Improve specrum visulaizer for transparent backgrounds (#467)

* Replace "hack" with hacky chars

* Remove unnecessary spaces

* Add config option visualizer_spectrum_use_legacy_chars

src/screens/visualizer.cpp

@@ -83,7 +83,8 @@ Visualizer::Visualizer()
   HZ_MIN(Config.visualizer_spectrum_hz_min),
   HZ_MAX(Config.visualizer_spectrum_hz_max),
   GAIN(Config.visualizer_spectrum_gain),
-  SMOOTH_CHARS(ToWString("▁▂▃▄▅▆▇█"))
+  SMOOTH_CHARS(ToWString("▁▂▃▄▅▆▇█")),
+  SMOOTH_CHARS_FLIPPED(ToWString("▔🮂🮃🮄🬎🮅🮆█")) // https://unicode.org/charts/PDF/U1FB00.pdf
 #endif
 {
 	InitDataSource();
@@ -518,8 +519,12 @@ void Visualizer::DrawFrequencySpectrum(const int16_t *buf, ssize_t samples, size
 				} else {
 					// fractional height
 					if (flipped) {
-						ch = SMOOTH_CHARS[size-idx-2];
-						color = NC::FormattedColor(color.color(), {NC::Format::Reverse});
+						if (Config.visualizer_spectrum_use_legacy_chars) {
+							ch = SMOOTH_CHARS_FLIPPED[idx];
+						} else {
+							ch = SMOOTH_CHARS[size-idx-2];
+							color = NC::FormattedColor(color.color(), {NC::Format::Reverse});
+						}
 					} else {
 						ch = SMOOTH_CHARS[idx];
 					}

src/screens/visualizer.h

@@ -113,6 +113,7 @@ private:
 	const double HZ_MAX;
 	const double GAIN;
 	const std::wstring SMOOTH_CHARS;
+	const std::wstring SMOOTH_CHARS_FLIPPED;
 	std::vector<double> m_dft_logspace;
 	std::vector<std::pair<size_t, double>> m_bar_heights;
 

src/settings.cpp

@@ -253,6 +253,7 @@ bool Configuration::read(const std::vector<std::string> &config_paths, bool igno
 			});
 	p.add("visualizer_autoscale", &visualizer_autoscale, "no", yes_no);
 	p.add("visualizer_spectrum_smooth_look", &visualizer_spectrum_smooth_look, "yes", yes_no);
+	p.add("visualizer_spectrum_use_legacy_chars", &visualizer_spectrum_use_legacy_chars, "yes", yes_no);
 	p.add("visualizer_spectrum_dft_size", &visualizer_spectrum_dft_size,
 			"2", [](std::string v) {
 			auto result = verbose_lexical_cast<size_t>(v);

src/settings.h

@@ -86,6 +86,7 @@ struct Configuration
 	size_t visualizer_fps;
 	bool visualizer_autoscale;
 	bool visualizer_spectrum_smooth_look;
+	bool visualizer_spectrum_use_legacy_chars;
 	uint32_t visualizer_spectrum_dft_size;
 	double visualizer_spectrum_gain;
 	double visualizer_spectrum_hz_min;