Mark the aerodromes in the window, and draw the lot on a vector display

The aerodromes were never on the window at all: only the animation drew
them, and the window's map had whatever airport glyphs the tiles happened to
carry.  They are drawn there now, in the same colour and the same square.

The first attempt at that had a bug worth naming, because it would have
looked like the feature simply not working.  They were fetched inside the
same pass of the fetching loop as a piece of map, so they queued behind a
hundred and twenty tiles coming off a network -- and once the map was in
hand there were no more passes, so they were never fetched again.  They are
their own question now, asked on the same thread but not behind the tiles,
and they arrive whether the tiles do or not.  An area that has been asked
about and has none in it is remembered as none, rather than asked about
again five times a second for the rest of the night.  And the thread now
starts if either the map or the aerodromes are wanted, so --no-basemap no
longer quietly takes the airports with it.

Then the themes, which change the window and the animated pictures together
because both read their colours out of the same palette.  night is what this
program has always drawn and is untouched.  digital, phosphor, amber and red
are the screens the phrase "air defence display" actually calls to mind: a
black tube, one phosphor, and thin bright vector lines with a halo round
them.

Three things follow from having one colour to spend, and they are
constraints rather than decoration.  Height becomes brightness, since hue is
no longer free -- low is dim and high burns, which is the trade those
displays made.  The map underneath drops to about a quarter of the
brightness asked for, because a tinted photograph of a county behind the
vectors is the one thing that stops a vector display looking like one.  And
a country is named in two letters rather than drawn as a flag, a flag being
half a dozen colours.

The glow is done twice, differently, because the two are different kinds of
picture.  The window lays each line down two or three times, wider and
fainter each pass, with the core last: trails, symbols, leader lines, box
borders and the aerodrome squares.  The animation cannot blend at all, a GIF
being indexed colour, so it dilates what it has drawn and fills the halo
with the dimmed copy of the colour underneath -- and the aircraft colours
already had dimmed copies, since those are the trail shades, so an aeroplane
glows into the colour its own trail is drawn in, which is the colour a
phosphor would have spread into.  The fixed colours get two rings each in
the palette for the purpose.  The halo goes over the map, the grid and the
background and over nothing else that was drawn, since a halo is what light
does to the dark around a line; where two rings meet the nearer wins.  It
costs about 55 ms a frame at 1400 by 1258 and the default theme skips the
pass entirely.

The palette is written over in place rather than replaced, because both
drawings and every one of their helpers hold a reference to that array and a
new one would leave half the program painting in the colours of the theme
before.  There is a test that every theme keeps the aerodrome colour more
than forty units of CIELAB from every altitude colour, stated as the
distance rather than as the colour, so that a new theme cannot quietly walk
an aircraft back into the airports.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016PsWPTweCT6pwxKngvVxcg

tests/test_themes.py

@@ -0,0 +1,261 @@
+"""The colour themes, and the glow that goes with the vector ones.
+
+A theme changes both drawings at once, because both read their colours out
+of the same palette: the animation looks indices up in it directly and the
+window asks it for a QColor.  So the tests here are mostly about that
+palette -- that it is rewritten rather than replaced, that every theme keeps
+the aerodromes distinguishable from the aircraft, and that the halo goes
+where light would go and nowhere else.
+"""
+import numpy as np
+import pytest
+
+from bandsaunter import flightmap as fm
+from bandsaunter import themes
+
+
+@pytest.fixture(autouse=True)
+def back_to_night():
+    """Every test leaves the program drawing the way it found it."""
+    yield
+    fm.set_theme(themes.DEFAULT_THEME)
+
+
+# ---------------------------------------------------------------------------
+# Choosing one
+# ---------------------------------------------------------------------------
+
+def test_every_theme_says_what_it_is():
+    for name, theme in themes.THEMES.items():
+        assert theme.name == name
+        assert theme.summary and not theme.summary.endswith(".")
+        assert len(theme.stops) >= 2
+        assert theme.stops[0][0] == 0.0
+
+
+def test_a_theme_can_be_asked_for_by_name_or_by_what_it_looks_like():
+    assert themes.theme_named("phosphor").name == "phosphor"
+    assert themes.theme_named("green").name == "phosphor"
+    assert themes.theme_named("wargames").name == "digital"
+    assert themes.theme_named("BLUE").name == "digital"
+    assert themes.theme_named("  amber  ").name == "amber"
+
+
+def test_a_name_nobody_recognises_is_the_default_rather_than_a_refusal():
+    """A theme is how the picture looks.  Refusing to draw an evening's
+    flying because of a misspelt colour would be the wrong trade."""
+    assert themes.theme_named("puce").name == themes.DEFAULT_THEME
+    assert themes.theme_named("").name == themes.DEFAULT_THEME
+    assert themes.theme_named(None).name == themes.DEFAULT_THEME
+
+
+def test_no_two_themes_share_a_name_or_an_alias():
+    seen = set()
+    for theme in themes.THEMES.values():
+        for word in (theme.name,) + tuple(theme.aliases):
+            assert word not in seen, word
+            seen.add(word)
+
+
+# ---------------------------------------------------------------------------
+# What setting one does to the palette
+# ---------------------------------------------------------------------------
+
+def test_the_palette_is_written_over_rather_than_replaced():
+    """Both drawings and every one of their helpers hold a reference to
+    this array.  A new one would leave half the program painting in the
+    colours of the theme before."""
+    before = fm.PALETTE
+    fm.set_theme("phosphor")
+    assert fm.PALETTE is before
+    assert tuple(fm.PALETTE[fm.BG]) != (14, 16, 22)
+
+
+def test_setting_a_theme_says_which_one_it_settled_on():
+    assert fm.set_theme("norad").name == "digital"
+    assert fm.set_theme("puce").name == themes.DEFAULT_THEME
+
+
+def test_the_default_theme_draws_exactly_what_it_always_drew():
+    """The colours this program has always used, unchanged: an existing
+    recording redrawn today has to come out the same picture."""
+    fm.set_theme("phosphor")
+    fm.set_theme("night")
+    assert tuple(fm.PALETTE[fm.BG]) == (14, 16, 22)
+    assert tuple(fm.PALETTE[fm.INK]) == (196, 204, 218)
+    assert tuple(fm.PALETTE[fm.RAMP]) == (252, 96, 72)
+    assert tuple(fm.PALETTE[fm.RAMP + fm.RAMP_STEPS - 1]) == (158, 142, 255)
+
+
+def _lab(rgb):
+    c = np.asarray(rgb, float) / 255.0
+    c = np.where(c > 0.04045, ((c + 0.055) / 1.055) ** 2.4, c / 12.92)
+    m = np.array([[0.4124, 0.3576, 0.1805], [0.2126, 0.7152, 0.0722],
+                  [0.0193, 0.1192, 0.9505]])
+    xyz = (c @ m.T) / np.array([0.9505, 1.0, 1.089])
+    f = np.where(xyz > 0.008856, np.cbrt(xyz), 7.787 * xyz + 16 / 116)
+    return np.array([116 * f[1] - 16, 500 * (f[0] - f[1]), 200 * (f[1] - f[2])])
+
+
+def test_no_theme_lets_an_aerodrome_be_mistaken_for_an_aircraft():
+    """The whole reason the aerodromes stopped being amber.  Stated as the
+    distance rather than as the colour, so that a new theme cannot quietly
+    walk an aircraft back into the airports."""
+    for name in themes.THEMES:
+        fm.set_theme(name)
+        airport = _lab(fm.PALETTE[fm.AIRPORT])
+        apart = min(float(np.linalg.norm(airport - _lab(fm.PALETTE[fm.RAMP + i])))
+                    for i in range(fm.RAMP_STEPS))
+        assert apart > 40, f"{name}: only {apart:.0f} units apart"
+
+
+def test_a_phosphor_theme_reads_height_as_brightness():
+    """One colour to spend, so it cannot be spent on hue.  Low is dim and
+    high burns, which is the constraint those screens actually had."""
+    for name in ("digital", "phosphor", "amber", "red"):
+        theme = fm.set_theme(name)
+        assert theme.height_is_brightness
+        weights = [int(fm.PALETTE[fm.RAMP + i].astype(int).sum())
+                   for i in range(fm.RAMP_STEPS)]
+        assert weights == sorted(weights), f"{name} is not monotonic"
+        assert weights[-1] > weights[0] * 3
+
+
+def test_the_default_theme_reads_height_as_hue_instead():
+    fm.set_theme("night")
+    assert not fm.THEME.height_is_brightness
+
+
+def test_every_theme_fills_the_palette_without_running_off_the_end():
+    for name in themes.THEMES:
+        fm.set_theme(name)
+        assert fm.PALETTE.shape == (256, 3)
+        assert fm.GLOW + 6 <= 256
+        # Nothing drawn with is left as the black the unused tail is.
+        for index in (fm.INK, fm.AIRPORT, fm.RAMP, fm.GROUND + 31):
+            assert fm.PALETTE[index].any(), (name, index)
+
+
+# ---------------------------------------------------------------------------
+# The glow
+# ---------------------------------------------------------------------------
+
+def _picture(width=80, height=60):
+    return np.full((height, width), fm.BG, dtype=np.uint8)
+
+
+def test_the_default_theme_has_no_glow_at_all():
+    fm.set_theme("night")
+    img = _picture()
+    img[30, 10:70] = fm.RAMP + 20
+    assert np.array_equal(fm.bloom(img), img)
+
+
+def test_a_line_on_a_vector_theme_gets_a_halo_either_side_of_it():
+    fm.set_theme("phosphor")
+    img = _picture()
+    img[30, 10:70] = fm.RAMP + 20
+    out = fm.bloom(img)
+    assert (out[30, 10:70] == fm.RAMP + 20).all(), "the core was painted over"
+    assert (out[29, 10:70] == fm.TRAIL + 20).all(), "no halo above the line"
+    assert (out[31, 10:70] == fm.TRAIL + 20).all(), "no halo below it"
+    assert (out[28, 10:70] == fm.OLD + 20).all(), "no second, fainter ring"
+    assert (out[27, 10:70] == fm.BG).all(), "the halo reaches too far"
+
+
+def test_the_halo_is_the_colour_of_the_thing_that_cast_it():
+    """A green aeroplane glows green and a red one red: the halo is the
+    aircraft's own dimmed colour, which is what a phosphor would spread."""
+    fm.set_theme("digital")
+    for step in (0, 12, 31):
+        img = _picture()
+        img[30, 10:70] = fm.RAMP + step
+        out = fm.bloom(img)
+        assert (out[29, 10:70] == fm.TRAIL + step).all()
+
+
+def test_a_halo_never_paints_over_something_else_that_was_drawn():
+    """A halo is what light does to the dark around a line.  Painting it
+    over another line would be light doing something light does not do."""
+    fm.set_theme("phosphor")
+    img = _picture()
+    img[30, 10:70] = fm.RAMP + 20            # an aeroplane
+    img[29, 10:70] = fm.AIRPORT              # an aerodrome right beside it
+    out = fm.bloom(img)
+    assert (out[29, 10:70] == fm.AIRPORT).all()
+
+
+def test_the_halo_does_not_wrap_round_the_edge_of_the_picture():
+    """Rolled and then cut: without the cut, a line down the left edge
+    would glow on the right edge of the picture."""
+    fm.set_theme("amber")
+    img = _picture()
+    img[:, 0] = fm.RAMP + 20
+    out = fm.bloom(img)
+    assert (out[:, 1] == fm.TRAIL + 20).all()
+    assert (out[:, -1] == fm.BG).all()
+    assert (out[:, -2] == fm.BG).all()
+
+    tall = _picture()
+    tall[0, :] = fm.AIRPORT
+    assert (fm.bloom(tall)[-1, :] == fm.BG).all()
+
+
+def test_the_halo_goes_over_the_map_and_the_grid_but_not_the_aircraft():
+    fm.set_theme("digital")
+    img = np.full((60, 80), fm.GROUND + 10, dtype=np.uint8)
+    img[30, 40] = fm.INK
+    out = fm.bloom(img)
+    assert out[30, 41] != fm.GROUND + 10, "no halo over the map"
+    assert out[30, 40] == fm.INK
+
+
+def test_the_nearer_ring_wins_where_two_meet():
+    """Which is what happens on the tube as well."""
+    fm.set_theme("phosphor")
+    img = _picture()
+    img[30, 40] = fm.RAMP + 20
+    out = fm.bloom(img)
+    assert out[31, 40] == fm.TRAIL + 20      # near
+    assert out[32, 40] == fm.OLD + 20        # far
+
+
+# ---------------------------------------------------------------------------
+# What else a vector theme changes
+# ---------------------------------------------------------------------------
+
+def test_a_phosphor_theme_names_the_country_instead_of_drawing_its_flag():
+    """A flag is half a dozen colours and a phosphor screen has one.  Two
+    letters are what a display of the period would have done anyway."""
+    from bandsaunter.flags import FLAG_H, FLAG_W
+
+    fm.set_theme("night")
+    flagged = np.full((40, 60), fm.BG, dtype=np.uint8)
+    fm.draw_flag(flagged, 5, 5, "US")
+    patch = flagged[5:5 + FLAG_H, 5:5 + FLAG_W]
+    assert ((patch >= fm.FLAG) & (patch < fm.FLAG + 12)).any()
+
+    fm.set_theme("phosphor")
+    lettered = np.full((40, 60), fm.BG, dtype=np.uint8)
+    fm.draw_flag(lettered, 5, 5, "US")
+    patch = lettered[5:5 + FLAG_H, 5:5 + FLAG_W]
+    assert not ((patch >= fm.FLAG) & (patch < fm.FLAG + 12)).any()
+    assert (lettered == fm.DIM).any(), "the letters were not drawn either"
+
+
+def test_a_vector_theme_pushes_the_map_underneath_well_back():
+    """A tinted photograph of a county behind the vectors is the one thing
+    that stops a vector display looking like one."""
+    levels = np.full((8, 8), fm.GROUND_SHADES - 1, dtype=np.uint8)
+    fm.set_theme("night")
+    plain = int(fm.dim_ground(levels, 0.7).max())
+    fm.set_theme("digital")
+    quiet = int(fm.dim_ground(levels, 0.7).max())
+    assert quiet < plain * 0.6, f"{quiet} is not much darker than {plain}"
+
+
+def test_the_brightness_setting_still_does_something_on_a_vector_theme():
+    levels = np.full((8, 8), fm.GROUND_SHADES - 1, dtype=np.uint8)
+    fm.set_theme("phosphor")
+    assert int(fm.dim_ground(levels, 1.0).max()) > \
+        int(fm.dim_ground(levels, 0.3).max())