[web-src] Add option to stream audio from player web interface

The audio implementation is based on
https://github.com/rainner/soma-fm-player and makes use of the  HTML5
Web Audio Context API.

web-src/src/audio.js

@@ -0,0 +1,51 @@
+/**
+ * Audio handler object
+ * Taken from https://github.com/rainner/soma-fm-player (released under MIT licence)
+ */
+export default {
+  _audio: new Audio(),
+  _context: new AudioContext(),
+  _source: null,
+  _gain: null,
+  _analyser: null,
+
+  // setup audio routing
+  setupAudio () {
+    this._source = this._context.createMediaElementSource(this._audio)
+    this._analyser = this._context.createAnalyser()
+    this._gain = this._context.createGain()
+
+    this._source.connect(this._gain)
+    this._source.connect(this._analyser)
+    this._gain.connect(this._context.destination)
+
+    this._audio.addEventListener('canplaythrough', e => {
+      this._audio.play()
+    })
+    return this._audio
+  },
+
+  // set audio volume
+  setVolume (volume) {
+    if (!this._gain) return
+    volume = parseFloat(volume) || 0.0
+    volume = (volume < 0) ? 0 : volume
+    volume = (volume > 1) ? 1 : volume
+    this._gain.gain.value = volume
+  },
+
+  // play audio source url
+  playSource (source) {
+    this.stopAudio()
+    this._audio.src = String(source || '') + '?x=' + Date.now()
+    this._audio.crossOrigin = 'anonymous'
+    this._audio.load()
+  },
+
+  // stop playing audio
+  stopAudio () {
+    try { this._audio.pause() } catch (e) {}
+    try { this._audio.stop() } catch (e) {}
+    try { this._audio.close() } catch (e) {}
+  }
+}

web-src/src/components/NavBarItemOutput.vue

@@ -3,7 +3,7 @@
     <div class="level is-mobile">
       <div class="level-left fd-expanded">
         <div class="level-item" style="flex-grow: 0;">
-          <span class="icon fd-has-action" :class="{ 'has-text-grey-light': !output.selected }" v-on:click="set_enabled"><i class="mdi mdi-18px" v-bind:class="type_class"></i></span>
+          <a class="button is-white is-small"><span class="icon fd-has-action" :class="{ 'has-text-grey-light': !output.selected }" v-on:click="set_enabled"><i class="mdi mdi-18px" v-bind:class="type_class"></i></span></a>
         </div>
         <div class="level-item fd-expanded">
           <div class="fd-expanded">

web-src/src/components/NavbarTop.vue

@@ -60,6 +60,31 @@
             <hr class="navbar-divider">
             <nav-bar-item-output v-for="output in outputs" :key="output.id" :output="output"></nav-bar-item-output>
 
+            <hr class="navbar-divider">
+            <div class="navbar-item">
+              <div class="level is-mobile">
+                <div class="level-left fd-expanded">
+                  <div class="level-item" style="flex-grow: 0;">
+                    <a class="button is-white is-small" :class="{ 'is-loading': loading }"><span class="icon fd-has-action" :class="{ 'has-text-grey-light': !playing && !loading, 'is-loading': loading }" @click="togglePlay"><i class="mdi mdi-18px mdi-radio-tower"></i></span></a>
+                  </div>
+                  <div class="level-item fd-expanded">
+                    <div class="fd-expanded">
+                      <p class="heading" :class="{ 'has-text-grey-light': !playing }">HTTP stream</p>
+                      <range-slider
+                        class="slider fd-has-action"
+                        min="0"
+                        max="100"
+                        step="1"
+                        :disabled="!playing"
+                        :value="stream_volume"
+                        @change="set_stream_volume">
+                      </range-slider>
+                    </div>
+                  </div>
+                </div>
+              </div>
+            </div>
+
             <hr class="navbar-divider">
             <div class="navbar-item">
               <div class="level is-mobile">
@@ -104,6 +129,7 @@
 
 <script>
 import webapi from '@/webapi'
+import _audio from '@/audio'
 import NavBarItemOutput from './NavBarItemOutput'
 import PlayerButtonPlayPause from './PlayerButtonPlayPause'
 import PlayerButtonNext from './PlayerButtonNext'
@@ -120,7 +146,11 @@ export default {
 
   data () {
     return {
-      search_query: ''
+      search_query: '',
+
+      playing: false,
+      loading: false,
+      stream_volume: 10
     }
   },
 
@@ -166,7 +196,72 @@ export default {
     open_about: function () {
       this.$store.commit(types.SHOW_BURGER_MENU, false)
       this.$router.push({ path: '/about' })
+    },
+
+    setupAudio: function () {
+      const a = _audio.setupAudio()
+
+      a.addEventListener('waiting', e => {
+        this.playing = false
+        this.loading = true
+      })
+      a.addEventListener('playing', e => {
+        this.playing = true
+        this.loading = false
+      })
+      a.addEventListener('ended', e => {
+        this.playing = false
+        this.loading = false
+      })
+      a.addEventListener('error', e => {
+        this.closeAudio()
+        this.$store.dispatch('add_notification', { text: 'HTTP stream error: failed to load stream or stopped loading due to network problem', type: 'danger' })
+        this.playing = false
+        this.loading = false
+      })
+    },
+
+    // close active audio
+    closeAudio: function () {
+      _audio.stopAudio()
+      this.playing = false
+    },
+
+    playChannel: function () {
+      if (this.playing) {
+        return
+      }
+
+      const channel = '/stream.mp3'
+      this.loading = true
+      _audio.playSource(channel)
+      _audio.setVolume(this.stream_volume / 100)
+    },
+
+    togglePlay: function () {
+      if (this.loading) {
+        return
+      }
+      if (this.playing) {
+        return this.closeAudio()
+      }
+      return this.playChannel()
+    },
+
+    set_stream_volume: function (newVolume) {
+      this.stream_volume = newVolume
+      _audio.setVolume(this.stream_volume / 100)
     }
+  },
+
+  // on app mounted
+  mounted () {
+    this.setupAudio()
+  },
+
+  // on app destroyed
+  destroyed () {
+    this.closeAudio()
   }
 }
 </script>

web-src/vue.config.js

@@ -24,10 +24,13 @@ module.exports = {
     // localhost:3689
     proxy: {
       '/api': {
-        target: 'http://localhost:3689',
+        target: 'http://localhost:3689'
       },
       '/artwork': {
-        target: 'http://localhost:3689',
+        target: 'http://localhost:3689'
+      },
+      '/stream.mp3': {
+        target: 'http://localhost:3689'
       }
     }
   }