Casting routine from files/header

CMakeLists.txt

@@ -174,6 +174,7 @@ endif()
 # ── Core library ────────────────────────────────────────────────────────────
 add_library(trx
     src/trx.cpp
+    src/legacy_io.cpp
     src/detail/dtype_helpers.cpp
     include/trx/trx.h
     include/trx/trx.tpp

include/trx/legacy_io.h

@@ -0,0 +1,62 @@
+#ifndef TRX_LEGACY_IO_H
+#define TRX_LEGACY_IO_H
+
+#include <string>
+#include <vector>
+#include <cstdint>
+#include <trx/trx.h>
+
+namespace trx {
+namespace legacy {
+
+struct Tractogram {
+    std::vector<float> pts;
+    std::vector<uint64_t> offsets;
+    json11::Json header;
+    std::shared_ptr<trx::AnyTrxFile> original_trx;
+};
+
+#pragma pack(push, 1)
+struct TrkHeader {
+    char magic_number[6];
+    int16_t dimensions[3];
+    float voxel_sizes[3];
+    float origin[3];
+    int16_t nb_scalars_per_point;
+    char scalar_name[10][20];
+    int16_t nb_properties_per_streamline;
+    char property_name[10][20];
+    float voxel_to_rasmm[4][4];
+    char reserved[444];
+    char voxel_order[4];
+    char pad2[4];
+    float image_orientation_patient[6];
+    char pad1[2];
+    char invert_x;
+    char invert_y;
+    char invert_z;
+    char swap_xy;
+    char swap_yz;
+    char swap_zx;
+    int32_t nb_streamlines;
+    int32_t version;
+    int32_t hdr_size;
+};
+#pragma pack(pop)
+
+bool load_trx(const std::string &filename, Tractogram &tr);
+bool load_trk(const std::string &filename, Tractogram &tr);
+bool load_tck(const std::string &filename, Tractogram &tr);
+bool load_vtk(const std::string &filename, Tractogram &tr);
+
+bool load_nifti_header(const std::string &ref_path, json11::Json &out_header);
+
+bool save_trx(const Tractogram &tr, const std::string &out_path, const std::string &ref_nifti_path = "");
+bool save_trk(const Tractogram &tr, const std::string &out_path, const std::string &original_filename = "", const std::string &ref_nifti_path = "");
+bool save_tck(const Tractogram &tr, const std::string &out_path);
+bool save_vtk(const Tractogram &tr, const std::string &out_path);
+
+} // namespace legacy
+} // namespace trx
+
+#endif // TRX_LEGACY_IO_H

main.cpp

@@ -0,0 +1,68 @@
+#include <iostream>
+#include <string>
+#include <trx/legacy_io.h>
+#include <trx/trx.h>
+
+int main(int argc, char** argv) {
+    std::string input_file;
+    std::string output_file;
+    std::string ref_path;
+
+    for (int i = 1; i < argc; ++i) {
+        std::string arg = argv[i];
+        if (arg == "--ref") {
+            if (i + 1 < argc) {
+                ref_path = argv[++i];
+            } else {
+                std::cerr << "Error: --ref requires an argument\n";
+                return 1;
+            }
+        } else if (input_file.empty()) {
+            input_file = arg;
+        } else if (output_file.empty()) {
+            output_file = arg;
+        }
+    }
+
+    if (input_file.empty() || output_file.empty()) {
+        std::cerr << "Usage: convert <input> <output> [--ref <nifti_file>]\n";
+        return 1;
+    }
+
+    trx::legacy::Tractogram tr;
+    bool success = false;
+
+    auto ends_with = [](const std::string& str, const std::string& suffix) {
+        return str.size() >= suffix.size() && str.compare(str.size() - suffix.size(), suffix.size(), suffix) == 0;
+    };
+
+    if (ends_with(input_file, ".trx")) success = trx::legacy::load_trx(input_file, tr);
+    else if (ends_with(input_file, ".trk")) success = trx::legacy::load_trk(input_file, tr);
+    else if (ends_with(input_file, ".tck")) success = trx::legacy::load_tck(input_file, tr);
+    else if (ends_with(input_file, ".vtk")) success = trx::legacy::load_vtk(input_file, tr);
+
+    if (!success) {
+        std::cerr << "Error loading input file\n";
+        return 1;
+    }
+
+    bool is_tck_vtk = ends_with(input_file, ".tck") || ends_with(input_file, ".vtk");
+    bool is_trx_trk = ends_with(output_file, ".trx") || ends_with(output_file, ".trk");
+
+    if (is_tck_vtk && is_trx_trk && ref_path.empty()) {
+        std::cerr << "Error: TCK/VTK -> TRX/TRK conversion requires --ref <nifti_file>\n";
+        return 1;
+    }
+
+    success = false;
+    if (ends_with(output_file, ".trx")) success = trx::legacy::save_trx(tr, output_file, ref_path);
+    else if (ends_with(output_file, ".trk")) success = trx::legacy::save_trk(tr, output_file, input_file, ref_path);
+    else if (ends_with(output_file, ".tck")) success = trx::legacy::save_tck(tr, output_file);
+    else if (ends_with(output_file, ".vtk")) success = trx::legacy::save_vtk(tr, output_file);
+
+    if (!success) {
+        std::cerr << "Error saving output file\n";
+        return 1;
+    }
+    return 0;
+}