Expose width and height in the file metadata

Fixes #149

src/model/metadata.js

@@ -30,6 +30,9 @@ class Metadata {
     this.animated = animated(exiftool)
     this.rating = rating(exiftool)
     this.favourite = favourite(picasa)
+    const size = dimensions(exiftool)
+    this.width = size.width
+    this.height = size.height
     this.exif = opts ? (opts.embedExif ? exiftool.EXIF : undefined) : undefined
     // metadata could also include fields like
     //  - lat = 51.5
@@ -127,4 +130,21 @@ function makeArray (value) {
   return Array.isArray(value) ? value : [value]
 }
 
+function dimensions (exif) {
+  // Use the Composite field to avoid having to check all possible tag groups (EXIF, QuickTime, ASF...)
+  if (!exif.Composite) {
+    return {
+      width: null,
+      height: null
+    }
+  } else {
+    const size = exif.Composite.ImageSize
+    const x = size.indexOf('x')
+    return {
+      width: parseInt(size.substr(0, x), 10),
+      height: parseInt(size.substr(x + 1), 10)
+    }
+  }
+}
+
 module.exports = Metadata

test/model/metadata.spec.js

@@ -218,4 +218,21 @@ describe('Metadata', function () {
       should(meta.favourite).eql(true)
     })
   })
+
+  describe('size', function () {
+    it('can get an image width and height', function () {
+      const exiftool = fixtures.exiftool()
+      exiftool.Composite = { ImageSize: '800x600' }
+      const meta = new Metadata(exiftool)
+      should(meta.width).eql(800)
+      should(meta.height).eql(600)
+    })
+
+    it('defaults to null otherwise', function () {
+      const exiftool = fixtures.exiftool()
+      const meta = new Metadata(exiftool)
+      should(meta.width).eql(null)
+      should(meta.width).eql(null)
+    })
+  })
 })