Add support for removing unused Type3 fonts as well

src/calibre/utils/podofo/__init__.py

@@ -10,7 +10,7 @@ from calibre.constants import plugins, preferred_encoding
 from calibre.ebooks.metadata import authors_to_string
 from calibre.ptempfile import TemporaryDirectory
 from calibre.utils.ipc.simple_worker import WorkerError, fork_job
-from polyglot.builtins import unicode_type, iteritems
+from polyglot.builtins import unicode_type
 
 
 def get_podofo():
@@ -127,20 +127,11 @@ def get_image_count(path):
 def list_fonts(pdf_doc):
     fonts = pdf_doc.list_fonts()
     ref_map = {f['Reference']: f for f in fonts}
-    for ref in pdf_doc.used_fonts_in_page_range():
-        ref_map[ref]['used'] = True
-    for font in fonts:
-        font['used'] = font.get('used', False)
-        if font['DescendantFont'] and font['used']:
-            ref_map[font['DescendantFont']]['used'] = True
     return ref_map
 
 
 def remove_unused_fonts(pdf_doc):
-    font_ref_map = list_fonts(pdf_doc)
-    unused = tuple(ref for ref, font in iteritems(font_ref_map) if not font['used'])
-    pdf_doc.remove_fonts(unused)
-    return len(tuple(f for f in unused if font_ref_map[f]['StreamRef']))
+    return pdf_doc.remove_unused_fonts()
 
 
 def test_remove_unused_fonts(src):

src/calibre/utils/podofo/doc.cpp

@@ -747,12 +747,12 @@ static PyMethodDef PDFDoc_methods[] = {
     {"list_fonts", (PyCFunction)list_fonts, METH_VARARGS,
      "list_fonts() -> Get list of fonts in document"
     },
-    {"used_fonts_in_page_range", (PyCFunction)used_fonts_in_page_range, METH_VARARGS,
-     "used_fonts_in_page_range() -> Get list of references to fonts used in the specified pages"
-    },
     {"remove_fonts", (PyCFunction)remove_fonts, METH_VARARGS,
      "remove_fonts() -> Remove the specified font objects."
     },
+    {"remove_unused_fonts", (PyCFunction)remove_unused_fonts, METH_NOARGS,
+     "remove_unused_fonts() -> Remove unused font objects."
+    },
     {"merge_fonts", (PyCFunction)merge_fonts, METH_VARARGS,
      "merge_fonts() -> Merge the specified fonts."
     },

src/calibre/utils/podofo/fonts.cpp

@@ -8,7 +8,6 @@
 #include "global.h"
 #include <iostream>
 #include <stack>
-#include <unordered_map>
 
 using namespace pdf;
 
@@ -72,7 +71,7 @@ replace_font_references(PDFDoc *self, std::unordered_map<uint64_t, uint64_t> &re
 }
 
 static bool
-used_fonts_in_page(PdfPage *page, int page_num, PyObject *ans) {
+used_fonts_in_page(PdfPage *page, unordered_reference_set &ans) {
     PdfContentsTokenizer tokenizer(page);
     bool in_text_block = false;
     const char* token = NULL;
@@ -96,11 +95,7 @@ used_fonts_in_page(PdfPage *page, int page_num, PyObject *ans) {
             if (stack.size() > 0 && stack.top().IsName()) {
                 const PdfName &reference_name = stack.top().GetName();
                 PdfObject* font = page->GetFromResources("Font", reference_name);
-                if (font) {
-                    pyunique_ptr r(ref_as_tuple(font->Reference()));
-                    if (!r) return false;
-                    if (PySet_Add(ans, r.get()) != 0) return false;
-                }
+                if (font) ans.insert(font->Reference());
             }
         }
     }
@@ -235,21 +230,6 @@ list_fonts(PDFDoc *self, PyObject *args) {
     return ans.release();
 }
 
-PyObject*
-used_fonts_in_page_range(PDFDoc *self, PyObject *args) {
-    int first = 1, last = self->doc->GetPageCount();
-    if (!PyArg_ParseTuple(args, "|ii", &first, &last)) return NULL;
-    pyunique_ptr ans(PySet_New(NULL));
-    if (!ans) return NULL;
-    for (int i = first - 1; i < last; i++) {
-        try {
-            PdfPage *page = self->doc->GetPage(i);
-            if (!used_fonts_in_page(page, i, ans.get())) return NULL;
-        } catch (const PdfError &err) { continue; }
-    }
-    return ans.release();
-}
-
 PyObject*
 remove_fonts(PDFDoc *self, PyObject *args) {
     PyObject *fonts;
@@ -267,6 +247,63 @@ remove_fonts(PDFDoc *self, PyObject *args) {
     Py_RETURN_NONE;
 }
 
+typedef std::unordered_map<PdfReference, unsigned long, PdfReferenceHasher> charprocs_usage_map;
+
+PyObject*
+remove_unused_fonts(PDFDoc *self, PyObject *args) {
+    unordered_reference_set used_fonts;
+    for (int i = 0; i < self->doc->GetPageCount(); i++) {
+        PdfPage *page = self->doc->GetPage(i);
+        if (page) used_fonts_in_page(page, used_fonts);
+    }
+    unordered_reference_set all_fonts;
+    unordered_reference_set type3_fonts;
+    charprocs_usage_map charprocs_usage;
+    PdfVecObjects &objects = self->doc->GetObjects();
+    for (TCIVecObjects it = objects.begin(); it != objects.end(); it++) {
+        if ((*it)->IsDictionary()) {
+            const PdfDictionary &dict = (*it)->GetDictionary();
+            if (dictionary_has_key_name(dict, PdfName::KeyType, "Font")) {
+                const std::string &font_type = dict.GetKey(PdfName::KeySubtype)->GetName().GetName();
+                if (font_type == "Type0") {
+                    all_fonts.insert((*it)->Reference());
+                } else if (font_type == "Type3") {
+                    all_fonts.insert((*it)->Reference());
+                    type3_fonts.insert((*it)->Reference());
+                    for (auto &x : dict.GetKey("CharProcs")->GetDictionary().GetKeys()) {
+                        const PdfReference &ref = x.second->GetReference();
+                        if (charprocs_usage.find(ref) == charprocs_usage.end()) charprocs_usage[ref] = 1;
+                        else charprocs_usage[ref] += 1;
+                    }
+                }
+            }
+        }
+    }
+
+    unsigned long count = 0;
+    for (auto &ref : all_fonts) {
+        if (used_fonts.find(ref) == used_fonts.end()) {
+            PdfObject *font = objects.GetObject(ref);
+            if (font) {
+                count++;
+                if (type3_fonts.find(ref) != type3_fonts.end()) {
+                    for (auto &x : font->GetIndirectKey("CharProcs")->GetDictionary().GetKeys()) {
+                        charprocs_usage[x.second->GetReference()] -= 1;
+                    }
+                }
+                remove_font(objects, font);
+            }
+        }
+    }
+
+    for (auto &x : charprocs_usage) {
+        if (x.second == 0u) {
+            delete objects.RemoveObject(x.first);
+        }
+    }
+    return Py_BuildValue("k", count);
+}
+
 PyObject*
 merge_fonts(PDFDoc *self, PyObject *args) {
     PyObject *items, *replacements;

src/calibre/utils/podofo/global.h

@@ -12,6 +12,8 @@
 
 #define USING_SHARED_PODOFO
 #include <podofo.h>
+#include <unordered_set>
+#include <unordered_map>
 using namespace PoDoFo;
 
 namespace pdf {
@@ -84,10 +86,19 @@ dictionary_has_key_name(const PdfDictionary &d, T key, const char *name) {
 	return false;
 }
 
+class PdfReferenceHasher {
+    public:
+        size_t operator()(const PdfReference & obj) const {
+            return std::hash<pdf_objnum>()(obj.ObjectNumber());
+        }
+};
+typedef std::unordered_set<PdfReference, PdfReferenceHasher> unordered_reference_set;
+
+
 extern "C" {
 PyObject* list_fonts(PDFDoc*, PyObject*);
-PyObject* used_fonts_in_page_range(PDFDoc *self, PyObject *args);
 PyObject* remove_fonts(PDFDoc *self, PyObject *args);
+PyObject* remove_unused_fonts(PDFDoc *self, PyObject *args);
 PyObject* merge_fonts(PDFDoc *self, PyObject *args);
 }
 }