Add an option to use a volume icon instead of the Background Music logo.

This is so the icon can show the current volume. Then you can hide the
built-in volume status bar item in System Preferences.

Closes #183.

.gitignore

@@ -7,6 +7,8 @@ tags
 cmake-build-debug/
 /Background-Music-*/
 BGM.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
+Images/*.aux
+Images/*.log
 
 # Everything below is from https://github.com/github/gitignore/blob/master/Objective-C.gitignore
 

BGMApp/BGMApp.xcodeproj/project.pbxproj

@@ -7,6 +7,12 @@
 	objects = {
 
 /* Begin PBXBuildFile section */
+		19FE7071FF5280BC38F35E1D /* BGMVolumeChangeListener.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 19FE7179EBFA116F3861E79D /* BGMVolumeChangeListener.cpp */; };
+		19FE719951725A698A419CBA /* BGMVolumeChangeListener.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 19FE7179EBFA116F3861E79D /* BGMVolumeChangeListener.cpp */; };
+		19FE77608F6C80D0B1F595A7 /* BGMStatusBarItem.mm in Sources */ = {isa = PBXBuildFile; fileRef = 19FE774DD758EC163EF4F28C /* BGMStatusBarItem.mm */; };
+		19FE7921FD1B6C037429ECA4 /* BGMStatusBarItem.mm in Sources */ = {isa = PBXBuildFile; fileRef = 19FE774DD758EC163EF4F28C /* BGMStatusBarItem.mm */; };
+		19FE7DFF63F69E77C53BF95E /* BGMVolumeChangeListener.cpp in Sources */ = {isa = PBXBuildFile; fileRef = 19FE7179EBFA116F3861E79D /* BGMVolumeChangeListener.cpp */; };
+		19FE7F77376562C179449013 /* BGMStatusBarItem.mm in Sources */ = {isa = PBXBuildFile; fileRef = 19FE774DD758EC163EF4F28C /* BGMStatusBarItem.mm */; };
 		1C0BD0A51BF1A8E6004F4CF5 /* BGMAutoPauseMusicPrefs.mm in Sources */ = {isa = PBXBuildFile; fileRef = 1C0BD0A41BF1A8E6004F4CF5 /* BGMAutoPauseMusicPrefs.mm */; settings = {COMPILER_FLAGS = "-frandom-seed=BGMApp-BGMAutoPauseMusicPrefs.mm"; }; };
 		1C0BD0A81BF1B029004F4CF5 /* BGMPreferencesMenu.mm in Sources */ = {isa = PBXBuildFile; fileRef = 1C0BD0A71BF1B029004F4CF5 /* BGMPreferencesMenu.mm */; settings = {COMPILER_FLAGS = "-frandom-seed=BGMApp-BGMPreferencesMenu.mm"; }; };
 		1C1465B81BCC3A73003AEFE6 /* BGMAutoPauseMusic.mm in Sources */ = {isa = PBXBuildFile; fileRef = 1C1465B71BCC3A73003AEFE6 /* BGMAutoPauseMusic.mm */; settings = {COMPILER_FLAGS = "-frandom-seed=BGMApp-BGMAutoPauseMusic.mm"; }; };
@@ -206,6 +212,10 @@
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXFileReference section */
+		19FE7179EBFA116F3861E79D /* BGMVolumeChangeListener.cpp */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.cpp; path = BGMVolumeChangeListener.cpp; sourceTree = "<group>"; };
+		19FE774DD758EC163EF4F28C /* BGMStatusBarItem.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; path = BGMStatusBarItem.mm; sourceTree = "<group>"; };
+		19FE799A86A285DD9423D164 /* BGMStatusBarItem.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = BGMStatusBarItem.h; sourceTree = "<group>"; };
+		19FE7FDAEBC3F0DB8C99823B /* BGMVolumeChangeListener.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = BGMVolumeChangeListener.h; sourceTree = "<group>"; };
 		1C0BD0A31BF1A8E6004F4CF5 /* BGMAutoPauseMusicPrefs.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = BGMAutoPauseMusicPrefs.h; path = Preferences/BGMAutoPauseMusicPrefs.h; sourceTree = "<group>"; };
 		1C0BD0A41BF1A8E6004F4CF5 /* BGMAutoPauseMusicPrefs.mm */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.cpp.objcpp; name = BGMAutoPauseMusicPrefs.mm; path = Preferences/BGMAutoPauseMusicPrefs.mm; sourceTree = "<group>"; };
 		1C0BD0A61BF1B029004F4CF5 /* BGMPreferencesMenu.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = BGMPreferencesMenu.h; path = Preferences/BGMPreferencesMenu.h; sourceTree = "<group>"; };
@@ -579,10 +589,14 @@
 				1C3D36701ED90E8600F98E66 /* BGMDeviceControlsList.cpp */,
 				1C1962E61BC94E91008A4DF7 /* BGMPlayThrough.h */,
 				1C1962E51BC94E91008A4DF7 /* BGMPlayThrough.cpp */,
+				19FE799A86A285DD9423D164 /* BGMStatusBarItem.h */,
+				19FE774DD758EC163EF4F28C /* BGMStatusBarItem.mm */,
 				1CC6593B1F91DEB400B0CCDC /* BGMTermination.h */,
 				1CC6593A1F91DEB400B0CCDC /* BGMTermination.mm */,
 				2743C9ED1D8538700089613B /* BGMUserDefaults.h */,
 				2743C9F01D853FBB0089613B /* BGMUserDefaults.m */,
+				19FE7FDAEBC3F0DB8C99823B /* BGMVolumeChangeListener.h */,
+				19FE7179EBFA116F3861E79D /* BGMVolumeChangeListener.cpp */,
 				2795973C1C982E8C00A002FB /* BGMXPCListener.h */,
 				2795973A1C982E4E00A002FB /* BGMXPCListener.mm */,
 				1C2FC3161EC7078F00A76592 /* Scripting */,
@@ -1004,6 +1018,8 @@
 				2795973B1C982E4E00A002FB /* BGMXPCListener.mm in Sources */,
 				27C457E61CF2BC2600A6C9A6 /* BGMAutoPauseMenuItem.m in Sources */,
 				1C1465B81BCC3A73003AEFE6 /* BGMAutoPauseMusic.mm in Sources */,
+				19FE7F77376562C179449013 /* BGMStatusBarItem.mm in Sources */,
+				19FE719951725A698A419CBA /* BGMVolumeChangeListener.cpp in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1061,6 +1077,8 @@
 				1CCC4F621E584100008053E4 /* BGMAppUITests.mm in Sources */,
 				1C2FC31C1EC7238A00A76592 /* BGMASOutputDevice.mm in Sources */,
 				1C2FC3151EC706E000A76592 /* BGMAppDelegate+AppleScript.mm in Sources */,
+				19FE7921FD1B6C037429ECA4 /* BGMStatusBarItem.mm in Sources */,
+				19FE7DFF63F69E77C53BF95E /* BGMVolumeChangeListener.cpp in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1134,6 +1152,8 @@
 				1CC6593E1F91DEB400B0CCDC /* BGMTermination.mm in Sources */,
 				2743CA011D86D3CB0089613B /* BGMMusicPlayers.mm in Sources */,
 				2743CA021D86D3CB0089613B /* BGMiTunes.m in Sources */,
+				19FE77608F6C80D0B1F595A7 /* BGMStatusBarItem.mm in Sources */,
+				19FE7071FF5280BC38F35E1D /* BGMVolumeChangeListener.cpp in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

BGMApp/BGMApp/BGMAppDelegate.mm

@@ -17,10 +17,10 @@
 //  BGMAppDelegate.mm
 //  BGMApp
 //
-//  Copyright © 2016-2018 Kyle Neideck
+//  Copyright © 2016-2019 Kyle Neideck
 //
 
-// Self Includes
+// Self Include
 #import "BGMAppDelegate.h"
 
 // Local Includes
@@ -33,6 +33,7 @@
 #import "BGMOutputVolumeMenuItem.h"
 #import "BGMPreferencesMenu.h"
 #import "BGMPreferredOutputDevices.h"
+#import "BGMStatusBarItem.h"
 #import "BGMSystemSoundsVolume.h"
 #import "BGMTermination.h"
 #import "BGMUserDefaults.h"
@@ -45,18 +46,19 @@
 
 #pragma clang assume_nonnull begin
 
-static float const     kStatusBarIconPadding = 0.25;
 static NSString* const kOptNoPersistentData  = @"--no-persistent-data";
 static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
 
 @implementation BGMAppDelegate {
-    // The button in the system status bar (the bar with volume, battery, clock, etc.) to show the main menu
+    // The button in the system status bar that shows the main menu.
-    // for the app. These are called "menu bar extras" in the Human Interface Guidelines.
+    BGMStatusBarItem* statusBarItem;
-    NSStatusItem* statusBarItem;
     
     // Only show the 'BGMXPCHelper is missing' error dialog once.
     BOOL haveShownXPCHelperErrorMessage;
 
+    // Persistently stores user settings and data.
+    BGMUserDefaults* userDefaults;
+
     BGMAutoPauseMusic* autoPauseMusic;
     BGMAutoPauseMenuItem* autoPauseMenuItem;
     BGMMusicPlayers* musicPlayers;
@@ -71,6 +73,8 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
 @synthesize audioDevices = audioDevices;
 
 - (void) awakeFromNib {
+    [super awakeFromNib];
+    
     // Show BGMApp in the dock, if the command-line option for that was passed. This is used by the
     // UI tests.
     if ([NSProcessInfo.processInfo.arguments indexOfObject:kOptShowDockIcon] != NSNotFound) {
@@ -79,72 +83,19 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
     
     haveShownXPCHelperErrorMessage = NO;
 
-    [self initStatusBarItem];
+    // Set up audioDevices, which coordinates BGMDevice and the output device. It manages
-}
+    // playthrough, volume/mute controls, etc.
-
+    if (![self initAudioDeviceManager]) {
-// Set up the status bar item. (The thing you click to show BGMApp's UI.)
+        return;
-- (void) initStatusBarItem {
-    statusBarItem = [[NSStatusBar systemStatusBar] statusItemWithLength:NSSquareStatusItemLength];
-
-    // NSStatusItem doesn't have the "button" property on OS X 10.9.
-    BOOL buttonAvailable = (floor(NSAppKitVersionNumber) >= NSAppKitVersionNumber10_10);
-
-    // Set the title/tooltip to "Background Music".
-    statusBarItem.title = [NSRunningApplication currentApplication].localizedName;
-    statusBarItem.toolTip = statusBarItem.title;
-
-    if (buttonAvailable) {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wpartial-availability"
-        statusBarItem.button.accessibilityLabel = statusBarItem.title;
-#pragma clang diagnostic pop
     }
 
-    // Set the icon.
+    // Stored user settings
-    NSImage* icon = [NSImage imageNamed:@"FermataIcon"];
+    userDefaults = [self createUserDefaults];
 
-    if (icon != nil) {
+    // Add the status bar item. (The thing you click to show BGMApp's main menu.)
-        NSRect statusBarItemFrame;
+    statusBarItem = [[BGMStatusBarItem alloc] initWithMenu:self.bgmMenu
-
+                                              audioDevices:audioDevices
-        if (buttonAvailable) {
+                                              userDefaults:userDefaults];
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wpartial-availability"
-            statusBarItemFrame = statusBarItem.button.frame;
-#pragma clang diagnostic pop
-        } else {
-            // OS X 10.9 fallback. I haven't tested this (or anything else on 10.9).
-            statusBarItemFrame = statusBarItem.view.frame;
-        }
-
-        CGFloat lengthMinusPadding = statusBarItemFrame.size.height * (1 - kStatusBarIconPadding);
-        [icon setSize:NSMakeSize(lengthMinusPadding, lengthMinusPadding)];
-
-        // Make the icon a "template image" so it gets drawn colour-inverted when it's highlighted or the status
-        // bar's in dark mode
-        [icon setTemplate:YES];
-
-        if (buttonAvailable) {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wpartial-availability"
-            statusBarItem.button.image = icon;
-#pragma clang diagnostic pop
-        } else {
-            statusBarItem.image = icon;
-        }
-    } else {
-        // If our icon is missing for some reason, fallback to a fermata character (1D110)
-        if (buttonAvailable) {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wpartial-availability"
-            statusBarItem.button.title = @"𝄐";
-#pragma clang diagnostic pop
-        } else {
-            statusBarItem.title = @"𝄐";
-        }
-    }
-    
-    // Set the main menu
-    statusBarItem.menu = self.bgmMenu;
 }
 
 - (void) applicationDidFinishLaunching:(NSNotification*)aNotification {
@@ -159,15 +110,6 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
           NSBundle.mainBundle.infoDictionary[@"CFBundleShortVersionString"],
           NSBundle.mainBundle.infoDictionary[@"CFBundleVersion"]);
 
-    // Set up audioDevices, which coordinates BGMDevice and the output device. It manages
-    // playthrough, volume/mute controls, etc.
-    if (![self initAudioDeviceManager]) {
-        return;
-    }
-
-    // Persistently stores user settings and data.
-    BGMUserDefaults* userDefaults = [self createUserDefaults];
-
     // Handles changing (or not changing) the output device when devices are added or removed. Must
     // be initialised before calling setBGMDeviceAsDefault.
     preferredOutputDevices =
@@ -191,7 +133,7 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
     autoPauseMusic = [[BGMAutoPauseMusic alloc] initWithAudioDevices:audioDevices
                                                         musicPlayers:musicPlayers];
     
-    [self setUpMainMenu:userDefaults];
+    [self setUpMainMenu];
     
     xpcListener = [[BGMXPCListener alloc] initWithAudioDevices:audioDevices
                                   helperConnectionErrorHandler:^(NSError* error) {
@@ -285,7 +227,7 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
     }
 }
 
-- (void) setUpMainMenu:(BGMUserDefaults*)userDefaults {
+- (void) setUpMainMenu {
     autoPauseMenuItem =
         [[BGMAutoPauseMenuItem alloc] initWithMenuItem:self.autoPauseMenuItemUnwrapped
                                         autoPauseMusic:autoPauseMusic
@@ -305,6 +247,7 @@ static NSString* const kOptShowDockIcon      = @"--show-dock-icon";
     prefsMenu = [[BGMPreferencesMenu alloc] initWithBGMMenu:self.bgmMenu
                                                audioDevices:audioDevices
                                                musicPlayers:musicPlayers
+                                              statusBarItem:statusBarItem
                                                  aboutPanel:self.aboutPanel
                                       aboutPanelLicenseView:self.aboutPanelLicenseView];
 

BGMApp/BGMApp/BGMOutputDeviceMenuSection.mm

@@ -202,7 +202,7 @@ static NSInteger const kOutputDeviceMenuItemTag = 5;
     NSMutableArray<NSMenuItem*>* items = [NSMutableArray new];
 
     AudioObjectPropertyScope scope = kAudioObjectPropertyScopeOutput;
-    UInt32 channel = 0;  // 0 is the master channel.
+    UInt32 channel = kAudioObjectPropertyElementMaster;
     
     // If the device has data sources, create a menu item for each. Otherwise, create a single menu item
     // for the device. This way the menu items' titles will be, for example, "Internal Speakers" rather

BGMApp/BGMApp/BGMOutputVolumeMenuItem.mm

@@ -17,7 +17,7 @@
 //  BGMOutputVolumeMenuItem.mm
 //  BGMApp
 //
-//  Copyright © 2017, 2018 Kyle Neideck
+//  Copyright © 2017-2019 Kyle Neideck
 //
 
 // Self Include
@@ -26,6 +26,7 @@
 // Local Includes
 #import "BGM_Utils.h"
 #import "BGMAudioDevice.h"
+#import "BGMVolumeChangeListener.h"
 
 // PublicUtility Includes
 #import "CAException.h"
@@ -46,7 +47,7 @@ NSString* const __nonnull      kGenericOutputDeviceName = @"Output Device";
     NSTextField* deviceLabel;
     NSSlider* volumeSlider;
     BGMAudioDevice outputDevice;
-    AudioObjectPropertyListenerBlock updateSliderListenerBlock;
+    BGMVolumeChangeListener* volumeChangeListener;
     AudioObjectPropertyListenerBlock updateLabelListenerBlock;
 }
 
@@ -66,9 +67,8 @@ NSString* const __nonnull      kGenericOutputDeviceName = @"Output Device";
         volumeSlider = slider;
         outputDevice = audioDevices.outputDevice;
 
-        // These are initialised in the methods called below.
+        // volumeChangeListener and updateLabelListenerBlock are initialised in the methods called
-        updateSliderListenerBlock = nil;
+        // below.
-        updateLabelListenerBlock = nil;
 
         // Apply our custom view from MainMenu.xib.
         self.view = view;
@@ -89,20 +89,6 @@ NSString* const __nonnull      kGenericOutputDeviceName = @"Output Device";
     // TODO: This call isn't thread safe. (But currently this dealloc method is only called if
     //       there's an error.)
     [self removeOutputDeviceDataSourceListener];
-
-    BGMLogAndSwallowExceptions("BGMOutputVolumeMenuItem::dealloc", ([&] {
-        audioDevices.bgmDevice.RemovePropertyListenerBlock(
-            CAPropertyAddress(kAudioDevicePropertyVolumeScalar, kScope),
-            dispatch_get_main_queue(),
-            updateSliderListenerBlock);
-    }));
-
-    BGMLogAndSwallowExceptions("BGMOutputVolumeMenuItem::dealloc", ([&] {
-        audioDevices.bgmDevice.RemovePropertyListenerBlock(
-            CAPropertyAddress(kAudioDevicePropertyMute, kScope),
-            dispatch_get_main_queue(),
-            updateSliderListenerBlock);
-    }));
 }
 
 - (void) initSlider {
@@ -118,32 +104,9 @@ NSString* const __nonnull      kGenericOutputDeviceName = @"Output Device";
     // Register a listener that will update the slider when the user changes the volume or
     // mutes/unmutes their audio.
     BGMOutputVolumeMenuItem* __weak weakSelf = self;
-
+    volumeChangeListener = new BGMVolumeChangeListener(audioDevices.bgmDevice, [&] {
-    updateSliderListenerBlock =
+        [weakSelf updateVolumeSlider];
-        ^(UInt32 inNumberAddresses, const AudioObjectPropertyAddress* inAddresses) {
+    });
-            // The docs for AudioObjectPropertyListenerBlock say inAddresses will always contain
-            // at least one property the block is listening to, so there's no need to check it.
-            #pragma unused (inNumberAddresses, inAddresses)
-            [weakSelf updateVolumeSlider];
-        };
-
-    // Instead of swallowing exceptions, we could try again later, but I doubt it would be worth the
-    // effort. And the documentation doesn't actually explain what could cause this to fail.
-    BGMLogAndSwallowExceptions("BGMOutputVolumeMenuItem::initSlider", ([&] {
-        // Register the listener to receive volume notifications.
-        audioDevices.bgmDevice.AddPropertyListenerBlock(
-            CAPropertyAddress(kAudioDevicePropertyVolumeScalar, kScope),
-            dispatch_get_main_queue(),
-            updateSliderListenerBlock);
-    }));
-
-    BGMLogAndSwallowExceptions("BGMOutputVolumeMenuItem::initSlider", ([&] {
-        // Register the same listener for mute/unmute notifications.
-        audioDevices.bgmDevice.AddPropertyListenerBlock(
-            CAPropertyAddress(kAudioDevicePropertyMute, kScope),
-            dispatch_get_main_queue(),
-            updateSliderListenerBlock);
-    }));
 }
 
 // Updates the value of the output volume slider. Should only be called on the main thread because
@@ -178,7 +141,7 @@ NSString* const __nonnull      kGenericOutputDeviceName = @"Output Device";
             volumeSlider.doubleValue = 0.0;
         }
     }));
-};
+}
 
 - (void) addOutputDeviceDataSourceListener {
     // Create the block that updates deviceLabel when the output device's data source changes, e.g.

BGMApp/BGMApp/BGMStatusBarItem.h

@@ -0,0 +1,63 @@
+// This file is part of Background Music.
+//
+// Background Music is free software: you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation, either version 2 of the
+// License, or (at your option) any later version.
+//
+// Background Music is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Background Music. If not, see <http://www.gnu.org/licenses/>.
+
+//
+//  BGMStatusBarItem.h
+//  BGMApp
+//
+//  Copyright © 2019 Kyle Neideck
+//
+//  The button in the system status bar (the bar with volume, battery, clock, etc.) to show the main
+//  menu for the app. These are called "menu bar extras" in the Human Interface Guidelines.
+//
+
+// Local Includes
+#import "BGMAudioDeviceManager.h"
+
+// System Includes
+#import <Cocoa/Cocoa.h>
+
+// Forward Declarations
+@class BGMUserDefaults;
+
+
+#pragma clang assume_nonnull begin
+
+typedef NS_ENUM(NSInteger, BGMStatusBarIcon) {
+    BGMFermataStatusBarIcon = 0,
+    BGMVolumeStatusBarIcon
+};
+
+static BGMStatusBarIcon const kBGMStatusBarIconMinValue     = BGMFermataStatusBarIcon;
+static BGMStatusBarIcon const kBGMStatusBarIconMaxValue     = BGMVolumeStatusBarIcon;
+static BGMStatusBarIcon const kBGMStatusBarIconDefaultValue = BGMFermataStatusBarIcon;
+
+@interface BGMStatusBarItem : NSObject
+
+- (instancetype) initWithMenu:(NSMenu*)bgmMenu
+                 audioDevices:(BGMAudioDeviceManager*)devices
+                 userDefaults:(BGMUserDefaults*)defaults;
+
+// Set this to BGMFermataStatusBarIcon to change the icon to the Background Music logo.
+//
+// Set this to BGMFermataStatusBarIcon to change the icon to a volume icon. This icon has the
+// advantage of indicating the volume level, but we can't make it the default because it looks the
+// same as the icon for the macOS volume status bar item.
+@property BGMStatusBarIcon icon;
+
+@end
+
+#pragma clang assume_nonnull end
+

BGMApp/BGMApp/BGMStatusBarItem.mm

@@ -0,0 +1,257 @@
+// This file is part of Background Music.
+//
+// Background Music is free software: you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation, either version 2 of the
+// License, or (at your option) any later version.
+//
+// Background Music is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Background Music. If not, see <http://www.gnu.org/licenses/>.
+
+//
+//  BGMStatusBarItem.m
+//  BGMApp
+//
+//  Copyright © 2019 Kyle Neideck
+//
+
+// Self Include
+#import "BGMStatusBarItem.h"
+
+// Local Includes
+#import "BGM_Utils.h"
+#import "BGMUserDefaults.h"
+#import "BGMVolumeChangeListener.h"
+
+
+#pragma clang assume_nonnull begin
+
+static CGFloat const kStatusBarIconPadding                = 0.25;
+static CGFloat const kVolumeIconAdditionalVerticalPadding = 0.075;
+
+@implementation BGMStatusBarItem
+{
+    BGMAudioDeviceManager* audioDevices;
+
+    // User settings and data.
+    BGMUserDefaults* userDefaults;
+
+    NSImage* fermataIcon;
+    NSImage* volumeIcon0SoundWaves;
+    NSImage* volumeIcon1SoundWave;
+    NSImage* volumeIcon2SoundWaves;
+    NSImage* volumeIcon3SoundWaves;
+
+    NSStatusItem* statusBarItem;
+    BGMVolumeChangeListener* volumeChangeListener;
+
+    BGMStatusBarIcon _icon;
+}
+
+- (instancetype) initWithMenu:(NSMenu*)bgmMenu
+                 audioDevices:(BGMAudioDeviceManager*)devices
+                 userDefaults:(BGMUserDefaults*)defaults {
+    if ((self = [super init])) {
+        statusBarItem =
+                [[NSStatusBar systemStatusBar] statusItemWithLength:NSVariableStatusItemLength];
+
+        audioDevices = devices;
+        userDefaults = defaults;
+
+        // Initialise the icons.
+        [self initIcons];
+
+        // Set the initial icon.
+        self.icon = userDefaults.statusBarIcon;
+
+        // Set the menu item to open the main menu.
+        statusBarItem.menu = bgmMenu;
+
+        // Set the accessibility label to "Background Music". (We intentionally don't set a title or
+        // a tooltip.)
+        if ([BGMStatusBarItem buttonAvailable]) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+            statusBarItem.button.accessibilityLabel =
+                    [NSRunningApplication currentApplication].localizedName;
+#pragma clang diagnostic pop
+        }
+
+        // Update the icon when BGMDevice's volume changes.
+        BGMStatusBarItem* __weak weakSelf = self;
+        volumeChangeListener = new BGMVolumeChangeListener(audioDevices.bgmDevice, [&] {
+            [weakSelf bgmDeviceVolumeDidChange];
+        });
+    }
+
+    return self;
+}
+
+- (void) dealloc {
+    delete volumeChangeListener;
+}
+
+- (void) initIcons {
+    // Load the icons.
+    fermataIcon = [NSImage imageNamed:@"FermataIcon"];
+    volumeIcon0SoundWaves = [NSImage imageNamed:@"Volume0"];
+    volumeIcon1SoundWave = [NSImage imageNamed:@"Volume1"];
+    volumeIcon2SoundWaves = [NSImage imageNamed:@"Volume2"];
+    volumeIcon3SoundWaves = [NSImage imageNamed:@"Volume3"];
+
+    // Set the icons' sizes.
+    NSRect statusBarItemFrame;
+
+    if ([BGMStatusBarItem buttonAvailable]) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+        statusBarItemFrame = statusBarItem.button.frame;
+#pragma clang diagnostic pop
+    } else {
+        // OS X 10.9 fallback. I haven't tested this (or anything else on 10.9).
+        statusBarItemFrame = statusBarItem.view.frame;
+    }
+
+    CGFloat heightMinusPadding = statusBarItemFrame.size.height * (1 - kStatusBarIconPadding);
+
+    // The fermata icon has equal width and height.
+    [fermataIcon setSize:NSMakeSize(heightMinusPadding, heightMinusPadding)];
+
+    // The volume icons are all the same width and height.
+    CGFloat volumeIconWidthToHeightRatio =
+            volumeIcon0SoundWaves.size.width / volumeIcon0SoundWaves.size.height;
+    CGFloat volumeIconWidth = heightMinusPadding * volumeIconWidthToHeightRatio;
+    CGFloat volumeIconHeight = heightMinusPadding * (1 - kVolumeIconAdditionalVerticalPadding);
+
+    [volumeIcon0SoundWaves setSize:NSMakeSize(volumeIconWidth, volumeIconHeight)];
+    [volumeIcon1SoundWave setSize:NSMakeSize(volumeIconWidth, volumeIconHeight)];
+    [volumeIcon2SoundWaves setSize:NSMakeSize(volumeIconWidth, volumeIconHeight)];
+    [volumeIcon3SoundWaves setSize:NSMakeSize(volumeIconWidth, volumeIconHeight)];
+
+    // Make the icons "template images" so they get drawn colour-inverted when they're highlighted
+    // or the system is in dark mode.
+    [fermataIcon setTemplate:YES];
+    [volumeIcon0SoundWaves setTemplate:YES];
+    [volumeIcon1SoundWave setTemplate:YES];
+    [volumeIcon2SoundWaves setTemplate:YES];
+    [volumeIcon3SoundWaves setTemplate:YES];
+}
+
++ (BOOL) buttonAvailable {
+    // NSStatusItem doesn't have the "button" property on OS X 10.9.
+    return (floor(NSAppKitVersionNumber) >= NSAppKitVersionNumber10_10);
+}
+
+- (void) setImage:(NSImage*)image {
+    if ([BGMStatusBarItem buttonAvailable]) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+        statusBarItem.button.image = image;
+#pragma clang diagnostic pop
+    } else {
+        statusBarItem.image = image;
+    }
+}
+
+- (BGMStatusBarIcon) icon {
+    return _icon;
+}
+
+- (void) setIcon:(BGMStatusBarIcon)icon {
+    _icon = icon;
+
+    // Save the setting.
+    userDefaults.statusBarIcon = self.icon;
+
+    // Change the icon (i.e. the image). Dispatch this to the main thread because it changes the UI.
+    dispatch_async(dispatch_get_main_queue(), ^{
+        if (_icon == BGMFermataStatusBarIcon) {
+            [self setImage:fermataIcon];
+
+            // If the icon was greyed out, change it back.
+            if ([BGMStatusBarItem buttonAvailable]) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+                statusBarItem.button.appearsDisabled = NO;
+#pragma clang diagnostic pop
+            }
+        } else {
+            BGMAssert((_icon == BGMVolumeStatusBarIcon), "Unknown icon in enum");
+
+            [self updateVolumeStatusBarIcon];
+        }
+    });
+}
+
+- (void) bgmDeviceVolumeDidChange {
+    if (self.icon == BGMVolumeStatusBarIcon) {
+        [self updateVolumeStatusBarIcon];
+    }
+}
+
+// Should only be called on the main thread because it calls UI functions.
+- (void) updateVolumeStatusBarIcon {
+    BGMAssert([[NSThread currentThread] isMainThread],
+              "updateVolumeStatusBarIcon called on non-main thread.");
+    BGMAssert((self.icon == BGMVolumeStatusBarIcon), "Volume status bar icon not enabled");
+
+    BGMAudioDevice bgmDevice = [audioDevices bgmDevice];
+
+    // BGMDevice should never return an error for these calls, so we just swallow any exceptions and
+    // give up.
+    BGM_Utils::LogAndSwallowExceptions(BGMDbgArgs, [&] {
+        AudioObjectPropertyScope scope = kAudioObjectPropertyScopeOutput;
+        AudioObjectPropertyScope element = kAudioObjectPropertyElementMaster;
+
+        BOOL hasVolume = bgmDevice.HasVolumeControl(scope, element);
+
+        // Show the button as greyed out if BGMDevice doesn't have a volume control (which means the
+        // output device doesn't have one).
+        if ([BGMStatusBarItem buttonAvailable]) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wpartial-availability"
+            statusBarItem.button.appearsDisabled = !hasVolume;
+#pragma clang diagnostic pop
+        }
+
+        if (hasVolume) {
+            if (bgmDevice.HasMuteControl(scope, element) &&
+                    bgmDevice.GetMuteControlValue(scope, element)) {
+                // The device is muted, so use the zero waves icon.
+                [self setImage:volumeIcon0SoundWaves];
+            } else {
+                // Set the icon to reflect the device's volume.
+                double volume = bgmDevice.GetVolumeControlScalarValue(scope, element);
+
+                // These values match the macOS volume status bar item, except for the first one. I
+                // don't know why, but at a very low volume macOS will show the zero waves icon even
+                // though the sound is still audible.
+                if (volume == 0.05) {
+                    [self setImage:volumeIcon0SoundWaves];
+                } else if (volume < 0.33) {
+                    [self setImage:volumeIcon1SoundWave];
+                } else if (volume < 0.66) {
+                    [self setImage:volumeIcon2SoundWaves];
+                } else {
+                    [self setImage:volumeIcon3SoundWaves];
+                }
+            }
+        } else {
+            // Always use the full-volume icon when the device has no volume control.
+            [self setImage:volumeIcon3SoundWaves];
+        }
+    });
+
+    DebugMsg("BGMStatusBarItem::updateVolumeStatusBarIcon: Set icon to %s",
+             statusBarItem.image.name.UTF8String);
+}
+
+@end
+
+#pragma clang assume_nonnull end
+

BGMApp/BGMApp/BGMUserDefaults.h

@@ -17,13 +17,16 @@
 //  BGMUserDefaults.h
 //  BGMApp
 //
-//  Copyright © 2016-2018 Kyle Neideck
+//  Copyright © 2016-2019 Kyle Neideck
 //
 //  A simple wrapper around our use of NSUserDefaults. Used to store the preferences/state that only
 //  apply to BGMApp. The others are stored by BGMDriver.
 //
 
-// System includes
+// Local Includes
+#import "BGMStatusBarItem.h"
+
+// System Includes
 #import <Cocoa/Cocoa.h>
 
 
@@ -44,6 +47,10 @@
 // device is at index 0. See BGMPreferredOutputDevices.
 @property NSArray<NSString*>* preferredDeviceUIDs;
 
+// The (type of) icon to show in the button in the status bar. (The button the user clicks to open
+// BGMApp's main menu.)
+@property BGMStatusBarIcon statusBarIcon;
+
 @end
 
 #pragma clang assume_nonnull end

BGMApp/BGMApp/BGMUserDefaults.m

@@ -17,7 +17,7 @@
 //  BGMUserDefaults.m
 //  BGMApp
 //
-//  Copyright © 2016-2018 Kyle Neideck
+//  Copyright © 2016-2019 Kyle Neideck
 //
 
 // Self Include
@@ -32,7 +32,8 @@
 // Keys
 static NSString* const BGMDefaults_AutoPauseMusicEnabled = @"AutoPauseMusicEnabled";
 static NSString* const BGMDefaults_SelectedMusicPlayerID = @"SelectedMusicPlayerID";
-static NSString* const BGMDefaults_PreferredDeviceUIDs = @"PreferredDeviceUIDs";
+static NSString* const BGMDefaults_PreferredDeviceUIDs   = @"PreferredDeviceUIDs";
+static NSString* const BGMDefaults_StatusBarIcon         = @"StatusBarIcon";
 
 @implementation BGMUserDefaults {
     // The defaults object wrapped by this object.
@@ -89,6 +90,22 @@ static NSString* const BGMDefaults_PreferredDeviceUIDs = @"PreferredDeviceUIDs";
     [self set:BGMDefaults_PreferredDeviceUIDs to:devices];
 }
 
+- (BGMStatusBarIcon) statusBarIcon {
+    NSInteger icon = [self getInt:BGMDefaults_StatusBarIcon or:kBGMStatusBarIconDefaultValue];
+
+    // Just in case we get an invalid value somehow.
+    if ((icon < kBGMStatusBarIconMinValue) || (icon > kBGMStatusBarIconMaxValue)) {
+        NSLog(@"BGMUserDefaults::statusBarIcon: Unknown BGMStatusBarIcon: %ld", (long)icon);
+        icon = kBGMStatusBarIconDefaultValue;
+    }
+
+    return (BGMStatusBarIcon)icon;
+}
+
+- (void) setStatusBarIcon:(BGMStatusBarIcon)icon {
+    [self setInt:BGMDefaults_StatusBarIcon to:icon];
+}
+
 #pragma mark Implementation
 
 - (id __nullable) get:(NSString*)key {
@@ -103,6 +120,7 @@ static NSString* const BGMDefaults_PreferredDeviceUIDs = @"PreferredDeviceUIDs";
     }
 }
 
+// TODO: This method should have a default value param.
 - (BOOL) getBool:(NSString*)key {
     return defaults ? [defaults boolForKey:key] : [transientDefaults[key] boolValue];
 }
@@ -111,7 +129,32 @@ static NSString* const BGMDefaults_PreferredDeviceUIDs = @"PreferredDeviceUIDs";
     if (defaults) {
         [defaults setBool:value forKey:key];
     } else {
-        transientDefaults[key] = [NSNumber numberWithBool:value];
+        transientDefaults[key] = @(value);
+    }
+}
+
+- (NSInteger) getInt:(NSString*)key or:(NSInteger)valueIfNil
+{
+    if (defaults) {
+        if ([defaults objectForKey:key]) {
+            return [defaults integerForKey:key];
+        } else {
+            return valueIfNil;
+        }
+    } else {
+        if (transientDefaults[key]) {
+            return [transientDefaults[key] intValue];
+        } else {
+            return valueIfNil;
+        }
+    }
+}
+
+- (void) setInt:(NSString*)key to:(NSInteger)value {
+    if (defaults) {
+        [defaults setInteger:value forKey:key];
+    } else {
+        transientDefaults[key] = @(value);
     }
 }
 

BGMApp/BGMApp/BGMVolumeChangeListener.cpp

@@ -0,0 +1,100 @@
+// This file is part of Background Music.
+//
+// Background Music is free software: you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation, either version 2 of the
+// License, or (at your option) any later version.
+//
+// Background Music is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Background Music. If not, see <http://www.gnu.org/licenses/>.
+
+//
+//  BGMVolumeChangeListener.cpp
+//  BGMApp
+//
+//  Copyright © 2019 Kyle Neideck
+//
+
+// Self Include
+#include "BGMVolumeChangeListener.h"
+
+// Local Includes
+#import "BGM_Utils.h"
+#import "BGMAudioDevice.h"
+
+// PublicUtility Includes
+#import "CAException.h"
+#import "CAPropertyAddress.h"
+
+
+#pragma clang assume_nonnull begin
+
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wexit-time-destructors"
+const static std::vector<CAPropertyAddress> kVolumeChangeProperties = {
+        // Output volume changes
+        CAPropertyAddress(kAudioDevicePropertyVolumeScalar, kAudioObjectPropertyScopeOutput),
+        // Mute/unmute
+        CAPropertyAddress(kAudioDevicePropertyMute, kAudioObjectPropertyScopeOutput),
+        // Received when controls are added to or removed from the device.
+        CAPropertyAddress(kAudioObjectPropertyControlList),
+        // Received when the device has changed and "clients should re-evaluate everything they need
+        // to know about the device, particularly the layout and values of the controls".
+        CAPropertyAddress(kAudioDevicePropertyDeviceHasChanged)
+};
+#pragma clang diagnostic pop
+
+BGMVolumeChangeListener::BGMVolumeChangeListener(BGMAudioDevice device,
+                                                 std::function<void(void)> handler)
+:
+    mDevice(device)
+{
+    // Register a listener that will update the slider when the user changes the volume or
+    // mutes/unmutes their audio.
+    mListenerBlock =
+            Block_copy(^(UInt32 inNumberAddresses, const AudioObjectPropertyAddress* inAddresses) {
+                // The docs for AudioObjectPropertyListenerBlock say inAddresses will always contain
+                // at least one property the block is listening to, so there's no need to check it.
+                (void)inNumberAddresses;
+                (void)inAddresses;
+
+                // Call the callback.
+                handler();
+            });
+
+    // Register for a number of properties that might indicate that clients need to update. For
+    // example, the mute property changing means UI elements that display the volume will need to be
+    // updated, even though it's not strictly a change in volume.
+    for(CAPropertyAddress property : kVolumeChangeProperties)
+    {
+        // Instead of swallowing exceptions here, we could try again later, but I doubt it would be
+        // worth the effort. And the documentation doesn't actually explain what could cause this
+        // call to fail.
+        BGM_Utils::LogAndSwallowExceptions(BGMDbgArgs, [&] {
+            mDevice.AddPropertyListenerBlock(property, dispatch_get_main_queue(), mListenerBlock);
+        });
+    }
+}
+
+BGMVolumeChangeListener::~BGMVolumeChangeListener()
+{
+    // Deregister and release the listener block.
+    for(CAPropertyAddress property : kVolumeChangeProperties)
+    {
+        BGM_Utils::LogAndSwallowExceptions(BGMDbgArgs, [&] {
+            mDevice.RemovePropertyListenerBlock(property,
+                                                dispatch_get_main_queue(),
+                                                mListenerBlock);
+        });
+    }
+
+    Block_release(mListenerBlock);
+}
+
+#pragma clang assume_nonnull end
+

BGMApp/BGMApp/BGMVolumeChangeListener.h

@@ -0,0 +1,59 @@
+// This file is part of Background Music.
+//
+// Background Music is free software: you can redistribute it and/or
+// modify it under the terms of the GNU General Public License as
+// published by the Free Software Foundation, either version 2 of the
+// License, or (at your option) any later version.
+//
+// Background Music is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with Background Music. If not, see <http://www.gnu.org/licenses/>.
+
+//
+//  BGMVolumeChangeListener.h
+//  BGMApp
+//
+//  Copyright © 2019 Kyle Neideck
+//
+
+// Local Includes
+#include "BGMBackgroundMusicDevice.h"
+
+// PublicUtility Includes
+#import "CAPropertyAddress.h"
+
+// STL Includes
+#include <functional>
+
+// System Includes
+#include <CoreAudio/CoreAudio.h>
+
+
+#pragma clang assume_nonnull begin
+
+class BGMVolumeChangeListener
+{
+
+public:
+    /*!
+     * @param device Listens for notifications about this device.
+     * @param handler The function to call when the device's volume (or mute) changes. Called on the
+     *                main queue.
+     */
+    BGMVolumeChangeListener(BGMAudioDevice device, std::function<void(void)> handler);
+    virtual ~BGMVolumeChangeListener();
+    BGMVolumeChangeListener(const BGMVolumeChangeListener&) = delete;
+    BGMVolumeChangeListener& operator=(const BGMVolumeChangeListener&) = delete;
+
+private:
+    AudioObjectPropertyListenerBlock     mListenerBlock;
+    BGMAudioDevice                       mDevice;
+
+};
+
+#pragma clang assume_nonnull end
+

BGMApp/BGMApp/Base.lproj/MainMenu.xib

@@ -52,7 +52,17 @@
                                 <modifierMask key="keyEquivalentModifierMask"/>
                             </menuItem>
                             <menuItem isSeparatorItem="YES" id="nb1-jq-97L"/>
-                            <menuItem title="About Background Music" tag="3" id="R45-Vo-Eto">
+                            <menuItem title="Status Bar Icon" enabled="NO" id="CmD-ot-1wE">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                            </menuItem>
+                            <menuItem title="Background Music Logo" state="on" tag="2" id="9VF-qy-6fh">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                            </menuItem>
+                            <menuItem title="Volume Icon" tag="3" toolTip="todo" id="B47-O2-wd0">
+                                <modifierMask key="keyEquivalentModifierMask"/>
+                            </menuItem>
+                            <menuItem isSeparatorItem="YES" id="pYP-Fy-nKA"/>
+                            <menuItem title="About Background Music" tag="4" id="R45-Vo-Eto">
                                 <modifierMask key="keyEquivalentModifierMask"/>
                             </menuItem>
                         </items>
@@ -205,7 +215,7 @@
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                         <clipView key="contentView" ambiguous="YES" drawsBackground="NO" id="Cdb-RA-YK0">
                             <rect key="frame" x="1" y="1" width="565" height="243"/>
-                            <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                            <autoresizingMask key="autoresizingMask"/>
                             <subviews>
                                 <textView ambiguous="YES" editable="NO" importsGraphics="NO" richText="NO" verticallyResizable="YES" id="LSG-PF-cl8">
                                     <rect key="frame" x="-6" y="0.0" width="577" height="243"/>
@@ -316,7 +326,7 @@
     </objects>
     <resources>
         <image name="FermataIcon" width="284" height="284"/>
-        <image name="NSComputer" width="128" height="128"/>
+        <image name="NSComputer" width="32" height="32"/>
         <image name="buttonCell:IXo-C7-3uE:image" width="1" height="1">
             <mutableData key="keyedArchiveRepresentation">
 YnBsaXN0MDDUAQIDBAUGPT5YJHZlcnNpb25YJG9iamVjdHNZJGFyY2hpdmVyVCR0b3ASAAGGoK4HCBMU

BGMApp/BGMApp/Images.xcassets/Volume0.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "mac",
+      "filename" : "Volume0.pdf"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

BGMApp/BGMApp/Images.xcassets/Volume1.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "mac",
+      "filename" : "Volume1.pdf"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

BGMApp/BGMApp/Images.xcassets/Volume2.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "mac",
+      "filename" : "Volume2.pdf"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

BGMApp/BGMApp/Images.xcassets/Volume3.imageset/Contents.json

@@ -0,0 +1,12 @@
+{
+  "images" : [
+    {
+      "idiom" : "mac",
+      "filename" : "Volume3.pdf"
+    }
+  ],
+  "info" : {
+    "version" : 1,
+    "author" : "xcode"
+  }
+}

BGMApp/BGMApp/Preferences/BGMPreferencesMenu.h

@@ -17,7 +17,7 @@
 //  BGMPreferencesMenu.h
 //  BGMApp
 //
-//  Copyright © 2016, 2018 Kyle Neideck
+//  Copyright © 2016, 2018, 2019 Kyle Neideck
 //
 //  Handles the preferences menu UI. The user's preference changes are often passed directly to the driver rather
 //  than to other BGMApp classes.
@@ -26,6 +26,7 @@
 // Local Includes
 #import "BGMAudioDeviceManager.h"
 #import "BGMMusicPlayers.h"
+#import "BGMStatusBarItem.h"
 
 // System Includes
 #import <Cocoa/Cocoa.h>
@@ -38,6 +39,7 @@ NS_ASSUME_NONNULL_BEGIN
 - (id) initWithBGMMenu:(NSMenu*)inBGMMenu
           audioDevices:(BGMAudioDeviceManager*)inAudioDevices
           musicPlayers:(BGMMusicPlayers*)inMusicPlayers
+         statusBarItem:(BGMStatusBarItem*)inStatusBarItem
             aboutPanel:(NSPanel*)inAboutPanel
  aboutPanelLicenseView:(NSTextView*)inAboutPanelLicenseView;
 

BGMApp/BGMApp/Preferences/BGMPreferencesMenu.mm

@@ -17,7 +17,7 @@
 //  BGMPreferencesMenu.mm
 //  BGMApp
 //
-//  Copyright © 2016, 2018 Kyle Neideck
+//  Copyright © 2016, 2018, 2019 Kyle Neideck
 //
 
 // Self Include
@@ -32,11 +32,18 @@ NS_ASSUME_NONNULL_BEGIN
 
 // Interface Builder tags
 static NSInteger const kPreferencesMenuItemTag = 1;
-static NSInteger const kAboutPanelMenuItemTag = 3;
+static NSInteger const kBGMIconMenuItemTag     = 2;
+static NSInteger const kVolumeIconMenuItemTag  = 3;
+static NSInteger const kAboutPanelMenuItemTag  = 4;
 
 @implementation BGMPreferencesMenu {
-    // Menu sections
+    // Menu sections/items
     BGMAutoPauseMusicPrefs* autoPauseMusicPrefs;
+    NSMenuItem* bgmIconMenuItem;
+    NSMenuItem* volumeIconMenuItem;
+
+    // The menu item you press to open BGMApp's main menu.
+    BGMStatusBarItem* statusBarItem;
 
     // The About Background Music window
     BGMAboutPanel* aboutPanel;
@@ -45,6 +52,7 @@ static NSInteger const kAboutPanelMenuItemTag = 3;
 - (id) initWithBGMMenu:(NSMenu*)inBGMMenu
           audioDevices:(BGMAudioDeviceManager*)inAudioDevices
           musicPlayers:(BGMMusicPlayers*)inMusicPlayers
+         statusBarItem:(BGMStatusBarItem*)inStatusBarItem
             aboutPanel:(NSPanel*)inAboutPanel
  aboutPanelLicenseView:(NSTextView*)inAboutPanelLicenseView {
     if ((self = [super init])) {
@@ -56,6 +64,21 @@ static NSInteger const kAboutPanelMenuItemTag = 3;
         
         aboutPanel = [[BGMAboutPanel alloc] initWithPanel:inAboutPanel licenseView:inAboutPanelLicenseView];
 
+        statusBarItem = inStatusBarItem;
+
+        // Set up the menu items under the "Status Bar Icon" heading.
+        bgmIconMenuItem = [prefsMenu itemWithTag:kBGMIconMenuItemTag];
+        bgmIconMenuItem.state =
+                (statusBarItem.icon == BGMFermataStatusBarIcon) ? NSOnState : NSOffState;
+        [bgmIconMenuItem setTarget:self];
+        [bgmIconMenuItem setAction:@selector(useBGMStatusBarIcon)];
+
+        volumeIconMenuItem = [prefsMenu itemWithTag:kVolumeIconMenuItemTag];
+        volumeIconMenuItem.state =
+                (statusBarItem.icon == BGMVolumeStatusBarIcon) ? NSOnState : NSOffState;
+        [volumeIconMenuItem setTarget:self];
+        [volumeIconMenuItem setAction:@selector(useVolumeStatusBarIcon)];
+
         // Set up the "About Background Music" menu item
         NSMenuItem* aboutMenuItem = [prefsMenu itemWithTag:kAboutPanelMenuItemTag];
         [aboutMenuItem setTarget:aboutPanel];
@@ -65,6 +88,29 @@ static NSInteger const kAboutPanelMenuItemTag = 3;
     return self;
 }
 
+- (void) useBGMStatusBarIcon {
+    // Change the icon.
+    statusBarItem.icon = BGMFermataStatusBarIcon;
+
+    // Select/deselect the menu items.
+    bgmIconMenuItem.state = NSOnState;
+    volumeIconMenuItem.state = NSOffState;
+}
+
+- (void) useVolumeStatusBarIcon {
+    // TODO: Maybe we should show a message that tells the user how to hide the built-in volume
+    //       icon. They probably won't want two status bar items that look the same. Or we might be
+    //       able to automatically hide the built-in icon while BGMApp is running and show it again
+    //       when BGMApp is closed.
+
+    // Change the icon.
+    statusBarItem.icon = BGMVolumeStatusBarIcon;
+
+    // Select/deselect the menu items.
+    bgmIconMenuItem.state = NSOffState;
+    volumeIconMenuItem.state = NSOnState;
+}
+
 @end
 
 NS_ASSUME_NONNULL_END

Images/VolumeIcons.tex

@@ -0,0 +1,69 @@
+% This file is part of Background Music.
+%
+% Background Music is free software: you can redistribute it and/or
+% modify it under the terms of the GNU General Public License as
+% published by the Free Software Foundation, either version 2 of the
+% License, or (at your option) any later version.
+%
+% Background Music is distributed in the hope that it will be useful,
+% but WITHOUT ANY WARRANTY; without even the implied warranty of
+% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+% GNU General Public License for more details.
+%
+% You should have received a copy of the GNU General Public License
+% along with Background Music. If not, see <http://www.gnu.org/licenses/>.
+
+%
+% VolumeIcons.tex
+%
+% Build with XeTeX:
+%   xelatex -jobname=Volume0 '\def\UseOption{}\input{VolumeIcons.tex}'
+%   xelatex -jobname=Volume1 '\def\UseOption{w1}\input{VolumeIcons.tex}'
+%   xelatex -jobname=Volume2 '\def\UseOption{w1,w2}\input{VolumeIcons.tex}'
+%   xelatex -jobname=Volume3 '\def\UseOption{w1,w2,w3}\input{VolumeIcons.tex}'
+%   for n in 0 1 2 3; do mv Volume$n.pdf ../BGMApp/BGMApp/Images.xcassets/Volume$n.imageset/; done
+%
+% Might build correctly with regular LaTeX. I haven't tried it.
+%
+
+\documentclass[tikz]{standalone}
+\usepackage{tikz}
+% "dummyOption" prevents "Package optional Warning: No options were selected,
+% so all optional text will be printed" when building Volume0.pdf.
+\usepackage[dummyOption]{optional}
+
+\begin{document}
+\begin{tikzpicture}
+
+% Speaker (Rounded box and triangle)
+\fill[rounded corners=5mm]
+    (0mm, 62.5mm) rectangle (25mm, 37.5mm) {};
+\draw[rounded corners=2.5mm,fill=black]
+    (3mm, 50mm)--(34mm, 76.5mm)--(34mm, 23.5mm)--cycle;
+
+% First sound wave (Curved line)
+\opt{w1}{
+    \draw[line width=4.3mm,line cap=round]
+        (44mm, 36.5mm) to[out=46,in=-46] (44mm, 63.5mm);
+}
+
+% Second sound wave (Curved line)
+\opt{w2}{
+    \draw[line width=4.3mm,line cap=round]
+        (57.5mm, 27.5mm) to[out=46,in=-46] (57.5mm, 72.5mm);
+}
+
+% Third sound wave (Curved line)
+\opt{w3}{
+    \draw[line width=4.3mm,line cap=round]
+        (72mm, 18.5mm) to[out=46,in=-46] (72mm, 81.5mm);
+}
+
+% Always draw a transparent copy of the third wave so the images will all have
+% the same width.
+\draw[line width=4.3mm,line cap=round,opacity=0]
+    (72mm, 18.5mm) to[out=46,in=-46] (72mm, 81.5mm);
+
+\end{tikzpicture}
+\end{document}
+

SharedSource/BGM_Types.h

@@ -17,7 +17,7 @@
 //  BGM_Types.h
 //  SharedSource
 //
-//  Copyright © 2016, 2017 Kyle Neideck
+//  Copyright © 2016, 2017, 2019 Kyle Neideck
 //
 
 #ifndef SharedSource__BGM_Types
@@ -77,7 +77,7 @@ enum
 
 // AudioObjectPropertyElement docs: "Elements are numbered sequentially where 0 represents the
 // master element."
-static const AudioObjectPropertyElement kMasterChannel = 0;
+static const AudioObjectPropertyElement kMasterChannel = kAudioObjectPropertyElementMaster;
 
 #pragma BGM Plug-in Custom Properties