From 1fa0c48aad9ddcdee756394f4ea16a7d25fa0186 Mon Sep 17 00:00:00 2001
From: ronso0 <ronso0@mixxx.org>
Date: Sat, 11 May 2024 21:48:43 +0200
Subject: [PATCH] feat: add support for scaling BPM by different ratios

---
 src/controllers/controlpickermenu.cpp | 24 +++++++++
 src/engine/controls/bpmcontrol.cpp    | 76 +++++++++++++++++++++++++++
 src/engine/controls/bpmcontrol.h      |  8 +++
 3 files changed, 108 insertions(+)

diff --git a/src/controllers/controlpickermenu.cpp b/src/controllers/controlpickermenu.cpp
index 039e3e4a018..1369065434c 100644
--- a/src/controllers/controlpickermenu.cpp
+++ b/src/controllers/controlpickermenu.cpp
@@ -262,6 +262,30 @@ ControlPickerMenu::ControlPickerMenu(QWidget* pParent)
             tr("BPM Tap"),
             tr("BPM tap button"),
             pBpmMenu);
+    addDeckAndSamplerControl("beats_set_halve",
+            tr("Halve BPM"),
+            tr("Multiply current BPM by 0.5"),
+            pBpmMenu);
+    addDeckAndSamplerControl("beats_set_twothirds",
+            tr("2/3 BPM"),
+            tr("Multiply current BPM by 0.666"),
+            pBpmMenu);
+    addDeckAndSamplerControl("beats_set_threefourths",
+            tr("3/4 BPM"),
+            tr("Multiply current BPM by 0.75"),
+            pBpmMenu);
+    addDeckAndSamplerControl("beats_set_fourthirds",
+            tr("4/3 BPM"),
+            tr("Multiply current BPM by 1.333"),
+            pBpmMenu);
+    addDeckAndSamplerControl("beats_set_threehalves",
+            tr("3/2 BPM"),
+            tr("Multiply current BPM by 1.5"),
+            pBpmMenu);
+    addDeckAndSamplerControl("beats_set_double",
+            tr("Double BPM"),
+            tr("Multiply current BPM by 2"),
+            pBpmMenu);
     pBpmMenu->addSeparator();
     addDeckAndSamplerControl("beats_adjust_faster",
             tr("Adjust Beatgrid Faster +.01"),
diff --git a/src/engine/controls/bpmcontrol.cpp b/src/engine/controls/bpmcontrol.cpp
index 90bdd09ba66..0f9d6c271b5 100644
--- a/src/engine/controls/bpmcontrol.cpp
+++ b/src/engine/controls/bpmcontrol.cpp
@@ -108,6 +108,66 @@ BpmControl::BpmControl(const QString& group,
             &BpmControl::slotTranslateBeatsMove,
             Qt::DirectConnection);
 
+    m_pBeatsHalve = std::make_unique<ControlPushButton>(ConfigKey(group, "beats_set_halve"), false);
+    connect(m_pBeatsHalve.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::Halve);
+                }
+            });
+    m_pBeatsTwoThirds = std::make_unique<ControlPushButton>(
+            ConfigKey(group, "beats_set_twothirds"), false);
+    connect(m_pBeatsTwoThirds.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::TwoThirds);
+                }
+            });
+    m_pBeatsThreeFourths = std::make_unique<ControlPushButton>(
+            ConfigKey(group, "beats_set_threefourths"), false);
+    connect(m_pBeatsThreeFourths.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::ThreeFourths);
+                }
+            });
+    m_pBeatsFourThirds = std::make_unique<ControlPushButton>(
+            ConfigKey(group, "beats_set_fourthirds"), false);
+    connect(m_pBeatsFourThirds.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::FourThirds);
+                }
+            });
+    m_pBeatsThreeHalves = std::make_unique<ControlPushButton>(
+            ConfigKey(group, "beats_set_threehalves"), false);
+    connect(m_pBeatsThreeHalves.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::ThreeHalves);
+                }
+            });
+    m_pBeatsDouble = std::make_unique<ControlPushButton>(
+            ConfigKey(group, "beats_set_double"), false);
+    connect(m_pBeatsDouble.get(),
+            &ControlObject::valueChanged,
+            this,
+            [this](int value) {
+                if (value > 0) {
+                    slotScaleBpm(mixxx::Beats::BpmScale::Double);
+                }
+            });
+
     // Pick a wide range (kBpmRangeMin to kBpmRangeMax) and allow out of bounds sets. This lets you
     // map a soft-takeover MIDI knob to the BPM. This also creates bpm_up and
     // bpm_down controls.
@@ -282,6 +342,22 @@ void BpmControl::slotTapFilter(double averageLength, int numSamples) {
     pTrack->trySetBeats(*newBeats);
 }
 
+void BpmControl::slotScaleBpm(mixxx::Beats::BpmScale bpmScale) {
+    const TrackPointer pTrack = getEngineBuffer()->getLoadedTrack();
+    if (!pTrack) {
+        return;
+    }
+    const mixxx::BeatsPointer pBeats = pTrack->getBeats();
+    if (!pBeats) {
+        return;
+    }
+    const auto newBeats = pBeats->tryScale(bpmScale);
+    if (!newBeats) {
+        return;
+    }
+    pTrack->trySetBeats(*newBeats);
+}
+
 // static
 double BpmControl::shortestPercentageChange(const double& current_percentage,
                                             const double& target_percentage) {
diff --git a/src/engine/controls/bpmcontrol.h b/src/engine/controls/bpmcontrol.h
index 90f46339eff..53409f58725 100644
--- a/src/engine/controls/bpmcontrol.h
+++ b/src/engine/controls/bpmcontrol.h
@@ -120,6 +120,7 @@ class BpmControl : public EngineControl {
     }
     double calcSyncAdjustment(bool userTweakingSync);
     void adjustBeatsBpm(double deltaBpm);
+    void slotScaleBpm(mixxx::Beats::BpmScale bpmScale);
 
     friend class SyncControl;
 
@@ -147,6 +148,13 @@ class BpmControl : public EngineControl {
     std::unique_ptr<ControlPushButton> m_pTranslateBeatsLater;
     ControlEncoder* m_pTranslateBeatsMove;
 
+    std::unique_ptr<ControlPushButton> m_pBeatsHalve;
+    std::unique_ptr<ControlPushButton> m_pBeatsTwoThirds;
+    std::unique_ptr<ControlPushButton> m_pBeatsThreeFourths;
+    std::unique_ptr<ControlPushButton> m_pBeatsFourThirds;
+    std::unique_ptr<ControlPushButton> m_pBeatsThreeHalves;
+    std::unique_ptr<ControlPushButton> m_pBeatsDouble;
+
     std::unique_ptr<ControlPushButton> m_pBpmLock;
 
     // The current effective BPM of the engine