WINGs: Add optional Pango text layout support

Currently WINGs renders text using Xft directly which does not support
any advanced text layout that is needed for scripts like Arabic or Indic
scripts (or even things like automatic ligature support for Latin
script).

With Pango we also get text fallback for free, so no more square boxes
for characters not supported in the current font (unless no font on the
system supports the specified character, of course).

This patch introduces support for using Pango to render the text (though
its Xft backed), to avoid forcing the additional dependency to everyone
it is made off by default.

Signed-off-by: Carlos R. Mafra <crmafra@gmail.com>

WINGs/Makefile.am

@@ -13,7 +13,7 @@ lib_LTLIBRARIES = libWUtil.la libWINGs.la
 
 
 LDADD= libWUtil.la libWINGs.la $(top_builddir)/wrlib/libwraster.la @INTLIBS@
-libWINGs_la_LIBADD = libWUtil.la $(top_builddir)/wrlib/libwraster.la @XLIBS@ @XFTLIBS@ @FCLIBS@ @LIBM@
+libWINGs_la_LIBADD = libWUtil.la $(top_builddir)/wrlib/libwraster.la @XLIBS@ @XFTLIBS@ @FCLIBS@ @LIBM@ @PANGOLIBS@
 libWUtil_la_LIBADD = @LIBBSD@
 
 EXTRA_DIST = BUGS make-rgb Examples Extras Tests get-wings-flags.in get-wutil-flags.in
@@ -106,7 +106,7 @@ WINGs.pc: Makefile
 	@echo 'Version: $(VERSION)' >> $@
 	@echo 'Requires: wrlib WUtil' >> $@
 	@echo 'Libs: $(lib_search_path) -lWINGs' >> $@
-	@echo 'Libs.private: $(XFTLIBS) $(XLIBS) -lm $(INTLIBS)' >> $@
+	@echo 'Libs.private: $(XFTLIBS) $(PANGOLIBS) $(XLIBS) -lm $(INTLIBS)' >> $@
 	@echo 'Cflags: $(inc_search_path)' >> $@
 
 get-wings-flags: get-wings-flags.in Makefile
@@ -115,6 +115,7 @@ get-wings-flags: get-wings-flags.in Makefile
 	        -e 's#$${lib_search_path}#$(lib_search_path)#;' \
 	        -e 's#$${GFXLIBS}#$(GFXLIBS)#;' \
 	        -e 's#$${XFTLIBS}#$(XFTLIBS)#;' \
+	        -e 's#$${PANGOLIBS}#$(PANGOLIBS)#;' \
 	        -e 's#$${INTLIBS}#$(INTLIBS)#;' \
 	        -e 's#$${XLIBS}#$(XLIBS)#;' < $(abs_srcdir)/get-wings-flags.in > $@
 	@chmod 755 $@

WINGs/WINGs/WINGsP.h

@@ -5,6 +5,9 @@
 #include <X11/Xlib.h>
 #include <X11/Xutil.h>
 
+#ifdef USE_PANGO
+#include <pango/pango.h>
+#endif
 
 #include <WINGs/WINGs.h>
 
@@ -445,6 +448,10 @@ typedef struct W_Font {
     short y;
     short refCount;
     char *name;
+
+#ifdef USE_PANGO
+    PangoLayout *layout;
+#endif
 } W_Font;
 
 #define W_FONTID(f)		(f)->font->fid

WINGs/get-wings-flags.in

@@ -2,7 +2,7 @@
 
 WCFLAGS="${inc_search_path}"
 WLFLAGS="${lib_search_path}"
-WLIBS="-lWINGs -lWUtil -lwraster ${GFXLIBS} ${XFTLIBS} ${XLIBS} -lm ${INTLIBS}"
+WLIBS="-lWINGs -lWUtil -lwraster ${GFXLIBS} ${XFTLIBS} ${XLIBS} -lm ${INTLIBS} ${PANGOLIBS}"
 
 usage="Usage: get-wings-flags [--cflags] [--ldflags] [--libs]"
 

WINGs/wfont.c

@@ -12,6 +12,12 @@
 #include <X11/Xft/Xft.h>
 #include <fontconfig/fontconfig.h>
 
+#ifdef USE_PANGO
+#include <pango/pango.h>
+#include <pango/pangofc-fontmap.h>
+#include <pango/pangoxft.h>
+#endif
+
 #define DEFAULT_FONT "sans serif:pixelsize=12"
 
 #define DEFAULT_SIZE WINGsConfiguration.defaultFontSize
@@ -120,6 +126,14 @@ WMFont *WMCreateFont(WMScreen * scrPtr, const char *fontName)
 	Display *display = scrPtr->display;
 	WMFont *font;
 	char *fname;
+#ifdef USE_PANGO
+	PangoFontMap *fontmap;
+	PangoContext *context;
+	PangoLayout *layout;
+	FcPattern *pattern;
+	PangoFontDescription *description;
+	double size;
+#endif
 
 	if (fontName[0] == '-') {
 		fname = xlfdToFcName(fontName);
@@ -156,6 +170,25 @@ WMFont *WMCreateFont(WMScreen * scrPtr, const char *fontName)
 
 	font->name = fname;
 
+#ifdef USE_PANGO
+	fontmap = pango_xft_get_font_map(scrPtr->display, scrPtr->screen);
+	context = pango_font_map_create_context(fontmap);
+	layout = pango_layout_new(context);
+
+	pattern = FcNameParse((FcChar8 *) font->name);
+	description = pango_fc_font_description_from_pattern(pattern, FALSE);
+
+	/* Pango examines FC_SIZE but not FC_PIXEL_SIZE of the patten, but
+	 * font-name has only "pixelsize", so set the size manually here.
+	 */
+	if (FcPatternGetDouble(pattern, FC_PIXEL_SIZE, 0, &size) == FcResultMatch)
+		pango_font_description_set_absolute_size(description, size * PANGO_SCALE);
+
+	pango_layout_set_font_description(layout, description);
+
+	font->layout = layout;
+#endif
+
 	assert(WMHashInsert(scrPtr->fontCache, font->name, font) == NULL);
 
 	return font;
@@ -252,18 +285,34 @@ WMFont *WMBoldSystemFontOfSize(WMScreen * scrPtr, int size)
 
 int WMWidthOfString(WMFont * font, const char *text, int length)
 {
+#ifdef USE_PANGO
+	const char *previous_text;
+	int width;
+#else
 	XGlyphInfo extents;
+#endif
 
 	wassertrv(font != NULL && text != NULL, 0);
+#ifdef USE_PANGO
+	previous_text = pango_layout_get_text(font->layout);
+	if ((previous_text == NULL) || (strcmp(text, previous_text) != 0))
+		pango_layout_set_text(font->layout, text, length);
+	pango_layout_get_pixel_size(font->layout, &width, NULL);
 
+	return width;
+#else
 	XftTextExtentsUtf8(font->screen->display, font->font, (XftChar8 *) text, length, &extents);
 
 	return extents.xOff;	/* don't ask :P */
+#endif
 }
 
 void WMDrawString(WMScreen * scr, Drawable d, WMColor * color, WMFont * font, int x, int y, const char *text, int length)
 {
 	XftColor xftcolor;
+#ifdef USE_PANGO
+	const char *previous_text;
+#endif
 
 	wassertr(font != NULL);
 
@@ -275,7 +324,14 @@ void WMDrawString(WMScreen * scr, Drawable d, WMColor * color, WMFont * font, in
 
 	XftDrawChange(scr->xftdraw, d);
 
+#ifdef USE_PANGO
+	previous_text = pango_layout_get_text(font->layout);
+	if ((previous_text == NULL) || (strcmp(text, previous_text) != 0))
+		pango_layout_set_text(font->layout, text, length);
+	pango_xft_render_layout(scr->xftdraw, &xftcolor, font->layout, x * PANGO_SCALE, y * PANGO_SCALE);
+#else
 	XftDrawStringUtf8(scr->xftdraw, &xftcolor, font->font, x, y + font->y, (XftChar8 *) text, length);
+#endif
 }
 
 void
@@ -284,6 +340,9 @@ WMDrawImageString(WMScreen * scr, Drawable d, WMColor * color, WMColor * backgro
 {
 	XftColor textColor;
 	XftColor bgColor;
+#ifdef USE_PANGO
+	const char *previous_text;
+#endif
 
 	wassertr(font != NULL);
 
@@ -303,7 +362,14 @@ WMDrawImageString(WMScreen * scr, Drawable d, WMColor * color, WMColor * backgro
 
 	XftDrawRect(scr->xftdraw, &bgColor, x, y, WMWidthOfString(font, text, length), font->height);
 
+#ifdef USE_PANGO
+	previous_text = pango_layout_get_text(font->layout);
+	if ((previous_text == NULL) || (strcmp(text, previous_text) != 0))
+		pango_layout_set_text(font->layout, text, length);
+	pango_xft_render_layout(scr->xftdraw, &textColor, font->layout, x * PANGO_SCALE, y * PANGO_SCALE);
+#else
 	XftDrawStringUtf8(scr->xftdraw, &textColor, font->font, x, y + font->y, (XftChar8 *) text, length);
+#endif
 }
 
 WMFont *WMCopyFontWithStyle(WMScreen * scrPtr, WMFont * font, WMFontStyle style)

configure.ac

@@ -625,6 +625,26 @@ fi
 AC_SUBST(XFTFLAGS)
 AC_SUBST(XFTLIBS)
 
+dnl PANGO support
+dnl =============
+pango=no
+AC_ARG_ENABLE(pango, AS_HELP_STRING([--enable-pango], [enable Pango text layout support]),
+                pango=$enableval, pango=no)
+
+PANGOFLAGS=
+PANGOLIBS=
+if test "$pango" = yes; then
+	PANGOLIBS=`$PKGCONFIG pangoxft --libs`
+	PANGOFLAGS=`$PKGCONFIG pangoxft --cflags`
+	if test "x$PANGOLIBS" = "x" ; then
+	        AC_MSG_RESULT([not found])
+	else
+		AC_DEFINE(USE_PANGO, 1, [Define if Pango is to be used])
+		AC_MSG_RESULT([found])
+	fi
+fi
+inc_search_path="$inc_search_path $PANGOFLAGS"
+AC_SUBST(PANGOLIBS)
 
 dnl ==============================================
 dnl         Graphic Format Libraries
@@ -869,6 +889,7 @@ echo "Supported X extensions:             :$supported_xext"
 echo "Supported graphic format libraries  :$supported_gfx"
 echo "Unsupported features                :$unsupported"
 echo "Antialiased text support in WINGs   : $xft"
+echo "Pango text layout support in WINGs  : $pango"
 echo "Translated message files to install : $mof"
 dnl echo "Supported languages beside English  : $languages"
 if test "x$MOFILES" != "x"; then