From 8a0dca38a3edd447a270a0eceff708f3375e6efc Mon Sep 17 00:00:00 2001
From: Jiri Drbalek <jiri.drbalek@firma.seznam.cz>
Date: Tue, 31 Jul 2018 14:06:31 +0000
Subject: [PATCH] Fix buffer-size with scale-factor

---
 .../mapnik/feature_style_processor_impl.hpp   |   2 +-
 .../renderer/buffer_size_scale_factor.cpp     | 100 ++++++++++++++++++
 2 files changed, 101 insertions(+), 1 deletion(-)
 create mode 100644 test/unit/renderer/buffer_size_scale_factor.cpp

diff --git a/include/mapnik/feature_style_processor_impl.hpp b/include/mapnik/feature_style_processor_impl.hpp
index 278ea5463..f5e605d4b 100644
--- a/include/mapnik/feature_style_processor_impl.hpp
+++ b/include/mapnik/feature_style_processor_impl.hpp
@@ -260,7 +260,7 @@ void feature_style_processor<Processor>::prepare_layer(layer_rendering_material
     box2d<double> query_ext = extent; // unbuffered
     box2d<double> buffered_query_ext(query_ext);  // buffered
 
-    double buffer_padding = 2.0 * scale;
+    double buffer_padding = 2.0 * scale * p.scale_factor();
     boost::optional<int> layer_buffer_size = lay.buffer_size();
     if (layer_buffer_size) // if layer overrides buffer size, use this value to compute buffered extent
     {
diff --git a/test/unit/renderer/buffer_size_scale_factor.cpp b/test/unit/renderer/buffer_size_scale_factor.cpp
new file mode 100644
index 000000000..ea36dc01a
--- /dev/null
+++ b/test/unit/renderer/buffer_size_scale_factor.cpp
@@ -0,0 +1,100 @@
+#include "catch.hpp"
+
+#include <mapnik/memory_datasource.hpp>
+#include <mapnik/feature.hpp>
+#include <mapnik/feature_factory.hpp>
+#include <mapnik/map.hpp>
+#include <mapnik/params.hpp>
+#include <mapnik/layer.hpp>
+#include <mapnik/rule.hpp>
+#include <mapnik/feature_type_style.hpp>
+#include <mapnik/symbolizer.hpp>
+#include <mapnik/geometry/geometry_type.hpp>
+#include <mapnik/agg_renderer.hpp>
+
+class test_datasource : public mapnik::memory_datasource
+{
+public:
+    test_datasource(mapnik::box2d<double> const& expected_query_bbox)
+        : expected_query_bbox_(expected_query_bbox),
+          mapnik::memory_datasource(prepare_params())
+    {
+    }
+
+    virtual mapnik::featureset_ptr features(mapnik::query const& q) const
+    {
+        mapnik::box2d<double> const& actual_bbox = q.get_bbox();
+        REQUIRE(actual_bbox.minx() == Approx(expected_query_bbox_.minx()));
+        REQUIRE(actual_bbox.miny() == Approx(expected_query_bbox_.miny()));
+        REQUIRE(actual_bbox.maxx() == Approx(expected_query_bbox_.maxx()));
+        REQUIRE(actual_bbox.maxy() == Approx(expected_query_bbox_.maxy()));
+        return mapnik::memory_datasource::features(q);
+    }
+
+private:
+    mapnik::parameters prepare_params() const
+    {
+        mapnik::parameters params;
+        params["type"] = "memory";
+        return params;
+    }
+
+    mapnik::box2d<double> expected_query_bbox_;
+};
+
+
+TEST_CASE("feature_style_processor: buffer-size with scale-factor") {
+
+SECTION("query extent with buffer-size should not be affected by scale-factor") {
+
+    const mapnik::box2d<double> expected_query_bbox(-0.5, -0.5, 1.5, 1.5);
+
+    using datasource_ptr = std::shared_ptr<test_datasource>;
+    datasource_ptr datasource = std::make_shared<test_datasource>(
+        expected_query_bbox);
+    mapnik::context_ptr ctx = std::make_shared<mapnik::context_type>();
+    {
+        mapnik::feature_ptr feature(mapnik::feature_factory::create(ctx, 2));
+        mapnik::geometry::line_string<double> path;
+        path.emplace_back(-10, -10);
+        path.emplace_back(10, 10);
+        feature->set_geometry(std::move(path));
+        datasource->push(feature);
+    }
+
+    mapnik::Map map(256, 256);
+    map.set_buffer_size(128);
+
+    mapnik::feature_type_style lines_style;
+    mapnik::rule rule;
+    mapnik::line_symbolizer line_sym;
+    rule.append(std::move(line_sym));
+    lines_style.add_rule(std::move(rule));
+    map.insert_style("lines", std::move(lines_style));
+
+    mapnik::layer lyr("layer");
+    lyr.set_datasource(datasource);
+    lyr.add_style("lines");
+    map.add_layer(lyr);
+
+    const mapnik::box2d<double> map_extent(0, 0, 1, 1);
+    map.zoom_to_box(map_extent);
+
+    {
+        mapnik::image_rgba8 image(map.width(), map.height());
+        mapnik::agg_renderer<mapnik::image_rgba8> ren(map, image);
+        ren.apply();
+    }
+
+    {
+        // Rendering with scale-factor 2.0 should query data
+        // with the same extent as with scale-factor 1.0.
+        map.resize(map.width() * 2, map.height() * 2);
+        mapnik::image_rgba8 image(map.width(), map.height());
+        mapnik::agg_renderer<mapnik::image_rgba8> ren(map, image, 2.0);
+        ren.apply();
+    }
+}
+
+}
+