Allow EXIF metadata to be set/update #650

docs/api-output.md

@@ -119,6 +119,7 @@ sRGB colour space and strip all metadata, including the removal of any ICC profi
 -   `options` **[Object][6]?** 
     -   `options.orientation` **[number][9]?** value between 1 and 8, used to update the EXIF `Orientation` tag.
     -   `options.icc` **[string][2]?** filesystem path to output ICC profile, defaults to sRGB.
+    -   `options.exif` **[Object][6]<[Object][6]>** Object keyed by IFD0, IFD1 etc. of key/value string pairs to write as EXIF data. (optional, default `{}`)
 
 ### Examples
 
@@ -129,6 +130,19 @@ sharp('input.jpg')
   .then(info => { ... });
 ```
 
+```javascript
+// Set "IFD0-Copyright" in output EXIF metadata
+await sharp(input)
+  .withMetadata({
+    exif: {
+      IFD0: {
+        Copyright: 'Wernham Hogg'
+      }
+    }
+  })
+  .toBuffer();
+```
+
 -   Throws **[Error][4]** Invalid parameters
 
 Returns **Sharp** 

docs/changelog.md

@@ -8,6 +8,9 @@ Requires libvips v8.10.6
 
 * Ensure all installation errors are logged with a more obvious prefix.
 
+* Allow `withMetadata` to set and update EXIF metadata.
+  [#650](https://github.com/lovell/sharp/issues/650)
+
 * Add support for OME-TIFF Sub Image File Directories (subIFD).
   [#2557](https://github.com/lovell/sharp/issues/2557)
 

lib/constructor.js

@@ -232,6 +232,7 @@ const Sharp = function (input, options) {
     withMetadata: false,
     withMetadataOrientation: -1,
     withMetadataIcc: '',
+    withMetadataStrs: {},
     resolveWithObject: false,
     // output format
     jpegQuality: 80,

lib/output.js

@@ -148,9 +148,22 @@ function toBuffer (options, callback) {
  *   .toFile('output-with-metadata.jpg')
  *   .then(info => { ... });
  *
+ * @example
+ * // Set "IFD0-Copyright" in output EXIF metadata
+ * await sharp(input)
+ *   .withMetadata({
+ *     exif: {
+ *       IFD0: {
+ *         Copyright: 'Wernham Hogg'
+ *       }
+ *     }
+ *   })
+ *   .toBuffer();
+ *
  * @param {Object} [options]
  * @param {number} [options.orientation] value between 1 and 8, used to update the EXIF `Orientation` tag.
  * @param {string} [options.icc] filesystem path to output ICC profile, defaults to sRGB.
+ * @param {Object<Object>} [options.exif={}] Object keyed by IFD0, IFD1 etc. of key/value string pairs to write as EXIF data.
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
  */
@@ -171,6 +184,25 @@ function withMetadata (options) {
         throw is.invalidParameterError('icc', 'string filesystem path to ICC profile', options.icc);
       }
     }
+    if (is.defined(options.exif)) {
+      if (is.object(options.exif)) {
+        for (const [ifd, entries] of Object.entries(options.exif)) {
+          if (is.object(entries)) {
+            for (const [k, v] of Object.entries(entries)) {
+              if (is.string(v)) {
+                this.options.withMetadataStrs[`exif-${ifd.toLowerCase()}-${k}`] = v;
+              } else {
+                throw is.invalidParameterError(`exif.${ifd}.${k}`, 'string', v);
+              }
+            }
+          } else {
+            throw is.invalidParameterError(`exif.${ifd}`, 'object', entries);
+          }
+        }
+      } else {
+        throw is.invalidParameterError('exif', 'object', options.exif);
+      }
+    }
   }
   return this;
 }

src/common.cc

@@ -36,6 +36,9 @@ namespace sharp {
   std::string AttrAsStr(Napi::Object obj, std::string attr) {
     return obj.Get(attr).As<Napi::String>();
   }
+  std::string AttrAsStr(Napi::Object obj, unsigned int const attr) {
+    return obj.Get(attr).As<Napi::String>();
+  }
   uint32_t AttrAsUint32(Napi::Object obj, std::string attr) {
     return obj.Get(attr).As<Napi::Number>().Uint32Value();
   }

src/common.h

@@ -95,6 +95,7 @@ namespace sharp {
   // Convenience methods to access the attributes of a Napi::Object
   bool HasAttr(Napi::Object obj, std::string attr);
   std::string AttrAsStr(Napi::Object obj, std::string attr);
+  std::string AttrAsStr(Napi::Object obj, unsigned int const attr);
   uint32_t AttrAsUint32(Napi::Object obj, std::string attr);
   int32_t AttrAsInt32(Napi::Object obj, std::string attr);
   int32_t AttrAsInt32(Napi::Object obj, unsigned int const attr);

src/pipeline.cc

@@ -717,11 +717,17 @@ class PipelineWorker : public Napi::AsyncWorker {
             ->set("input_profile", "srgb")
             ->set("intent", VIPS_INTENT_PERCEPTUAL));
       }
-
       // Override EXIF Orientation tag
       if (baton->withMetadata && baton->withMetadataOrientation != -1) {
         image = sharp::SetExifOrientation(image, baton->withMetadataOrientation);
       }
+      // Metadata key/value pairs, e.g. EXIF
+      if (!baton->withMetadataStrs.empty()) {
+        image = image.copy();
+        for (const auto& s : baton->withMetadataStrs) {
+          image.set(s.first.data(), s.second.data());
+        }
+      }
 
       // Number of channels used in output image
       baton->channels = image.bands();
@@ -1379,6 +1385,12 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->withMetadata = sharp::AttrAsBool(options, "withMetadata");
   baton->withMetadataOrientation = sharp::AttrAsUint32(options, "withMetadataOrientation");
   baton->withMetadataIcc = sharp::AttrAsStr(options, "withMetadataIcc");
+  Napi::Object mdStrs = options.Get("withMetadataStrs").As<Napi::Object>();
+  Napi::Array mdStrKeys = mdStrs.GetPropertyNames();
+  for (unsigned int i = 0; i < mdStrKeys.Length(); i++) {
+    std::string k = sharp::AttrAsStr(mdStrKeys, i);
+    baton->withMetadataStrs.insert(std::make_pair(k, sharp::AttrAsStr(mdStrs, k)));
+  }
   // Format-specific
   baton->jpegQuality = sharp::AttrAsUint32(options, "jpegQuality");
   baton->jpegProgressive = sharp::AttrAsBool(options, "jpegProgressive");

src/pipeline.h

@@ -18,6 +18,7 @@
 #include <memory>
 #include <string>
 #include <vector>
+#include <unordered_map>
 
 #include <napi.h>
 #include <vips/vips8>
@@ -168,6 +169,7 @@ struct PipelineBaton {
   bool withMetadata;
   int withMetadataOrientation;
   std::string withMetadataIcc;
+  std::unordered_map<std::string, std::string> withMetadataStrs;
   std::unique_ptr<double[]> convKernel;
   int convKernelWidth;
   int convKernelHeight;

test/unit/metadata.js

@@ -599,6 +599,30 @@ describe('Image metadata', function () {
       });
   });
 
+  it('Add EXIF metadata to JPEG', async () => {
+    const data = await sharp({
+      create: {
+        width: 8,
+        height: 8,
+        channels: 3,
+        background: 'red'
+      }
+    })
+      .jpeg()
+      .withMetadata({
+        exif: {
+          IFD0: { Software: 'sharp' },
+          IFD2: { ExposureTime: '0.2' }
+        }
+      })
+      .toBuffer();
+
+    const { exif } = await sharp(data).metadata();
+    const parsedExif = exifReader(exif);
+    assert.strictEqual(parsedExif.image.Software, 'sharp');
+    assert.strictEqual(parsedExif.exif.ExposureTime, 0.2);
+  });
+
   it('chromaSubsampling 4:4:4:4 CMYK JPEG', function () {
     return sharp(fixtures.inputJpgWithCmykProfile)
       .metadata()
@@ -717,5 +741,20 @@ describe('Image metadata', function () {
         sharp().withMetadata({ icc: true });
       });
     });
+    it('Non object exif', function () {
+      assert.throws(function () {
+        sharp().withMetadata({ exif: false });
+      });
+    });
+    it('Non string value in object exif', function () {
+      assert.throws(function () {
+        sharp().withMetadata({ exif: { ifd0: false } });
+      });
+    });
+    it('Non string value in nested object exif', function () {
+      assert.throws(function () {
+        sharp().withMetadata({ exif: { ifd0: { fail: false } } });
+      });
+    });
   });
 });