From 755d178d20ec12b8afe8bcac87f77a7fe0356c3a Mon Sep 17 00:00:00 2001
From: artemp <artem@mapnik.org>
Date: Tue, 31 Jan 2017 17:44:25 +0100
Subject: [PATCH] alternative exaustive face fallback implementation ref #3534
 #3559

---
 include/mapnik/text/harfbuzz_shaper.hpp | 81 +++++++++++--------------
 1 file changed, 37 insertions(+), 44 deletions(-)

diff --git a/include/mapnik/text/harfbuzz_shaper.hpp b/include/mapnik/text/harfbuzz_shaper.hpp
index 56887e5fc..e4672526f 100644
--- a/include/mapnik/text/harfbuzz_shaper.hpp
+++ b/include/mapnik/text/harfbuzz_shaper.hpp
@@ -80,17 +80,17 @@ static void shape_text(text_line & line,
     line.reserve(length);
 
     auto hb_buffer_deleter = [](hb_buffer_t * buffer) { hb_buffer_destroy(buffer);};
-    const std::unique_ptr<hb_buffer_t, decltype(hb_buffer_deleter)> buffer(hb_buffer_create(),hb_buffer_deleter);
+    const std::unique_ptr<hb_buffer_t, decltype(hb_buffer_deleter)> buffer(hb_buffer_create(), hb_buffer_deleter);
     hb_buffer_pre_allocate(buffer.get(), safe_cast<int>(length));
     mapnik::value_unicode_string const& text = itemizer.text();
-
     for (auto const& text_item : list)
     {
+        auto item_length = static_cast<int>(text_item.end - text_item.start);
         face_set_ptr face_set = font_manager.get_face_set(text_item.format_->face_name, text_item.format_->fontset);
         double size = text_item.format_->text_size * scale_factor;
         face_set->set_unscaled_character_sizes();
         std::size_t num_faces = face_set->size();
-        std::size_t pos = 0;
+
         font_feature_settings const& ff_settings = text_item.format_->ff_settings;
         int ff_count = safe_cast<int>(ff_settings.count());
 
@@ -101,41 +101,37 @@ static void shape_text(text_line & line,
             hb_glyph_info_t glyph;
             hb_glyph_position_t position;
         };
-        // this table is filled with information for rendering each glyph, so that 
+        // this table is filled with information for rendering each glyph, so that
         // several font faces can be used in a single text_item
         std::vector<glyph_face_info> glyphinfos;
-        unsigned valid_glyphs = 0;
-
+        int valid_glyphs = 0;
+        std::size_t pos = 0;
         for (auto const& face : *face_set)
         {
             ++pos;
             hb_buffer_clear_contents(buffer.get());
-            hb_buffer_add_utf16(buffer.get(), uchar_to_utf16(text.getBuffer()), text.length(), text_item.start, static_cast<int>(text_item.end - text_item.start));
-            hb_buffer_set_direction(buffer.get(), (text_item.dir == UBIDI_RTL)?HB_DIRECTION_RTL:HB_DIRECTION_LTR);
+            hb_buffer_add_utf16(buffer.get(), uchar_to_utf16(text.getBuffer()), text.length(), text_item.start, item_length);
+            hb_buffer_set_direction(buffer.get(), (text_item.dir == UBIDI_RTL) ? HB_DIRECTION_RTL : HB_DIRECTION_LTR);
             hb_buffer_set_script(buffer.get(), _icu_script_to_script(text_item.script));
             hb_font_t *font(hb_ft_font_create(face->get_face(), nullptr));
             // https://github.com/mapnik/test-data-visual/pull/25
-            #if HB_VERSION_MAJOR > 0
-             #if HB_VERSION_ATLEAST(1, 0 , 5)
-            hb_ft_font_set_load_flags(font,FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING);
-             #endif
-            #endif
+#if (HB_VERSION_MAJOR > 0 && HB_VERSION_ATLEAST(1, 0, 5))
+            hb_ft_font_set_load_flags(font, FT_LOAD_DEFAULT | FT_LOAD_NO_HINTING);
+#endif
             hb_shape(font, buffer.get(), ff_settings.get_features(), ff_count);
             hb_font_destroy(font);
 
             unsigned num_glyphs = hb_buffer_get_length(buffer.get());
+            hb_glyph_info_t *glyphs = hb_buffer_get_glyph_infos(buffer.get(), &num_glyphs);
+            hb_glyph_position_t *positions = hb_buffer_get_glyph_positions(buffer.get(), &num_glyphs);
 
-            // if the number of rendered glyphs has increased, we need to resize the table 
+            // if the number of rendered glyphs has increased, we need to resize the table
             if (num_glyphs > glyphinfos.size())
             {
                 glyphinfos.resize(num_glyphs);
             }
-
-            hb_glyph_info_t *glyphs = hb_buffer_get_glyph_infos(buffer.get(), nullptr);
-            hb_glyph_position_t *positions = hb_buffer_get_glyph_positions(buffer.get(), nullptr);
-
             // Check if all glyphs are valid.
-            for (unsigned i=0; i<num_glyphs; ++i)
+            for (unsigned i = 0; i < num_glyphs; ++i)
             {
                 // if we have a valid codepoint, save rendering info.
                 if (glyphs[i].codepoint)
@@ -143,41 +139,38 @@ static void shape_text(text_line & line,
                     if (!glyphinfos[i].glyph.codepoint)
                     {
                         ++valid_glyphs;
+                        glyphinfos[i] = { face, glyphs[i], positions[i] };
                     }
-                    glyphinfos[i] = { face, glyphs[i], positions[i] };
                 }
             }
-            if (valid_glyphs < num_glyphs && (pos < num_faces))
+            if (valid_glyphs < item_length && (pos < num_faces))
             {
                 //Try next font in fontset
                 continue;
             }
-
             double max_glyph_height = 0;
-            for (unsigned i=0; i<num_glyphs; ++i)
+            for (auto const& info : glyphinfos)
             {
-                auto& gpos = positions[i];
-                auto& glyph = glyphs[i];
-                face_ptr theface = face;
-                if (glyphinfos[i].glyph.codepoint)
+                if (info.glyph.codepoint)
                 {
-                    gpos = glyphinfos[i].position;
-                    glyph = glyphinfos[i].glyph;
-                    theface = glyphinfos[i].face;
-                }
-                unsigned char_index = glyph.cluster;
-                glyph_info g(glyph.codepoint,char_index,text_item.format_);
-                if (theface->glyph_dimensions(g))
-                {
-                    g.face = theface;
-                    g.scale_multiplier = size / theface->get_face()->units_per_EM;
-                    //Overwrite default advance with better value provided by HarfBuzz
-                    g.unscaled_advance = gpos.x_advance;
-                    g.offset.set(gpos.x_offset * g.scale_multiplier, gpos.y_offset * g.scale_multiplier);
-                    double tmp_height = g.height();
-                    if (tmp_height > max_glyph_height) max_glyph_height = tmp_height;
-                    width_map[char_index] += g.advance();
-                    line.add_glyph(std::move(g), scale_factor);
+                    auto const& gpos = info.position;
+                    auto const& glyph = info.glyph;
+                    auto const& theface = info.face;
+
+                    unsigned char_index = glyph.cluster;
+                    glyph_info g(glyph.codepoint, char_index, text_item.format_);
+                    if (theface->glyph_dimensions(g))
+                    {
+                        g.face = theface;
+                        g.scale_multiplier = size / theface->get_face()->units_per_EM;
+                        //Overwrite default advance with better value provided by HarfBuzz
+                        g.unscaled_advance = gpos.x_advance;
+                        g.offset.set(gpos.x_offset * g.scale_multiplier, gpos.y_offset * g.scale_multiplier);
+                        double tmp_height = g.height();
+                        if (tmp_height > max_glyph_height) max_glyph_height = tmp_height;
+                        width_map[char_index] += g.advance();
+                        line.add_glyph(std::move(g), scale_factor);
+                    }
                 }
             }
             line.update_max_char_height(max_glyph_height);