KMix: system tray icon enhancements

* XDG-compliant icon names with volume level specification (low, medium, high)
  Low-Medium threshold:  33%
  Medium-High threshold: 67%
* Improved built-in icon theme with distinct volume levels (according to above)
* Choice between classic KMix icon theme, imrpoved KMix icon theme and system theme.
* New KMixDockWidget::getAvgVolume() method
  Gets average volume in %. Code actually comes from KMixDockWidget::setVolumeTip(),
  but was put into a separate method to be reused for determination of icon according
  to the volume level

(cherry picked from commit 3168c39ef1e445db1a6e22a7ba63e8cb4714e6e8)

13 files changed, 32 insertions, 2 deletions

diff --git a/kmix/pics/CMakeLists.txt b/kmix/pics/CMakeLists.txt
index 35ea82c5..92af67f8 100644
--- a/kmix/pics/CMakeLists.txt
+++ b/kmix/pics/CMakeLists.txt
@@ -16,8 +16,10 @@ install( FILES
     mix_microphone.png mix_midi.png mix_recmon.png
     mix_treble.png mix_unknown.png mix_volume.png
     mix_surround.png mix_video.png mix_headphone.png
-    mix_digital.png mix_ac97.png kmixdocked.png
-    kmixdocked_mute.png kmixdocked_error.png mix_record.png
+    mix_digital.png mix_ac97.png mix_record.png
     SpeakerFrontLeft.png SpeakerRearLeft.png SpeakerFrontRight.png
     SpeakerRearRight.png Listener.png
   DESTINATION ${DATA_INSTALL_DIR}/kmix/pics )
+
+add_subdirectory(oldcrystal)
+add_subdirectory(crystal)
\ No newline at end of file
diff --git a/kmix/pics/crystal/CMakeLists.txt b/kmix/pics/crystal/CMakeLists.txt
new file mode 100644
index 00000000..71f61d26
--- /dev/null
+++ b/kmix/pics/crystal/CMakeLists.txt
@@ -0,0 +1,13 @@
+################################################################################
+#  Copyright © 2024 Mavridis Philippe <[email protected]>                    #
+#                                                                              #
+#  This file is released under the GNU GPL version 3 or later.                 #
+#  Improvements and feedback are welcome!                                      #
+################################################################################
+
+set(theme "crystal")
+
+install(FILES audio-volume-error.png audio-volume-muted.png
+              audio-volume-low.png audio-volume-medium.png
+              audio-volume-high.png
+        DESTINATION ${DATA_INSTALL_DIR}/kmix/pics/${theme})
\ No newline at end of file
diff --git a/kmix/pics/kmixdocked_error.png b/kmix/pics/crystal/audio-volume-error.png
index b0497662..b0497662 100644
--- a/kmix/pics/kmixdocked_error.png
+++ b/kmix/pics/crystal/audio-volume-error.png
diff --git a/kmix/pics/crystal/audio-volume-high.png b/kmix/pics/crystal/audio-volume-high.png
new file mode 100644
index 00000000..bfa7234b
--- /dev/null
+++ b/kmix/pics/crystal/audio-volume-high.png
diff --git a/kmix/pics/crystal/audio-volume-low.png b/kmix/pics/crystal/audio-volume-low.png
new file mode 100644
index 00000000..e42f7c8b
--- /dev/null
+++ b/kmix/pics/crystal/audio-volume-low.png
diff --git a/kmix/pics/crystal/audio-volume-medium.png b/kmix/pics/crystal/audio-volume-medium.png
new file mode 100644
index 00000000..4be127eb
--- /dev/null
+++ b/kmix/pics/crystal/audio-volume-medium.png
diff --git a/kmix/pics/crystal/audio-volume-muted.png b/kmix/pics/crystal/audio-volume-muted.png
new file mode 100644
index 00000000..8ceb8690
--- /dev/null
+++ b/kmix/pics/crystal/audio-volume-muted.png
diff --git a/kmix/pics/oldcrystal/CMakeLists.txt b/kmix/pics/oldcrystal/CMakeLists.txt
new file mode 100644
index 00000000..47b37e11
--- /dev/null
+++ b/kmix/pics/oldcrystal/CMakeLists.txt
@@ -0,0 +1,13 @@
+################################################################################
+#  Copyright © 2024 Mavridis Philippe <[email protected]>                    #
+#                                                                              #
+#  This file is released under the GNU GPL version 3 or later.                 #
+#  Improvements and feedback are welcome!                                      #
+################################################################################
+
+set(theme "oldcrystal")
+
+install(FILES audio-volume-error.png audio-volume-muted.png
+              audio-volume-low.png audio-volume-medium.png
+              audio-volume-high.png
+        DESTINATION ${DATA_INSTALL_DIR}/kmix/pics/${theme})
\ No newline at end of file
diff --git a/kmix/pics/oldcrystal/audio-volume-error.png b/kmix/pics/oldcrystal/audio-volume-error.png
new file mode 100644
index 00000000..b0497662
--- /dev/null
+++ b/kmix/pics/oldcrystal/audio-volume-error.png
diff --git a/kmix/pics/oldcrystal/audio-volume-high.png b/kmix/pics/oldcrystal/audio-volume-high.png
new file mode 120000
index 00000000..dd3d1eea
--- /dev/null
+++ b/kmix/pics/oldcrystal/audio-volume-high.png
@@ -0,0 +1 @@
+audio-volume-low.png
\ No newline at end of file
diff --git a/kmix/pics/kmixdocked.png b/kmix/pics/oldcrystal/audio-volume-low.png
index 0c3f17d7..9e8997e5 100644
--- a/kmix/pics/kmixdocked.png
+++ b/kmix/pics/oldcrystal/audio-volume-low.png
diff --git a/kmix/pics/oldcrystal/audio-volume-medium.png b/kmix/pics/oldcrystal/audio-volume-medium.png
new file mode 120000
index 00000000..dd3d1eea
--- /dev/null
+++ b/kmix/pics/oldcrystal/audio-volume-medium.png
@@ -0,0 +1 @@
+audio-volume-low.png
\ No newline at end of file
diff --git a/kmix/pics/kmixdocked_mute.png b/kmix/pics/oldcrystal/audio-volume-muted.png
index 0dae0f15..70764025 100644
--- a/kmix/pics/kmixdocked_mute.png
+++ b/kmix/pics/oldcrystal/audio-volume-muted.png