Merge pull request #288 from nickjwhite/opentypeligatures

Enable all ligatures available in a font for text2image rendering
tesseract-ocr · Jun 19, 2016 · 13d789d · 13d789d
2 parents ad66dd2 + 76ed9de
commit 13d789d
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diff --git a/training/stringrenderer.cpp b/training/stringrenderer.cpp
@@ -120,6 +120,7 @@ StringRenderer::StringRenderer(const string& font_desc, int page_width,
       box_padding_(0),
       total_chars_(0),
       font_index_(0),
+      features_(NULL),
       last_offset_(0) {
   pen_color_[0] = 0.0;
   pen_color_[1] = 0.0;
@@ -149,6 +150,7 @@ void StringRenderer::set_underline_continuation_prob(const double frac) {
 }
 
 StringRenderer::~StringRenderer() {
+  free(features_);
   ClearBoxes();
   FreePangoCairo();
 }
@@ -204,6 +206,14 @@ void StringRenderer::SetLayoutProperties() {
     spacing_attr->end_index = static_cast<guint>(-1);
     pango_attr_list_change(attr_list, spacing_attr);
   }
+#if (PANGO_VERSION_MAJOR == 1 && PANGO_VERSION_MINOR >= 38)
+  if (add_ligatures_) {
+    set_features("liga, clig, dlig, hlig");
+    PangoAttribute* feature_attr =
+      pango_attr_font_features_new(features_);
+    pango_attr_list_change(attr_list, feature_attr);
+  }
+#endif
   pango_layout_set_attributes(layout_, attr_list);
   pango_attr_list_unref(attr_list);
   // Adjust line spacing

diff --git a/training/stringrenderer.h b/training/stringrenderer.h
@@ -90,6 +90,10 @@ class StringRenderer {
   void set_underline_style(const PangoUnderline style) {
     underline_style_ = style;
   }
+  void set_features(char *features) {
+    free(features_);
+    features_ = strdup(features);
+  }
   void set_page(int page) {
     page_ = page;
   }
@@ -185,6 +189,7 @@ class StringRenderer {
   double underline_start_prob_;
   double underline_continuation_prob_;
   PangoUnderline underline_style_;
+  char *features_;
   // Text filtering options
   bool drop_uncovered_chars_;
   bool strip_unrenderable_words_;