Add sele mode so that each input file has an even number of pages

README.rst

@@ -83,9 +83,17 @@ Examples:
     # reverse some of the pages in a.pdf by specifying a negative range
     stapler sel a.pdf 1-3 9-6 10 output.pdf
 
+The ``sele`` command is an extension of ``sel``. The usage is the same as that
+of ``sel``, but ``sele`` inserts an empty page after each input file if that
+input file has an odd number of pages so that each input file starts with an
+even page number in the generated output. The empty page shall have the same
+size as the page previous to it. You may find this mode useful if you read in
+double-page layout or if you want to print the concatenated output.
+
 The delete command works almost exactly the same as select, but inverse.
 It uses the pages and ranges which you *didn't* specify.
 
+
 split/burst:
 ~~~~~~~~~~~~
 

staplelib/commands.py

@@ -11,13 +11,14 @@
 from . import CommandError, iohelper
 import staplelib
 
-
-def select(args, inverse=False):
+def select(args, inverse=False, even_page=False):
     """
     Concatenate files / select pages from files.
 
     inverse=True excludes rather than includes the selected pages from
     the file.
+    even_page=True inserts an empty page at the end of each input
+    file if it ends with an odd page number.
     """
 
     filesandranges = iohelper.parse_ranges(args[:-1])
@@ -28,6 +29,7 @@ def select(args, inverse=False):
         raise CommandError("Both input and output filenames are required.")
 
     output = PdfFileWriter()
+    pagecnt = 0
     try:
         for input in filesandranges:
             pdf = input['pdf']
@@ -51,12 +53,18 @@ def select(args, inverse=False):
                         print "Using page: {} (rotation: {} deg.)".format(
                             pageno, rotate)
 
-                    output.addPage(pdf.getPage(pageno-1)
-                                   .rotateClockwise(rotate))
+                    page = pdf.getPage(pageno-1)
+                    output.addPage(page.rotateClockwise(rotate))
+                    pagecnt += 1
                 else:
                     raise CommandError("Page {} not found in {}.".format(
                         pageno, input['name']))
 
+            if even_page:
+                if pagecnt % 2 == 1:
+                    output.addPage(iohelper.create_empty_page(page))
+                    pagecnt += 1
+
     except Exception, e:
         raise CommandError(e)
 
@@ -66,6 +74,16 @@ def select(args, inverse=False):
         iohelper.write_pdf(output, staplelib.OPTIONS.destdir +
                            os.sep + outputfilename)
 
+def select_even(args, inverse=False):
+    """
+    Concatenate files / select pages from files.
+
+    Inserts an empty page at the end of each input file if it ends with
+    an odd page number.
+    """
+
+    select(args, inverse, True)
+
 
 def delete(args):
     """Concatenate files and remove pages from files."""

staplelib/iohelper.py

@@ -10,6 +10,9 @@
 except ImportError:
     from pyPdf import PdfFileWriter, PdfFileReader
 
+from reportlab.lib import pagesizes
+from reportlab.pdfgen import canvas
+from StringIO import StringIO
 
 from . import CommandError
 import staplelib
@@ -124,3 +127,25 @@ def parse_ranges(files_and_ranges):
                 current['pages'].append((p, rotate))
 
     return operations
+
+
+def create_empty_page(refpage=None):
+    """Create an empty page with the same size as refpage."""
+
+    if refpage is not None:
+        pagesize = refpage.mediaBox[-2:]
+    else:
+        pagesize = pagesizes.letter
+
+    c = canvas.Canvas(None)
+    c.setPageSize(pagesize)
+    c.showPage()
+
+    buf = StringIO()
+    buf.write(c.getpdfdata())
+    buf.seek(0)
+
+    reader = PdfFileReader(buf)
+    return reader.getPage(0)
+
+

staplelib/stapler.py

@@ -14,7 +14,7 @@
 usage: %prog [options] mode input.pdf ... [output.pdf]
 
 Modes:
-cat/sel: <inputfile> [<pagerange>[<rotation>]] ... (output needed)
+cat/sel/sele: <inputfile> [<pagerange>[<rotation>]] ... (output needed)
     Select the given pages/ranges from input files.
     No range means all pages.
 del: <inputfile> [<pagerange>[<rotation>]] ... (output needed)
@@ -68,6 +68,7 @@ def main():
     modes = {
         "cat": commands.select,
         "sel": commands.select,
+        "sele": commands.select_even,
         "split": commands.split,
         "burst": commands.split,
         "del": commands.delete,