Add tests and examples for triangle wave

Author: yuma-m

example/play_440hz.py

@@ -20,6 +20,11 @@ def main():
     player.play_wave(synthesizer.generate_constant_wave(440.0, 3.0))
     time.sleep(0.5)
 
+    print("play triangle wave")
+    synthesizer = Synthesizer(osc1_waveform=Waveform.triangle, osc1_volume=0.8, use_osc2=False)
+    player.play_wave(synthesizer.generate_constant_wave(440.0, 3.0))
+    time.sleep(0.5)
+
     print("play synthesized wave 1")
     synthesizer = Synthesizer(
         osc1_waveform=Waveform.sawtooth, osc1_volume=1.0,

synthesizer/synthesizer.py

@@ -45,8 +45,10 @@ def generate_wave(self, phases):
         phases = np.copy(phases) * self._freq_transpose
         return self._volume * self._wave_func(phases)
 
-    def gen_triang(self,t,width=0.5):
-	    return scipy.signal.sawtooth(t,width)
+    @staticmethod
+    def gen_triang(t, width=0.5):
+        return scipy.signal.sawtooth(t, width)
+
 
 class Synthesizer(object):
     u""" Virtual analog synthesizer object

test/test_synthesizer.py

@@ -31,3 +31,12 @@ def test_square_wave():
     assert_almost_equal(wave.max(), 1.0, places=3)
     assert_almost_equal(wave.min(), -1.0, places=3)
     assert_almost_equal(wave.mean(), 0.0, places=3)
+
+
+def test_triangle_wave():
+    synthesizer = Synthesizer(osc1_waveform=Waveform.triangle, osc1_volume=1.0, use_osc2=False, rate=RATE)
+    wave = synthesizer.generate_constant_wave(440.0, 1.0)
+    eq_(wave.size, RATE)
+    assert_almost_equal(wave.max(), 1.0, places=3)
+    assert_almost_equal(wave.min(), -1.0, places=3)
+    assert_almost_equal(wave.mean(), 0.0, places=3)