add experimental animation with `async for`

src/apps/homescreen/layout_homescreen.py

@@ -10,9 +10,14 @@ async def swipe_to_rotate():
 
 
 async def animate_logo():
-    def func(foreground):
-        ui.display.icon(0, 0, res.load('apps/homescreen/res/trezor.toig'), foreground, ui.BLACK)
-    await ui.animate_pulse(func, ui.WHITE, ui.GREY, speed=400000)
+    # def func(foreground):
+    #     ui.display.icon(0, 0, res.load(
+    #         'apps/homescreen/res/trezor.toig'), foreground, ui.BLACK)
+    # await ui.animate_pulse(func, ui.WHITE, ui.GREY, speed=400000)
+
+    async for fg in ui.pulse_animation(ui.WHITE, ui.GREY, speed=400000):
+        icon = res.load('apps/homescreen/res/trezor.toig')
+        ui.display.icon(0, 0, icon, fg, ui.BLACK)
 
 
 @unimport_gen

src/trezor/ui/__init__.py

@@ -76,6 +76,25 @@ def animate_pulse(func, ca, cb, speed=200000, delay=30000):
         yield loop.Sleep(delay)
 
 
+class pulse_animation:
+
+    def __init__(self, color_a, color_b, speed=200000, delay=30000):
+        self.color_a = color_a
+        self.color_b = color_b
+        self.speed = speed
+        self.delay = delay
+
+    async def __aiter__(self):
+        return self
+
+    async def __anext__(self):
+        # normalize sin from interval -1:1 to 0:1
+        y = 0.5 + 0.5 * math.sin(utime.ticks_us() / self.speed)
+        c = blend(self.color_a, self.color_b, y)
+        await loop.Sleep(self.delay)
+        return c
+
+
 def rotate_coords(pos: tuple) -> tuple:
     r = display.orientation()
     if r == 0: