Updated background color handling for label

adafruit_display_text/label.py

@@ -72,13 +72,19 @@ def __init__(
         color=0xFFFFFF,
         background_color=None,
         line_spacing=1.25,
+        background_tight=False,
+        padding_top=0,
+        padding_bottom=0,
+        padding_left=0,
+        padding_right=0,
         **kwargs
     ):
         if not max_glyphs and not text:
             raise RuntimeError("Please provide a max size, or initial text")
         if not max_glyphs:
-            max_glyphs = len(text)
+            max_glyphs = len(text) + 1  # add one for the background bitmap tileGrid
         super().__init__(max_size=max_glyphs, **kwargs)
+
         self.width = max_glyphs
         self._font = font
         self._text = None
@@ -87,28 +93,48 @@ def __init__(
         self.y = y
 
         self.palette = displayio.Palette(2)
-        if background_color is not None:
-            self.palette[0] = background_color
-            self.palette.make_opaque(0)
-            self._transparent_background = False
-        else:
-            self.palette[0] = 0
-            self.palette.make_transparent(0)
-            self._transparent_background = True
+        self.palette[0] = 0
+        self.palette.make_transparent(0)
+        self._transparent_background = True
         self.palette[1] = color
 
+        self._background_color = background_color
+
         bounds = self._font.get_bounding_box()
         self.height = bounds[1]
         self._line_spacing = line_spacing
         self._boundingbox = None
 
+        self._background_tight = background_tight  # sets padding status for text background
+
+        self._background_palette = displayio.Palette(1)
+        self.append(
+            displayio.TileGrid(
+                displayio.Bitmap(0, 0, 1), pixel_shader=self._background_palette
+            )
+        )  # initialize with a blank tilegrid placeholder for background
+
+        self._padding_top = padding_top
+        self._padding_bottom = padding_bottom
+        self._padding_left = padding_left
+        self._padding_right = padding_right
+
         if text is not None:
             self._update_text(str(text))
 
+    def _update_background_color(self, new_color):
+
+        if new_color == None:
+            self._background_palette.make_transparent(0)
+        else:
+            self._background_palette.make_opaque(0)
+            self._background_palette[0] = new_color
+        self._background_color = new_color
+
     def _update_text(self, new_text):  # pylint: disable=too-many-locals
         x = 0
         y = 0
-        i = 0
+        i = 1
         old_c = 0
         y_offset = int(
             (
@@ -118,17 +144,21 @@ def _update_text(self, new_text):  # pylint: disable=too-many-locals
             / 2
         )
         left = right = top = bottom = 0
+        lines = 1
         for character in new_text:
             if character == "\n":
                 y += int(self.height * self._line_spacing)
                 x = 0
+                lines += 1
                 continue
             glyph = self._font.get_glyph(ord(character))
             if not glyph:
                 continue
-            right = max(right, x + glyph.width + glyph.shift_x)
+            right = max(
+                right, x + glyph.shift_x
+            )  # studied the docs! This is the correct spacing
             if y == 0:  # first line, find the Ascender height
-                top = min(top, -glyph.height + y_offset)
+                top = min(top, -glyph.height - glyph.dy + y_offset)
             bottom = max(bottom, y - glyph.dy + y_offset)
             position_y = y - glyph.height - glyph.dy + y_offset
             position_x = x + glyph.dx
@@ -161,14 +191,14 @@ def _update_text(self, new_text):  # pylint: disable=too-many-locals
                 else:
                     self.append(face)
             elif self._text and character == self._text[old_c]:
+
                 try:
                     self[i].position = (position_x, position_y)
                 except AttributeError:
                     self[i].x = position_x
                     self[i].y = position_y
 
             x += glyph.shift_x
-
             # TODO skip this for control sequences or non-printables.
             i += 1
             old_c += 1
@@ -188,6 +218,46 @@ def _update_text(self, new_text):  # pylint: disable=too-many-locals
         self._text = new_text
         self._boundingbox = (left, top, left + right, bottom - top)
 
+        if self._background_tight:  # draw a tight bounding box
+            box_width = self._boundingbox[2]
+            box_height = self._boundingbox[3]
+            x_box_offset = 0
+            y_box_offset = top
+
+        else:  # draw a "loose" bounding box to include any ascenders/descenders.
+
+            # check a few glyphs for maximum ascender and descender height
+            # Enhancement: it would be preferred to access the font "FONT_ASCENT" and "FONT_DESCENT" in the imported BDF file
+            glyphs = "M j'"  # choose glyphs with highest ascender and lowest descender, will depend upon font used
+            ascender_max = descender_max = 0
+            for char in glyphs:
+                thisGlyph = self._font.get_glyph(ord(char))
+                ascender_max = max(ascender_max, thisGlyph.height + thisGlyph.dy)
+                descender_max = max(descender_max, -thisGlyph.dy)
+
+            box_width = self._boundingbox[2] + self._padding_left + self._padding_right
+            x_box_offset = -self._padding_left
+            box_height = (
+                (ascender_max + descender_max)
+                + int((lines - 1) * self.height * self._line_spacing)
+                + self._padding_top
+                + self._padding_bottom
+            )
+            y_box_offset = -ascender_max + y_offset - self._padding_top
+
+        self._update_background_color(self._background_color)
+        box_width = max(0, box_width)  # remove any negative values
+        box_height = max(0, box_height)  # remove any negative values
+
+        background_bitmap = displayio.Bitmap(box_width, box_height, 1)
+        tile_grid = displayio.TileGrid(
+            background_bitmap,
+            pixel_shader=self._background_palette,
+            x=left + x_box_offset,
+            y=y_box_offset,
+        )
+        self[0] = tile_grid  # update the background bitmap in first item of the group
+
     @property
     def bounding_box(self):
         """An (x, y, w, h) tuple that completely covers all glyphs. The
@@ -216,20 +286,11 @@ def color(self, new_color):
     @property
     def background_color(self):
         """Color of the background as an RGB hex number."""
-        if not self._transparent_background:
-            return self.palette[0]
-        return None
+        return self._background_color
 
     @background_color.setter
     def background_color(self, new_color):
-        if new_color is not None:
-            self.palette[0] = new_color
-            self.palette.make_opaque(0)
-            self._transparent_background = False
-        else:
-            self.palette[0] = 0
-            self.palette.make_transparent(0)
-            self._transparent_background = True
+        self._update_background_color(new_color)
 
     @property
     def text(self):

examples/display_text_background_color_padding.py

@@ -0,0 +1,130 @@
+"""
+This examples shows the use color and background_color
+"""
+import board
+import displayio
+import time
+import terminalio
+import fontio
+import sys
+import busio
+
+# from adafruit_st7789 import ST7789
+from adafruit_ili9341 import ILI9341
+from adafruit_display_text import label
+
+#  Setup the SPI display
+
+print("Starting the display...")  # goes to serial only
+displayio.release_displays()
+
+
+spi = board.SPI()
+tft_cs = board.D9  # arbitrary, pin not used
+tft_dc = board.D10
+tft_backlight = board.D12
+tft_reset = board.D11
+
+while not spi.try_lock():
+    spi.configure(baudrate=32000000)
+    pass
+spi.unlock()
+
+display_bus = displayio.FourWire(
+    spi,
+    command=tft_dc,
+    chip_select=tft_cs,
+    reset=tft_reset,
+    baudrate=32000000,
+    polarity=1,
+    phase=1,
+)
+
+print("spi.frequency: {}".format(spi.frequency))
+
+DISPLAY_WIDTH = 320
+DISPLAY_HEIGHT = 240
+
+# display = ST7789(display_bus, width=240, height=240, rotation=0, rowstart=80, colstart=0)
+display = ILI9341(
+    display_bus,
+    width=DISPLAY_WIDTH,
+    height=DISPLAY_HEIGHT,
+    rotation=180,
+    auto_refresh=True,
+)
+
+display.show(None)
+
+# font=terminalio.FONT
+
+from adafruit_bitmap_font import bitmap_font
+
+font = bitmap_font.load_font("fonts/BitstreamVeraSans-Roman-24.bdf")
+
+
+text = []
+text.append("none")  # no ascenders or descenders
+text.append("pop quops")  # only descenders
+text.append("MONSTERs are tall")  # only ascenders
+text.append("MONSTERs ate pop quops")  # both ascenders and descenders
+text.append("MONSTER quops\nnewline quops")  # with newline
+
+display.auto_refresh = True
+myGroup = displayio.Group(max_size=6)
+display.show(myGroup)
+
+text_area = []
+myPadding = 4
+
+for i, thisText in enumerate(text):
+    text_area.append(
+        label.Label(
+            font,
+            text=thisText,
+            color=0xFFFFFF,
+            background_color=None,
+            background_tight=False,
+            padding_top=myPadding,
+            padding_bottom=myPadding,
+            padding_left=myPadding,
+            padding_right=myPadding,
+        )
+    )
+
+    this_x = 10
+    this_y = 10 + i * 40
+    text_area[i].x = 10
+    text_area[i].y = 3 + i * 50
+    text_area[i].anchor_point = (0, 0)
+    text_area[i].anchored_position = (this_x, this_y)
+    myGroup.append(text_area[i])
+
+print("background color is {}".format(text_area[0].background_color))
+
+
+while True:
+    time.sleep(2)
+    text_area[
+        0
+    ].text = "text"  # change some text in an existing text box (must fit within existing # of characters)
+
+    for area in text_area:
+        area.background_color = 0xFF0000
+    print("background color is {:06x}".format(text_area[0].background_color))
+    time.sleep(2)
+    for area in text_area:
+        area.background_color = 0x000088
+    print("background color is {:06x}".format(text_area[0].background_color))
+    time.sleep(2)
+    for area in text_area:
+        area.background_color = 0x00FF00
+    print("background color is {:06x}".format(text_area[0].background_color))
+    time.sleep(2)
+    for area in text_area:
+        area.background_color = 0xFF0000
+    print("background color is {:06x}".format(text_area[0].background_color))
+    time.sleep(2)
+    for area in text_area:
+        area.background_color = None
+    print("background color is {}".format(text_area[0].background_color))