Merge gl_font() changes for Xft+X11 (STR #1809)

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.1@5999 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

CHANGES

@@ -4,6 +4,7 @@ CHANGES IN FLTK 1.1.8
 	  STR #1457, STR #1458, STR #1460, STR #1481, STR #1578,
 	  STR #1639, STR #1645, STR #1644, STR #1792, STR #1793,
 	  STR #1742, STR #1777, STR #1794, STR #1827, STR #1843)
+	- gl_font() support for Xft+X11 (STR #1809)
 	- Fl_Gl_Window::mode() needed to hide and show the window
 	  when toggling stereo mode (STR #1846)
 	- Fl_Gl_Window::show() did not work reliably on Mac OS X

src/fl_font_xft.cxx

@@ -3,7 +3,7 @@
 //
 // Xft font code for the Fast Light Tool Kit (FLTK).
 //
-// Copyright 2001-2005 Bill Spitzak and others.
+// Copyright 2001-2007 Bill Spitzak and others.
 //
 // This library is free software; you can redistribute it and/or
 // modify it under the terms of the GNU Library General Public
@@ -125,28 +125,111 @@ void fl_font(int fnum, int size) {
 }
 
 static XftFont* fontopen(const char* name, bool core) {
+  // Check: does it look like we have been passed an old-school XLFD fontname?
+  bool is_xlfd = false;
+  int hyphen_count = 0;
+  int comma_count = 0;
+  unsigned len = strlen(name);
+  if (len > 512) len = 512; // ensure we are not passed an unbounded font name
+  for(unsigned idx = 0; idx < len; idx++) {
+    if(name[idx] == '-') hyphen_count++; // check for XLFD hyphens
+    if(name[idx] == ',') comma_count++;  // are there multiple names?
+  }
+  if(hyphen_count >= 14) is_xlfd = true; // Not a robust check, but good enough?
+
   fl_open_display();
+
+  if(!is_xlfd) { // Not an XLFD - open as a XFT style name
+    XftFont *the_font; // the font we will return;
+    XftPattern *fnt_pat = XftPatternCreate(); // the pattern we will use for matching
     int slant = XFT_SLANT_ROMAN;
     int weight = XFT_WEIGHT_MEDIUM;
-  // may be efficient, but this is non-obvious
+
+    /* This "converts" FLTK-style font names back into "regular" names, extracting
+     * the BOLD and ITALIC codes as it does so - all FLTK font names are prefixed
+     * by 'I' (italic) 'B' (bold) 'P' (bold italic) or ' ' (regular) modifiers.
+     * This gives a fairly limited font selection ability, but is retained for
+     * compatability reasons. If you really need a more complex choice, you are best
+     * calling Fl::set_fonts(*) then selecting the font by font-index rather than by
+     * name anyway. Probably.
+     * If you want to load a font who's name does actually begin with I, B or P, you
+     * MUST use a leading space OR simply use lowercase for the name...
+     */
+    /* This may be efficient, but it is non-obvious. */
     switch (*name++) {
-  case 'I': slant = XFT_SLANT_ITALIC; break;
+    case 'I': slant = XFT_SLANT_ITALIC; break; // italic
-  case 'P': slant = XFT_SLANT_ITALIC;
+    case 'P': slant = XFT_SLANT_ITALIC;        // bold-italic (falls-through)
-  case 'B': weight = XFT_WEIGHT_BOLD; break;
+    case 'B': weight = XFT_WEIGHT_BOLD; break; // bold
-  case ' ': break;
+    case ' ': break;                           // regular
-  default: name--;
+    default: name--;                           // no prefix, restore name
     }
-  // this call is extremely slow...
+
-  return XftFontOpen(fl_display, fl_screen,
+    if(comma_count) { // multiple comma-spearated names were passed
-		     XFT_FAMILY, XftTypeString, name,
+      char *local_name = strdup(name); // duplicate the full name so we can edit the copy
-		     XFT_WEIGHT, XftTypeInteger, weight,
+      char *curr = local_name; // points to first name in string
-		     XFT_SLANT, XftTypeInteger, slant,
+      char *nxt; // next name in string
-		     XFT_ENCODING, XftTypeString, fl_encoding_,
+      do {
-		     XFT_PIXEL_SIZE, XftTypeDouble, (double)fl_size_,
+        nxt = strchr(curr, ','); // find comma seperator
-		     core ? XFT_CORE : 0, XftTypeBool, true,
+        if (nxt) {
-		     XFT_RENDER, XftTypeBool, false,
+          *nxt = 0; // terminate first name
-		     (void *)0);
+          nxt++; // first char of next name
-}
+        }
+
+	// Add the current name to the match pattern
+	XftPatternAddString(fnt_pat, XFT_FAMILY, curr);
+
+        if(nxt) curr = nxt; // move onto next name (if it exists)
+	// Now do a cut-down version of the FLTK name conversion.
+	// NOTE: we only use the slant and weight of the first name,
+	// subsequent names we ignore this for... But we still need to do the check.
+        switch (*curr++) {
+        case 'I': break; // italic
+        case 'P':        // bold-italic (falls-through)
+        case 'B': break; // bold
+        case ' ': break; // regular
+        default: curr--; // no prefix, restore name
+        }
+
+        comma_count--; // decrement name sections count
+      } while (comma_count >= 0);
+      free(local_name); // release our local copy of font names
+    }
+    else { // single name was passed - add it directly
+      XftPatternAddString(fnt_pat, XFT_FAMILY, name);
+    }
+
+    // Construct a match pattern for the font we want...
+    XftPatternAddInteger(fnt_pat, XFT_WEIGHT, weight);
+    XftPatternAddInteger(fnt_pat, XFT_SLANT, slant);
+    XftPatternAddDouble (fnt_pat, XFT_PIXEL_SIZE, (double)fl_size_);
+    XftPatternAddString (fnt_pat, XFT_ENCODING, fl_encoding_);
+    if (core) {
+      XftPatternAddBool(fnt_pat, XFT_CORE, FcTrue);
+      XftPatternAddBool(fnt_pat, XFT_RENDER, FcFalse);
+    }
+
+    XftPattern *match_pat;  // the best available match on the system
+    XftResult match_result; // the result of our matching attempt
+    // query the system to find a match for this font
+    match_pat = XftFontMatch(fl_display, fl_screen, fnt_pat, &match_result);
+    // open the matched font
+    the_font = XftFontOpenPattern(fl_display, match_pat);
+    // Tidy up the resources we allocated
+    XftPatternDestroy(fnt_pat);
+//  XftPatternDestroy(match_pat); // FontConfig will destroy this resource for us. We must not!
+    return the_font;
+  }
+  else { // We were passed a font name in XLFD format
+    char *local_name = strdup(name);
+    if(comma_count) { // This means we were passed multiple XLFD's
+      char *pc = strchr(local_name, ',');
+      *pc = 0; // terminate the XLFD at the first comma
+    }
+    XftFont *the_font = XftFontOpenXlfd(fl_display, fl_screen, local_name);
+    free(local_name);
+   return the_font;
+  }
+} // end of fontopen
 
 Fl_FontSize::Fl_FontSize(const char* name) {
   encoding = fl_encoding_;
@@ -184,18 +267,92 @@ double fl_width(uchar c) {
 }
 
 #if HAVE_GL
-// This call is used by opengl to get a bitmapped font.
+/* This code is used by opengl to get a bitmapped font. The original XFT-1 code
+ * used XFT's "core" fonts methods to load an XFT font that was actually a
+ * X-bitmap font, that could then be readily used with GL.
+ * But XFT-2 does not provide that ability, and there is no easy method to use
+ * an XFT font directly with GL. So...
+*/
+
+#  if XFT_MAJOR > 1
+// This function attempts, on XFT2 systems, to find a suitable "core" Xfont
+// for GL to use, since we dont have an XglUseXftFont(...) function.
+// There's probably a better way to do this. I can't believe it is this hard...
+// Anyway... This code attempts to make an XLFD out of the fltk-style font
+// name it is passed, then tries to load that font. Surprisingly, this quite
+// often works - boxes that have XFT generally also have a fontserver that
+// can serve TTF and other fonts to X, and so the font name that fltk makes
+// from the XFT name often also "exists" as an "core" X font...
+// If this code fails to load the requested font, it falls back through a
+// series of tried 'n tested alternatives, ultimately resorting to what the
+// original fltk code did.
+// NOTE:
+// On my test boxes (FC6, FC7) this works well for the fltk "built-in" font names.
+static XFontStruct* load_xfont_for_xft2(void) {
+  XFontStruct* xgl_font = 0;
+  int size = fl_size_;
+  char *weight = "medium"; // no specifc weight requested - accept any
+  char slant = 'r';   // regular non-italic by default
+  char xlfd[128];     // we will put our synthetic XLFD in here
+  char *pc = strdup(fl_fonts[fl_font_].name); // what font were we asked for?
+  char *name = pc;    // keep a handle to the original name for freeing later
+  // Parse the "fltk-name" of the font
+  switch (*name++) {
+  case 'I': slant = 'i'; break;     // italic
+  case 'P': slant = 'i';            // bold-italic (falls-through)
+  case 'B': weight = "bold"; break; // bold
+  case ' ': break;                  // regular
+  default: name--;                  // no prefix, restore name
+  }
+
+  // first, we do a query with no prefered size, to see if the font exists at all
+  snprintf(xlfd, 128, "-*-*%s*-%s-%c-*--*-*-*-*-*-*-*-*", name, weight, slant); // make up xlfd style name
+  xgl_font = XLoadQueryFont(fl_display, xlfd);
+  if(xgl_font) { // the face exists, but can we get it in a suitable size?
+    XFreeFont(fl_display, xgl_font); // release the non-sized version
+    snprintf(xlfd, 128, "-*-*%s*-%s-%c-*--*-%d-*-*-*-*-*-*", name, weight, slant, (size*10));
+    xgl_font = XLoadQueryFont(fl_display, xlfd); // attempt to load the font at the right size
+  }
+  free(pc); // release our copy of the font name
+
+  // if we have nothing loaded, try a generic proportional font
+  if(!xgl_font) {
+    snprintf(xlfd, 128, "-*-helvetica-*-%c-*--*-%d-*-*-*-*-*-*", slant, (size*10));
+    xgl_font = XLoadQueryFont(fl_display, xlfd);
+  }
+  // If that still didn't work, try this instead
+  if(!xgl_font) {
+    snprintf(xlfd, 128, "-*-courier-medium-%c-*--*-%d-*-*-*-*-*-*", slant, (size*10));
+    xgl_font = XLoadQueryFont(fl_display, xlfd);
+  }
+  // Last chance fallback - this usually loads something...
+  if (!xgl_font) xgl_font = XLoadQueryFont(fl_display, "fixed");
+
+  return xgl_font;
+} // end of load_xfont_for_xft2
+#  endif
+
 XFontStruct* fl_xxfont() {
 #  if XFT_MAJOR > 1
-  // kludge!
+  // kludge! XFT 2 and later does not provide core fonts for us to use with GL
-  static XFontStruct* fixed = 0;
+  // try to load a bitmap X font instead
-  if (!fixed) fixed = XLoadQueryFont(fl_display, "fixed");
+  static XFontStruct* xgl_font = 0;
-  return fixed;
+  static int glsize = 0;
-#  else
+  static int glfont = -1;
-  if (current_font->core) return current_font->u.core.font;
+  // Do we need to load a new font?
+  if ((!xgl_font) || (glsize != fl_size_) || (glfont != fl_font_)) {
+    if (xgl_font) XFreeFont(fl_display, xgl_font); // font already loaded, free it
+    glsize = fl_size_; // record current font size
+    glfont = fl_font_; // and face
+    // create a dummy XLFD for some font of the appropriate size...
+    xgl_font = load_xfont_for_xft2();
+  }
+  return xgl_font;
+#  else // XFT-1 provides a means to load a "core" font directly
+  if (current_font->core) return current_font->u.core.font; // is the current font a "core" font? If so, use it.
   static XftFont* xftfont;
   if (xftfont) XftFontClose (fl_display, xftfont);
-  xftfont = fontopen(fl_fonts[fl_font_].name, true);
+  xftfont = fontopen(fl_fonts[fl_font_].name, true); // else request XFT to load a suitable "core" font instead.
   return xftfont->u.core.font;
 #  endif // XFT_MAJOR > 1
 }