X11 platform: Add optional use of the pango library to draw text, gaining the possibility to draw text in any script supported by Unicode.

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.4@12153 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

CHANGES

@@ -17,13 +17,17 @@ Changes in FLTK 1.4.0					Released: ??? ?? 2017
 
   New Features and Extensions
 
-  - (add here)
   - Added '--enable-print' option to configure effective under X11 platforms
     and with 'yes' default value. Using '--enable-print=no' removes print
     and PostScript support from the FLTK library, thus reducing its size.
   - Added Fl_Surface_Device::push_current(new_surface) and
     Fl_Surface_Device::pop_current() to set/unset the current surface
     receiving graphics commands.
+  - X11 platform: Added support for drawing text with the pango library
+    which allows to draw most scripts supported by Unicode, including CJK
+    and right-to-left scripts. The corresponding CMake option is
+    OPTION_USE_PANGO. The corresponding configure option is --enable-pango.
+    This option is OFF by default.
 
   New Configuration Options (ABI Version)
 

CMake/options.cmake

@@ -372,8 +372,46 @@ endif(OPTION_USE_XCURSOR)
 #######################################################################
 if(X11_Xft_FOUND)
    option(OPTION_USE_XFT "use lib Xft" ON)
+   option(OPTION_USE_PANGO "use lib Pango" OFF)
 endif(X11_Xft_FOUND)
 
+#######################################################################
+if(X11_Xft_FOUND AND OPTION_USE_PANGO)
+#this covers Debian, Ubuntu, FreeBSD, NetBSD, Darwin
+   if(APPLE AND OPTION_APPLE_X11)
+	list(APPEND CMAKE_INCLUDE_PATH  /sw/include)
+    	list(APPEND CMAKE_LIBRARY_PATH  /sw/lib)
+   endif(APPLE AND OPTION_APPLE_X11)
+   find_file(HAVE_PANGO_H pango-1.0/pango/pango.h ${CMAKE_INCLUDE_PATH})
+   find_file(HAVE_PANGOXFT_H pango-1.0/pango/pangoxft.h ${CMAKE_INCLUDE_PATH})
+
+  if(HAVE_PANGO_H AND HAVE_PANGOXFT_H)
+    find_library(HAVE_LIB_PANGO pango-1.0 ${CMAKE_LIBRARY_PATH})
+    find_library(HAVE_LIB_PANGOXFT pangoxft-1.0 ${CMAKE_LIBRARY_PATH})
+    if(APPLE)
+    	set(HAVE_LIB_GOBJECT TRUE)
+    else()
+    	find_library(HAVE_LIB_GOBJECT gobject-2.0 ${CMAKE_LIBRARY_PATH})
+    endif(APPLE)
+  endif(HAVE_PANGO_H AND HAVE_PANGOXFT_H)
+  if(HAVE_LIB_PANGO AND HAVE_LIB_PANGOXFT AND HAVE_LIB_GOBJECT)
+    set(USE_PANGO TRUE)
+    message(STATUS "USE_PANGO=" ${USE_PANGO})
+    #remove last 3 components of HAVE_PANGO_H and put in PANGO_H_PREFIX
+    get_filename_component(PANGO_H_PREFIX ${HAVE_PANGO_H} PATH)
+    get_filename_component(PANGO_H_PREFIX ${PANGO_H_PREFIX} PATH)
+    get_filename_component(PANGO_H_PREFIX ${PANGO_H_PREFIX} PATH)
+
+    get_filename_component(PANGOLIB_DIR ${HAVE_LIB_PANGO} PATH)
+    #glib.h is usually in ${PANGO_H_PREFIX}/glib-2.0/ ...
+    find_path(GLIB_H_PATH glib.h ${PANGO_H_PREFIX}/glib-2.0)
+    if(NOT GLIB_H_PATH) # ... but not under NetBSD
+		find_path(GLIB_H_PATH glib.h ${PANGO_H_PREFIX}/glib/glib-2.0)
+    endif(NOT GLIB_H_PATH)
+    include_directories(${PANGO_H_PREFIX}/pango-1.0 ${GLIB_H_PATH} ${PANGOLIB_DIR}/glib-2.0/include)
+  endif(HAVE_LIB_PANGO AND HAVE_LIB_PANGOXFT AND HAVE_LIB_GOBJECT)
+endif(X11_Xft_FOUND AND OPTION_USE_PANGO)
+
 if(OPTION_USE_XFT)
    set(USE_XFT X11_Xft_FOUND)
    list(APPEND FLTK_LDLIBS -lXft)

configh.cmake.in

@@ -91,6 +91,14 @@
 
 #cmakedefine01 USE_XFT
 
+/*
+* USE_PANGO:
+*
+* Use the pango library to draw UTF8 text.
+*/
+
+#cmakedefine USE_PANGO 1
+
 /*
  * HAVE_XDBE:
  *

configh.in

@@ -85,11 +85,19 @@
 /*
  * USE_XFT
  *
- * Use the new Xft library to draw anti-aliased text.
+ * Use the Xft library to draw anti-aliased text.
  */
 
 #define USE_XFT 0
 
+/*
+ * USE_PANGO
+ *
+ * Use the pango library to draw UTF-8 text.
+ */
+
+#define USE_PANGO 0
+
 /*
  * HAVE_XDBE:
  *

configure.ac

@@ -1041,6 +1041,41 @@ case $host_os_gui in
 	    fi
 	fi
 
+	dnl Check for the pango library unless disabled...
+        AC_ARG_ENABLE(pango, [  --enable-pango          turn on Pango support [[default=no]]])
+
+        pango_found=no
+	if test x$enable_pango = xyes; then
+	    case $host_os in
+    		darwin*)
+	    	  CXXFLAGS="-I/sw/include/pango-1.0 -I/sw/include/glib-2.0 -I/sw/lib/glib-2.0/include $CXXFLAGS"
+	    	  PANGOLIBDIR="-L/sw/lib"
+	    	  ;;
+    		linux*)
+	    	  CXXFLAGS="-I/usr/include/pango-1.0 -I/usr/include/glib-2.0 -I/usr/lib/glib-2.0/include $CXXFLAGS"
+	    	  CXXFLAGS="-I/usr/lib/i386-linux-gnu/glib-2.0/include -I/usr/lib/x86_64-linux-gnu/glib-2.0/include $CXXFLAGS"
+    	    	  ;;
+    	    	freebsd*)
+	    	  CXXFLAGS="-I/usr/local/include/pango-1.0 -I/usr/local/include/glib-2.0 -I/usr/local/lib/glib-2.0/include $CXXFLAGS"
+	    	  ;;
+     	    	netbsd*)
+	    	  CXXFLAGS="-I/usr/pkg/include/pango-1.0 -I/usr/pkg/include/glib-2.0 -I/usr/pkg/lib/glib-2.0/include $CXXFLAGS"
+	    	  CXXFLAGS="-I/usr/pkg/include/glib/glib-2.0 $CXXFLAGS"
+	    	  PANGOLIBDIR="-L/usr/pkg/lib"
+	    	  LDFLAGS="-Wl,-rpath,/usr/pkg/lib $LDFLAGS"
+	    	  ;;
+   	    esac
+	        CPPFLAGS="$PANGOLIBDIR $CXXFLAGS"
+	        AC_CHECK_HEADER(pango/pango.h,
+		  AC_CHECK_HEADER(pango/pangoxft.h,
+		   AC_CHECK_LIB(pango-1.0, pango_layout_new,
+		    AC_CHECK_LIB(pangoxft-1.0, pango_xft_render_layout,
+			AC_DEFINE(USE_PANGO)
+                        pango_found=yes
+			LIBS="$PANGOLIBDIR -lpango-1.0 -lpangoxft-1.0 -lgobject-2.0 $LIBS"))))
+		CPPFLAGS=$CXXFLAGS
+	fi
+
 	dnl Check for the Xdbe extension unless disabled...
 	AC_ARG_ENABLE(xdbe, [  --enable-xdbe           turn on Xdbe support [[default=yes]]])
 
@@ -1507,6 +1542,9 @@ case $host_os_gui in
 	if test x$xrender_found = xyes; then
 	    graphics="$graphics + Xrender"
 	fi
+        if test x$pango_found = xyes; then
+            graphics="$graphics + pango"
+        fi
 	;;
 esac
 

documentation/src/drawing.dox

@@ -620,8 +620,9 @@ void fl_draw(const char *, int x, int y) <br>
 void fl_draw(const char *, int n, int x, int y)
 
 \par
-Draw a nul-terminated string or an array of \p n characters
+Draw a nul-terminated string or an array of \p n bytes
-starting at the given location. Text is aligned to the left and to
+starting at the given location. In both cases, the text must be UTF-8 encoded.
+Text is aligned to the left and to
 the baseline of the font. To align to the bottom, subtract
 \p %fl_descent() from \p y.
 To align to the top, subtract \p %fl_descent() and add \p %fl_height().
@@ -629,6 +630,11 @@ This version of \p %fl_draw()  provides direct access to
 the text drawing function of the underlying OS. It does not apply any 
 special handling to control characters. 
 
+void fl_rtl_draw(const char *str, int n, int x, int y)
+
+\par
+Draw a UTF-8 string of length n bytes right to left starting at the given x, y location. 
+
 void fl_draw(const char* str, int x, int y, int w, int h, Fl_Align align, Fl_Image* img, int draw_symbols)
 
 \par
@@ -775,6 +781,17 @@ FLTK expects individual characters, characters that are not part of
 a string, in UCS-4 encoding, which is also ASCII compatible, but 
 requires 4 bytes to store a Unicode character.
 
+FLTK can draw accurately any Unicode-supported script for which the system
+contains relevant fonts. Under X11 platforms, this requires
+to build the library with the OPTION_USE_PANGO CMake option turned On 
+(or with configure --enable-pango).
+
+Plain text drawing starting at a user-given coordinate
+is well supported by FLTK, including for right-to-left scripts. 
+Further text-related operations
+(i.e., selection, formatting, input, and editing) are functional with
+left-to-right scripts only.
+
 For more information about character encodings, see the chapter on
 \ref unicode.
 

src/CMakeLists.txt

@@ -470,6 +470,13 @@ if (HAVE_XRENDER)
     list (APPEND OPTIONAL_LIBS ${X11_Xrender_LIB})
 endif (HAVE_XRENDER)
 
+if (USE_PANGO)
+  list (APPEND OPTIONAL_LIBS ${HAVE_LIB_PANGO} ${HAVE_LIB_PANGOXFT})
+  if(NOT APPLE)
+  	list (APPEND OPTIONAL_LIBS ${HAVE_LIB_GOBJECT} )
+  endif(NOT APPLE)
+endif(USE_PANGO)
+
 if (USE_XFT)
     list (APPEND OPTIONAL_LIBS ${X11_Xft_LIB})
     if (LIB_fontconfig)

src/drivers/Xlib/Fl_Font.H

@@ -45,8 +45,12 @@ public:
   Fl_Fontsize size; /**< font size */
 #ifndef FL_DOXYGEN // don't bother with platorm dependant details in the doc. 
 #  if USE_XFT
-  XftFont* font;
+#    if USE_PANGO
-  //const char* encoding;
+        int descent_;
+        int height_;
+#    else
+        XftFont* font;
+#    endif
   int angle;
   FL_EXPORT Fl_Font_Descriptor(const char* xfontname, Fl_Fontsize size, int angle);
 #  else

src/drivers/Xlib/Fl_Xlib_Graphics_Driver.H

@@ -1,8 +1,7 @@
 //
 // "$Id$"
 //
-// Definition of classes Fl_Graphics_Driver, Fl_Surface_Device, Fl_Display_Device
+// Definition of class Fl_Xlib_Graphics_Driver for the Fast Light Tool Kit (FLTK).
-// for the Fast Light Tool Kit (FLTK).
 //
 // Copyright 2010-2016 by Bill Spitzak and others.
 //
@@ -43,12 +42,31 @@ struct _XRegion {
 };
 #endif // HAVE_X11_XREGION_H
 
+#if USE_PANGO
+#include <pango/pangoxft.h>
+#endif
+
+
 /**
  \brief The Xlib-specific graphics class.
  *
  This class is implemented only on the Xlib platform.
  */
 class FL_EXPORT Fl_Xlib_Graphics_Driver : public Fl_Graphics_Driver {
+#if USE_XFT
+  void drawUCS4(const void *str, int n, int x, int y);
+#endif
+#if USE_PANGO
+  friend class Fl_X11_Screen_Driver;
+  static PangoContext *pctxt_;
+  static PangoFontMap *pfmap_;
+  static PangoLayout *playout_;
+protected:
+  PangoFontDescription *pfd_;
+  void do_draw(int from_right, const char *str, int n, int x, int y);
+  static PangoContext *context();
+  static void init_built_in_fonts();
+#endif
 protected:
   static GC gc_;
   uchar **mask_bitmap_;
@@ -59,9 +77,13 @@ protected:
   XPOINT *p;
   int line_width_;
   int clip_x(int x);
+#if USE_XFT
+  static Window draw_window;
+  static struct _XftDraw* draw_;
+#endif
 public:
   Fl_Xlib_Graphics_Driver(void);
-  virtual ~Fl_Xlib_Graphics_Driver() { if (p) free(p); }
+  virtual ~Fl_Xlib_Graphics_Driver();
   virtual int has_feature(driver_feature mask) { return mask & NATIVE; }
   virtual void *gc() { return gc_; }
   virtual void gc(void *value);
@@ -100,7 +122,7 @@ public:
   Fl_Region XRectangleRegion(int x, int y, int w, int h);
   void XDestroyRegion(Fl_Region r);
 protected:
-  void transformed_vertex0(short x, short y);
+  virtual void transformed_vertex0(short x, short y);
   void fixloop();
   // --- implementation is in src/fl_rect.cxx which includes src/cfg_gfx/xlib_rect.cxx
   void point(int x, int y);

src/drivers/Xlib/Fl_Xlib_Graphics_Driver.cxx

@@ -57,8 +57,20 @@ Fl_Xlib_Graphics_Driver::Fl_Xlib_Graphics_Driver(void) {
   p_size = 0;
   p = NULL;
   line_width_ = 0;
+#if USE_PANGO
+  pfd_ = pango_font_description_new();
+  Fl_Graphics_Driver::font(0, 0);
+#endif
 }
 
+Fl_Xlib_Graphics_Driver::~Fl_Xlib_Graphics_Driver() {
+  if (p) free(p);
+#if USE_PANGO
+  pango_font_description_free(pfd_);
+#endif
+}
+
+
 void Fl_Xlib_Graphics_Driver::gc(void *value) {
   gc_ = (GC)value;
   fl_gc = gc_;