From 5f4711a019a6cff7adbc6256e8c35dc777754876 Mon Sep 17 00:00:00 2001
From: Artem Pavlenko <artemp@users.noreply.github.com>
Date: Wed, 23 Nov 2022 15:53:08 +0000
Subject: [PATCH] SVG - refactor and minimise internal group usage [WIP] [skip
 ci]

---
 include/mapnik/svg/svg_converter.hpp    |  2 ++
 include/mapnik/svg/svg_renderer_agg.hpp | 38 ++++++++++++++++---------
 src/marker_helpers.cpp                  |  1 +
 src/svg/svg_parser.cpp                  | 15 +++++-----
 4 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/include/mapnik/svg/svg_converter.hpp b/include/mapnik/svg/svg_converter.hpp
index 5b093fdab..e351c88b9 100644
--- a/include/mapnik/svg/svg_converter.hpp
+++ b/include/mapnik/svg/svg_converter.hpp
@@ -65,6 +65,8 @@ class svg_converter : util::noncopyable
           svg_height_(0.0)
     {}
 
+    void set_opacity(double opacity) { svg_group_.opacity = opacity; }
+
     void begin_group()
     {
         current_group_->elements.emplace_back(group {cur_attr().opacity, {}, current_group_});
diff --git a/include/mapnik/svg/svg_renderer_agg.hpp b/include/mapnik/svg/svg_renderer_agg.hpp
index 386484531..dc9decd33 100644
--- a/include/mapnik/svg/svg_renderer_agg.hpp
+++ b/include/mapnik/svg/svg_renderer_agg.hpp
@@ -145,10 +145,27 @@ class renderer_agg : util::noncopyable
                 box2d<double> const& symbol_bbox)
 
     {
-        for (auto const& elem : svg_group_.elements)
+        double adjusted_opacity = opacity * svg_group_.opacity; // adjust top level opacity
+        if (adjusted_opacity < 1.0)
         {
-            mapbox::util::apply_visitor(group_renderer<Rasterizer, Scanline, Renderer>
-                                        (*this, ras, sl, ren, mtx, opacity, symbol_bbox, true), elem);
+            mapnik::image_rgba8 im(ren.width(), ren.height(), true, true);
+            agg::rendering_buffer buf(im.bytes(), im.width(), im.height(), im.row_size());
+            PixelFormat pixf(buf);
+            Renderer ren_g(pixf);
+            for (auto const& elem : svg_group_.elements)
+            {
+                mapbox::util::apply_visitor(group_renderer<Rasterizer, Scanline, Renderer>
+                    (*this, ras, sl, ren_g, mtx, symbol_bbox), elem);
+            }
+            ren.blend_from(ren_g.ren(), 0, 0, 0, unsigned(adjusted_opacity * 255));
+        }
+        else
+        {
+            for (auto const& elem : svg_group_.elements)
+            {
+                mapbox::util::apply_visitor(group_renderer<Rasterizer, Scanline, Renderer>
+                                            (*this, ras, sl, ren, mtx, symbol_bbox), elem);
+            }
         }
     }
 
@@ -158,17 +175,13 @@ class renderer_agg : util::noncopyable
         group_renderer(renderer_agg& renderer,
                        Rasterizer & ras, Scanline& sl, Renderer& ren,
                        agg::trans_affine const& mtx,
-                       double opacity,
-                       box2d<double> const& symbol_bbox,
-                       bool first = false)
+                       box2d<double> const& symbol_bbox)
             : renderer_(renderer),
               ras_(ras),
               sl_(sl),
               ren_(ren),
               mtx_(mtx),
-              opacity_(opacity),
-              symbol_bbox_(symbol_bbox),
-              first_(first)
+              symbol_bbox_(symbol_bbox)
         {}
 
         void render_gradient(Rasterizer& ras,
@@ -281,7 +294,6 @@ class renderer_agg : util::noncopyable
         void operator() (group const& g) const
         {
             double opacity = g.opacity;
-            if (first_) opacity *= opacity_; // adjust top level opacity
             if (opacity < 1.0)
             {
                 mapnik::image_rgba8 im(ren_.width(), ren_.height(), true, true);
@@ -291,7 +303,7 @@ class renderer_agg : util::noncopyable
                 for (auto const& elem : g.elements)
                 {
                     mapbox::util::apply_visitor(
-                        group_renderer(renderer_, ras_, sl_, ren, mtx_, opacity_, symbol_bbox_), elem);
+                        group_renderer(renderer_, ras_, sl_, ren, mtx_, symbol_bbox_), elem);
                 }
                 ren_.blend_from(ren.ren(), 0, 0, 0, unsigned(opacity * 255));
             }
@@ -300,7 +312,7 @@ class renderer_agg : util::noncopyable
                 for (auto const& elem : g.elements)
                 {
                     mapbox::util::apply_visitor(
-                        group_renderer(renderer_, ras_, sl_, ren_, mtx_, opacity_, symbol_bbox_), elem);
+                        group_renderer(renderer_, ras_, sl_, ren_, mtx_, symbol_bbox_), elem);
                 }
             }
         }
@@ -463,9 +475,7 @@ class renderer_agg : util::noncopyable
         Scanline& sl_;
         Renderer& ren_;
         agg::trans_affine const& mtx_;
-        double opacity_;
         box2d<double> const& symbol_bbox_;
-        bool first_;
     };
 
 #if defined(GRID_RENDERER)
diff --git a/src/marker_helpers.cpp b/src/marker_helpers.cpp
index eeac80a21..575be957d 100644
--- a/src/marker_helpers.cpp
+++ b/src/marker_helpers.cpp
@@ -189,6 +189,7 @@ bool push_explicit_style(svg::group const& src,
     auto stroke_width = get_optional<double>(sym, keys::stroke_width, feature, vars);
     auto stroke_opacity = get_optional<double>(sym, keys::stroke_opacity, feature, vars);
     bool success = false;
+    dst.opacity = src.opacity;
     if (fill_color || fill_opacity || stroke_color || stroke_width || stroke_opacity)
     {
         for (auto const& elem : src.elements)
diff --git a/src/svg/svg_parser.cpp b/src/svg/svg_parser.cpp
index e43587f83..00352b0a8 100644
--- a/src/svg/svg_parser.cpp
+++ b/src/svg/svg_parser.cpp
@@ -548,7 +548,9 @@ void traverse_tree(svg_parser& parser, rapidxml::xml_node<char> const* node)
                         if (parser.css_style_)
                             process_css(parser, node);
                         parse_attr(parser, node);
+                        if (parser.path_.cur_attr().opacity < 1.0) parser.path_.begin_group();
                         parse_use(parser, node);
+                        if (parser.path_.cur_attr().opacity < 1.0) parser.path_.end_group();
                         parser.path_.pop_attr();
                         break;
                     default:
@@ -622,11 +624,10 @@ void end_element(svg_parser& parser, rapidxml::xml_node<char> const* node)
     }
     else if (name == "svg"_case)
     {
-        parser.path_.end_group();
-        if (node->first_node() != nullptr)
-        {
-            parser.path_.pop_attr();
-        }
+        //if (node->first_node() != nullptr)
+        //{
+            //parser.path_.pop_attr();
+        //}
     }
     else if (name == "defs"_case)
     {
@@ -675,10 +676,10 @@ void parse_element(svg_parser& parser, char const* name, rapidxml::xml_node<char
             parse_ellipse(parser, node);
             break;
         case "svg"_case:
-            parser.path_.begin_group();
-            parser.path_.push_attr();
+            //parser.path_.push_attr();
             parse_dimensions(parser, node);
             parse_attr(parser, node);
+            parser.path_.set_opacity(parser.path_.cur_attr().opacity);
             break;
         default:
             handle_unsupported(parser, unsupported_elements, name, "element");