Fixes #166 - Add delay to png capture (#167)

* Add delay before invoking capturePage, fixes #166

* bump version #166

* set window on the job as soon as it is created so the client can access it when the created event is emitted #166

lib/exportJob.js

@@ -29,6 +29,8 @@ const HUNG_WINDOW_THRESHOLD = process.env.ELECTRONPDF_WINDOW_LIFE_THRESHOLD || 1
 const MICRONS_INCH_RATIO = 25400
 /** When a ready event option is set, this is the default timeout.  It is overridden by the wait option */
 const MAX_READY_EVENT_WAIT = 10000
+/** Amount of millis to wait before invoking WebContents.capturePage for PNG exports */
+const PNG_CAPTURE_DELAY = process.env.ELECTRONPDF_PNG_CAPTURE_DELAY || 100
 /** The event name for which Electron IPC is done over */
 const IPC_MAIN_CHANNEL_RENDER = 'READY_TO_RENDER'
 /** Prepended to events emitted during rendering */
@@ -139,9 +141,8 @@ class ExportJob extends EventEmitter {
    */
   render () {
     this.emit(`${RENDER_EVENT_PREFIX}start`)
-
-    const win = this._launchBrowserWindow()
-    this.window = win
+    this._launchBrowserWindow()
+    const win = this.window
     registerOpenWindow(this)
 
     // TODO: Check for different domains, this is meant to support only a single origin
@@ -340,6 +341,7 @@ class ExportJob extends EventEmitter {
     const browserConfig = this._getBrowserConfiguration(this.args)
     this.emit('window.open.start', {})
     let win = new electron.BrowserWindow(browserConfig)
+    this.window = win
     this.emit('window.open.end', {
       width: browserConfig.width,
       height: browserConfig.height
@@ -348,8 +350,6 @@ class ExportJob extends EventEmitter {
     win.on('closed', function () {
       win = null
     })
-
-    return win
   }
 
   /**
@@ -643,18 +643,22 @@ class ExportJob extends EventEmitter {
   }
 
   _captureImage (window, outputFile, done) {
-    window.webContents.capturePage(image => {
-      // http://electron.atom.io/docs/api/native-image/#imagetopng
-      const pngBuffer = image.toPNG()
-      if (this.options.inMemory) {
-        this._emitResourceEvents(undefined, pngBuffer, done)
-      } else {
-        const target = path.resolve(outputFile)
-        fs.writeFile(target, pngBuffer, function (err) {
-          this._emitResourceEvents(err, target, done)
-        }.bind(this))
-      }
-    })
+    // We need a short timeout here or the image may not be captured fully
+    // https://github.com/electron/electron/issues/6622
+    setTimeout(() => {
+      window.webContents.capturePage(image => {
+        // http://electron.atom.io/docs/api/native-image/#imagetopng
+        const pngBuffer = image.toPNG()
+        if (this.options.inMemory) {
+          this._emitResourceEvents(undefined, pngBuffer, done)
+        } else {
+          const target = path.resolve(outputFile)
+          fs.writeFile(target, pngBuffer, function (err) {
+            this._emitResourceEvents(err, target, done)
+          }.bind(this))
+        }
+      })
+    }, PNG_CAPTURE_DELAY)
   }
 
   _capturePDF (args, window, done, outputFile) {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "electron-pdf",
-  "version": "1.1.5",
+  "version": "1.1.6",
   "description": "A command line tool to generate PDF from URL, HTML or Markdown files",
   "main": "lib/index.js",
   "scripts": {