Apply patch from Marcin to handle smooth transitions between raster layers for both gdal and raster plugin - closed #295

CHANGELOG

@@ -14,6 +14,8 @@ For a complete change history, see the SVN log.
 0.6.1 SVN
 ---------
 
+- Rasters: Handle rounding to allow better alignment of raster layers (r1079) (#295)
+
 - AGG Renderer: Added option to control output JPEG quality (r1078) (#198)
 
 - Plugins: Fixed segfault in OGC Plugin with empty geometries (r1074) (#292)

plugins/input/gdal/gdal_featureset.cpp

@@ -125,10 +125,10 @@ feature_ptr gdal_featureset::next()
       Envelope<double> intersection = raster_extent.intersect(query_extent_);
       Envelope<double> box = t.forward(intersection);
       
-      int start_x = int(box.minx());
+      int start_x = int(box.minx()+0.5);
-      int start_y = int(box.miny());
+      int start_y = int(box.miny()+0.5);
-      int width = int(box.width());
+      int width = int(box.width()+0.5);
-      int height = int(box.height());
+      int height = int(box.height()+0.5);
       
       if (width > 0 && height > 0)
       {

plugins/input/raster/raster_featureset.cpp

@@ -68,8 +68,8 @@ feature_ptr raster_featureset<LookupPolicy>::next()
                Envelope<double> intersect=extent_.intersect(curIter_->envelope());
                Envelope<double> ext=t.forward(intersect);
                     
-               ImageData32 image((int)ext.width(),(int)ext.height());
+               ImageData32 image((int)(ext.width()+0.5),(int)(ext.height()+0.5));
-               reader->read((int)ext.minx(),(int)ext.miny(),image);
+               reader->read((int)(ext.minx()+0.5),(int)(ext.miny()+0.5),image);
                feature->set_raster(mapnik::raster_ptr(new raster(intersect,image)));
             }
          }

src/agg_renderer.cpp

@@ -669,6 +669,8 @@ namespace mapnik
       {
          Envelope<double> ext=t_.forward(raster->ext_);
          ImageData32 target(int(ext.width() + 0.5),int(ext.height() + 0.5));
+         int start_x = int(ext.minx()+0.5);
+         int start_y = int(ext.miny()+0.5);
 
          if (sym.get_scaling() == "fast"){
             scale_image<ImageData32>(target,raster->data_);
@@ -682,31 +684,31 @@ namespace mapnik
 
          if (sym.get_mode() == "normal"){
              if (sym.get_opacity() == 1.0) {
-                pixmap_.set_rectangle(int(ext.minx()),int(ext.miny()),target);
+                pixmap_.set_rectangle(start_x,start_y,target);
              } else {
-                pixmap_.set_rectangle_alpha2(target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+                pixmap_.set_rectangle_alpha2(target,start_x,start_y, sym.get_opacity());
              }
          } else if (sym.get_mode() == "grain_merge"){
-            pixmap_.template merge_rectangle<MergeGrain> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<MergeGrain> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "grain_merge2"){
-            pixmap_.template merge_rectangle<MergeGrain2> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<MergeGrain2> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "multiply"){
-            pixmap_.template merge_rectangle<Multiply> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<Multiply> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "multiply2"){
-            pixmap_.template merge_rectangle<Multiply2> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<Multiply2> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "divide"){
-            pixmap_.template merge_rectangle<Divide> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<Divide> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "divide2"){
-            pixmap_.template merge_rectangle<Divide2> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<Divide2> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "screen"){
-            pixmap_.template merge_rectangle<Screen> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<Screen> (target,start_x,start_y, sym.get_opacity());
          } else if (sym.get_mode() == "hard_light"){
-            pixmap_.template merge_rectangle<HardLight> (target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+            pixmap_.template merge_rectangle<HardLight> (target,start_x,start_y, sym.get_opacity());
          } else {
              if (sym.get_opacity() == 1.0){
-                 pixmap_.set_rectangle(int(ext.minx()),int(ext.miny()),target);
+                 pixmap_.set_rectangle(start_x,start_y,target);
              } else {
-                pixmap_.set_rectangle_alpha2(target,int(ext.minx()),int(ext.miny()), sym.get_opacity());
+                pixmap_.set_rectangle_alpha2(target,start_x,start_y, sym.get_opacity());
              }
          }
          // TODO: other modes? (add,diff,sub,...)

src/cairo_renderer.cpp

@@ -987,7 +987,7 @@ namespace mapnik
          cairo_context context(context_);
 
          //TODO -- support for advanced image merging
-         context.add_image(int(ext.minx()), int(ext.miny()), target, sym.get_opacity());
+         context.add_image(int(ext.minx()+0.5), int(ext.miny()+0.5), target, sym.get_opacity());
       }
    }