Grayscale rasterizer for Region

src/db/db/gsiDeclDbRegion.cc

@@ -780,6 +780,39 @@ size_dvm (db::Region *region, const db::Vector &dv, unsigned int mode)
   return *region;
 }
 
+static std::vector<std::vector<double> >
+rasterize2 (const db::Region *region, const db::Point &origin, const db::Vector &pixel_distance, const db::Vector &pixel_size, unsigned int nx, unsigned int ny)
+{
+  db::AreaMap am (origin, pixel_distance, pixel_size, nx, ny);
+
+  auto si = region->begin ();
+  si = si.confined (am.bbox (), false /*not overlapping*/);
+
+  while (! si.at_end ()) {
+    db::rasterize (*si, am);
+    ++si;
+  }
+
+  std::vector<std::vector<double> > result;
+  result.reserve (ny);
+  for (unsigned int y = 0; y < ny; ++y) {
+    result.push_back (std::vector<double> ());
+    std::vector<double> &row = result.back ();
+    row.reserve (nx);
+    for (unsigned int x = 0; x < nx; ++x) {
+      row.push_back (am.get (x, y));
+    }
+  }
+
+  return result;
+}
+
+static std::vector<std::vector<double> >
+rasterize1 (const db::Region *region, const db::Point &origin, const db::Vector &pixel_size, unsigned int nx, unsigned int ny)
+{
+  return rasterize2 (region, origin, pixel_size, pixel_size, nx, ny);
+}
+
 static db::Point default_origin;
 
 //  provided by gsiDeclDbPolygon.cc:
@@ -3071,6 +3104,38 @@ Class<db::Region> decl_Region (decl_dbShapeCollection, "db", "Region",
     "@brief Converts the region to a string\n"
     "This version allows specification of the maximum number of polygons contained in the string."
   ) +
+  method_ext ("rasterize", &rasterize1, gsi::arg ("origin"), gsi::arg ("pixel_size"), gsi::arg ("nx"), gsi::arg ("ny"),
+    "@brief A grayscale rasterizer delivering the area covered per pixel\n"
+    "@param origin The lower-left corner of the lowest-left pixel\n"
+    "@param pixel_size The dimension of each pixel (the x component gives the width, the y component the height)\n"
+    "@param nx The number of pixels in horizontal direction\n"
+    "@param ny The number of pixels in vertical direction\n"
+    "The method will create a grayscale, high-resolution density map of a rectangular region.\n"
+    "The scan region is defined by the origin, the pixel size and the number of pixels in horizontal (nx) and\n"
+    "vertical (ny) direction. The resulting array will contain the area covered by polygons from the region\n"
+    "in square database units.\n"
+    "\n"
+    "For non-overlapping polygons, the maximum density value is px*py. Overlapping polygons are counted multiple\n"
+    "times, so the actual values may be larger. If you want overlaps removed, you have to\n"
+    "merge the region before. Merge semantics does not apply for the 'rasterize' method.\n"
+    "\n"
+    "Although the resulting area values are floating-point, internal computation is done with integer precision currently.\n"
+    "This implies a certain area error when skew angle edges are involved. The pixel area is precise for Manhattan and\n""
+    "half-Manhattan (45 degree multiples) input geometries.\n"
+    "\n"
+    "A second version exists that allows specifying an active pixel size which is smaller than the\n"
+    "pixel distance hence allowing pixels samples that do not cover the full area, but leave gaps between the pixels.\n"
+    "\n"
+    "This method has been added in version 0.29.\n"
+  ) +
+  method_ext ("rasterize", &rasterize2, gsi::arg ("origin"), gsi::arg ("pixel_distance"), gsi::arg ("pixel_size"), gsi::arg ("nx"), gsi::arg ("ny"),
+    "@brief A version of 'rasterize' that allows a pixel step distance which is larger than the pixel size\n"
+    "This version behaves like the first variant of 'rasterize', but the pixel distance (pixel-to-pixel step raster)\n"
+    "can be specified separately from the pixel size. Currently, the pixel size must be equal or smaller than the\n"
+    "pixel distance - i.e. the pixels must not overlap.\n"
+    "\n"
+    "This method has been added in version 0.29.\n"
+  ) +
   method ("enable_progress", &db::Region::enable_progress, gsi::arg ("label"),
     "@brief Enable progress reporting\n"
     "After calling this method, the region will report the progress through a progress bar while "

testdata/ruby/dbRegionTest.rb

@@ -1188,6 +1188,36 @@ class DBRegion_TestClass < TestBase
 
   end
 
+  # rasterize
+  def test_rasterize
+
+    r = RBA::Region::new()
+    r.insert(RBA::Polygon::new([[0, 0], [100, 100], [200, 0]]))
+    r.insert(RBA::Polygon::new(RBA::Box::new([0, 200], [100, 300])))
+
+    pd = RBA::Vector::new(50, 50)
+    ps = RBA::Vector::new(25, 25)
+
+    sum = 0
+    2.times do |ix|
+      2.times do |iy|
+        am = r.rasterize(RBA::Point::new(-50 + ix * ps.x, -20 + iy * ps.y), pd, ps, 7, 7)
+        sum += am.collect { |r| r.sum }.sum
+      end
+    end
+
+    assert_equal(sum, 8.0 * pd.x * pd.y)
+
+    tot = 0.0
+    pd = RBA::Vector::new(50, 50)
+
+    am = r.rasterize(RBA::Point::new(-50, -20), pd, 7, 7)
+    sum = am.collect { |r| r.sum }.sum
+
+    assert_equal(sum, 8.0 * pd.x * pd.y)
+
+  end
+
 end
 
 load("test_epilogue.rb")