Add compile time switch for HarfBuzz support

Now that it's possible to switch shapers at runtime, it also becomes a
lot easier to disable them at compile time. Add ifdefs and build system
changes so that HarfBuzz can be safely disabled. It's autodetected now
and enabled if available.

This shuffles a bit of code around, but there are no functional changes.

Note that FriBidi remains mandatory for the time being, but this
shouldn't pose any problems, since it is a small and very portable
library without any special dependencies.

4 files changed, 87 insertions, 53 deletions

diff --git a/configure.ac b/configure.ac
index 56655ee..d9496fc 100644
--- a/configure.ac
+++ b/configure.ac
@@ -40,8 +40,8 @@ AC_ARG_ENABLE([enca], AS_HELP_STRING([--disable-enca],
     [disable enca (charset autodetect) support @<:@default=check@:>@]))
 AC_ARG_ENABLE([fontconfig], AS_HELP_STRING([--disable-fontconfig],
     [disable fontconfig support @<:@default=enabled@:>@]))
-AC_ARG_ENABLE([fribidi], AS_HELP_STRING([--disable-fribidi],
-    [disable bidi support @<:@default=enabled@:>@]))
+AC_ARG_ENABLE([harfbuzz], AS_HELP_STRING([--disable-harfbuzz],
+    [disable HarfBuzz support @<:@default=check@:>@]))
 
 PKG_CHECK_MODULES([FREETYPE], freetype2 >= 9.10.3, [
     CFLAGS="$CFLAGS $FREETYPE_CFLAGS"
@@ -49,6 +49,12 @@ PKG_CHECK_MODULES([FREETYPE], freetype2 >= 9.10.3, [
     AC_DEFINE(CONFIG_FREETYPE, 1, [found freetype2 via pkg-config])
     ])
 
+PKG_CHECK_MODULES([FRIBIDI], fribidi >= 0.19.0, [
+    CFLAGS="$CFLAGS $FRIBIDI_CFLAGS"
+    LIBS="$LIBS $FRIBIDI_LIBS"
+    AC_DEFINE(CONFIG_FRIBIDI, 1, [found fribidi via pkg-config])
+    ])
+
 if test x$enable_fontconfig != xno; then
 PKG_CHECK_MODULES([FONTCONFIG], fontconfig >= 2.4.2, [
     CFLAGS="$CFLAGS $FONTCONFIG_CFLAGS"
@@ -58,22 +64,13 @@ PKG_CHECK_MODULES([FONTCONFIG], fontconfig >= 2.4.2, [
     ])
 fi
 
-if test x$enable_fribidi != xno; then
-PKG_CHECK_MODULES([FRIBIDI], fribidi >= 0.19.0, [
-    CFLAGS="$CFLAGS $FRIBIDI_CFLAGS"
-    LIBS="$LIBS $FRIBIDI_LIBS"
-    AC_DEFINE(CONFIG_FRIBIDI, 1, [found fribidi via pkg-config])
-	fribidi=true
-    ])
-fi
-
 if test x$enable_harfbuzz != xno; then
 PKG_CHECK_MODULES([HARFBUZZ], harfbuzz >= 0.7.0, [
     CFLAGS="$CFLAGS $HARFBUZZ_CFLAGS"
     LIBS="$LIBS $HARFBUZZ_LIBS"
     AC_DEFINE(CONFIG_HARFBUZZ, 1, [found harfbuzz-ng via pkg-config])
 	harfbuzz=true
-    ])
+    ], [harfbuzz=false])
 fi
 
 if test x$enable_enca != xno; then
@@ -98,15 +95,13 @@ AM_CONDITIONAL([HAVE_LIBPNG], [test x$libpng = xtrue])
 
 # Add dependent libraries to pkg-config for static linking
 PKG_REQUIRES="freetype2 >= 9.6.3"
+PKG_REQUIRES="fribidi >= 0.19.0, ${PKG_REQUIRES}"
 if test x$enca = xtrue; then
     PKG_REQUIRES="enca, ${PKG_REQUIRES}"
 fi
 if test x$fontconfig = xtrue; then
     PKG_REQUIRES="fontconfig >= 2.2.0, ${PKG_REQUIRES}"
 fi
-if test x$fribidi = xtrue; then
-    PKG_REQUIRES="fribidi >= 0.19.0, ${PKG_REQUIRES}"
-fi
 if test x$harfbuzz = xtrue; then
     PKG_REQUIRES="harfbuzz >= 0.7.0, ${PKG_REQUIRES}"
 fi
diff --git a/libass/ass_render.c b/libass/ass_render.c
index 85d30b4..0bc7d38 100644
--- a/libass/ass_render.c
+++ b/libass/ass_render.c
@@ -77,7 +77,11 @@ ASS_Renderer *ass_renderer_init(ASS_Library *library)
 
     priv->shaper = ass_shaper_new(0);
     ass_shaper_info(library);
+#ifdef CONFIG_HARFBUZZ
     priv->settings.shaper = ASS_SHAPING_COMPLEX;
+#else
+    priv->settings.shaper = ASS_SHAPING_SIMPLE;
+#endif
 
   ass_init_exit:
     if (priv)
diff --git a/libass/ass_render_api.c b/libass/ass_render_api.c
index 1d8cba6..8bf9e5d 100644
--- a/libass/ass_render_api.c
+++ b/libass/ass_render_api.c
@@ -60,11 +60,13 @@ void ass_set_frame_size(ASS_Renderer *priv, int w, int h)
 
 void ass_set_shaper(ASS_Renderer *priv, ASS_ShapingLevel level)
 {
+#ifdef CONFIG_HARFBUZZ
     // select the complex shaper for illegal values
     if (level == ASS_SHAPING_SIMPLE || level == ASS_SHAPING_COMPLEX)
         priv->settings.shaper = level;
     else
         priv->settings.shaper = ASS_SHAPING_COMPLEX;
+#endif
 }
 
 void ass_set_margins(ASS_Renderer *priv, int t, int b, int l, int r)
diff --git a/libass/ass_shaper.c b/libass/ass_shaper.c
index f6724d3..4eb99f7 100644
--- a/libass/ass_shaper.c
+++ b/libass/ass_shaper.c
@@ -16,8 +16,9 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
+#include "config.h"
+
 #include <fribidi/fribidi.h>
-#include <hb-ft.h>
 
 #include "ass_shaper.h"
 #include "ass_render.h"
@@ -27,15 +28,19 @@
 
 #define MAX_RUNS 50
 
+#ifdef CONFIG_HARFBUZZ
+#include <hb-ft.h>
 enum {
     VERT = 0,
     VKNA,
     KERN
 };
 #define NUM_FEATURES 3
+#endif
 
 struct ass_shaper {
     ASS_ShapingLevel shaping_level;
+
     // FriBidi log2vis
     int n_glyphs;
     FriBidiChar *event_text;
@@ -43,14 +48,19 @@ struct ass_shaper {
     FriBidiLevel *emblevels;
     FriBidiStrIndex *cmap;
     FriBidiParType base_direction;
+
+#ifdef CONFIG_HARFBUZZ
     // OpenType features
     int n_features;
     hb_feature_t *features;
     hb_language_t language;
+
     // Glyph metrics cache, to speed up shaping
     Cache *metrics_cache;
+#endif
 };
 
+#ifdef CONFIG_HARFBUZZ
 struct ass_shaper_metrics_data {
     Cache *metrics_cache;
     GlyphMetricsHashKey hash_key;
@@ -61,14 +71,19 @@ struct ass_shaper_font_data {
     hb_font_funcs_t *font_funcs[ASS_FONT_MAX_FACES];
     struct ass_shaper_metrics_data *metrics_data[ASS_FONT_MAX_FACES];
 };
+#endif
 
 /**
  * \brief Print version information
  */
 void ass_shaper_info(ASS_Library *lib)
 {
-    ass_msg(lib, MSGL_V, "Complex text layout enabled, using FriBidi "
-            FRIBIDI_VERSION " HarfBuzz-ng %s", hb_version_string());
+    ass_msg(lib, MSGL_V, "Shaper: FriBidi "
+            FRIBIDI_VERSION " (SIMPLE)"
+#ifdef CONFIG_HARFBUZZ
+            " HarfBuzz-ng %s (COMPLEX)", hb_version_string()
+#endif
+           );
 }
 
 /**
@@ -86,55 +101,24 @@ static void check_allocations(ASS_Shaper *shaper, size_t new_size)
 }
 
 /**
- * \brief set up the HarfBuzz OpenType feature list with some
- * standard features.
- */
-static void init_features(ASS_Shaper *shaper)
-{
-    shaper->features = calloc(sizeof(hb_feature_t), NUM_FEATURES);
-
-    shaper->n_features = NUM_FEATURES;
-    shaper->features[VERT].tag = HB_TAG('v', 'e', 'r', 't');
-    shaper->features[VERT].end = INT_MAX;
-    shaper->features[VKNA].tag = HB_TAG('v', 'k', 'n', 'a');
-    shaper->features[VKNA].end = INT_MAX;
-    shaper->features[KERN].tag = HB_TAG('k', 'e', 'r', 'n');
-    shaper->features[KERN].end = INT_MAX;
-}
-
-/**
- * \brief Create a new shaper instance and preallocate data structures
- * \param prealloc preallocation size
- */
-ASS_Shaper *ass_shaper_new(size_t prealloc)
-{
-    ASS_Shaper *shaper = calloc(sizeof(*shaper), 1);
-
-    shaper->base_direction = FRIBIDI_PAR_ON;
-    init_features(shaper);
-    check_allocations(shaper, prealloc);
-
-    shaper->metrics_cache = ass_glyph_metrics_cache_create();
-
-    return shaper;
-}
-
-/**
  * \brief Free shaper and related data
  */
 void ass_shaper_free(ASS_Shaper *shaper)
 {
+#ifdef CONFIG_HARFBUZZ
     ass_cache_done(shaper->metrics_cache);
+    free(shaper->features);
+#endif
     free(shaper->event_text);
     free(shaper->ctypes);
     free(shaper->emblevels);
     free(shaper->cmap);
-    free(shaper->features);
     free(shaper);
 }
 
 void ass_shaper_font_data_free(ASS_ShaperFontData *priv)
 {
+#ifdef CONFIG_HARFBUZZ
     int i;
     for (i = 0; i < ASS_FONT_MAX_FACES; i++)
         if (priv->fonts[i]) {
@@ -143,6 +127,25 @@ void ass_shaper_font_data_free(ASS_ShaperFontData *priv)
             hb_font_funcs_destroy(priv->font_funcs[i]);
         }
     free(priv);
+#endif
+}
+
+#ifdef CONFIG_HARFBUZZ
+/**
+ * \brief set up the HarfBuzz OpenType feature list with some
+ * standard features.
+ */
+static void init_features(ASS_Shaper *shaper)
+{
+    shaper->features = calloc(sizeof(hb_feature_t), NUM_FEATURES);
+
+    shaper->n_features = NUM_FEATURES;
+    shaper->features[VERT].tag = HB_TAG('v', 'e', 'r', 't');
+    shaper->features[VERT].end = INT_MAX;
+    shaper->features[VKNA].tag = HB_TAG('v', 'k', 'n', 'a');
+    shaper->features[VKNA].end = INT_MAX;
+    shaper->features[KERN].tag = HB_TAG('k', 'e', 'r', 'n');
+    shaper->features[KERN].end = INT_MAX;
 }
 
 /**
@@ -482,6 +485,7 @@ static void shape_harfbuzz(ASS_Shaper *shaper, GlyphInfo *glyphs, size_t len)
     }
 
 }
+#endif
 
 /**
  * \brief Shape event text with FriBidi. Does mirroring and simple
@@ -517,7 +521,9 @@ static void shape_fribidi(ASS_Shaper *shaper, GlyphInfo *glyphs, size_t len)
  */
 void ass_shaper_set_kerning(ASS_Shaper *shaper, int kern)
 {
+#ifdef CONFIG_HARFBUZZ
     shaper->features[KERN].value = !!kern;
+#endif
 }
 
 /**
@@ -564,7 +570,9 @@ void ass_shaper_set_base_direction(ASS_Shaper *shaper, FriBidiParType dir)
  */
 void ass_shaper_set_language(ASS_Shaper *shaper, const char *code)
 {
+#ifdef CONFIG_HARFBUZZ
     shaper->language = hb_language_from_string(code);
+#endif
 }
 
 /**
@@ -607,6 +615,7 @@ void ass_shaper_shape(ASS_Shaper *shaper, TextInfo *text_info)
         glyphs[i].shape_run_id += shaper->emblevels[i];
     }
 
+#ifdef CONFIG_HARFBUZZ
     switch (shaper->shaping_level) {
     case ASS_SHAPING_SIMPLE:
         shape_fribidi(shaper, glyphs, text_info->length);
@@ -615,6 +624,10 @@ void ass_shaper_shape(ASS_Shaper *shaper, TextInfo *text_info)
         shape_harfbuzz(shaper, glyphs, text_info->length);
         break;
     }
+#else
+        shape_fribidi(shaper, glyphs, text_info->length);
+#endif
+
 
     // clean up
     for (i = 0; i < text_info->length; i++) {
@@ -629,6 +642,26 @@ void ass_shaper_shape(ASS_Shaper *shaper, TextInfo *text_info)
 }
 
 /**
+ * \brief Create a new shaper instance and preallocate data structures
+ * \param prealloc preallocation size
+ */
+ASS_Shaper *ass_shaper_new(size_t prealloc)
+{
+    ASS_Shaper *shaper = calloc(sizeof(*shaper), 1);
+
+    shaper->base_direction = FRIBIDI_PAR_ON;
+    check_allocations(shaper, prealloc);
+
+#ifdef CONFIG_HARFBUZZ
+    init_features(shaper);
+    shaper->metrics_cache = ass_glyph_metrics_cache_create();
+#endif
+
+    return shaper;
+}
+
+
+/**
  * \brief clean up additional data temporarily needed for shaping and
  * (e.g. additional glyphs allocated)
  */