Replaced gm by cross-spawn

.gitignore

@@ -58,5 +58,7 @@ typings/
 .env
 
 .idea/
-test/*.jpg
+
+#test results
+test/results/*.jpg
 .DS_Store

README.md

@@ -16,7 +16,7 @@
 
 ## Getting started
 
-This module works with gm, so you have to install imagemagick and ghostscript on your pc.
+This module works with cross-spawn to delegate all the work to imagemagick and ghostscript, so you have to install these programs on your pc.
 
 On Mac OS X:
 

lib/generatePreview.js

@@ -1,5 +1,5 @@
+const spawn = require("cross-spawn")
 const promiseWaterfall = require("promise.waterfall")
-const gm = require("gm").subClass({ imageMagick: true })
 const compress = require("./operations/compress")
 const crop = require("./operations/crop")
 const resize = require("./operations/resize")
@@ -13,15 +13,31 @@ const allTasks = {
 if (!Object.entries)
   Object.entries = obj => Object.keys(obj).map(prop => [prop, obj[prop]])
 
-module.exports = (body, options = {}) => {
-  const flattened = gm(body, "test.pdf[0]").flatten()
-
+function toBuffer(body) {
+  if (Buffer.isBuffer(body)) return Promise.resolve(body)
+  return new Promise((resolve, reject) => {
+    const chunks = []
+    body.on("data", chunk => chunks.push(chunk))
+    body.on("end", () => resolve(Buffer.concat(chunks)))
+    body.on("error", reject)
+  })
+}
 
-  const tasks = Object.entries(options).reduce((acc, [operation, params]) => {
-    acc.push(data => allTasks[operation](data, params))
-    return acc
-  }, [() => Promise.resolve(flattened)])
+module.exports = (body, options = {}) => {
+  return toBuffer(body).then(buffer => {
+    const tasks = Object.entries(options).reduce((acc, [operation, params]) => {
+      acc.push(state => allTasks[operation](state, params))
+      return acc
+    }, [() => Promise.resolve({ args: [], buffer })])
 
-  return promiseWaterfall(tasks)
-    .then(result => result.stream("jpg"))
+    return promiseWaterfall(tasks).then(({ args, buffer }) => {
+      return new Promise((resolve, reject) => {
+        const proc = spawn("convert", ["pdf:-[0]", "-flatten", ...args, "jpg:-"])
+        proc.on("error", reject)
+        proc.stdin.on("error", reject)
+        proc.stdin.end(buffer)
+        resolve(proc.stdout)
+      })
+    })
+  })
 }

lib/operations/compress.js

@@ -1,8 +1,5 @@
-module.exports = (input, params) =>
-  new Promise (resolve => {
+module.exports = ({ args, buffer }, params) =>
+  new Promise(resolve => {
     const { type, quality } = Object.assign({ type: "JPEG", quality: 70 }, params)
-    resolve(input
-      .compress(type)
-      .quality(quality)
-    )
+    resolve({ args: [...args, "-compress", type, "-quality", String(quality)], buffer })
   })

lib/operations/crop.js

@@ -1,13 +1,30 @@
-module.exports = (input, { width: maxWidth, height: maxHeight, x, y, ratio }) =>
+const spawn = require("cross-spawn")
+
+function getImageSize(buffer) {
+  return new Promise((resolve, reject) => {
+    const proc = spawn("convert", ["pdf:-[0]", "-flatten", "-format", "%wx%h", "info:"])
+    let output = ""
+    proc.stdout.on("data", data => { output += data.toString() })
+    proc.stderr.on("data", () => {})
+    proc.on("close", code => {
+      if (code !== 0) return reject(new Error(`convert exited with code ${code}`))
+      const match = output.match(/(\d+)x(\d+)/)
+      if (!match) return reject(new Error("Could not parse image size"))
+      resolve({ width: parseInt(match[1]), height: parseInt(match[2]) })
+    })
+    proc.on("error", reject)
+    proc.stdin.end(buffer)
+  })
+}
+
+module.exports = ({ args, buffer }, { width: maxWidth, height: maxHeight, x, y, ratio }) =>
   new Promise((resolve, reject) => {
     if (ratio) {
-      input
-        .size({ bufferStream: true }, (err, size) => {
-          if (err) return reject(err)
-          const { width, height } = size
-          const ratio = height / width
+      getImageSize(buffer)
+        .then(({ width, height }) => {
+          const imgRatio = height / width
           const finalRatio = maxHeight / maxWidth
-          const [finalWidth, finalHeight] = ratio > finalRatio ?
+          const [finalWidth, finalHeight] = imgRatio > finalRatio ?
             [width, width * finalRatio] :
             [height / finalRatio, height]
           const [cropX, cropY] = [
@@ -47,9 +64,13 @@ module.exports = (input, { width: maxWidth, height: maxHeight, x, y, ratio }) =>
             return (originalDimension - finalDimension) / 2
           })
 
-          resolve(input.crop(finalWidth, finalHeight, cropX, cropY))
+          resolve({
+            args: [...args, "-crop", `${Math.round(finalWidth)}x${Math.round(finalHeight)}+${Math.round(cropX)}+${Math.round(cropY)}`],
+            buffer
+          })
         })
+        .catch(reject)
     }
     else
-      resolve(input.crop(maxWidth, maxHeight, x, y))
+      resolve({ args: [...args, "-crop", `${maxWidth}x${maxHeight}+${x || 0}+${y || 0}`], buffer })
   })

lib/operations/resize.js

@@ -1,5 +1,5 @@
-module.exports = (input, params) =>
+module.exports = ({ args, buffer }, params) =>
   new Promise(resolve => {
     const { width, height } = Object.assign({ width: 200, height: 200 }, params)
-    resolve(input.resize(width, height))
+    resolve({ args: [...args, "-resize", `${width}x${height}`], buffer })
   })