Merge pull request #3477 from mapycz/cairo-style-level-comp-op

Style level comp-op and opacity for Cairo renderer

include/mapnik/cairo/cairo_context.hpp

@@ -308,6 +308,7 @@ public:
     void stroke();
     void fill();
     void paint();
+    void paint(double opacity);
     void set_pattern(cairo_pattern const& pattern);
     void set_gradient(cairo_gradient const& pattern, box2d<double> const& bbox);
     void add_image(double x, double y, image_rgba8 const& data, double opacity = 1.0);
@@ -327,6 +328,9 @@ public:
                   composite_mode_e halo_comp_op = src_over,
                   double scale_factor = 1.0);
 
+    void push_group();
+    void pop_group();
+
     template <typename T>
     void add_path(T& path, unsigned start_index = 0)
     {

include/mapnik/cairo/cairo_renderer.hpp

@@ -177,6 +177,7 @@ protected:
     cairo_context context_;
     renderer_common common_;
     cairo_face_manager face_manager_;
+    bool style_level_compositing_;
     void setup(Map const& m);
 
 };

src/cairo/cairo_context.cpp

@@ -304,6 +304,12 @@ void cairo_context::paint()
     check_object_status_and_throw_exception(*this);
 }
 
+void cairo_context::paint(double opacity)
+{
+    cairo_paint_with_alpha(cairo_.get(), opacity);
+    check_object_status_and_throw_exception(*this);
+}
+
 void cairo_context::set_pattern(cairo_pattern const& pattern)
 {
     cairo_set_source(cairo_.get(), pattern.pattern());
@@ -489,6 +495,18 @@ void cairo_context::add_text(glyph_positions const& pos,
 
 }
 
+void cairo_context::push_group()
+{
+    cairo_push_group(cairo_.get());
+    check_object_status_and_throw_exception(*this);
+}
+
+void cairo_context::pop_group()
+{
+    cairo_pop_group_to_source(cairo_.get());
+    check_object_status_and_throw_exception(*this);
+}
+
 cairo_face_manager::cairo_face_manager(std::shared_ptr<font_library> font_library)
   : font_library_(font_library)
 {

src/cairo/cairo_renderer.cpp

@@ -36,6 +36,7 @@
 #include <mapnik/label_collision_detector.hpp>
 #include <mapnik/marker.hpp>
 #include <mapnik/marker_cache.hpp>
+#include <mapnik/feature_type_style.hpp>
 
 // agg
 #include "agg/include/agg_trans_affine.h"  // for trans_affine, etc
@@ -58,7 +59,8 @@ cairo_renderer<T>::cairo_renderer(Map const& m,
       m_(m),
       context_(cairo),
       common_(m, attributes(), offset_x, offset_y, m.width(), m.height(), scale_factor),
-      face_manager_(common_.shared_font_library_)
+      face_manager_(common_.shared_font_library_),
+      style_level_compositing_(false)
 {
     setup(m);
 }
@@ -75,7 +77,9 @@ cairo_renderer<T>::cairo_renderer(Map const& m,
       m_(m),
       context_(cairo),
       common_(m, req, vars, offset_x, offset_y, req.width(), req.height(), scale_factor),
-      face_manager_(common_.shared_font_library_)
+      face_manager_(common_.shared_font_library_),
+      style_level_compositing_(false)
+
 {
     setup(m);
 }
@@ -91,7 +95,9 @@ cairo_renderer<T>::cairo_renderer(Map const& m,
       m_(m),
       context_(cairo),
       common_(m, attributes(), offset_x, offset_y, m.width(), m.height(), scale_factor, detector),
-      face_manager_(common_.shared_font_library_)
+      face_manager_(common_.shared_font_library_),
+      style_level_compositing_(false)
+
 {
     setup(m);
 }
@@ -191,15 +197,30 @@ void cairo_renderer<T>::end_layer_processing(layer const&)
 }
 
 template <typename T>
-void cairo_renderer<T>::start_style_processing(feature_type_style const&)
+void cairo_renderer<T>::start_style_processing(feature_type_style const & st)
 {
     MAPNIK_LOG_DEBUG(cairo_renderer) << "cairo_renderer:start style processing";
+
+    style_level_compositing_ = st.comp_op() || st.get_opacity() < 1;
+
+    if (style_level_compositing_)
+    {
+        context_.push_group();
+    }
 }
 
 template <typename T>
-void cairo_renderer<T>::end_style_processing(feature_type_style const&)
+void cairo_renderer<T>::end_style_processing(feature_type_style const & st)
 {
     MAPNIK_LOG_DEBUG(cairo_renderer) << "cairo_renderer:end style processing";
+
+    if (style_level_compositing_)
+    {
+        context_.pop_group();
+        composite_mode_e comp_op = st.comp_op() ? *st.comp_op() : src_over;
+        context_.set_operator(comp_op);
+        context_.paint(st.get_opacity());
+    }
 }
 
 struct cairo_render_marker_visitor

test/data-visual

@@ -1 +1 @@
-Subproject commit 5f0e6f86696a2a9a6733e42b1f400ba4ec2f8847
+Subproject commit 4a054f2efe35a65aa5163f080304fb90ae9c6194