New parameter and example creation for testing and future reference

adafruit_display_text/label.py

@@ -59,7 +59,9 @@ class Label(displayio.Group):
      (E.g. (0,0) is top left, (1.0, 0.5): is middle right.)
     :param (int,int) anchored_position: Position relative to the anchor_point. Tuple
      containing x,y pixel coordinates.
-    :param int scale: Integer value of the pixel scaling"""
+    :param int scale: Integer value of the pixel scaling
+    :param bool base_alignment: when True allows to align text label to the baseline.
+     This is helpful when two or more labels need to be aligned to the same baseline"""
 
     # pylint: disable=too-many-instance-attributes, too-many-locals
     # This has a lot of getters/setters, maybe it needs cleanup.
@@ -83,6 +85,7 @@ def __init__(
         anchor_point=None,
         anchored_position=None,
         scale=1,
+        base_alignment=False,
         **kwargs
     ):
         if not max_glyphs and not text:
@@ -131,6 +134,7 @@ def __init__(
         self._padding_right = padding_right
 
         self._scale = scale
+        self.base_alignment = base_alignment
 
         if text is not None:
             self._update_text(str(text))
@@ -161,7 +165,10 @@ def _create_background_box(self, lines, y_offset):
                 + self._padding_top
                 + self._padding_bottom
             )
-            y_box_offset = -ascent + y_offset - self._padding_top
+            if self.base_alignment:
+                y_box_offset = -ascent - self._padding_top
+            else:
+                y_box_offset = -ascent + y_offset - self._padding_top
 
         box_width = max(0, box_width)  # remove any negative values
         box_height = max(0, box_height)  # remove any negative values
@@ -265,8 +272,10 @@ def _update_text(
         else:
             i = 0
         tilegrid_count = i
-
-        y_offset = self._get_ascent() // 2
+        if self.base_alignment:
+            y_offset = 0
+        else:
+            y_offset = self._get_ascent() // 2
 
         right = top = bottom = 0
         left = None

examples/display_text_label_align_baseline_comparison.py

@@ -0,0 +1,79 @@
+# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
+# SPDX-License-Identifier: MIT
+
+"""
+This examples shows the use of base_alignment parameter.
+"""
+
+import time
+import board
+import displayio
+from adafruit_bitmap_font import bitmap_font
+from adafruit_display_text import label
+
+
+display = board.DISPLAY
+
+# Font definition. You can choose any two fonts available in your system
+MEDIUM_FONT = bitmap_font.load_font("Helvetica-Bold-16.bdf")
+BIG_FONT = bitmap_font.load_font("LeagueSpartan-Bold-16.bdf")
+
+# Test parameters
+TEXT_BACKGROUND_COLOR = 0x990099
+TEXT_COLOR = 0x00FF00
+X_COL_POS = [10, 90]  # X position of the Label boxes
+TEST_TEXT = [
+    "aApPqQ.",
+    "ppppppp",
+    "llllll",
+    "oooooo",
+    "ñúÇèüß",
+]  # Iteration text for testing
+LOCALISATION_Y = [40, 80, 120, 160, 200]  # Y coordinate of the text labels
+NUMBER_TEXT_LABELS = len(LOCALISATION_Y) * len(
+    X_COL_POS
+)  # Calculation for Display.Group function
+TIME_BETWEEN_TEXTS = 5  # Seconds
+BASE_ALIGNMENT_OPTIONS = [False, True]
+
+# Test
+for behaviour in BASE_ALIGNMENT_OPTIONS:
+    for text_test in TEST_TEXT:
+        main_group = displayio.Group(max_size=NUMBER_TEXT_LABELS + 1)
+        for position in LOCALISATION_Y:
+            text = label.Label(
+                font=MEDIUM_FONT,
+                text=text_test,
+                color=TEXT_COLOR,
+                background_tight=True,
+                background_color=TEXT_BACKGROUND_COLOR,
+                x=X_COL_POS[0],
+                y=position,
+                base_alignment=behaviour,
+            )
+            main_group.append(text)
+            text = label.Label(
+                font=BIG_FONT,
+                text=text_test,
+                color=TEXT_COLOR,
+                background_tight=False,
+                background_color=TEXT_BACKGROUND_COLOR,
+                x=X_COL_POS[1],
+                y=position,
+                base_alignment=behaviour,
+            )
+            main_group.append(text)
+            display.show(main_group)
+            display.refresh()
+        time.sleep(TIME_BETWEEN_TEXTS)
+
+
+bitmap = displayio.Bitmap(280, 5, 2)
+palette = displayio.Palette(2)
+palette[0] = 0x004400
+palette[1] = 0x00FFFF
+tile_grid2 = displayio.TileGrid(bitmap, pixel_shader=palette, x=10, y=160)
+main_group.append(tile_grid2)
+
+while True:
+    pass