Allow withMetadata to set density #967

docs/api-output.md

@@ -120,6 +120,7 @@ sRGB colour space and strip all metadata, including the removal of any ICC profi
     -   `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 `{}`)
+    -   `options.density` **[number][9]?** Number of pixels per inch (DPI).
 
 ### Examples
 
@@ -132,7 +133,7 @@ sharp('input.jpg')
 
 ```javascript
 // Set "IFD0-Copyright" in output EXIF metadata
-await sharp(input)
+const data = await sharp(input)
   .withMetadata({
     exif: {
       IFD0: {
@@ -141,6 +142,12 @@ await sharp(input)
     }
   })
   .toBuffer();
+
+ * @example
+// Set output metadata to 96 DPI
+const data = await sharp(input)
+  .withMetadata({ density: 96 })
+  .toBuffer();
 ```
 
 -   Throws **[Error][4]** Invalid parameters

docs/changelog.md

@@ -6,6 +6,9 @@ Requires libvips v8.10.6
 
 ### v0.28.2 - TBD
 
+* Allow `withMetadata` to set `density`.
+  [#967](https://github.com/lovell/sharp/issues/967)
+
 * Skip shrink-on-load where one dimension <4px.
   [#2653](https://github.com/lovell/sharp/issues/2653)
 

lib/constructor.js

@@ -231,6 +231,7 @@ const Sharp = function (input, options) {
     streamOut: false,
     withMetadata: false,
     withMetadataOrientation: -1,
+    withMetadataDensity: 0,
     withMetadataIcc: '',
     withMetadataStrs: {},
     resolveWithObject: false,

lib/output.js

@@ -150,7 +150,7 @@ function toBuffer (options, callback) {
  *
  * @example
  * // Set "IFD0-Copyright" in output EXIF metadata
- * await sharp(input)
+ * const data = await sharp(input)
  *   .withMetadata({
  *     exif: {
  *       IFD0: {
@@ -160,10 +160,17 @@ function toBuffer (options, callback) {
  *   })
  *   .toBuffer();
  *
+ *  * @example
+ * // Set output metadata to 96 DPI
+ * const data = await sharp(input)
+ *   .withMetadata({ density: 96 })
+ *   .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.
+ * @param {number} [options.density] Number of pixels per inch (DPI).
  * @returns {Sharp}
  * @throws {Error} Invalid parameters
  */
@@ -177,6 +184,13 @@ function withMetadata (options) {
         throw is.invalidParameterError('orientation', 'integer between 1 and 8', options.orientation);
       }
     }
+    if (is.defined(options.density)) {
+      if (is.number(options.density) && options.density > 0) {
+        this.options.withMetadataDensity = options.density;
+      } else {
+        throw is.invalidParameterError('density', 'positive number', options.density);
+      }
+    }
     if (is.defined(options.icc)) {
       if (is.string(options.icc)) {
         this.options.withMetadataIcc = options.icc;

package.json

@@ -130,7 +130,7 @@
     "async": "^3.2.0",
     "cc": "^3.0.1",
     "decompress-zip": "^0.3.3",
-    "documentation": "^13.2.0",
+    "documentation": "^13.2.1",
     "exif-reader": "^1.0.3",
     "icc": "^2.0.0",
     "license-checker": "^25.0.1",

src/common.cc

@@ -520,9 +520,8 @@ namespace sharp {
   VImage SetDensity(VImage image, const double density) {
     const double pixelsPerMm = density / 25.4;
     VImage copy = image.copy();
-    copy.set("Xres", pixelsPerMm);
-    copy.set("Yres", pixelsPerMm);
-    copy.set(VIPS_META_RESOLUTION_UNIT, "in");
+    copy.get_image()->Xres = pixelsPerMm;
+    copy.get_image()->Yres = pixelsPerMm;
     return copy;
   }
 

src/pipeline.cc

@@ -722,6 +722,10 @@ class PipelineWorker : public Napi::AsyncWorker {
       if (baton->withMetadata && baton->withMetadataOrientation != -1) {
         image = sharp::SetExifOrientation(image, baton->withMetadataOrientation);
       }
+      // Override pixel density
+      if (baton->withMetadataDensity > 0) {
+        image = sharp::SetDensity(image, baton->withMetadataDensity);
+      }
       // Metadata key/value pairs, e.g. EXIF
       if (!baton->withMetadataStrs.empty()) {
         image = image.copy();
@@ -1385,6 +1389,7 @@ Napi::Value pipeline(const Napi::CallbackInfo& info) {
   baton->fileOut = sharp::AttrAsStr(options, "fileOut");
   baton->withMetadata = sharp::AttrAsBool(options, "withMetadata");
   baton->withMetadataOrientation = sharp::AttrAsUint32(options, "withMetadataOrientation");
+  baton->withMetadataDensity = sharp::AttrAsDouble(options, "withMetadataDensity");
   baton->withMetadataIcc = sharp::AttrAsStr(options, "withMetadataIcc");
   Napi::Object mdStrs = options.Get("withMetadataStrs").As<Napi::Object>();
   Napi::Array mdStrKeys = mdStrs.GetPropertyNames();

src/pipeline.h

@@ -168,6 +168,7 @@ struct PipelineBaton {
   std::string err;
   bool withMetadata;
   int withMetadataOrientation;
+  double withMetadataDensity;
   std::string withMetadataIcc;
   std::unordered_map<std::string, std::string> withMetadataStrs;
   std::unique_ptr<double[]> convKernel;
@@ -290,6 +291,7 @@ struct PipelineBaton {
     heifLossless(false),
     withMetadata(false),
     withMetadataOrientation(-1),
+    withMetadataDensity(0.0),
     convKernelWidth(0),
     convKernelHeight(0),
     convKernelScale(0.0),

test/unit/metadata.js

@@ -623,6 +623,44 @@ describe('Image metadata', function () {
     assert.strictEqual(parsedExif.exif.ExposureTime, 0.2);
   });
 
+  it('Set density of JPEG', async () => {
+    const data = await sharp({
+      create: {
+        width: 8,
+        height: 8,
+        channels: 3,
+        background: 'red'
+      }
+    })
+      .withMetadata({
+        density: 300
+      })
+      .jpeg()
+      .toBuffer();
+
+    const { density } = await sharp(data).metadata();
+    assert.strictEqual(density, 300);
+  });
+
+  it('Set density of PNG', async () => {
+    const data = await sharp({
+      create: {
+        width: 8,
+        height: 8,
+        channels: 3,
+        background: 'red'
+      }
+    })
+      .withMetadata({
+        density: 96
+      })
+      .png()
+      .toBuffer();
+
+    const { density } = await sharp(data).metadata();
+    assert.strictEqual(density, 96);
+  });
+
   it('chromaSubsampling 4:4:4:4 CMYK JPEG', function () {
     return sharp(fixtures.inputJpgWithCmykProfile)
       .metadata()
@@ -736,6 +774,16 @@ describe('Image metadata', function () {
         sharp().withMetadata({ orientation: 9 });
       });
     });
+    it('Non-numeric density', function () {
+      assert.throws(function () {
+        sharp().withMetadata({ density: '1' });
+      });
+    });
+    it('Negative density', function () {
+      assert.throws(function () {
+        sharp().withMetadata({ density: -1 });
+      });
+    });
     it('Non string icc', function () {
       assert.throws(function () {
         sharp().withMetadata({ icc: true });