feat: add option to configure default image quality

Fixes #4873

packages/gatsby-transformer-sharp/README.md

@@ -1,7 +1,7 @@
 # gatsby-transformer-sharp
 
 Creates `ImageSharp` nodes from image types that are supported by the
-[Sharp](https:/lovell/sharp) image processing library and provides
+[Sharp][sharp] image processing library and provides
 fields in their GraphQL types for processing your images in a variety of ways
 including resizing, cropping, and creating responsive images.
 
@@ -21,6 +21,25 @@ module.exports = {
 }
 ```
 
+### Configure default quality
+
+By default, all image operations presume a default quality threshold passed to [sharp][sharp] (currently configured to `50`). To set a default quality for all image operations, do so with a configurable threshold passed to the plugin like so:
+
+```javascript
+// In your gatsby-config.js
+module.exports = {
+ plugins: [
+ `gatsby-plugin-sharp`,
+ {
+ resolve: `gatsby-transformer-sharp`,
+ options: {
+ defaultQuality: 60 // 60% of the time it works every time
+ }
+ }
+ ]
+}
+```
+
 ## Parsing algorithm
 
 It recognizes files with the following extensions as images.
@@ -33,3 +52,5 @@ It recognizes files with the following extensions as images.
 - tiff
 
 Each image file is parsed into a node of type `ImageSharp`.
+
+[sharp]: (https:/lovell/sharp)

packages/gatsby-transformer-sharp/src/__tests__/extend-node-type.js

@@ -0,0 +1,53 @@
+const extendNodeType = require(`../extend-node-type`)
+const { __DEFAULT_QUALITY__ } = extendNodeType
+
+const getOptions = (options = {}) => {return {
+ type: {
+ name: `ImageSharp`,
+ },
+ pathPrefix: `/`,
+ getNodeAndSavePathDependency: jest.fn(),
+ reporter: jest.fn(),
+ ...options,
+}}
+
+describe(`basic functionality`, () => {
+ it(`returns empty object if not ImageSharp type`, () => {
+ const options = getOptions({ type: `MarkdownRemark` })
+
+ expect(extendNodeType(options)).toEqual({})
+ })
+
+ it(`returns expected image operations`, () => {
+ const expected = [`fixed`, `resolutions`, `fluid`, `sizes`, `original`, `resize`]
+ .reduce((merged, key) => {
+ merged[key] = expect.any(Object)
+ return merged
+ }, {})
+
+ expect(extendNodeType(getOptions())).toEqual(expected)
+ })
+})
+
+describe(`quality`, () => {
+ const options = getOptions()
+
+ it(`uses fallback quality if not passed`, () => {
+ const node = extendNodeType(options);
+
+ [node.fixed, node.fluid]
+ .forEach(type => {
+ expect(type.args.quality.defaultValue).toBe(__DEFAULT_QUALITY__)
+ })
+ })
+
+ it(`allows for configuration of quality`, () => {
+ const defaultQuality = 100
+ const node = extendNodeType(options, { defaultQuality });
+
+ [node.fixed, node.fluid]
+ .forEach(type => {
+ expect(type.args.quality.defaultValue).toBe(defaultQuality)
+ })
+ })
+})

packages/gatsby-transformer-sharp/src/extend-node-type.js

@@ -27,6 +27,8 @@ const {
  PotraceType,
 } = require(`./types`)
 
+const DEFAULT_QUALITY = 50
+
 function toArray(buf) {
  var arr = new Array(buf.length)
 
@@ -50,6 +52,7 @@ const fixedNodeType = ({
  getNodeAndSavePathDependency,
  reporter,
  name,
+ defaultQuality,
 }) => {
  return {
  type: new GraphQLObjectType({
@@ -128,7 +131,7 @@ const fixedNodeType = ({
  },
  quality: {
  type: GraphQLInt,
- defaultValue: 50,
+ defaultValue: defaultQuality,
  },
  toFormat: {
  type: ImageFormatType,
@@ -169,6 +172,7 @@ const fluidNodeType = ({
  getNodeAndSavePathDependency,
  reporter,
  name,
+ defaultQuality,
 }) => {
  return {
  type: new GraphQLObjectType({
@@ -245,7 +249,7 @@ const fluidNodeType = ({
  },
  quality: {
  type: GraphQLInt,
- defaultValue: 50,
+ defaultValue: defaultQuality,
  },
  toFormat: {
  type: ImageFormatType,
@@ -285,7 +289,7 @@ module.exports = ({
  pathPrefix,
  getNodeAndSavePathDependency,
  reporter,
-}) => {
+}, { defaultQuality = DEFAULT_QUALITY } = {}) => {
  if (type.name !== `ImageSharp`) {
  return {}
  }
@@ -295,6 +299,7 @@ module.exports = ({
  pathPrefix,
  getNodeAndSavePathDependency,
  reporter,
+ defaultQuality,
  }
 
  // TODO: Remove resolutionsNode and sizesNode for Gatsby v3
@@ -451,3 +456,5 @@ module.exports = ({
  },
  }
 }
+
+module.exports.__DEFAULT_QUALITY__ = 50