Add resolutionUnit to metadata and as tiff option #3023

Co-authored-by: Lovell Fuller <github@lovell.info>

src/metadata.cc

@@ -77,6 +77,9 @@ class MetadataWorker : public Napi::AsyncWorker {
       if (image.get_typeof("heif-compression") == VIPS_TYPE_REF_STRING) {
         baton->compression = image.get_string("heif-compression");
       }
+      if (image.get_typeof(VIPS_META_RESOLUTION_UNIT) == VIPS_TYPE_REF_STRING) {
+        baton->resolutionUnit = image.get_string(VIPS_META_RESOLUTION_UNIT);
+      }
       if (image.get_typeof("openslide.level-count") == VIPS_TYPE_REF_STRING) {
         int const levels = std::stoi(image.get_string("openslide.level-count"));
         for (int l = 0; l < levels; l++) {
@@ -198,6 +201,9 @@ class MetadataWorker : public Napi::AsyncWorker {
       if (!baton->compression.empty()) {
         info.Set("compression", baton->compression);
       }
+      if (!baton->resolutionUnit.empty()) {
+        info.Set("resolutionUnit", baton->resolutionUnit == "in" ? "inch" : baton->resolutionUnit);
+      }
       if (!baton->levels.empty()) {
         int i = 0;
         Napi::Array levels = Napi::Array::New(env, static_cast<size_t>(baton->levels.size()));

src/metadata.h

@@ -40,6 +40,7 @@ struct MetadataBaton {
   std::vector<int> delay;
   int pagePrimary;
   std::string compression;
+  std::string resolutionUnit;
   std::vector<std::pair<int, int>> levels;
   int subifds;
   std::vector<double> background;

src/pipeline.cc

@@ -913,7 +913,8 @@ class PipelineWorker : public Napi::AsyncWorker {
             ->set("tile_height", baton->tiffTileHeight)
             ->set("tile_width", baton->tiffTileWidth)
             ->set("xres", baton->tiffXres)
-            ->set("yres", baton->tiffYres)));
+            ->set("yres", baton->tiffYres)
+            ->set("resunit", baton->tiffResolutionUnit)));
           baton->bufferOut = static_cast<char*>(area->data);
           baton->bufferOutLength = area->length;
           area->free_fn = nullptr;
@@ -1071,7 +1072,8 @@ class PipelineWorker : public Napi::AsyncWorker {
             ->set("tile_height", baton->tiffTileHeight)
             ->set("tile_width", baton->tiffTileWidth)
             ->set("xres", baton->tiffXres)
-            ->set("yres", baton->tiffYres));
+            ->set("yres", baton->tiffYres)
+            ->set("resunit", baton->tiffResolutionUnit));
           baton->formatOut = "tiff";
         } else if (baton->formatOut == "heif" || (mightMatchInput && isHeif) ||
           (willMatchInput && inputImageType == sharp::ImageType::HEIF)) {
@@ -1542,6 +1544,10 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->tiffPredictor = static_cast<VipsForeignTiffPredictor>(
   vips_enum_from_nick(nullptr, VIPS_TYPE_FOREIGN_TIFF_PREDICTOR,
     sharp::AttrAsStr(options, "tiffPredictor").data()));
+  baton->tiffResolutionUnit = static_cast<VipsForeignTiffResunit>(
+  vips_enum_from_nick(nullptr, VIPS_TYPE_FOREIGN_TIFF_RESUNIT,
+    sharp::AttrAsStr(options, "tiffResolutionUnit").data()));
+
   baton->heifQuality = sharp::AttrAsUint32(options, "heifQuality");
   baton->heifLossless = sharp::AttrAsBool(options, "heifLossless");
   baton->heifCompression = static_cast<VipsForeignHeifCompression>(
@@ -1550,6 +1556,7 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->heifEffort = sharp::AttrAsUint32(options, "heifEffort");
   baton->heifChromaSubsampling = sharp::AttrAsStr(options, "heifChromaSubsampling");
 
+
   // Raw output
   baton->rawDepth = static_cast<VipsBandFormat>(
     vips_enum_from_nick(nullptr, VIPS_TYPE_BAND_FORMAT,

src/pipeline.h

@@ -167,6 +167,7 @@ struct PipelineBaton {
   int tiffTileWidth;
   double tiffXres;
   double tiffYres;
+  VipsForeignTiffResunit tiffResolutionUnit;
   int heifQuality;
   VipsForeignHeifCompression heifCompression;
   int heifEffort;
@@ -305,6 +306,7 @@ struct PipelineBaton {
     tiffTileWidth(256),
     tiffXres(1.0),
     tiffYres(1.0),
+    tiffResolutionUnit(VIPS_FOREIGN_TIFF_RESUNIT_INCH),
     heifQuality(50),
     heifCompression(VIPS_FOREIGN_HEIF_COMPRESSION_AV1),
     heifEffort(4),