mapnik: Harden build. New: --with-gdal --with-geos

- Mapnik searches for py2cairo -> added dep if --with-cairo
- Explicitly give includes and libs for icu, boost, proj,
  jpeg, libtif, and cairo
- pkg-config is not only used for cairo -> moved it out
  of the `if build.include? 'with-cairo'` block

Closes Homebrew/homebrew#17032.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/mapnik.rb

@@ -8,6 +8,8 @@ class Mapnik < Formula
   head 'https://github.com/mapnik/mapnik.git'
 
   option 'with-cairo', 'Build with Cairo'
+  option 'with-gdal', 'Build with optional "Geospatial Data Abstraction Library"'
+  option 'with-geos', 'Build with the GEOS (Geometry Engine)'
 
   depends_on :libtool => :build
   depends_on :freetype
@@ -17,15 +19,23 @@ class Mapnik < Formula
   depends_on 'icu4c'
   depends_on 'jpeg'
   depends_on 'boost'
+  depends_on 'gdal' if build.include? 'with-gdal'
+  depends_on 'geos' if build.include? 'with-geos'
+  depends_on 'pkg-config' => :build
 
   if build.include? 'with-cairo'
-    depends_on 'pkg-config' => :build
     depends_on 'cairo' => :optional
+    depends_on 'py2cairo'
     depends_on 'cairomm' => :optional
   end
 
   def install
-    icu = Formula.factory("icu4c")
+    icu = Formula.factory("icu4c").opt_prefix
+    boost = Formula.factory('boost').opt_prefix
+    proj = Formula.factory('proj').opt_prefix
+    jpeg = Formula.factory('jpeg').opt_prefix
+    libtiff = Formula.factory('libtiff').opt_prefix
+    cairo = Formula.factory('cairo').opt_prefix if build.include? 'cairo'
     # mapnik compiles can take ~1.5 GB per job for some .cpp files
     # so lets be cautious by limiting to CPUS/2
     jobs = ENV.make_jobs
@@ -33,16 +43,33 @@ class Mapnik < Formula
         jobs = Integer(jobs/2)
     end
 
-    system "python",
-           "scons/scons.py",
-           "configure",
-           "CC=\"#{ENV.cc}\"",
-           "CXX=\"#{ENV.cxx}\"",
-           "JOBS=#{jobs}",
-           "PREFIX=#{prefix}",
-           "ICU_INCLUDES=#{icu.include}",
-           "ICU_LIBS=#{icu.lib}",
-           "PYTHON_PREFIX=#{prefix}"  # Install to Homebrew's site-packages
+    args = [ "scons/scons.py",
+             "configure",
+             "CC=\"#{ENV.cc}\"",
+             "CXX=\"#{ENV.cxx}\"",
+             "JOBS=#{jobs}",
+             "PREFIX=#{prefix}",
+             "ICU_INCLUDES=#{icu}/include",
+             "ICU_LIBS=#{icu}/lib",
+             "PYTHON_PREFIX=#{prefix}",  # Install to Homebrew's site-packages
+             "JPEG_INCLUDES=#{jpeg}/include",
+             "JPEG_LIBS=#{jpeg}/lib",
+             "TIFF_INCLUDES=#{libtiff}/include",
+             "TIFF_LIBS=#{libtiff}/lib",
+             "BOOST_INCLUDES=#{boost}/include",
+             "BOOST_LIBS=#{boost}/lib",
+             "PROJ_INCLUDES=#{proj}/include",
+             "PROJ_LIBS=#{proj}/lib" ]
+
+    if build.include? 'cairo'
+      args << "CAIRO_INCLUDES=#{cairo}/include"
+      args << "CAIRO_LIBS=#{cairo}/lib"
+    end
+    args << "GEOS_CONFIG=#{Formula.factory('geos').opt_prefix}/bin/geos-config" if build.include? 'with-geos'
+    args << "GDAL_CONFIG=#{Formula.factory('gdal').opt_prefix}/bin/gdal-config" if build.include? 'with-gdal'
+
+    system "python", *args
+
     system "python",
            "scons/scons.py",
            "install"