Fix up python_bindings build

- support run_apps, run_apps_headless without first installing globally.
- fix dependencies in basic build rules.
- make setup.py support `$BUILD_PREFIX` as used by the main Halide build.

Author: jrk

python_bindings/Makefile

@@ -1,14 +1,13 @@
-
 all: halide/cHalide_wrap.cxx halide/_cHalide.so
 
-halide/_cHalide.so: halide/*.py halide/cHalide.i ../src/*.cpp ../src/runtime/*.cpp ../src/*.h ../include/*.h halide/py_util.cpp halide/py_util.h halide/expand_types.h
+halide/_cHalide.so: halide/cHalide_wrap.cxx halide/*.py halide/cHalide.i ../src/*.cpp ../src/runtime/*.cpp ../src/*.h ../include/*.h halide/py_util.cpp halide/py_util.h halide/expand_types.h setup.py
 	python setup.py build_ext --inplace
 
-halide/cHalide_wrap.cxx: halide/cHalide.i ../src/*.cpp ../src/runtime/*.cpp ../src/*.h ../include/*.h halide/py_util.cpp halide/py_util.h halide/expand_types.h
+halide/cHalide_wrap.cxx: halide/cHalide.i ../src/*.cpp ../src/runtime/*.cpp ../src/*.h ../include/*.h halide/py_util.cpp halide/py_util.h halide/expand_types.h setup.py
 	make -C ..
 	swig -c++ -python -w362,325,314,389,381,382,361,401,503,509 -I../include halide/cHalide.i
 
-install: halide/cHalide_wrap.cxx
+install: all
 	python setup.py install
 
 clean:
@@ -19,18 +18,18 @@ clean:
 	rm -f halide/cHalide.py halide/*.pyc
 
 run_apps:
-	python apps/local_laplacian.py
-	python apps/interpolate.py
-	python apps/bilateral_grid.py
-	python apps/erode.py
-	python apps/blur.py
+	PYTHONPATH=.:$(PYTHONPATH) python apps/local_laplacian.py
+	PYTHONPATH=.:$(PYTHONPATH) python apps/interpolate.py
+	PYTHONPATH=.:$(PYTHONPATH) python apps/bilateral_grid.py
+	PYTHONPATH=.:$(PYTHONPATH) python apps/erode.py
+	PYTHONPATH=.:$(PYTHONPATH) python apps/blur.py
 
 run_apps_headless:
-	python apps/local_laplacian.py apps/out_local_laplacian.png
-	python apps/interpolate.py apps/out_interpolate.png
-	python apps/bilateral_grid.py apps/out_bilateral_grid.png
-	python apps/erode.py apps/out_erode.png
-	python apps/blur.py apps/out_blur.png
+	PYTHONPATH=.:$(PYTHONPATH) python apps/local_laplacian.py apps/out_local_laplacian.png
+	PYTHONPATH=.:$(PYTHONPATH) python apps/interpolate.py apps/out_interpolate.png
+	PYTHONPATH=.:$(PYTHONPATH) python apps/bilateral_grid.py apps/out_bilateral_grid.png
+	PYTHONPATH=.:$(PYTHONPATH) python apps/erode.py apps/out_erode.png
+	PYTHONPATH=.:$(PYTHONPATH) python apps/blur.py apps/out_blur.png
 
 test:
-	python test_halide.py
+	PYTHONPATH=.:$(PYTHONPATH) python test_halide.py

python_bindings/setup.py

@@ -6,17 +6,25 @@
 import subprocess
 import shutil
 
+build_prefix = os.getenv('BUILD_PREFIX')
+if not build_prefix:
+    build_prefix = ''
+halide_root = '..'
+include_path = os.path.join(halide_root, 'include')
+bin_path = os.path.join(halide_root, 'bin', build_prefix)
+image_path = os.path.join(halide_root, 'apps', 'images')
+
 png_cflags  = subprocess.check_output('libpng-config --cflags',  shell=True).strip()
 png_ldflags = subprocess.check_output('libpng-config --ldflags', shell=True).strip()
 
 ext_modules = [Extension("halide/_cHalide", ["halide/cHalide_wrap.cxx", 'halide/py_util.cpp'],
-                         include_dirs=['../include'],
+                         include_dirs=[include_path],
                          extra_compile_args=('-ffast-math -O3 -msse -Wl,-dead_strip -fno-common' + ' ' + png_cflags).split(),
-                         extra_link_args=['../bin/libHalide.a', '-lpthread', '-ldl', '-lstdc++', '-lc']+png_ldflags.split(),
+                         extra_link_args=[os.path.join(bin_path, 'libHalide.a'), '-lpthread', '-ldl', '-lstdc++', '-lc']+png_ldflags.split(),
                          language='c++')]
 
 if glob.glob('halide/data/*.png') == []:
-    shutil.copytree('../apps/images/', 'halide/data')
+    shutil.copytree(image_path, 'halide/data')
 
 setup(
     name = 'halide',