = %s"), lf.lfFaceName)) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; } |
CHOSFONT.RC//Microsoft Developer Studio generated resource script. #include "resource.h" #include "afxres.h" ///////////////////////////////////////////////////////////////////////////// // Menu CHOSFONT MENU DISCARDABLE BEGIN MENUITEM "&Font!", IDM_FONT END |
RESOURCE.H// Microsoft Developer Studio generated include file. // Used by ChosFont.rc #define IDM_FONT 40001 |
As usual with the common dialog boxes, a Flags field in the CHOOSEFONT structure lets you pick lots of options. The CF_INITLOGFONTSTRUCT flag that CHOSFONT specifies causes Windows to initialize the dialog box selection based on the LOGFONT structure passed to the ChooseFont structure. You can use flags to specify TrueType fonts only (CF_TTONLY) or fixed-pitch fonts only (CF_FIXEDPITCHONLY) or no symbol fonts (CF_SCRIPTSONLY). You can display screen fonts (CF_SCREENFONTS), printer fonts (CF_PRINTERFONTS), or both (CF_BOTH). In the latter two cases, the hDC field of the CHOOSEFONT structure must reference a printer device context. The CHOSFONT program uses the CF_SCREENFONTS flag.
The CF_EFFECTS flag (the third flag that the CHOSFONT program uses) forces the dialog box to include check boxes for underlining and strikeout and also allows the selection of a text color. It's not hard to implement text color in your code, so try it.
Notice the Script field in the Font dialog displayed by ChooseFont. This lets the user select a character set available for the particular font; the appropriate character set ID is returned in the LOGFONT structure.
The ChooseFont function uses the logical inch to calculate the lfHeight field from the point size. For example, suppose you have Small Fonts installed from the Display Properties dialog. That means that GetDeviceCaps with a video display device context and the argument LOGPIXELSY returns 96. If you use ChooseFont to choose a 72-point Times Roman Font, you really want a 1-inch tall font. When ChooseFont returns, the lfHeight field of the LOGFONT structure will equal -96 (note the minus sign), meaning that the point size of the font is equivalent to 96 pixels, or one logical inch.
Good. That's probably what we want. But keep the following in mind:
- If you set one of the metric mapping modes under Windows NT, logical coordinates will be inconsistent with the physical size of the font. For example, if you draw a ruler next to the text based on a metric mapping mode, it will be not match the font. You should use the Logical Twips mapping mode described above to draw graphics that are consistent with the font size.
- If you're going to be using any non-MM_TEXT mapping mode, make sure the mapping mode is not set when you select the font into the device context and display the text. Otherwise, GDI will interpret the lfHeight field of the LOGFONT structure as being expressed in logical coordinates.
- The lfHeight field of the LOGFONT structure set by ChooseFont is always in pixels, and it is only appropriate for the video display. When you create a font for a printer device context, you must adjust the lfHeight value. The ChooseFont function uses the hDC field of the CHOOSEFONT structure only for obtaining printer fonts to be listed in the dialog box. This device context handle does not affect the value of lfHeight.
Fortunately, the CHOOSEFONT structure includes an iPointSize field that provides the size of the selected font in units of 1/10 of a point. Regardless of the device context and mapping mode, you can always convert this field to a logical size and use that for the lfHeight field. The appropriate code can be found in the EZFONT.C file. You can probably simplify it based on your needs.
Another program that uses ChooseFont is UNICHARS, shown in Figure 17-8. This program lets you view all the characters of a font and is particularly useful for studying the Lucida Sans Unicode font, which it uses by default for display, or the Bitstream CyberBit font. UNICHARS always uses the TextOutW function for displaying the font characters, so you can run it under Windows NT or Windows 98.
Figure 17-8. The UNICHARS program.
UNICHARS.C /*----------------------------------------------- UNICHARS.C -- Displays 16-bit character codes (c) Charles Petzold, 1998 -----------------------------------------------*/ #include <windows.h> #include "resource.h" LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ; int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, PSTR szCmdLine, int iCmdShow) { static TCHAR szAppName[] = TEXT ("UniChars") ; HWND hwnd ; MSG msg ; WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ; wndclass.lpfnWndProc = WndProc ; wndclass.cbClsExtra = 0 ; wndclass.cbWndExtra = 0 ; wndclass.hInstance = hInstance ; wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ; wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ; wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ; wndclass.lpszMenuName = szAppName ; wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass)) { MessageBox (NULL, TEXT ("This program requies Windows NT!"), szAppName, MB_ICONERROR) ; return 0 ; } hwnd = CreateWindow (szAppName, TEXT ("Unicode Characters"), WS_OVERLAPPEDWINDOW | WS_VSCROLL, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL) ; ShowWindow (hwnd, iCmdShow) ; UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg) ; DispatchMessage (&msg) ; } return msg.wParam ; } LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { static CHOOSEFONT cf ; static int iPage ; static LOGFONT lf ; HDC hdc ; int cxChar, cyChar, x, y, i, cxLabels ; PAINTSTRUCT ps ; SIZE size ; TCHAR szBuffer [8] ; TEXTMETRIC tm ; WCHAR ch ; switch (message) { case WM_CREATE: hdc = GetDC (hwnd) ; lf.lfHeight = - GetDeviceCaps (hdc, LOGPIXELSY) / 6 ; // 12 points lstrcpy (lf.lfFaceName, TEXT ("Lucida Sans Unicode")) ; ReleaseDC (hwnd, hdc) ; cf.lStructSize = sizeof (CHOOSEFONT) ; cf.hwndOwner = hwnd ; cf.lpLogFont = &lf ; cf.Flags = CF_INITTOLOGFONTSTRUCT | CF_SCREENFONTS ; SetScrollRange (hwnd, SB_VERT, 0, 255, FALSE) ; SetScrollPos (hwnd, SB_VERT, iPage, TRUE ) ; return 0 ; case WM_COMMAND: switch (LOWORD (wParam)) { case IDM_FONT: if (ChooseFont (&cf)) InvalidateRect (hwnd, NULL, TRUE) ; return 0 ; } return 0 ; case WM_VSCROLL: switch (LOWORD (wParam)) { case SB_LINEUP: iPage -= 1 ; break ; case SB_LINEDOWN: iPage += 1 ; break ; case SB_PAGEUP: iPage -= 16 ; break ; case SB_PAGEDOWN: iPage += 16 ; break ; case SB_THUMBPOSITION: iPage = HIWORD (wParam) ; break ; default: return 0 ; } iPage = max (0, min (iPage, 255)) ; SetScrollPos (hwnd, SB_VERT, iPage, TRUE) ; InvalidateRect (hwnd, NULL, TRUE) ; return 0 ; case WM_PAINT: hdc = BeginPaint (hwnd, &ps) ; SelectObject (hdc, CreateFontIndirect (&lf)) ; GetTextMetrics (hdc, &tm) ; cxChar = tm.tmMaxCharWidth ; cyChar = tm.tmHeight + tm.tmExternalLeading ; cxLabels = 0 ; for (i = 0 ; i < 16 ; i++) { wsprintf (szBuffer, TEXT (" 000%1X: "), i) ; GetTextExtentPoint (hdc, szBuffer, 7, &size) ; cxLabels = max (cxLabels, size.cx) ; } for (y = 0 ; y < 16 ; y++) { wsprintf (szBuffer, TEXT (" %03X_: "), 16 * iPage + y) ; TextOut (hdc, 0, y * cyChar, szBuffer, 7) ; for (x = 0 ; x < 16 ; x++) { ch = (WCHAR) (256 * iPage + 16 * y + x) ; TextOutW (hdc, x * cxChar + cxLabels, y * cyChar, &ch, 1) ; } } DeleteObject (SelectObject (hdc, GetStockObject (SYSTEM_FONT))) ; EndPaint (hwnd, &ps) ; return 0 ; case WM_DESTROY: PostQuitMessage (0) ; return 0 ; } return DefWindowProc (hwnd, message, wParam, lParam) ; } |
UNICHARS.RC//Microsoft Developer Studio generated resource script. #include "resource.h" #include "afxres.h" ///////////////////////////////////////////////////////////////////////////// // Menu UNICHARS MENU DISCARDABLE BEGIN MENUITEM "&Font!", IDM_FONT END |
RESOURCE.H// Microsoft Developer Studio generated include file. // Used by Unichars.rc #define IDM_FONT 40001 |
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