Buffered segments are now shown on the progress bar

multiplayer.js

@@ -646,6 +646,7 @@
             this.setActivePlaylistItem();
             this.autoBlurControls();
             this.initProgressTracking();
+            this.initBuffer();
         }
 
         /*
@@ -702,6 +703,48 @@
             );
         }
 
+        /*
+         * Initialize display of buffered segments in the progress bar.
+         */
+        initBuffer() {
+            const color = window.getComputedStyle(this._root)
+                  .getPropertyValue('--foreground');
+            const buffer = this._progressBuffer;
+            const control = this._controlSource;
+            var needsUpdate = false;
+
+            function paintBuffer() {
+                if(needsUpdate) {
+                    buffer.width = buffer.clientWidth;
+                    buffer.height = buffer.clientHeight;
+
+                    const context = buffer.getContext('2d');
+                    context.clearRect(0, 0, buffer.width, buffer.height);
+                    context.fillStyle = color;
+                    context.strokeStyle = color;
+
+                    const inc = buffer.width / control.duration;
+                    const buffered = control.buffered;
+                    for(let i = 0; i < buffered.length; i++) {
+                        const start = buffered.start(i) * inc;
+                        const end = buffered.end(i) * inc;
+                        const width = end - start;
+                        context.fillRect(start, 0, width, buffer.height);
+                    }
+                    needsUpdate = false;
+                }
+                requestAnimationFrame(paintBuffer);
+            }
+
+            function flagUpdate(event) {
+                needsUpdate = true;
+            }
+
+            control.addEventListener('progress', flagUpdate);
+            window.addEventListener('resize', flagUpdate);
+            window.requestAnimationFrame(paintBuffer);
+        }
+
         /*
          * Update the playlist to reflect which item is playing
          *