Extend compatible keys from 4 to 6 possible keys

CHANGELOG

@@ -5,7 +5,8 @@
 * Fix missing manual in deb package lp:1889776
 * Fix caching of duplicate tracks that reference the same file #3027
 * Fix loss of precision when dealing with floating-point sample positions while setting loop out position and seeking using vinyl control #3126 #3127
-* prevent moving a loop beyond track end #3117 https://bugs.launchpad.net/mixxx/+bug/1799574
+* Prevent moving a loop beyond track end #3117 https://bugs.launchpad.net/mixxx/+bug/1799574
+* Use 6 instead of only 4 compatible musical keys (major/minor) #3205
 
 ==== 2.2.4 2020-05-10 ====
 

src/test/keyutilstest.cpp

@@ -1,13 +1,12 @@
-#include <gtest/gtest.h>
 #include <gmock/gmock.h>
+#include <gtest/gtest.h>
+
 #include <QDebug>
 
-#include "track/keyutils.h"
 #include "proto/keys.pb.h"
+#include "track/keyutils.h"
 
-using ::testing::ElementsAre;
-
-namespace {
+using ::testing::UnorderedElementsAre;
 
 class KeyUtilsTest : public testing::Test {
 };
@@ -206,30 +205,31 @@ TEST_F(KeyUtilsTest, ShortestStepsToKey) {
 }
 
 TEST_F(KeyUtilsTest, GetCompatibleKeys) {
-    // The relative major, the perfect 4th and the perfect 5th are all
-    // compatible. This is easily checked with the Circle of Fifths.
+    // The relative major/minor, the perfect 4th major/minor and the
+    // perfect 5th major/minor are all compatible. This is easily
+    // checked with the Circle of Fifths.
 
     // Test keys on the boundary between 1 and 12 to check that wrap-around
     // works.
     mixxx::track::io::key::ChromaticKey key =
             mixxx::track::io::key::A_MINOR;
     QList<mixxx::track::io::key::ChromaticKey> compatible =
             KeyUtils::getCompatibleKeys(key);
-    qSort(compatible);
-    EXPECT_THAT(compatible, ElementsAre(
-        mixxx::track::io::key::C_MAJOR,
-        mixxx::track::io::key::D_MINOR,
-        mixxx::track::io::key::E_MINOR,
-        mixxx::track::io::key::A_MINOR));
+    EXPECT_THAT(compatible,
+            UnorderedElementsAre(mixxx::track::io::key::C_MAJOR,
+                    mixxx::track::io::key::F_MAJOR,
+                    mixxx::track::io::key::G_MAJOR,
+                    mixxx::track::io::key::D_MINOR,
+                    mixxx::track::io::key::E_MINOR,
+                    mixxx::track::io::key::A_MINOR));
 
     key = mixxx::track::io::key::F_MAJOR;
     compatible = KeyUtils::getCompatibleKeys(key);
-    qSort(compatible);
-    EXPECT_THAT(compatible, ElementsAre(
-        mixxx::track::io::key::C_MAJOR,
-        mixxx::track::io::key::F_MAJOR,
-        mixxx::track::io::key::B_FLAT_MAJOR,
-        mixxx::track::io::key::D_MINOR));
+    EXPECT_THAT(compatible,
+            UnorderedElementsAre(mixxx::track::io::key::C_MAJOR,
+                    mixxx::track::io::key::F_MAJOR,
+                    mixxx::track::io::key::B_FLAT_MAJOR,
+                    mixxx::track::io::key::D_MINOR,
+                    mixxx::track::io::key::A_MINOR,
+                    mixxx::track::io::key::G_MINOR));
 }
-
-}  // namespace

src/test/rescalertest.cpp

@@ -1,15 +1,9 @@
 #include <gtest/gtest.h>
-#include <gmock/gmock.h>
 #include <QDebug>
 
 #include "util/math.h"
 #include "util/rescaler.h"
 
-
-using ::testing::ElementsAre;
-
-namespace {
-
 class RescalerUtilsTest : public testing::Test {
 };
 
@@ -62,5 +56,3 @@ TEST_F(RescalerUtilsTest, Test) {
     result = RescalerUtils::oneByXToLinear(result, 1000, 0, 100);
     EXPECT_TRUE(fabs(result - 50) < 0.0000000001);
 }
-
-}  // namespace

src/track/keyutils.cpp

@@ -515,15 +515,15 @@ QList<mixxx::track::io::key::ChromaticKey> KeyUtils::getCompatibleKeys(
         return compatible;
     }
 
+    int openKeyNumber = KeyUtils::keyToOpenKeyNumber(key);
     // We know the key is in the set of valid values. Save whether or not the
     // value is minor.
     bool major = keyIsMajor(key);
-    int openKeyNumber = KeyUtils::keyToOpenKeyNumber(key);
 
     // The compatible keys of particular key are:
     // * The relative major/minor key.
-    // * The perfect 4th (sub-dominant) key.
-    // * The perfect 5th (dominant) key.
+    // * The perfect 4th (sub-dominant) major/minor key.
+    // * The perfect 5th (dominant) major/minor key.
     //
     // The Circle of Fifths is a handy tool that encodes this compatibility.
     // Keys on the same radial of the circle are compatible and adjacent keys on
@@ -535,14 +535,22 @@ QList<mixxx::track::io::key::ChromaticKey> KeyUtils::getCompatibleKeys(
     // The key is compatible with tracks in the same key.
     compatible << key;
 
+    auto relativeKey = openKeyNumberToKey(openKeyNumber, !major);
+    int relativeOpenKeyNumber = KeyUtils::keyToOpenKeyNumber(relativeKey);
+
     // The relative major/minor key is compatible.
-    compatible << openKeyNumberToKey(openKeyNumber, !major);
+    compatible << relativeKey;
 
-    // The perfect 4th and perfect 5th are compatible.
+    // The perfect 4th and perfect 5th of BOTH major and minor key are compatible
+    // (as explained by Phil Morse: https://youtu.be/9eECvYYAwbg?t=2370)
     compatible << openKeyNumberToKey(
             openKeyNumber == 12 ? 1 : openKeyNumber + 1, major);
+    compatible << openKeyNumberToKey(
+            relativeOpenKeyNumber == 12 ? 1 : relativeOpenKeyNumber + 1, !major);
     compatible << openKeyNumberToKey(
             openKeyNumber == 1 ? 12 : openKeyNumber - 1, major);
+    compatible << openKeyNumberToKey(
+            relativeOpenKeyNumber == 1 ? 12 : relativeOpenKeyNumber - 1, !major);
     return compatible;
 }