Mesh: add support of thumbnails of 3MF format

src/Mod/Mesh/App/Core/IO/Writer3MF.cpp

@@ -76,6 +76,11 @@ bool Writer3MF::AddMesh(const MeshKernel& mesh, const Base::Matrix4D& mat)
     return SaveObject(zip, id, mesh);
 }
 
+void Writer3MF::AddResource(const Resource3MF& res)
+{
+    resources.emplace_back(res);
+}
+
 bool Writer3MF::Save()
 {
     Finish(zip);
@@ -90,6 +95,12 @@ bool Writer3MF::Save()
     if (!SaveContent(zip))
         return false;
     zip.closeEntry();
+    for (const auto& it : resources) {
+        zip.putNextEntry(it.fileNameInZip);
+        zip.write(it.fileContent.data(), it.fileContent.size());
+        zip.closeEntry();
+    }
+
     return true;
 }
 
@@ -163,19 +174,24 @@ std::string Writer3MF::DumpMatrix(const Base::Matrix4D& mat) const
 
 bool Writer3MF::SaveRels(std::ostream &str) const
 {
+    int ids = 1;
     str << "<?xml version='1.0' encoding='UTF-8'?>\n"
-        << "<Relationships xmlns=\"http://schemas.openxmlformats.org/package/2006/relationships\">"
-           "<Relationship Id=\"rel0\" Target=\"/3D/3dmodel.model\" Type=\"http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel\" />"
-           "</Relationships>";
+        << "<Relationships xmlns=\"http://schemas.openxmlformats.org/package/2006/relationships\">\n"
+        << " <Relationship Target=\"/3D/3dmodel.model\" Id=\"rel0\" Type=\"http://schemas.microsoft.com/3dmanufacturing/2013/01/3dmodel\" />\n";
+    for (const auto& it : resources)
+        str << " <Relationship Target=\"" << it.relationshipTarget << "\" Id=\"rel" << ++ids << "\" Type=\"" << it.relationshipType << "\" />\n";
+    str << "</Relationships>\n";
     return true;
 }
 
 bool Writer3MF::SaveContent(std::ostream &str) const
 {
     str << "<?xml version='1.0' encoding='UTF-8'?>\n"
-        << "<Types xmlns=\"http://schemas.openxmlformats.org/package/2006/content-types\">"
-           "<Default ContentType=\"application/vnd.openxmlformats-package.relationships+xml\" Extension=\"rels\" />"
-           "<Default ContentType=\"application/vnd.ms-package.3dmanufacturing-3dmodel+xml\" Extension=\"model\" />"
-           "</Types>";
+        << "<Types xmlns=\"http://schemas.openxmlformats.org/package/2006/content-types\">\n"
+        << " <Default Extension=\"rels\" ContentType=\"application/vnd.openxmlformats-package.relationships+xml\"/>\n"
+        << " <Default Extension=\"model\" ContentType=\"application/vnd.ms-package.3dmanufacturing-3dmodel+xml\"/>\n";
+    for (const auto& it : resources)
+        str << " <Default Extension=\"" << it.extension << "\" ContentType=\"" << it.contentType << "\"/>\n";
+    str << "</Types>";
     return true;
 }

src/Mod/Mesh/App/Core/IO/Writer3MF.h

@@ -25,14 +25,26 @@
 #define MESH_IO_WRITER_3MF_H
 
 #include <iosfwd>
-
-#include "Core/Elements.h"
 #include <zipios++/zipoutputstream.h>
+#include <Mod/Mesh/MeshGlobal.h>
+
+namespace Base {
+class Matrix4D;
+}
 
 namespace MeshCore
 {
 class MeshKernel;
 
+struct Resource3MF {
+    std::string extension;
+    std::string contentType;
+    std::string relationshipTarget;
+    std::string relationshipType;
+    std::string fileNameInZip;
+    std::string fileContent;
+};
+
 /** Saves the mesh object into 3MF format. */
 class MeshExport Writer3MF
 {
@@ -58,6 +70,11 @@ public:
      * \return true if the added mesh could be written successfully, false otherwise.
      */
     bool AddMesh(const MeshKernel& mesh, const Base::Matrix4D& mat);
+    /*!
+     * \brief AddResource
+     * Add an additional resource to the 3MF file.
+     */
+    void AddResource(const Resource3MF&);
     /*!
      * \brief After having added the mesh objects with \ref AddMesh save the meta-information
      * to the 3MF file.
@@ -79,6 +96,7 @@ private:
     zipios::ZipOutputStream zip;
     int objectIndex;
     std::vector<std::string> items;
+    std::vector<Resource3MF> resources;
 };
 
 } // namespace MeshCore

src/Mod/Mesh/App/Exporter.cpp

@@ -229,12 +229,29 @@ bool MergeExporter::addMesh(const char *name, const MeshObject & mesh)
 
 // ----------------------------------------------------------------------------
 
+void Extension3MFFactory::addProducer(AbstractExtensionProducer* ext)
+{
+    producer.emplace_back(ext);
+}
+
+std::vector<Extension3MFPtr> Extension3MFFactory::create()
+{
+    std::vector<Extension3MFPtr> ext;
+    for (const auto& it : producer)
+        ext.emplace_back(it->create());
+    return ext;
+}
+
+std::vector<AbstractExtensionProducerPtr> Extension3MFFactory::producer;
+
 class Exporter3MF::Private {
 public:
     Private(const std::string& filename)
       : writer3mf(filename) {
+        ext = Extension3MFFactory::create();
     }
     MeshCore::Writer3MF writer3mf;
+    std::vector<Extension3MFPtr> ext;
 };
 
 Exporter3MF::Exporter3MF(std::string fileName)
@@ -251,7 +268,14 @@ Exporter3MF::~Exporter3MF()
 bool Exporter3MF::addMesh(const char *name, const MeshObject & mesh)
 {
     boost::ignore_unused(name);
-    return d->writer3mf.AddMesh(mesh.getKernel(), mesh.getTransform());
+    bool ok = d->writer3mf.AddMesh(mesh.getKernel(), mesh.getTransform());
+    if (ok) {
+        for (const auto& it : d->ext) {
+            d->writer3mf.AddResource(it->addMesh(mesh));
+        }
+    }
+
+    return ok;
 }
 
 void Exporter3MF::write()
@@ -410,7 +434,7 @@ bool ExporterAMF::addMesh(const char *name, const MeshObject & mesh)
 
     *outputStreamPtr << "\t\t\t</vertices>\n"
                      << "\t\t\t<volume>\n";
-    
+
     // Now that we've output all the vertices, we can
     // output the facets that refer to them!
     for (auto triItr(facets.begin()); triItr != facets.end(); ) {

src/Mod/Mesh/App/Exporter.h

@@ -34,6 +34,7 @@
 #include "MeshFeature.h"
 #include "Core/MeshIO.h"
 #include "Core/MeshKernel.h"
+#include "Core/IO/Writer3MF.h"
 
 namespace Mesh
 {
@@ -91,6 +92,50 @@ protected:
     std::string fName;
 };
 
+/*!
+ * \brief The Extension3MF class
+ * Abstract base class for 3MF extensions
+ */
+class MeshExport Extension3MF
+{
+public:
+    using Resource = MeshCore::Resource3MF;
+    Extension3MF() = default;
+    virtual ~Extension3MF() = default;
+
+    virtual Resource addMesh(const MeshObject & mesh) = 0;
+};
+
+using Extension3MFPtr = std::shared_ptr<Extension3MF>;
+
+/*!
+ * \brief The AbstractExtensionProducer class
+ * Abstract base class to create an instance of an Extension3MF.
+ */
+class MeshExport AbstractExtensionProducer
+{
+public:
+    AbstractExtensionProducer() = default;
+    virtual ~AbstractExtensionProducer() = default;
+    virtual Extension3MFPtr create() const = 0;
+};
+
+using AbstractExtensionProducerPtr = std::shared_ptr<AbstractExtensionProducer>;
+
+/*!
+ * \brief The Extension3MFFactory class
+ * Factor class to manage the producers of Extension3MF
+ */
+class MeshExport Extension3MFFactory
+{
+public:
+    static void addProducer(AbstractExtensionProducer* ext);
+    static std::vector<Extension3MFPtr> create();
+
+private:
+    static std::vector<AbstractExtensionProducerPtr> producer;
+};
+
 /// Used for exporting to 3D Manufacturing Format (3MF)
 /*!
  * The constructor and destructor write the beginning and end of the 3MF,