Refactor test_pictures so we can add test_pdfs without code duplication. 
Review URL: https://codereview.appspot.com/6611050

git-svn-id: http://skia.googlecode.com/svn/trunk@5878 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/test_rendering.py b/tools/test_rendering.py
new file mode 100644
index 0000000..35e6d94
--- /dev/null
+++ b/tools/test_rendering.py
@@ -0,0 +1,118 @@
+'''
+Compares the rendererings of serialized SkPictures to expected result.
+
+Copyright 2012 Google Inc.
+
+Use of this source code is governed by a BSD-style license that can be
+found in the LICENSE file.
+'''
+# common Python modules
+import os
+import optparse
+import sys
+import shutil
+import tempfile
+
+USAGE_STRING = 'Usage: %s input... expectedDir render_app [reander_app_args]'
+HELP_STRING = '''
+
+Compares the renderings of serialized SkPicture files and directories specified
+by input with the files in expectedDir. Note, files in directoriers are
+expected to end with .skp.
+'''
+
+def RunCommand(command):
+    """Run a command.
+
+    @param command the command as a single string
+    """
+    print 'running command [%s]...' % command
+    os.system(command)
+
+
+def FindPathToProgram(program):
+    """Return path to an existing program binary, or raise an exception if we
+    cannot find one.
+
+    @param program the name of the program that is being looked for
+    """
+    trunk_path = os.path.abspath(os.path.join(os.path.dirname(__file__),
+                                              os.pardir))
+    possible_paths = [os.path.join(trunk_path, 'out', 'Release', program),
+                      os.path.join(trunk_path, 'out', 'Debug', program),
+                      os.path.join(trunk_path, 'out', 'Release',
+                                   program + ".exe"),
+                      os.path.join(trunk_path, 'out', 'Debug',
+                                   program + ".exe")]
+    for try_path in possible_paths:
+        if os.path.isfile(try_path):
+            return try_path
+    raise Exception('cannot find %s in paths %s; maybe you need to '
+                    'build %s?' % (program, possible_paths, program))
+
+
+def RenderSkps(inputs, render_dir, render_app, args):
+    """Renders the serialized SkPictures.
+
+    Uses the render_pictures program to do the rendering.
+
+    @param inputs the location(s) to read the serlialized SkPictures
+    @param render_dir the location to write out the rendered images
+    """
+    renderer_path = FindPathToProgram(render_app)
+    inputs_as_string = " ".join(inputs)
+    command = '%s %s %s' % (renderer_path, inputs_as_string, render_dir)
+
+    command += args
+
+    RunCommand(command)
+
+
+def DiffRenderings(expected_dir, comparison_dir, diff_dir):
+    """Diffs the rendered SkPicture files with the baseline files.
+
+    Uses the skdiff program to do the diffing.
+
+    @param expected_dir the location of the baseline images.
+    @param comparison_dir the location of the images to comapre with the
+           baseline
+    @param diff_dir the location to write out the diff results
+    """
+    skdiff_path = FindPathToProgram('skdiff')
+    RunCommand('%s %s %s %s %s' %
+               (skdiff_path, expected_dir, comparison_dir, diff_dir,
+                '--noprintdirs'))
+
+
+def Cleanup(render_dir_option, diff_dir_option, render_dir, diff_dir):
+    """Deletes any temporary folders and files created.
+
+    @param foo_option The OptionParser parsed render_dir or diff_dir vars.
+            If these variables are not passed by user we ended up creating
+            temporary directories (render_dir, diff_dir) which we will remove.
+    @param render_dir the directory where the rendered images were written
+    @param diff_dir the directory where the diff results were written
+    """
+    if (not render_dir_option):
+        if (os.path.isdir(render_dir)):
+            shutil.rmtree(render_dir)
+    if (not diff_dir_option):
+        if (os.path.isdir(diff_dir)):
+            shutil.rmtree(diff_dir)
+
+def TestRenderSkps(inputs, expected_dir, render_dir_option, diff_dir_option,
+                   render_app, render_args):
+    if (render_dir_option):
+        render_dir = render_dir_option
+    else:
+        render_dir = tempfile.mkdtemp()
+
+    if (diff_dir_option):
+        diff_dir = diff_dir_option
+    else:
+        diff_dir = tempfile.mkdtemp()
+    try:    
+        RenderSkps(inputs, render_dir, render_app, render_args)
+        DiffRenderings(expected_dir, render_dir, diff_dir)
+    finally:
+        Cleanup(render_dir_option, diff_dir_option, render_dir, diff_dir)