Implement imposing headers/footers onto their target pages

setup/extensions.json

@@ -116,7 +116,7 @@
     },
     {
         "name": "podofo",
-        "sources": "calibre/utils/podofo/utils.cpp calibre/utils/podofo/output.cpp calibre/utils/podofo/doc.cpp calibre/utils/podofo/outline.cpp calibre/utils/podofo/fonts.cpp calibre/utils/podofo/podofo.cpp",
+        "sources": "calibre/utils/podofo/utils.cpp calibre/utils/podofo/output.cpp calibre/utils/podofo/doc.cpp calibre/utils/podofo/outline.cpp calibre/utils/podofo/fonts.cpp calibre/utils/podofo/impose.cpp calibre/utils/podofo/podofo.cpp",
         "headers": "calibre/utils/podofo/global.h",
         "libraries": "podofo",
         "lib_dirs": "!podofo_lib",

src/calibre/ebooks/pdf/html_writer.py

@@ -860,7 +860,7 @@ def add_header_footer(manager, opts, pdf_doc, container, page_number_display_map
     root = container.parsed(name)
     body = root[-1]
     body.attrib.pop('id', None)
-    body.set('style', 'margin: 0; padding: 0; border-width: 0')
+    body.set('style', 'margin: 0; padding: 0; border-width: 0; background-color: unset')
     job = job_for_name(container, name, Margins(0, 0, 0, 0), page_layout)
 
     def m(tag_name, text=None, style=None, **attrs):
@@ -928,6 +928,7 @@ def add_header_footer(manager, opts, pdf_doc, container, page_number_display_map
             'padding': '0',
             'border-width': '0',
             'overflow': 'hidden',
+            'background-color': 'unset',
         }
 
         ans = m('div', style=style, id='p{}'.format(page_num))
@@ -944,7 +945,7 @@ def add_header_footer(manager, opts, pdf_doc, container, page_number_display_map
         style = ans.get('style') or ''
         style = (
             'margin: 0; padding: 0; height: {height}pt; border-width: 0;'
-            'display: flex; align-items: center; overflow: hidden').format(height=height) + style
+            'display: flex; align-items: center; overflow: hidden; background-color: unset').format(height=height) + style
         ans.set('style', style)
         for child in ans.xpath('descendant-or-self::*[@class]'):
             cls = frozenset(child.get('class').split())
@@ -970,7 +971,13 @@ def add_header_footer(manager, opts, pdf_doc, container, page_number_display_map
     if not isinstance(data, bytes):
         raise SystemExit(data)
     doc = data_as_pdf_doc(data)
+    first_page_num = pdf_doc.page_count()
+    num_pages = doc.page_count()
+    if first_page_num != num_pages:
+        raise ValueError('The number of header/footers pages ({}) != number of document pages ({})'.format(
+            num_pages, first_page_num))
     pdf_doc.append(doc)
+    pdf_doc.impose(1, first_page_num + 1, num_pages)
     report_progress(0.9, _('Headers and footers added'))
 
 # }}}

src/calibre/utils/podofo/doc.cpp

@@ -756,6 +756,9 @@ static PyMethodDef PDFDoc_methods[] = {
     {"dedup_type3_fonts", (PyCFunction)py_dedup_type3_fonts, METH_VARARGS,
      "dedup_type3_fonts() -> De-duplicate repeated glyphs in Type3 fonts"
     },
+    {"impose", (PyCFunction)py_impose, METH_VARARGS,
+     "impose() -> impose pages onto each other"
+    },
     {"delete_pages", (PyCFunction)PDFDoc_delete_pages, METH_VARARGS,
      "delete_page(page_num, count=1) -> Delete the specified pages from the pdf."
     },

src/calibre/utils/podofo/fonts.cpp

@@ -11,14 +11,6 @@
 
 using namespace pdf;
 
-#define PYWRAP(name) extern "C" PyObject* py_##name(PDFDoc *self, PyObject *args) { \
-    try { \
-        return name(self, args); \
-    } catch (const PdfError &err) { podofo_set_exception(err); return NULL; \
-    } catch (const std::exception &err) { PyErr_Format(Error, "Error in %s(): %s", #name, err.what()); return NULL; \
-    } catch (...) { PyErr_SetString(Error, "An unknown error occurred in " #name); return NULL; } \
-}
-
 static inline PyObject*
 ref_as_tuple(const PdfReference &ref) {
     unsigned long num = ref.ObjectNumber(), generation = ref.GenerationNumber();

src/calibre/utils/podofo/global.h

@@ -100,5 +100,14 @@ PyObject* py_list_fonts(PDFDoc*, PyObject*);
 PyObject* py_remove_unused_fonts(PDFDoc *self, PyObject *args);
 PyObject* py_merge_fonts(PDFDoc *self, PyObject *args);
 PyObject* py_dedup_type3_fonts(PDFDoc *self, PyObject *args);
+PyObject* py_impose(PDFDoc *self, PyObject *args);
 }
 }
+
+#define PYWRAP(name) extern "C" PyObject* py_##name(PDFDoc *self, PyObject *args) { \
+    try { \
+        return name(self, args); \
+    } catch (const PdfError &err) { podofo_set_exception(err); return NULL; \
+    } catch (const std::exception &err) { PyErr_Format(Error, "Error in %s(): %s", #name, err.what()); return NULL; \
+    } catch (...) { PyErr_SetString(Error, "An unknown error occurred in " #name); return NULL; } \
+}

src/calibre/utils/podofo/impose.cpp

@@ -0,0 +1,40 @@
+/*
+ * impose.cpp
+ * Copyright (C) 2019 Kovid Goyal <kovid at kovidgoyal.net>
+ *
+ * Distributed under terms of the GPL3 license.
+ */
+
+#include "global.h"
+
+using namespace pdf;
+
+static void
+impose_page(PdfMemDocument *doc, unsigned long dest_page_num, unsigned long src_page_num) {
+    PdfXObject *xobj = new PdfXObject(doc, src_page_num, "HeaderFooter");
+    PdfPage *dest = doc->GetPage(dest_page_num);
+    dest->AddResource(xobj->GetIdentifier(), xobj->GetObject()->Reference(), "XObject");
+    PdfStream *stream = dest->GetContents()->GetStream();
+    char *buffer = NULL; pdf_long sz;
+    stream->GetFilteredCopy(&buffer, &sz);
+    stream->BeginAppend();
+    stream->Append("q\n1 0 0 1 0 0 cm\n/");
+    stream->Append(xobj->GetIdentifier().GetName());
+    stream->Append(" Do\nQ\n");
+    stream->Append(buffer, sz);
+    stream->EndAppend();
+    podofo_free(buffer);
+}
+
+static PyObject*
+impose(PDFDoc *self, PyObject *args) {
+    unsigned long dest_page_num, src_page_num, count;
+    if (!PyArg_ParseTuple(args, "kkk", &dest_page_num, &src_page_num, &count)) return NULL;
+    for (unsigned long i = 0; i < count; i++) {
+        impose_page(self->doc, dest_page_num - 1 + i, src_page_num - 1 + i);
+    }
+    self->doc->DeletePages(src_page_num - 1, count);
+    Py_RETURN_NONE;
+}
+
+PYWRAP(impose)