Support Node.js object URLs as image sources

CHANGELOG.md

@@ -10,6 +10,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 ### Changed
 ### Added
 ### Fixed
+* Load images from Node.js object URLs (#2525)
 
 3.2.3
 ==================

lib/image.js

@@ -13,13 +13,15 @@
 const bindings = require('./bindings')
 const Image = module.exports = bindings.Image
 const util = require('util')
+const { resolveObjectURL } = require('node:buffer')
 
 const { GetSource, SetSource } = bindings
 
 Object.defineProperty(Image.prototype, 'src', {
   /**
    * src setter. Valid values:
    *  * `data:` URI
+   *  * Node.js object URL
    *  * Local file path
    *  * HTTP or HTTPS URL
    *  * Buffer containing image data (i.e. not a `data:` URI stored in a Buffer)
@@ -28,22 +30,34 @@ Object.defineProperty(Image.prototype, 'src', {
    * @api public
    */
   set (val) {
+    const onerror = err => {
+      if (typeof this.onerror === 'function') {
+        this.onerror(err)
+      } else {
+        throw err
+      }
+    }
+
     if (typeof val === 'string') {
       if (/^\s*data:/.test(val)) { // data: URI
         const commaI = val.indexOf(',')
         // 'base64' must come before the comma
         const isBase64 = val.lastIndexOf('base64', commaI) !== -1
         const content = val.slice(commaI + 1)
         setSource(this, Buffer.from(content, isBase64 ? 'base64' : 'utf8'), val)
-      } else if (/^\s*https?:\/\//.test(val)) { // remote URL
-        const onerror = err => {
-          if (typeof this.onerror === 'function') {
-            this.onerror(err)
-          } else {
-            throw err
-          }
+      } else if (/^\s*blob:nodedata:/.test(val)) { // Node.js object URL
+        const blob = resolveObjectURL(val)
+        if (!blob) {
+          onerror(new Error('Invalid object URL'))
+          return
         }
 
+        blob.arrayBuffer()
+          .then(data => {
+            setSource(this, Buffer.from(data), val)
+          })
+          .catch(onerror)
+      } else if (/^\s*https?:\/\//.test(val)) { // remote URL
         fetch(val, {
           method: 'GET',
           headers: { 'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/102.0.0.0 Safari/537.36' }
@@ -64,9 +78,8 @@ Object.defineProperty(Image.prototype, 'src', {
     } else if (Buffer.isBuffer(val)) {
       setSource(this, val)
     } else {
-      const err = new Error("Invalid image source")
-      if (typeof this.onerror === 'function') this.onerror(err)
-      else throw err
+      const err = new Error('Invalid image source')
+      onerror(err)
     }
   },
 

test/image.test.js

@@ -10,6 +10,8 @@ const assertRejects = require('assert-rejects')
 const fs = require('fs')
 const path = require('path')
 const os = require('os')
+const { Blob } = require('node:buffer')
+const { URL } = require('node:url')
 
 const { createCanvas, loadImage, rsvgVersion, Image } = require('../')
 const HAVE_SVG = rsvgVersion !== undefined
@@ -90,6 +92,34 @@ describe('Image', function () {
     })
   })
 
+  it('loads PNG object URL', async function () {
+    const objectURL = URL.createObjectURL(new Blob([
+      fs.readFileSync(pngClock)
+    ], { type: 'image/png' }))
+
+    try {
+      const img = await loadImage(objectURL)
+      assert.strictEqual(img.src, objectURL)
+      assert.strictEqual(img.width, 320)
+      assert.strictEqual(img.height, 320)
+
+      const canvas = createCanvas(img.width, img.height)
+      const ctx = canvas.getContext('2d')
+      assert.doesNotThrow(() => ctx.drawImage(img, 0, 0))
+    } finally {
+      URL.revokeObjectURL(objectURL)
+    }
+  })
+
+  it('rejects revoked object URLs', async function () {
+    const objectURL = URL.createObjectURL(new Blob([
+      fs.readFileSync(pngClock)
+    ], { type: 'image/png' }))
+    URL.revokeObjectURL(objectURL)
+
+    await assert.rejects(loadImage(objectURL), /Invalid object URL/)
+  })
+
   it('detects invalid PNG', function (done) {
     if (process.platform === 'win32') this.skip() // TODO
     const img = new Image()