Fix epaper demo initial refresh.

README.md

@@ -3090,26 +3090,40 @@ connecting to any host. The hardware_setup.py should be copied or adapted from
 `setup_examples/pico_epaper_42_pico.py`. If using the socket, default args may
 be used (see code comment).
 
-After an initial refresh to clear the screen the driver is put into partial
+Some attention to detail is required to handle the refresh characteristics.
-mode. This provides a reasonably quick and visually satisfactory response to
+The application must wait for the initial full refresh (which occurs
-user inputs such as button events. See the 
+automatically) before putting the display into partial mode. This is done by
+the screen constructor issuing
+```python
+        asyncio.create_task(set_partial())
+```
+to run
+```python
+async def set_partial():  # Ensure 1st refresh is a full refresh
+    await Screen.rfsh_done.wait()  # Wait for first refresh to end
+    ssd.set_partial()
+```
+The application then runs in partial mode with a reasonably quick and visually
+satisfactory response to user inputs such as button events. See the 
 [epaper demo](https://github.com/peterhinch/micropython-micro-gui/blob/main/gui/demos/epaper.py).
-This provides for a full refresh via the `reset` button. Provision of full
-refresh is application dependent. It should be done as follows:
 
+It is likely that applications will provide a full refresh method to clear any
+ghosting. The demo provides for a full refresh via the `reset` button. A full
+refresh should be done as follows:
 ```python
 async def full_refresh():
     Screen.rfsh_done.clear()  # Enable completion flag
     await Screen.rfsh_done.wait()  # Wait for a refresh to end
     ssd.set_full()
-    Screen.rfsh_done.clear()  # Enable completion flag
+    Screen.rfsh_done.clear()  # Re-enable completion flag
     await Screen.rfsh_done.wait()  # Wait for a single full refresh to end
-    ssd.set_partial()
+    ssd.set_partial()  # Subsequent refreshes are partial
 ```
-
 The driver for the supported display uses 1-bit color mapping: this means that
 greying-out has no visible effect. Greyed-out controls cannot accept the focus
-and are therefore disabled but appearance is unchanged.
+and are therefore disabled but appearance is unchanged. `nano-gui` has a 2-bit
+driver which supports greyscales, but there is no partial support so this is
+unsuitable for `micro_gui`.
 
 ###### [Contents](./README.md#0-contents)
 

gui/demos/calendar.py

@@ -28,6 +28,8 @@ class BaseScreen(Screen):
         row = 2
         rows = 6
         cols = 7
+        self.ncells = cols * (rows - 1)  # Row 0 has day labels
+        self.last_cell = cols * rows
         colwidth = 35
         self.lbl = Label(wri, row, col, text = (colwidth + 4) * cols, justify=Label.CENTRE)
         row = self.lbl.mrow
@@ -72,49 +74,28 @@ class BaseScreen(Screen):
             d.now()
         self.update()
 
-    def update(self):
+    def days(self, month_length):  # Produce content for every cell
-        def cell():
+        for n in range(self.ncells + 1):
-            if cur.year == today.year and cur.month == today.month and mday == today.mday:  # Today
+            yield str(n + 1) if n < month_length else ""
-                d["fgcolor"] = RED
-            elif mday == cur.mday:  # Currency
-                d["fgcolor"] = YELLOW
-            elif mday in sundays:
-                d["fgcolor"] = BLUE
-            else:
-                d["fgcolor"] = GREEN
-            d["text"] = str(mday)
-            self.grid[idx] = d
 
-        today = DateCal()
+    def update(self):
+        grid = self.grid
         cur = self.date  # Currency
         self.lbl.value(f"{DateCal.months[cur.month - 1]} {cur.year}")
-        d = {}  # Args for Label.value
+        # Populate day number cells
-        wday = 0
+        values = self.days(cur.month_length)  # Instantiate generator
-        wday_1 = cur.wday_n(1)  # Weekday of 1st of month
+        idx_1 = 7 + cur.wday_n(1)  # Index of 1st of month
-        mday = 1
+        grid[idx_1 : self.last_cell] = values  # Populate from mday 1 to last cell
-        seek = True
+        grid[7 : idx_1] = values  # Populate cells before 1st of month
-        sundays = cur.mday_list(6)
+        # Color cells of Sunday, today and currency. In collisions (e.g. today==Sun)
-        for idx in range(7, self.grid.ncells):
+        # last color applied is effective
-            if seek:  # Find column for 1st of month
+        grid[1:6, 6] = {"fgcolor": BLUE}  # Sunday color
-                if wday < wday_1:
+        grid[idx_1 + cur.mday - 1] = {"fgcolor": YELLOW}  # Currency
-                    self.grid[idx] = ""
+        today = DateCal()
-                    wday += 1
+        if cur.year == today.year and cur.month == today.month:  # Today is in current month
-                else:
+            grid[idx_1 + today.mday - 1] = {"fgcolor": RED}
-                    seek = False
-            if not seek:
-                if mday <= cur.month_length:
-                    cell()
-                    mday += 1
-                else:
-                    self.grid[idx] = ""
-        idx = 7  # Where another row would be needed, roll over to top few cells.
-        while mday <= cur.month_length:
-            cell()
-            idx += 1
-            mday += 1
         self.lblnow.value(f"{today.day_str} {today.mday} {today.month_str} {today.year}")
 
-
 def test():
     print('Calendar demo.')
     Screen.change(BaseScreen)  # A class is passed here, not an instance.

gui/demos/epaper.py

@@ -47,6 +47,9 @@ async def full_refresh():
     await Screen.rfsh_done.wait()  # Wait for a single full refresh to end
     ssd.set_partial()
 
+async def set_partial():  # Ensure 1st refresh is a full refresh
+    await Screen.rfsh_done.wait()  # Wait for first refresh to end
+    ssd.set_partial()
 
 class FooScreen(Screen):
     def __init__(self):
@@ -161,6 +164,7 @@ class FooScreen(Screen):
         Label(wri_large, lbl.mrow + 5, col, "y = sinc(x)")
 
         CloseButton(wri, bgcolor=BLACK)
+        asyncio.create_task(set_partial())  # After 1st full refresh
         asyncio.create_task(run(dial, lbltim, m0, scale))
 
     def callback(self, button, buttons, val):
@@ -186,7 +190,6 @@ class FooScreen(Screen):
                 x += 0.05
 
         Curve(self.graph, None, populate())
-        asyncio.create_task(full_refresh())
 
 
 async def run(dial, lbltim, m0, scale):

gui/widgets/label.py

@@ -28,24 +28,25 @@ class Label(Widget):
             self.value(text, invert)
 
     def value(self, text=None, invert=False, fgcolor=None, bgcolor=None, bdcolor=None, justify=None):
-        sl = self.writer.stringlen(text)
+        if text is not None:
-        if justify is None:
+            sl = self.writer.stringlen(text)
-            justify = self.justify
+            if justify is None:
-        self.tcol = self.col  # Default is left justify
+                justify = self.justify
-        if sl > self.width:  # Clip
+            self.tcol = self.col  # Default is left justify
-            font = self.writer.font
+            if sl > self.width:  # Clip
-            pos = 0
+                font = self.writer.font
-            n = 0
+                pos = 0
-            for ch in text:
+                n = 0
-                pos += font.get_ch(ch)[2]  # width of current char
+                for ch in text:
-                if pos > self.width:
+                    pos += font.get_ch(ch)[2]  # width of current char
-                    break
+                    if pos > self.width:
-                n += 1
+                        break
-            text = text[: n]
+                    n += 1
-        elif justify == 1:  # Centre
+                text = text[: n]
-            self.tcol = self.col + (self.width - sl) // 2
+            elif justify == 1:  # Centre
-        elif justify == 2:  # Right
+                self.tcol = self.col + (self.width - sl) // 2
-            self.tcol = self.col + self.width - sl
+            elif justify == 2:  # Right
+                self.tcol = self.col + self.width - sl
             
         txt = super().value(text)
         self.draw = True  # Redraw unconditionally: colors may have changed.

setup_examples/pico_epaper_42_pico.py

@@ -56,4 +56,3 @@ decrease = Pin(17, Pin.IN, Pin.PULL_UP)  # Decrease control's value
 # display = Display(ssd, nxt, sel, prev)  # 3-button mode
 display = Display(ssd, nxt, sel, prev, increase, decrease)  # 5-button mode
 ssd.wait_until_ready()  # Blocking wait
-ssd.set_partial()  # Subsequent refreshes are partial