Add option to keep metadata in files processed by gatsby-plugin-sharp

packages/gatsby-plugin-sharp/README.md

@@ -22,7 +22,15 @@ images. By default it uses a quality setting of [50-75].
 
 ```javascript
 // In your gatsby-config.js
-plugins: [`gatsby-plugin-sharp`]
+plugins: [
+  {
+    resolve: `gatsby-plugin-sharp`,
+    options: {
+      useMozJpeg: process.env.GATSBY_JPEG_ENCODER === `MOZJPEG`,
+      stripMetadata: true,
+    },
+  },
+]
 ```
 
 ## Methods
@@ -242,12 +250,21 @@ You can opt-in to use [MozJPEG][16] for jpeg-encoding. MozJPEG provides even
 better image compression than the default encoder used in `gatsby-plugin-sharp`.
 However, when using MozJPEG the build time of your Gatsby project will increase
 significantly.
-To enable MozJPEG set the [environment variable](/docs/environment-variables/#environment-variables):
+To enable MozJPEG, you can set the `useMozJpeg` plugin option to `true` in
+`gatsby-config.js` or set
+the [environment variable](/docs/environment-variables/#environment-variables):
 
 ```shell
 GATSBY_JPEG_ENCODER=MOZJPEG
 ```
 
+### EXIF and ICC metadata
+
+By default, `gatsby-plugin-sharp` strips all EXIF, ICC and other metadata
+present in your source file. If you wish to preserve this metadata, you can
+set the `stripMetadata` plugin option to `false` in
+`gatsby-config.js`.
+
 [1]: https://alistapart.com/article/finessing-fecolormatrix
 [2]: http://blog.72lions.com/blog/2015/7/7/duotone-in-js
 [3]: https://ines.io/blog/dynamic-duotone-svg-jade

packages/gatsby-plugin-sharp/src/gatsby-node.js

@@ -1,7 +1,8 @@
-const { setBoundActionCreators } = require(`./index`)
+const { setBoundActionCreators, setPluginOptions } = require(`./index`)
 
-exports.onPreInit = ({ actions }) => {
+exports.onPreInit = ({ actions }, pluginOptions) => {
   setBoundActionCreators(actions)
+  setPluginOptions(pluginOptions)
 }
 
 // TODO

packages/gatsby-plugin-sharp/src/index.js

@@ -41,6 +41,22 @@ exports.setBoundActionCreators = actions => {
   boundActionCreators = actions
 }
 
+/// Plugin options are loaded onPreInit in gatsby-node
+let pluginOptions = {
+  useMozJpeg: process.env.GATSBY_JPEG_ENCODER === `MOZJPEG`,
+  stripMetadata: true,
+}
+exports.setPluginOptions = options => {
+  // Typechecks
+  if (typeof options.useMozJpeg === `boolean`) {
+    pluginOptions.useMozJpeg = options.useMozJpeg
+  }
+
+  if (typeof options.stripMetadata === `boolean`) {
+    pluginOptions.stripMetadata = options.stripMetadata
+  }
+}
+
 // Promisify the sharp prototype (methods) to promisify the alternative (for
 // raw) callback-accepting toBuffer(...) method
 Promise.promisifyAll(sharp.prototype, { multiArgs: true })
@@ -110,8 +126,6 @@ const healOptions = (args, defaultArgs) => {
   return options
 }
 
-const useMozjpeg = process.env.GATSBY_JPEG_ENCODER === `MOZJPEG`
-
 let totalJobs = 0
 const processFile = (file, jobs, cb, reporter) => {
   // console.log("totalJobs", totalJobs)
@@ -124,7 +138,14 @@ const processFile = (file, jobs, cb, reporter) => {
 
   let pipeline
   try {
-    pipeline = sharp(file).rotate()
+    pipeline = sharp(file)
+
+    // Keep Metadata
+    if (pluginOptions.stripMetadata === false) {
+      pipeline = pipeline.withMetadata()
+    }
+
+    pipeline = pipeline.rotate()
   } catch (err) {
     reportError(`Failed to process image ${file}`, err, reporter)
     jobs.forEach(job => job.outsideReject(err))
@@ -170,7 +191,7 @@ const processFile = (file, jobs, cb, reporter) => {
       })
 
     // jpeg
-    if (!useMozjpeg) {
+    if (!pluginOptions.useMozJpeg) {
       clonedPipeline = clonedPipeline.jpeg({
         quality: args.quality,
         progressive: args.jpegProgressive,
@@ -242,7 +263,7 @@ const processFile = (file, jobs, cb, reporter) => {
         .catch(onFinish)
       // Compress jpeg
     } else if (
-      useMozjpeg &&
+      pluginOptions.useMozJpeg &&
       ((job.file.extension === `jpg` && args.toFormat === ``) ||
         (job.file.extension === `jpeg` && args.toFormat === ``) ||
         args.toFormat === `jpg`)