Add TileGrid example that uses the built in font to display text

[tannewt]

Similar to terminalio but without using it.

[caternuson]

from discord:

Maybe a multi-line Hello World example that does not use Label would make it clearer how terminal style text could work.

[caternuson]

I'm not sure I understand what can/can't be used here? Like how far down the rabbit hole are we going?

Wouldn't a multi-line example without using Label essentially just be a recreation of the code in Label._update_text() ?

[jepler]

@caternuson This stems from discussion over the memory usage of Label. There is a way to display text using a built-in font that uses much less RAM memory than Label does, by having a single TileGrid rather than a TileGrid for each character.

[caternuson]

@jepler Ah, thanks. I think that was the clarification I was after.

[jepler]

class GridLabel(displayio.TileGrid):
    def __init__(self, font, *, text=None, max_size=None, color=0xffffff,
                 width=None, height=None, **kwargs):
        if not text and not max_size:
            raise RuntimeError("Please provide a max size, or initial text")
        cwidth, cheight = self.calc_size(text)
        width = width or cwidth
        height = height or cheight

        self._width = width
        self._height = height
        self.font = font
        self.palette = displayio.Palette(2)
        self.palette.make_transparent(0)
        self.palette[1] = color

        tile_width, tile_height = font.get_bounding_box()[:2]
        super().__init__(width=width, height=height, tile_width=tile_width,
                         tile_height=tile_height, bitmap=font.bitmap,
                         pixel_shader=self.palette,
                         default_tile=self.font.get_glyph(ord('Z')).tile_index,
                         **kwargs)
        self._update_text(text or '')

    def calc_size(self, text):
        start = 0
        width = 0
        height = 1
        while True:
            end = text.find('\n', start)
            if end == -1:
                width = max(width, len(text)-start)
                break
            width = max(width, end-start)
            height += 1
            start = end + 1
        print(width, height)
        return (width, height)

    def _update_text(self, text):
        self._text = text
        r = c = 0
        space = self.font.get_glyph(ord(' ')).tile_index
        for codepoint in text:
            if codepoint == '\n':
                for i in range(c, self._width):
                    self[i, r] = space
                c = 0
                r = r + 1
                continue
            if c == self._width:
                c = 0
                r = r + 1
            if r >= self._height: break
            self[c, r] = self.font.get_glyph(ord(codepoint)).tile_index
            c = c + 1
        while r < self._height:
            for i in range(c, self._width):
                self[i, r] = space
            c = 0
            r = r + 1
        
    @property
    def text(self):
        return self._text

    @text.setter
    def text(self, new_text):
        if new_text != self._text:
            self._update_text(new_text)

[gmeader]

I'm the newbie that made the request in Discord. I was looking for a complete working example/demo that would run as code.py and be included in the /examples folder of the libs. I guess this class is the first step towards that.

[jepler]

Updated version of gridlabel (there was at least one bug, hopefully fixed): https://gist.github.com/e7a159b28048dc8637f69db17caba5ea
A silly little demo that I ran on my pygamer: https://gist.github.com/4e17ebc6b3a6e762856d2338fdfb99d9

@gmeader Being new to something is an exciting time, enjoy it!

[jepler]

@gmeader We discussed this in the CIrcuitPython chat, and @tannewt would like to see this made into a pull request in the https://github.com/adafruit/Adafruit_CircuitPython_Display_Text -- both this module and an example.

Would you be interested in helping us out on this?

[gmeader]

Yes, happy to help.

[gmeader]

I think GridLabel should have a "color" property (not just the constructor param) that may be set and read.
Perhaps even a background color property that also may be set to transparent as well?

[jepler]

Thank you!

I definitely agree with adding a "color" property. This would make the GridLabel more like the existing Label, which has a color property.

I think adding a background constructor and property is fine, if it is useful.

[kmatch98]

Here is another example of using text in a tileGrid: https://github.com/kmatch98/simpleTerminal

In modifying a text editor for use with CircuitPython (see the modules branch of the MicroPython editor pye), I developed a simpleTerminal class that creates a tileGrid of text with some additions for cursor control. It has a wrapper class editorTerminal that handles some VT100 style commands.

---

Performance-related issue for label:

As mentioned by @jepler and @caternuson, the performance of the tileGrid is much superior to using label. I think this stems from the fact that label handles proportional fonts while tileGrid can only handle fixed width fonts.

I'm struggling with the performance of label. It seems like there should be a better way, rather than combining so many tileGrids each holding just one character. Anyone have any suggestions on a path forward?

edit: Just found the function for load_glyphs. It takes a while to load the glyphs, but the actual label creation (or text value changes) is at a more reasonable level. Feel free to ignore the question above.

glyphs = b'0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-,.:?! '
font = bitmap_font.load_font("/BebasNeue-Bold-62.bdf")
font.load_glyphs(glyphs)

[tannewt]

Is this done?

[caternuson]

I think so? Looks like it became a PR?

[skerr92]

This appears to have been fixed/done back in 2020. see Display_text #75 PR

[caternuson]

closing