optimize raster rendering when not resizing

include/mapnik/renderer_common/process_raster_symbolizer.hpp

@@ -23,6 +23,9 @@
 #ifndef MAPNIK_RENDERER_COMMON_PROCESS_RASTER_SYMBOLIZER_HPP
 #define MAPNIK_RENDERER_COMMON_PROCESS_RASTER_SYMBOLIZER_HPP
 
+// mapnik
+#include <mapnik/warp.hpp>
+
 // agg
 #include "agg_rendering_buffer.h"
 #include "agg_pixfmt_rgba.h"
@@ -55,10 +58,8 @@ void render_raster_symbolizer(raster_symbolizer const &sym,
         int raster_height = end_y - start_y;
         if (raster_width > 0 && raster_height > 0)
         {
-            raster target(target_ext, raster_width, raster_height, source->get_filter_factor());
             scaling_method_e scaling_method = get<scaling_method_e>(sym, keys::scaling, feature, common.vars_, SCALING_NEAR);
             composite_mode_e comp_op = get<composite_mode_e>(sym, keys::comp_op, feature, common.vars_, src_over);
-
             double opacity = get<double>(sym,keys::opacity,feature, common.vars_, 1.0);
             bool premultiply_source = !source->premultiplied_alpha_;
             auto is_premultiplied = get_optional<bool>(sym, keys::premultiplied, feature, common.vars_);
@@ -80,6 +81,7 @@ void render_raster_symbolizer(raster_symbolizer const &sym,
             {
                 double offset_x = ext.minx() - start_x;
                 double offset_y = ext.miny() - start_y;
+                raster target(target_ext, raster_width, raster_height, source->get_filter_factor());
                 unsigned mesh_size = static_cast<unsigned>(get<value_integer>(sym,keys::mesh_size,feature, common.vars_, 16));
                 reproject_and_scale_raster(target,
                                            *source,
@@ -88,9 +90,23 @@ void render_raster_symbolizer(raster_symbolizer const &sym,
                                            offset_y,
                                            mesh_size,
                                            scaling_method);
+                composite(target.data_, comp_op, opacity, start_x, start_y);
             }
             else
             {
+                double image_ratio_x = ext.width() / source->data_.width();
+                double image_ratio_y = ext.height() / source->data_.height();
+                double eps = 1e-5;
+                if ( (std::fabs(image_ratio_x - 1) <= eps) &&
+                     (std::fabs(image_ratio_y - 1) <= eps) &&
+                     (std::fabs(start_x) <= eps) &&
+                     (std::fabs(start_y) <= eps) )
+                {
+                    composite(source->data_, comp_op, opacity, start_x, start_y);
+                }
+                else
+                {
+                    raster target(target_ext, raster_width, raster_height, source->get_filter_factor());
                     if (scaling_method == SCALING_BILINEAR8)
                     {
                         scale_image_bilinear8<image_data_32>(target.data_,
@@ -111,8 +127,9 @@ void render_raster_symbolizer(raster_symbolizer const &sym,
                                                        0.0,
                                                        source->get_filter_factor());
                     }
+                    composite(target.data_, comp_op, opacity, start_x, start_y);
+                }
             }
-            composite(target, comp_op, opacity, start_x, start_y);
         }
     }
 }

src/agg/process_raster_symbolizer.cpp

@@ -33,7 +33,6 @@
 #include <mapnik/image_util.hpp>
 #include <mapnik/raster.hpp>
 #include <mapnik/box2d.hpp>
-#include <mapnik/warp.hpp>
 #include <mapnik/config.hpp>
 #include <mapnik/renderer_common/process_raster_symbolizer.hpp>
 
@@ -53,11 +52,12 @@ void agg_renderer<T0,T1>::process(raster_symbolizer const& sym,
 {
     render_raster_symbolizer(
         sym, feature, prj_trans, common_,
-        [&](raster &target, composite_mode_e comp_op, double opacity, 
+        [&](image_data_32 & target, composite_mode_e comp_op, double opacity,
             int start_x, int start_y) {
-            composite(current_buffer_->data(), target.data_,
+            composite(current_buffer_->data(), target,
                       comp_op, opacity, start_x, start_y, false);
-        });
+        }
+    );
 }
 
 template void agg_renderer<image_32>::process(raster_symbolizer const&,

src/cairo_renderer.cpp

@@ -761,14 +761,14 @@ void cairo_renderer_base::process(raster_symbolizer const& sym,
                                   proj_transform const& prj_trans)
 {
     cairo_save_restore guard(context_);
-
     render_raster_symbolizer(
         sym, feature, prj_trans, common_,
-        [&](raster &target, composite_mode_e comp_op, double opacity, 
+        [&](image_data_32 &target, composite_mode_e comp_op, double opacity,
             int start_x, int start_y) {
             context_.set_operator(comp_op);
-            context_.add_image(start_x, start_y, target.data_, opacity);
+            context_.add_image(start_x, start_y, target, opacity);
-        });
+        }
+    );
 }
 
 namespace detail {