Pandoc filter execute

_filters/execute_magick.py

@@ -0,0 +1,149 @@
+#!/bin/env python
+
+"""
+Pandoc filter to run all imagemagick code in code blocks
+"""
+
+import os
+import sys
+import hashlib
+from pandocfilters import toJSONFilter, Image, CodeBlock, Para
+from subprocess import Popen, PIPE
+
+DEBUG = False
+
+IMAGEDIR = '_images'
+
+# List of imagemagick tools; only commands in this list will be allowed to be run by the filter
+IM_COMMANDS = ('animate', 'compare', 'composite', 'conjure', 'convert', 'display', 'identify', 'import', 'mogrify', 'montage', 'stream', 'echo', 'printf')
+IM_IMAGE_TYPES = ('png', 'jpg', 'gif', 'tif')
+
+# Needed for writing unicode to stdout/stderr:
+reload(sys)
+sys.setdefaultencoding('utf-8')
+
+def sha1(x):
+    return hashlib.sha1(x.encode(sys.getfilesystemencoding())).hexdigest()
+
+def execute(code):
+    """
+    Executes the code.
+    Performs some sanity checks first.
+    """
+#    if DEBUG:
+#        sys.stderr.write('-'*100 + '\n')
+    code = remove_slash(code)
+    for line in code:
+        if DEBUG:
+            sys.stderr.write(line + u'\n')
+        commandline = line.split()
+        if commandline[0] not in IM_COMMANDS:
+            sys.stderr.write("Not a ImageMagick command: %s\n" % commandline[0])
+            return
+        image_name = commandline[-1]
+        image_type = os.path.splitext(image_name)[1][1:].lower()
+        if os.path.isfile(image_name):
+            sys.stderr.write("Image already exists: '%s'\n" % image_name)
+            return os.path.join('..', IMAGEDIR, image_name)
+        if image_type not in IM_IMAGE_TYPES:
+            sys.stderr.write("Not a ImageMagick Image Type: %s\n" % image_type)
+            return
+        p = Popen(' '.join(commandline), close_fds=True, stdout=PIPE, stderr=PIPE, shell=True)
+        out, err = p.communicate()
+        if out and DEBUG:
+            sys.stderr.write(out + '\n')
+        if err:
+            sys.stderr.write(err + '\n')
+    return os.path.join('..', IMAGEDIR, image_name)
+
+def remove_slash(text):
+    """
+    Joins lines, removing line-extending Backslashes ('\') from the text code
+    :returns: list of strings
+    """
+    retval = []
+    cummulative_line = ''
+    for line in text.split('\n'):
+        line = line.strip()
+        if line.endswith('\\'):
+            line = line.strip('\\')
+            cummulative_line += line
+        else:
+            cummulative_line += line
+#            execute(cummulative_line)
+            retval.append(cummulative_line)
+            cummulative_line = ''
+    return retval
+
+def magick(key, value, format, meta):
+    """
+    Filter to scan CodeBlocks for ImageMagick code and execute it to generate images.
+
+    Example CodeBlock:
+        ~~~{generate_image=True include_image=False}
+        convert -size 40x20 xc:red xc:blue -append -rotate 90 append_rotate.gif
+        ~~~
+
+    All images are created in the '_images' directory (might need to be created first)
+    Existing images will not be overwritten - we might want to add a command to the makefile like clean_images
+
+    The filter will not blindly execute any codeblock, but expects a key/value pair:
+
+        generate_image [True|False]
+        Another switch enables the automatic generation of HTML code including the  tag for the generated image:
+
+        include_image [True|False]
+
+    Example CodeBlock:
+
+        ~~~{generate_image=True include_image=False}
+        convert -size 40x20 xc:red xc:blue -append -rotate 90 append_rotate.gif
+        ~~~
+
+    Note: Using fenced code blocks
+        see http://pandoc.org/README.html#fenced-code-blocks
+        and https://github.com/jgm/pandoc/issues/673
+
+    Current limitations:
+
+    - Image names need to be unique throughout the whole tree.
+    - Complex commands, such as using perl/grep/pipes etc.
+    - Will need to change image location for those examples which already explicitly include the image (ex. examples at the top of the antialising file)
+    """
+    if key == 'CodeBlock':
+        [[ident, classes, keyvals], code] = value
+        keyvals = dict(keyvals)
+        if keyvals and keyvals.has_key('generate_image') and keyvals['generate_image']:
+
+            # outfile = os.path.join(IMAGEDIR, sha1(code))
+            # if format == "latex":
+            #     filetype = "pdf"
+            # else:
+            #     filetype = "png"
+            # src = outfile + '.' + filetype
+            if not os.path.isdir(IMAGEDIR):
+                try:
+                    os.mkdir(IMAGEDIR)
+                    sys.stderr.write('Created directory %s' % IMAGEDIR)
+                except OSError:
+                    sys.stderr.write('Could not create directory %s' % IMAGEDIR)
+                    return
+#            sys.stderr.write("classes: " + ','.join(classes) + '\n')
+#            sys.stderr.write(str(zip(keyvals)) + '\n')
+
+#        sys.stderr.write('Created image ' + src + '\n')
+            prev_dir = os.getcwd()
+            os.chdir(IMAGEDIR)
+            image = execute(code)
+            os.chdir(prev_dir)
+            if image:
+                if keyvals and keyvals.has_key('include_image') and keyvals['include_image']:
+                    return [CodeBlock(("", [], []), code), Para([Image([], [image, "generated my ImageMagick"])])]
+                else:
+                    return [CodeBlock(("", [], []), code)]
+            else:
+                return
+
+
+if __name__ == "__main__":
+    toJSONFilter(magick)