Preview (thumbnail) extraction.

Read-only at the moment.

4 files changed, 73 insertions, 0 deletions

diff --git a/src/exiv2wrapper.cpp b/src/exiv2wrapper.cpp
index 914657a..3dbd8b2 100644
--- a/src/exiv2wrapper.cpp
+++ b/src/exiv2wrapper.cpp
@@ -398,6 +398,24 @@ void Image::deleteXmpTag(std::string key)
         throw Exiv2::Error(KEY_NOT_FOUND, key);
 }
 
+boost::python::list Image::previews()
+{
+    CHECK_METADATA_READ
+
+    boost::python::list previews;
+    Exiv2::PreviewManager pm(*_image);
+    Exiv2::PreviewPropertiesList props = pm.getPreviewProperties();
+    for (Exiv2::PreviewPropertiesList::const_iterator i = props.begin();
+         i != props.end();
+         ++i)
+    {
+        previews.append(Preview(pm.getPreviewImage(*i)));
+    }
+
+    return previews;
+}
+
+
 /*
 boost::python::tuple Image::getThumbnailData()
 {
@@ -774,6 +792,29 @@ const boost::python::dict XmpTag::getLangAltValue()
 }
 
 
+Preview::Preview(const Exiv2::PreviewImage& previewImage)
+{
+    _mimeType = previewImage.mimeType();
+    _extension = previewImage.extension();
+    _size = previewImage.size();
+    _dimensions = boost::python::make_tuple(previewImage.width(),
+                                            previewImage.height());
+    // Copy the data buffer in a string. Since the data buffer can contain null
+    // characters ('\x00'), the string cannot be simply constructed like that:
+    //     _data = std::string((char*) previewImage.pData());
+    // because it would be truncated after the first occurence of a null
+    // character. Therefore, it has to be copied character by character.
+    const Exiv2::byte* pData = previewImage.pData();
+    // First allocate the memory for the whole string...
+    _data = std::string(_size, ' ');
+    // ... then fill it with the raw data.
+    for(unsigned int i = 0; i < _size; ++i)
+    {
+        _data[i] = pData[i];
+    }
+}
+
+
 // TODO: update the errors code to reflect changes from src/error.cpp in libexiv2
 void translateExiv2Error(Exiv2::Error const& error)
 {
diff --git a/src/exiv2wrapper.hpp b/src/exiv2wrapper.hpp
index 26fb784..eaffeaa 100644
--- a/src/exiv2wrapper.hpp
+++ b/src/exiv2wrapper.hpp
@@ -29,6 +29,7 @@
 #include <string>
 
 #include "exiv2/image.hpp"
+#include "exiv2/preview.hpp"
 
 #include "boost/python.hpp"
 
@@ -129,6 +130,19 @@ private:
 };
 
 
+class Preview
+{
+public:
+    Preview(const Exiv2::PreviewImage& previewImage);
+
+    std::string _mimeType;
+    std::string _extension;
+    unsigned int _size;
+    boost::python::tuple _dimensions;
+    std::string _data;
+};
+
+
 class Image
 {
 public:
@@ -196,6 +210,9 @@ public:
 
     // Read and write access to the thumbnail embedded in the image.
 
+    // Read-only ATM.
+    boost::python::list previews();
+
     // Return a tuple containing the format of the thumbnail ("TIFF" or
     // "JPEG") and the thumbnail raw data as a string buffer.
     // Throw an exception if the thumbnail data cannot be accessed.
diff --git a/src/exiv2wrapper_python.cpp b/src/exiv2wrapper_python.cpp
index bce46fa..a5f9d6d 100644
--- a/src/exiv2wrapper_python.cpp
+++ b/src/exiv2wrapper_python.cpp
@@ -93,6 +93,15 @@ BOOST_PYTHON_MODULE(libexiv2python)
         .def("_getLangAltValue", &XmpTag::getLangAltValue)
     ;
 
+    class_<Preview>("Preview", init<Exiv2::PreviewImage>())
+
+        .def_readonly("mime_type", &Preview::_mimeType)
+        .def_readonly("extension", &Preview::_extension)
+        .def_readonly("size", &Preview::_size)
+        .def_readonly("dimensions", &Preview::_dimensions)
+        .def_readonly("data", &Preview::_data)
+    ;
+
     class_<Image>("Image", init<std::string>())
 
         .def("readMetadata", &Image::readMetadata)
@@ -115,6 +124,8 @@ BOOST_PYTHON_MODULE(libexiv2python)
         .def("setXmpTagLangAltValue", &Image::setXmpTagLangAltValue)
         .def("deleteXmpTag", &Image::deleteXmpTag)
 
+        .def("previews", &Image::previews)
+
 //        .def("getThumbnailData", &Image::getThumbnailData)
 //        .def("setThumbnailData", &Image::setThumbnailData)
 //        .def("deleteThumbnail", &Image::deleteThumbnail)
diff --git a/src/pyexiv2/metadata.py b/src/pyexiv2/metadata.py
index 05e762b..77900d3 100644
--- a/src/pyexiv2/metadata.py
+++ b/src/pyexiv2/metadata.py
@@ -301,3 +301,7 @@ class ImageMetadata(object):
         except AttributeError:
             raise KeyError(key)
 
+    @property
+    def previews(self):
+        return self._image.previews()
+