feat(ui): add Gold and Stone themes, and shrink the theme tiles

Only one hue was genuinely free. Measuring the distance between every pair of
theme primaries, the existing six hold a minimum of 52.7, and the two greens
that were reported as looking alike measured 40.6, so that is roughly where
"different theme" stops being true.

Gold takes the warm gap at 49.4. It is nearer yellow than the metal usually
is because a redder gold falls to 39.8 against Dirt once Material darkens it
for light mode. Stone is distinct by having no hue at all, which is also what
it is for: something quiet to work against.

Lapis was the obvious third and is not here. Blue sits between Diamond's cyan
and Obsidian's purple, and nothing in the seed or variant space gets it past
42 from both, which is nearer the two greens than the rest of the set.

The distinctness test allowed 24, low enough that it would have passed the
greens it was written after. It now allows 45, just under what the set holds,
and a second test checks each theme's art is on disk and bundled, which
otherwise fails only when someone picks that theme in a real build.

The tiles are smaller and the grid denser, since eight of them at the old
size wrapped awkwardly.

The two new logos are recoloured from dirt.png by a script rather than drawn,
because those blocks are the same speckle in another colour.

Author: joanroig

docs/logo/LOGO_DESIGN.md

@@ -37,6 +37,24 @@ The `variants` folder contains the Admincraft logo and its alternative versions.
 
    - App icons for all platforms will be updated and applied the next time the app is built.
 
+### Recoloured Variants
+
+Several Minecraft blocks are the same speckled stone in a different colour, so
+a variant for one of those does not need drawing from scratch.
+[recolor_variant.py](recolor_variant.py) builds one by mapping the brightness of
+`dirt.png`'s texture onto a new pair of colours, leaving the prompt glyph alone.
+`gold.png` and `stone.png` are made this way; add a ramp to `RAMPS` and rerun it
+to add another:
+
+```
+cd docs\logo
+pip install -r requirements.txt
+python recolor_variant.py
+```
+
+Blocks whose pattern differs from dirt, and anything with a face on it, still
+need to be drawn by hand as above.
+
 ### Technical Details
 
 - The Python scripts upscale the logo to ensure suitability for various sizes and formats across platforms, while maintaining the crispness of pixel art.

docs/logo/recolor_variant.py

@@ -0,0 +1,87 @@
+"""Builds a logo variant by recolouring the block texture of an existing one.
+
+Several Minecraft blocks are the same speckled stone in a different colour, so
+a variant for one of those is a recolour rather than a new drawing. The prompt
+glyph is left alone: it is near-grey, and the texture is not, which is enough
+to tell them apart without hand-marking pixels.
+
+    cd docs/logo
+    python recolor_variant.py
+
+Writes into variants/. Existing files are overwritten, so it is safe to rerun
+after changing a ramp.
+"""
+
+import os
+
+from PIL import Image
+
+SOURCE = os.path.join("variants", "dirt.png")
+
+# Darkest and lightest tone of each block. The shades in between are taken from
+# the source's own brightness, which is what keeps the speckle pattern.
+RAMPS = {
+    # Gold is a flatter block in game, so its ramp is deliberately short: the
+    # same speckle at full strength reads as sand.
+    "gold": ((0xC2, 0x9E, 0x1A), (0xFA, 0xF0, 0x62)),
+    # Stone is speckled exactly like this, so it takes the full contrast.
+    "stone": ((0x5E, 0x5E, 0x5E), (0xA8, 0xA8, 0xA8)),
+}
+
+
+def luminance(pixel):
+    r, g, b = pixel[:3]
+    return 0.299 * r + 0.587 * g + 0.114 * b
+
+
+def is_texture(pixel):
+    """True for block pixels, false for the glyph drawn on top of them.
+
+    The glyph is white or near-grey; every texture tone is saturated, so the
+    spread between the channels separates the two cleanly.
+    """
+    r, g, b = pixel[:3]
+    return max(r, g, b) - min(r, g, b) > 25
+
+
+def recolor(image, dark, light):
+    # Read through tobytes rather than getdata, which Pillow has deprecated in
+    # favour of a method too new to rely on here.
+    raw = image.tobytes()
+    pixels = [tuple(raw[i:i + 4]) for i in range(0, len(raw), 4)]
+    texture = [p for p in pixels if is_texture(p)]
+    low = min(luminance(p) for p in texture)
+    high = max(luminance(p) for p in texture)
+    span = high - low or 1
+
+    out = []
+    for pixel in pixels:
+        if not is_texture(pixel):
+            out.append(pixel)
+            continue
+        t = (luminance(pixel) - low) / span
+        out.append(
+            (
+                round(dark[0] + (light[0] - dark[0]) * t),
+                round(dark[1] + (light[1] - dark[1]) * t),
+                round(dark[2] + (light[2] - dark[2]) * t),
+                pixel[3],
+            )
+        )
+
+    return Image.frombytes(
+        "RGBA", image.size, bytes(channel for pixel in out for channel in pixel)
+    )
+
+
+def main():
+    source = Image.open(SOURCE).convert("RGBA")
+    for name, (dark, light) in RAMPS.items():
+        path = os.path.join("variants", f"{name}.png")
+        recolor(source, dark, light).save(path)
+        print(f"wrote {path}")
+    source.close()
+
+
+if __name__ == "__main__":
+    main()

docs/logo/variants/gold.png

@@ -43,6 +43,28 @@ enum AppTheme {
     description: 'Soft and rosy',
     seedColor: Color(0xFFD2536B),
     logoAsset: 'docs/logo/variants/pig.png',
+  ),
+  // The last warm hue with room left. It is nearer yellow than the metal
+  // usually is, because a redder gold collapses into Dirt once Material
+  // darkens it for light mode, and it takes the vibrant variant for the same
+  // reason Creeper does.
+  gold(
+    label: 'Gold',
+    description: 'Bright and precious',
+    seedColor: Color(0xFFF9EC4E),
+    logoAsset: 'docs/logo/variants/gold.png',
+    variant: DynamicSchemeVariant.vibrant,
+  ),
+  // Distinct by having no hue at all rather than by finding a free one, which
+  // is also the point of it: something quiet to work against. Blue was the
+  // obvious alternative and does not work, because Diamond and Obsidian sit
+  // either side of it and leave no room.
+  stone(
+    label: 'Stone',
+    description: 'Quiet and neutral',
+    seedColor: Color(0xFF7A7A7A),
+    logoAsset: 'docs/logo/variants/stone.png',
+    variant: DynamicSchemeVariant.neutral,
   );
 
   final String label;

docs/logo/variants/stone.png

@@ -86,11 +86,17 @@ class _PreferencesViewState extends State<PreferencesView> {
                     const SizedBox(height: 8),
                     LayoutBuilder(
                       builder: (context, constraints) {
-                        final columns = constraints.maxWidth >= 720
-                            ? 5
-                            : constraints.maxWidth >= 440
-                                ? 3
-                                : 2;
+                        // Every breakpoint keeps a tile at roughly 100px or
+                        // more, which is what the longest label needs. The
+                        // icon stays 32px: it is 16x16 pixel art, so only
+                        // multiples of 16 scale without blurring it.
+                        final columns = constraints.maxWidth >= 880
+                            ? 8
+                            : constraints.maxWidth >= 720
+                                ? 6
+                                : constraints.maxWidth >= 440
+                                    ? 4
+                                    : 3;
                         const spacing = 8.0;
                         final width =
                             (constraints.maxWidth - spacing * (columns - 1)) /
@@ -289,23 +295,24 @@ class _ThemeChoice extends StatelessWidget {
         key: ValueKey('app-theme-${theme.name}'),
         onTap: onTap,
         child: Padding(
-          padding: const EdgeInsets.symmetric(horizontal: 8, vertical: 10),
+          padding: const EdgeInsets.symmetric(horizontal: 6, vertical: 8),
           child: Column(
             children: [
               Image.asset(
                 theme.logoAsset,
+                // A multiple of 16 keeps the pixel grid exact.
                 width: 32,
                 height: 32,
                 fit: BoxFit.fill,
                 filterQuality: FilterQuality.none,
                 isAntiAlias: false,
               ),
-              const SizedBox(height: 6),
+              const SizedBox(height: 4),
               Text(
                 theme.label,
                 maxLines: 1,
                 overflow: TextOverflow.ellipsis,
-                style: Theme.of(context).textTheme.labelLarge,
+                style: Theme.of(context).textTheme.labelMedium,
               ),
             ],
           ),

lib/models/app_theme.dart

@@ -75,6 +75,9 @@ flutter:
     - docs/logo/variants/diamond.png
     - docs/logo/variants/obsidian_glow.png
     - docs/logo/variants/pig.png
+    # Recoloured from dirt.png by docs/logo/recolor_variant.py.
+    - docs/logo/variants/gold.png
+    - docs/logo/variants/stone.png
     # Item icons from mcicons (MIT), named after Minecraft identifiers.
     # See the credits in README.md.
     - assets/mcicons/