adding thermometer example

examples/gizmo_tft_termometer.py

@@ -0,0 +1,94 @@
+"""
+This example will initialize the display using displayio and draw a bmp image
+background, and overlay text containing the value read from the on-board temperature sensor.
+User may press the A button to switch between celsius and fahrenheit units.
+
+Required libraries:
+* Adafruit_CircuitPython_Gizmo
+* Adafruit_CircuitPython_ST7789
+* Adafruit_CircuitPython_Display_Text
+* Adafruit_CircuitPython_CircuitPlayground
+"""
+import time
+from adafruit_circuitplayground import cp
+import displayio
+import terminalio
+from adafruit_display_text import label
+from adafruit_gizmo import tft_gizmo
+display = tft_gizmo.TFT_Gizmo()
+
+
+# text scaling factor
+TEXT_SCALE = 2
+
+# previous iteration button value
+old_a_val = cp.button_a
+
+# boolean for current unit type
+show_c_units = True
+
+
+# function to convert celsius degrees to fahrenheit
+def c_to_f(c_val):
+    return (c_val * 9/5) + 32
+
+
+# Open the background image file
+with open("/thermometer_background.bmp", "rb") as bitmap_file:
+
+    # Setup the file as the bitmap data source
+    bitmap = displayio.OnDiskBitmap(bitmap_file)
+
+    # Create a TileGrid to hold the bitmap
+    tile_grid = displayio.TileGrid(bitmap, pixel_shader=displayio.ColorConverter())
+
+    # Create a Group to hold the TileGrid
+    group = displayio.Group()
+
+    # Add the TileGrid to the Group
+    group.append(tile_grid)
+
+    # variable with initial text value, temperature rounded to 2 places
+    text = "%.2f C" % (round(cp.temperature, 2))
+
+    # Create a Group for the text so we can scale it
+    text_group = displayio.Group(max_size=1, scale=TEXT_SCALE, x=0, y=0)
+
+    # Create a Label to show the initial temperature value
+    text_area = label.Label(terminalio.FONT, text=text, color=0xFFFFFF)
+
+    # Set the anchor_point for center,top
+    text_area.anchor_point = (0.5, 0.0)
+
+    # Set the location to center of display, accounting for text_scale
+    text_area.anchored_position = (240/(2*TEXT_SCALE), 240/(2*TEXT_SCALE))
+
+    # Subgroup for text scaling
+    text_group.append(text_area)
+
+    # Add the text_group to main Group
+    group.append(text_group)
+
+    # Add the main Group to the Display
+    display.show(group)
+
+    # Loop forever
+    while True:
+        # set current button state to variable
+        cur_a_val = cp.button_a
+        if cur_a_val and not old_a_val:  # if the button was released
+            print('Just released')
+            # flip the units boolean to the opposite value
+            show_c_units = not show_c_units
+
+        if show_c_units:
+            # Update the text
+            text_area.text = "%.2f C" % (round(cp.temperature, 2))
+        else:  # show f units
+            # Update the text
+            text_area.text = "%.2f F" % (round(c_to_f(cp.temperature), 2))
+
+        # set previous button value for next time
+        old_a_val = cur_a_val
+        # Wait a little bit
+        time.sleep(0.2)