Adding the wrap_by_pixels function

adafruit_display_text/__init__.py

@@ -1,4 +1,4 @@
-# SPDX-FileCopyrightText: 2020 Tim C for Adafruit Industries
+# SPDX-FileCopyrightText: 2020 Tim C, 2021 Jeff Epler for Adafruit Industries
 #
 # SPDX-License-Identifier: MIT
 
@@ -7,6 +7,92 @@
 """
 
 
+def wrap_text_to_pixels(string, max_width, font=None, indent0="", indent1=""):
+    """wrap_text_to_pixels function
+    A helper that will return a list of lines with word-break wrapping.
+    Leading and trailing whitespace in your string will be removed. If
+    you wish to use leading whitespace see `indend0` and `indent1`
+    parameters.
+
+    :param str string: The text to be wrapped.
+    :param int max_width: The maximum number of pixels on a line before wrapping.
+    :param Font font: The font to use for measuring the text.
+    :param str indent0: Additional character(s) to add to the first line.
+    :param str indent1: Additional character(s) to add to all other lines.
+
+
+    :return list lines: A list of the lines resulting from wrapping the
+      input text at max_width pixels size
+
+    """
+    # pylint: disable=too-many-locals too-many-branches
+    if font is None:
+
+        def measure(string):
+            return len(string)
+
+    else:
+        if hasattr(font, "load_glyphs"):
+            font.load_glyphs(string)
+
+        def measure(string):
+            return sum(font.get_glyph(ord(c)).shift_x for c in string)
+
+    lines = []
+    partial = [indent0]
+    width = measure(indent0)
+    swidth = measure(" ")
+    firstword = True
+    for line_in_input in string.split("\n"):
+        for index, word in enumerate(line_in_input.split(" ")):
+            wwidth = measure(word)
+            word_parts = []
+            cur_part = ""
+
+            if wwidth > max_width:
+                for char in word:
+                    if (
+                        measure("".join(partial))
+                        + measure(cur_part)
+                        + measure(char)
+                        + measure("-")
+                        > max_width
+                    ):
+                        word_parts.append("".join(partial) + cur_part + "-")
+                        cur_part = char
+                        partial = [indent1]
+                    else:
+                        cur_part += char
+                if cur_part:
+                    word_parts.append(cur_part)
+                for line in word_parts[:-1]:
+                    lines.append(line)
+                partial.append(word_parts[-1])
+                width = measure(word_parts[-1])
+                if firstword:
+                    firstword = False
+            else:
+                if firstword:
+                    partial.append(word)
+                    firstword = False
+                    width += wwidth
+                elif width + swidth + wwidth < max_width:
+                    if index > 0:
+                        partial.append(" ")
+                    partial.append(word)
+                    width += wwidth + swidth
+                else:
+                    lines.append("".join(partial))
+                    partial = [indent1, word]
+                    width = measure(indent1) + wwidth
+
+        lines.append("".join(partial))
+        partial = [indent1]
+        width = measure(indent1)
+
+    return lines
+
+
 def wrap_text_to_lines(string, max_chars):
     """wrap_text_to_lines function
     A helper that will return a list of lines with word-break wrapping

examples/display_text_wrap_pixels_test.py

@@ -0,0 +1,63 @@
+# SPDX-FileCopyrightText: 2021 Tim C, written for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+"""
+Test the wrap_text_to_pixels function. Try changing WRAP_WIDTH or text
+and observe the results. The red bar represents the full size of
+WRAP_WIDTH.
+"""
+
+import board
+import displayio
+import terminalio
+from adafruit_display_text import label, wrap_text_to_pixels
+
+WRAP_WIDTH = 140
+text = (
+    "CircuitPython is a programming language designed to simplify experimenting "
+    "and learning to code on low-cost microcontroller boards. "
+)
+
+# use built in display (PyPortal, PyGamer, PyBadge, CLUE, etc.)
+# see guide for setting up external displays (TFT / OLED breakouts, RGB matrices, etc.)
+# https://learn.adafruit.com/circuitpython-display-support-using-displayio/display-and-display-bus
+display = board.DISPLAY
+
+# Make the display context
+main_group = displayio.Group(max_size=10)
+display.show(main_group)
+
+font = terminalio.FONT
+
+print(text)
+print(display.width)
+
+text_area = label.Label(
+    font,
+    text="\n".join(wrap_text_to_pixels(text, WRAP_WIDTH, font)),
+    background_color=0x0000DD,
+)
+
+text_area.anchor_point = (0, 0)
+text_area.anchored_position = (0, 0)
+
+main_group.append(text_area)
+
+# Create a bitmap with two colors
+size_checker = displayio.Bitmap(WRAP_WIDTH, 10, 2)
+# Create a two color palette
+palette = displayio.Palette(2)
+palette[0] = 0x0000DD
+palette[1] = 0xDD0000
+
+# Create a TileGrid using the Bitmap and Palette
+tile_grid = displayio.TileGrid(size_checker, pixel_shader=palette)
+
+tile_grid.y = text_area.bounding_box[1] + text_area.bounding_box[3] + 10
+
+size_checker.fill(1)
+
+main_group.append(tile_grid)
+
+while True:
+    pass