Merge pull request #115 from jposada202020/base_alignement_proposal

New parameter and example creation for testing and future reference

Author: FoamyGuy

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:
@@ -129,6 +132,7 @@ def __init__(
         self._padding_bottom = padding_bottom
         self._padding_left = padding_left
         self._padding_right = padding_right
+        self.base_alignment = base_alignment
 
         if text is not None:
             self._update_text(str(text))
@@ -159,7 +163,10 @@ 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
@@ -263,8 +270,10 @@ 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 +1,75 @@
+# SPDX-FileCopyrightText: 2021 Jose David Montoya for Adafruit Industries
+# SPDX-License-Identifier: MIT
+
+"""
+This example shows the use of base_alignment parameter.
+"""
+
+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("LeagueSpartan-Bold-16.bdf")
+BIG_FONT = bitmap_font.load_font("IBMPlexMono-Medium-24_jep.bdf")
+
+TEXT_RIGHT = "MG"
+TEXT_LEFT = "32.47"
+
+main_group = displayio.Group()
+
+# Create labels
+# Base Alignment parameter False
+left_text = label.Label(
+    BIG_FONT,
+    text=TEXT_LEFT,
+    color=0x000000,
+    background_color=0x999999,
+    x=10,
+    y=50,
+    base_alignment=False,
+)
+main_group.append(left_text)
+
+right_text = label.Label(
+    MEDIUM_FONT,
+    text=TEXT_RIGHT,
+    color=0x000000,
+    background_color=0x999999,
+    x=80,
+    y=50,
+    base_alignment=False,
+)
+main_group.append(right_text)
+
+# Base Alignment parameter True
+left_text_aligned = label.Label(
+    BIG_FONT,
+    text=TEXT_LEFT,
+    color=0x000000,
+    background_color=0x999999,
+    x=10,
+    y=100,
+    base_alignment=True,
+)
+main_group.append(left_text_aligned)
+
+right_text_aligned = label.Label(
+    MEDIUM_FONT,
+    text=TEXT_RIGHT,
+    color=0x000000,
+    background_color=0x999999,
+    x=80,
+    y=100,
+    base_alignment=True,
+)
+
+main_group.append(right_text_aligned)
+display.show(main_group)
+
+while True:
+    pass