Object classifier

Pdf4QtLib/sources/pdfobjectutils.h

@@ -20,23 +20,30 @@
 
 #include "pdfobject.h"
 
+#include <QtCore>
+
 #include <set>
+#include <vector>
 
 namespace pdf
 {
 class PDFObjectStorage;
+class PDFDocument;
 
 /// Utilities for manipulation with objects
 class PDFObjectUtils
 {
 public:
-    /// Returns list of references referenced by \p objects. So, all references, which are present
+    /// Returns a list of references referenced by \p objects. So, all references, which are present
     /// in objects, appear in the result set, including objects, which are referenced by referenced
     /// objects (so, transitive closure above reference graph is returned).
     /// \param objects Objects
     /// \param storage Storage
     static std::set<PDFObjectReference> getReferences(const std::vector<PDFObject>& objects, const PDFObjectStorage& storage);
 
+    /// Returns a list of references directly referenced from object. References itself are not followed.
+    static std::set<PDFObjectReference> getDirectReferences(const PDFObject& object);
+
     static PDFObject replaceReferences(const PDFObject& object, const std::map<PDFObjectReference, PDFObjectReference>& referenceMapping);
 
 private:
@@ -97,6 +104,67 @@ private:
     bool m_locked;
 };
 
+/// Classifies objects according to their type. Some heuristic is used
+/// when object type is missing or document is not well-formed.
+class Pdf4QtLIBSHARED_EXPORT PDFObjectClassifier
+{
+public:
+
+    inline PDFObjectClassifier() = default;
+
+    /// Performs object classification on a document. Old classification
+    /// is being cleared.
+    /// \param document Document
+    void classify(const PDFDocument* document);
+
+    enum Type : uint32_t
+    {
+        None            = 0x00000000,
+        Page            = 0x00000001,
+        ContentStream   = 0x00000002,
+        GraphicState    = 0x00000004,
+        ColorSpace      = 0x00000008,
+        Pattern         = 0x00000010,
+        Shading         = 0x00000020,
+        Image           = 0x00000040,
+        Form            = 0x00000080,
+        Font            = 0x00000100,
+        Action          = 0x00000200,
+        Annotation      = 0x00000400
+    };
+
+    Q_DECLARE_FLAGS(Types, Type)
+
+    /// Returns true, if object with given reference exists
+    /// and was classified.
+    /// \param reference Reference
+    bool hasObject(PDFObjectReference reference) const;
+
+    /// Returns true, if any object with given type is present in a document
+    /// \param type Object type
+    bool hasType(Type type) const { return m_allTypesUsed.testFlag(type); }
+
+    /// Returns a list of objects with a given type
+    /// \param type Type
+    std::vector<PDFObjectReference> getObjectsByType(Type type) const;
+
+private:
+    struct Classification
+    {
+        PDFObjectReference reference;
+        Types types = None;
+    };
+
+    /// Marks object with a given type
+    void mark(PDFObjectReference reference, Type type);
+
+    /// Marks objects in dictionary with a given type
+    void markDictionary(const PDFDocument* document, PDFObject object, Type type);
+
+    std::vector<Classification> m_classification;
+    Types m_allTypesUsed;
+};
+
 } // namespace pdf
 
 #endif // PDFOBJECTUTILS_H