Transfer the scale attribute down to the inner local_group and keep the scale of Label at 1

[lesamouraipourpre]

This is a fix for #113 .

It keeps the scale of this outer Label at 1 and passes any scale setting
through to the local_group inside as described in the comments already in
the init method.

[jposada202020]

I verify the changes for the proposal using a WIO terminal in CircuitPython 6.1.0 with the following code adapted from @lesamouraipourpre

"""
This examples shows the use of scale 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
FONT = bitmap_font.load_font("/fonts/Helvetica-Bold-16.bdf")

# Test parameters
SCREEN_BACKGROUND_COLOR = 0x990099
TEXT_BACKGROUND_COLOR = 0x440044
TEXT_COLOR = 0x00FF00
X_COL_POS = [10]  # X position of the Label boxes

TEST_TEXT = "pqQñúÇß"  # text for testing

LOCALISATION_Y = [50, 100, 150]  # Y coordinate of the text labels
TEST_SCALES = [1, 2, 3]


main_group = displayio.Group(max_size=len(LOCALISATION_Y)+1)
bg_bitmap = displayio.Bitmap(display.width, display.height , 1)
bg_palette = displayio.Palette(1)
bg_palette[0] = SCREEN_BACKGROUND_COLOR
main_group.append(displayio.TileGrid(bg_bitmap, pixel_shader=bg_palette))

# Test
for i, numerto_test in enumerate(TEST_SCALES):
    text = label.Label(
        font=FONT, 
        text=TEST_TEXT, 
        color=TEXT_COLOR, 
        background_color=TEXT_BACKGROUND_COLOR,
        scale=TEST_SCALES[i], 
        x=X_COL_POS[0], 
        y=LOCALISATION_Y[i]
    )

    main_group.append(text)

display.show(main_group)
display.refresh()

while True:
    pass

The solution works well in the WIO Terrminal

[kmatch98]

This PR change causes an issue with the anchor_point and anchored_position calculations that rely on the self._scale value.

By changing all current references to scale._scale to self.scale will ensure that the overridden scale setter will be used. (Note: I think this will resolve the differences observed in Blinka, since the Blika's definition of displayio.Group contains a conflicting self._scale that is causing conflicts.) I also reviewed bitmap_label.py and it may have similar issues as observed with label.py and Blinka. Can you please check this?

Here's the error I got when running on a pyPortal:

test_label3.bounding_box: (0, -7, 30, 14)
Traceback (most recent call last):
  File "code.py", line 53, in <module>
  File "/lib/adafruit_display_text/label.py", line 454, in anchored_position
AttributeError: 'Label' object has no attribute '_scale'

Here's the code I ran, adding a change to the position using anchor_point and anchored_position:

import board
import displayio
from adafruit_pyportal import PyPortal
import terminalio

from adafruit_display_text import label
#from adafruit_display_text import bitmap_label as label

display = board.DISPLAY

# Make the display context
splash = displayio.Group(max_size=10)
#splash._scale=2
display.show(splash)

WIDTH = 320
HEIGHT = 240

# Draw a black background
bg_bitmap = displayio.Bitmap(WIDTH, HEIGHT , 1)
bg_palette = displayio.Palette(1)
bg_palette[0] = 0x000000
splash.append(displayio.TileGrid(bg_bitmap, pixel_shader=bg_palette))

test_label1 = label.Label(terminalio.FONT, text="Scale", scale=1, color=0xFFFFFF, x=8, y=8)
print("Test1 : before append to splash")
print(f"  Scale {test_label1.scale}")
splash.append(test_label1)
print("Test1 : after append to splash")
print(f"  Scale {test_label1.scale}")
print("test_label1.bounding_box: {}".format(test_label1.bounding_box))

print()
test_label2 = label.Label(terminalio.FONT, text="Scale", scale=2, color=0xFFFFFF, x=8, y=38)
print("Test2 : before append to splash")
print(f"  Scale {test_label2.scale}")
splash.append(test_label2)
print("Test2 : after append to splash")
print(f"  Scale {test_label2.scale}")
print("test_label2.bounding_box: {}".format(test_label2.bounding_box))

print()
test_label3 = label.Label(terminalio.FONT, text="Scale", scale=3, color=0xFFFFFF, x=8, y=88)
print("Test3 : before append to splash")
print(f"  Scale {test_label3.scale}")
splash.append(test_label3)
print("Test3 : after append to splash")
print(f"  Scale {test_label3.scale}")
print("test_label3.bounding_box: {}".format(test_label3.bounding_box))



##### Try moving the anchored_position
test_label3.anchor_point=(1,1)
test_label3.anchored_position=(WIDTH,HEIGHT)

[lesamouraipourpre]

I will invesigate and test this tomorrow.

I originally came up three fixes:

1. Remove the inner local_group so that there is only one scale value to deal with. I discounted this because I assume there was a good rationale for using the inner local_group.
2. Follow the comments in the code and store the scale in the local_group and keep the outer scale at 1.
3. Force the scale of the local_group to be 1 and store the scale on the outer Label.

This change currently implements option 2 because of the existing comments in the code. My preferred choice would actually be 3 and store the scale in the outer object.

Are there any preferences of whether to stick with option 2 or switch to option 3?

[kmatch98]

Thanks for working on this.

Here’s what I remember about the rationale for the two nested groups in Label and Bitmap_Label.

When changing the scale of a label, we need “intercept” the scale change so we also update the position using anchored_position.

When overriding the Group’s scale setter, I ran into an issue where I could no longer access the Group’s class variable for scale. I think regular Python has a way using __set__ to access the parent’s variables. But I couldn’t get this to work in CircuitPython (that I was running on microcontrollers. It will probably work on Blinka.).

So as a solution, I added this second local_group to handle the scaling while leaving the top-level Group with scale=1 permanently.

Probably doesn’t help you find a solution, but I wanted to highlight a difference I’d seen in Blinka versus on microcontrollers. Also, I observed that Blinka’s displayio.Group definition has a self._scale variable, so that is another confusion that should be avoided in the solution.

To clarify, I think you’ll need to follow some form of 2 but if you can solve the parent __set__ problem then 1 is the way to go, but be sure to debug on a microcontroller since Blinka will likely act totally different.

Let me know if you have more questions.

[kmatch98]

Looks good to me, I tested on a PyPortal. The use of anchor_point and anchored_position work fine now. I think this is ok to merge.

Note: The issue that this PR resolves (of using self._scale that causes problems on Blinka) is still present in bitmap_label. I will add an issue.

Tested with this code on a PyPortal:

import board
import displayio
from adafruit_pyportal import PyPortal
import terminalio

from adafruit_display_text import label
#from adafruit_display_text import bitmap_label as label

display = board.DISPLAY

# Make the display context
splash = displayio.Group(max_size=10)
display.show(splash)

WIDTH = 320
HEIGHT = 240

# Draw a black background
bg_bitmap = displayio.Bitmap(WIDTH, HEIGHT , 1)
bg_palette = displayio.Palette(1)
bg_palette[0] = 0x000000
splash.append(displayio.TileGrid(bg_bitmap, pixel_shader=bg_palette))

test_label1 = label.Label(terminalio.FONT, text="Scale", scale=1, color=0xFFFFFF, x=8, y=8)
print("Test1 : before append to splash")
print(f"  Scale {test_label1.scale}")
splash.append(test_label1)
print("Test1 : after append to splash")
print(f"  Scale {test_label1.scale}")
print("test_label1.bounding_box: {}".format(test_label1.bounding_box))

print()
test_label2 = label.Label(terminalio.FONT, text="Scale", scale=2, color=0xFFFFFF, x=8, y=38)
print("Test2 : before append to splash")
print(f"  Scale {test_label2.scale}")
splash.append(test_label2)
print("Test2 : after append to splash")
print(f"  Scale {test_label2.scale}")
print("test_label2.bounding_box: {}".format(test_label2.bounding_box))

print()
test_label3 = label.Label(terminalio.FONT, text="Scale", scale=3, color=0xFFFFFF, x=8, y=88)
print("Test3 : before append to splash")
print(f"  Scale {test_label3.scale}")
splash.append(test_label3)
print("Test3 : after append to splash")
print(f"  Scale {test_label3.scale}")
print("test_label3.bounding_box: {}".format(test_label3.bounding_box))

test_label3.anchor_point=(1,1)
test_label3.anchored_position=(WIDTH,HEIGHT)


while True:
    pass

[lesamouraipourpre]

That's great. I was holding off on the bitmap one as I don't have a microcontroller to test it with, just a Raspberry Pi. I'm going to continue and have a deeper look at the code.

[kmatch98]

Thanks @lesamouraipourpre. I went ahead and submitted a PR on bitmap version. #117

Please review and let me know if you see issues.

[kmatch98]

BTW - your github handle had a few french-speaking folks confused during this week's CircuitPython weekly meeting phonecall. Again thanks for this work!

[lesamouraipourpre]

BTW - your github handle had a few french-speaking folks confused during this week's CircuitPython weekly meeting phonecall. Again thanks for this work!

It's meant to be Purple Samurai which I think translates as le samouraï violet, but I like pourpre better than violet. And 'Le samouraï' is one of my favourite films.

[FoamyGuy]

Looks good to me. Tested with Blinka_Displayio and PyPortal. Scaling works consistently across the board now.

Thank you @lesamouraipourpre for this fix!