From 4654ee13786532e35125f61d2d5025c4c298113a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ren=C3=A9e=20Kooi?= <renee@kooi.me>
Date: Mon, 13 Nov 2017 15:20:00 +0100
Subject: [PATCH] webcam,dashboard: Add `isSupported()` API for providers

Providers can signal whether they support the current environment using
an optional `isSupported()` method. Providers that always work (eg.
Google Drive) do not need to specify this method.

The check for the Webcam currently only checks if the `getUserMedia`
method exists at all. We could maybe do some more checks, like, if the
mode is `video-only` or `video-audio` but MediaRecorder is not
supported.
---
 src/plugins/Dashboard/index.js | 11 ++++++++++-
 src/plugins/Webcam/index.js    | 33 +++++++++++++++++++++------------
 2 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/plugins/Dashboard/index.js b/src/plugins/Dashboard/index.js
index bbd94c524..672eceb70 100644
--- a/src/plugins/Dashboard/index.js
+++ b/src/plugins/Dashboard/index.js
@@ -311,8 +311,17 @@ module.exports = class DashboardUI extends Plugin {
       })
     }
 
+    const isSupported = (target) => {
+      const plugin = this.core.getPlugin(target.id)
+      // If the plugin does not provide a `supported` check, assume the plugin works everywhere.
+      if (typeof plugin.isSupported !== 'function') {
+        return true
+      }
+      return plugin.isSupported()
+    }
+
     const acquirers = pluginState.targets
-      .filter(target => target.type === 'acquirer')
+      .filter(target => target.type === 'acquirer' && isSupported(target))
       .map(attachRenderFunctionToTarget)
 
     const progressindicators = pluginState.targets
diff --git a/src/plugins/Webcam/index.js b/src/plugins/Webcam/index.js
index 5a540db08..9f9f7f5e9 100644
--- a/src/plugins/Webcam/index.js
+++ b/src/plugins/Webcam/index.js
@@ -16,7 +16,7 @@ function getMediaDevices () {
     return navigator.mediaDevices
   }
 
-  let getUserMedia = navigator.mozGetUserMedia || navigator.webkitGetUserMedia
+  const getUserMedia = navigator.mozGetUserMedia || navigator.webkitGetUserMedia
   if (!getUserMedia) {
     return null
   }
@@ -94,25 +94,34 @@ module.exports = class Webcam extends Plugin {
     }
   }
 
-  start () {
-    if (!this.mediaDevices) {
-      return Promise.reject(new Error('Webcam access not supported'))
-    }
-
-    this.webcamActive = true
+  isSupported () {
+    return !!this.mediaDevices
+  }
 
+  getConstraints () {
     const acceptsAudio = this.opts.modes.indexOf('video-audio') !== -1 ||
       this.opts.modes.indexOf('audio-only') !== -1
     const acceptsVideo = this.opts.modes.indexOf('video-audio') !== -1 ||
       this.opts.modes.indexOf('video-only') !== -1 ||
       this.opts.modes.indexOf('picture') !== -1
 
+    return {
+      audio: acceptsAudio,
+      video: acceptsVideo
+    }
+  }
+
+  start () {
+    if (!this.isSupported()) {
+      return Promise.reject(new Error('Webcam access not supported'))
+    }
+
+    this.webcamActive = true
+
+    const constraints = this.getConstraints()
+
     // ask user for access to their camera
-    return this.mediaDevices
-      .getUserMedia({
-        audio: acceptsAudio,
-        video: acceptsVideo
-      })
+    return this.mediaDevices.getUserMedia(constraints)
       .then((stream) => {
         this.stream = stream
         this.streamSrc = URL.createObjectURL(this.stream)