Merge pull request #1503 from Wazzledi/master

QLC+ 5: Add linear regression to BPM tapping

qmlui/js/TimeUtils.js

@@ -320,3 +320,42 @@ function timeToBeatSize(time, bpmNumber, beatsDivision, tickSize)
     // tickSize : barDuration = x : time
     return (tickSize * time) / barDuration;
 }
+
+
+/**
+ * Return the average time between two taps given by a list of tap times.
+ * It caculates the linear regression of the recorded tap times. The slope of the resulting 
+ * linear function represents the average time between two taps.
+ */
+function calculateBPMByTapIntervals(tapHistory)
+{
+    var tapHistorySorted = []
+
+    //reduce size to only 16 taps
+    while (tapHistory.length > 16) tapHistory.splice(0,1)
+
+    //copy tap history to sort it
+    tapHistorySorted = tapHistory.slice()
+    tapHistorySorted.sort()
+
+    // Find the median time between taps, assume that the tempo is +-40% of this
+    var tapHistoryMedian = tapHistorySorted[Math.floor(tapHistorySorted.length/2)]
+
+    //init needed variables
+    var n = 1, tapx = 0, tapy = 0, sum_x = 0, sum_y = 0, sum_xx = 0, sum_xy = 0
+
+    for (var i = 0; i < tapHistory.length; i++)
+    {
+        var intervalMs = tapHistory[i]
+        n++
+        // Divide by tapHistoryMedian to determine if a tap was skipped during input
+        tapx += Math.floor((tapHistoryMedian/2 + intervalMs) / tapHistoryMedian)
+        tapy += intervalMs
+        sum_x += tapx
+        sum_y += tapy
+        sum_xx += tapx * tapx
+        sum_xy += tapx * tapy                 
+    }
+
+    return (n * sum_xy - sum_x * sum_y) / (n * sum_xx - sum_x * sum_x)
+}

qmlui/qml/KeyPad.qml

@@ -20,6 +20,8 @@
 import QtQuick 2.0
 import QtQuick.Layouts 1.1
 
+import "TimeUtils.js" as TimeUtils
+
 import "."
 
 Rectangle
@@ -32,10 +34,16 @@ Rectangle
 
     property bool showDMXcontrol: true
     property bool showTapButton: false
-    property double tapTimeValue: 0
+
     property alias commandString: commandBox.text
     property real itemHeight: Math.max(UISettings.iconSizeDefault, keyPadRoot.height / keyPadGrid.rows) - 3
 
+    //needed for bpm tapping
+    property double tapTimeValue: 0
+    property int tapCount: 0
+    property double lastTap: 0
+    property var tapHistory: []
+
     onVisibleChanged: if (visible) commandBox.selectAndFocus()
 
     signal executeCommand(string cmd)
@@ -95,18 +103,31 @@ Rectangle
                 {
                     tapTimer.stop()
                     tapButton.border.color = UISettings.bgMedium
-                    tapTimeValue = 0
+                    lastTap = 0
+                    tapHistory = []
                 }
                 else
                 {
                     var currTime = new Date().getTime()
-                    if (tapTimeValue != 0)
+
+                    if (lastTap != 0 && currTime - lastTap < 1500)
                     {
-                        keyPadRoot.tapTimeChanged(currTime - tapTimeValue)
-                        tapTimer.interval = currTime - tapTimeValue
+                        var newTime = currTime - lastTap
+
+                        tapHistory.push(newTime)
+
+                        tapTimeValue = TimeUtils.calculateBPMByTapIntervals(tapHistory)
+
+                        keyPadRoot.tapTimeChanged(tapTimeValue)
+                        tapTimer.interval = tapTimeValue
                         tapTimer.restart()
                     }
-                    tapTimeValue = currTime
+                    else
+                    {
+                        lastTap = 0
+                        tapHistory = []
+                    }
+                    lastTap = currTime
                 }
             }
         }

qmlui/qml/TimeEditTool.qml

@@ -42,6 +42,10 @@ GridLayout
 
     /* The TAP time counter */
     property double tapTimeValue: 0
+    //needed for bpm tapping
+    property int tapCount: 0
+    property double lastTap: 0
+    property var tapHistory: []
 
     /* If needed, this property can be used to recognize which type
        of speed value is being edited */
@@ -177,23 +181,36 @@ GridLayout
         onClicked:
         {
             /* right click resets the current TAP time */
-            if (mouseButton === Qt.RightButton)
-            {
-                tapTimer.stop()
-                tapButton.border.color = UISettings.bgMedium
-                tapTimeValue = 0
-            }
-            else
-            {
-                var currTime = new Date().getTime()
-                if (tapTimeValue != 0)
+                if (mouseButton === Qt.RightButton)
                 {
-                    updateTime(currTime - tapTimeValue, "")
-                    tapTimer.interval = timeValue
-                    tapTimer.restart()
+                    tapTimer.stop()
+                    tapButton.border.color = UISettings.bgMedium
+                    lastTap = 0
+                    tapHistory = []
+                }
+                else
+                {
+                    var currTime = new Date().getTime()
+
+                    if (lastTap != 0 && currTime - lastTap < 1500)
+                    {
+                        var newTime = currTime - lastTap
+
+                        tapHistory.push(newTime)
+
+                        tapTimeValue = TimeUtils.calculateBPMByTapIntervals(tapHistory)
+
+                        updateTime(tapTimeValue, "")
+                        tapTimer.interval = timeValue
+                        tapTimer.restart()
+                    }
+                    else
+                    {
+                        lastTap = 0
+                        tapHistory = []
+                    }
+                    lastTap = currTime
                 }
-                tapTimeValue = currTime
-            }
         }
     }