Add Chordal Hold to zsa/qmk_firmware. (#405)

* Add Chordal Hold to zsa/qmk_firmware.

* Add chordal_hold_layout weak def for Moonlander.

lib/python/qmk/cli/generate/keyboard_c.py

@@ -1,5 +1,9 @@
 """Used by the make system to generate keyboard.c from info.json.
 """
+import bisect
+import dataclasses
+from typing import Optional
+
 from milc import cli
 
 from qmk.info import info_json
@@ -87,6 +91,128 @@ def _gen_matrix_mask(info_data):
         lines.append(f'    0b{"".join(reversed(mask[i]))},')
     lines.append('};')
     lines.append('#endif')
+    lines.append('')
+
+    return lines
+
+
+@dataclasses.dataclass
+class LayoutKey:
+    """Geometric info for one key in a layout."""
+    row: int
+    col: int
+    x: float
+    y: float
+    w: float = 1.0
+    h: float = 1.0
+    hand: Optional[str] = None
+
+    @staticmethod
+    def from_json(key_json):
+        row, col = key_json['matrix']
+        return LayoutKey(
+            row=row,
+            col=col,
+            x=key_json['x'],
+            y=key_json['y'],
+            w=key_json.get('w', 1.0),
+            h=key_json.get('h', 1.0),
+            hand=key_json.get('hand', None),
+        )
+
+    @property
+    def cx(self):
+        """Center x coordinate of the key."""
+        return self.x + self.w / 2.0
+
+    @property
+    def cy(self):
+        """Center y coordinate of the key."""
+        return self.y + self.h / 2.0
+
+
+class Layout:
+    """Geometric info of a layout."""
+    def __init__(self, layout_json):
+        self.keys = [LayoutKey.from_json(key_json) for key_json in layout_json['layout']]
+        self.x_min = min(key.cx for key in self.keys)
+        self.x_max = max(key.cx for key in self.keys)
+        self.x_mid = (self.x_min + self.x_max) / 2
+        # If there is one key with width >= 6u, it is probably the spacebar.
+        i = [i for i, key in enumerate(self.keys) if key.w >= 6.0]
+        self.spacebar = self.keys[i[0]] if len(i) == 1 else None
+
+    def is_symmetric(self, tol: float = 0.02):
+        """Whether the key positions are symmetric about x_mid."""
+        x = sorted([key.cx for key in self.keys])
+        for i in range(len(x)):
+            x_i_mirrored = 2.0 * self.x_mid - x[i]
+            # Find leftmost x element greater than or equal to (x_i_mirrored - tol).
+            j = bisect.bisect_left(x, x_i_mirrored - tol)
+            if j == len(x) or abs(x[j] - x_i_mirrored) > tol:
+                return False
+
+        return True
+
+    def widest_horizontal_gap(self):
+        """Finds the x midpoint of the widest horizontal gap between keys."""
+        x = sorted([key.cx for key in self.keys])
+        x_mid = self.x_mid
+        max_sep = 0
+        for i in range(len(x) - 1):
+            sep = x[i + 1] - x[i]
+            if sep > max_sep:
+                max_sep = sep
+                x_mid = (x[i + 1] + x[i]) / 2
+
+        return x_mid
+
+
+def _gen_chordal_hold_layout(info_data):
+    """Convert info.json content to chordal_hold_layout
+    """
+    # NOTE: If there are multiple layouts, only the first is read.
+    for layout_name, layout_json in info_data['layouts'].items():
+        layout = Layout(layout_json)
+        break
+
+    if layout.is_symmetric():
+        # If the layout is symmetric (e.g. most split keyboards), guess the
+        # handedness based on the sign of (x - layout.x_mid).
+        hand_signs = [key.x - layout.x_mid for key in layout.keys]
+    elif layout.spacebar is not None:
+        # If the layout has a spacebar, form a dividing line through the spacebar,
+        # nearly vertical but with a slight angle to follow typical row stagger.
+        x0 = layout.spacebar.cx - 0.05
+        y0 = layout.spacebar.cy - 1.0
+        hand_signs = [(key.x - x0) - (key.y - y0) / 3.0 for key in layout.keys]
+    else:
+        # Fallback: assume handedness based on the widest horizontal separation.
+        x_mid = layout.widest_horizontal_gap()
+        hand_signs = [key.x - x_mid for key in layout.keys]
+
+    for key, hand_sign in zip(layout.keys, hand_signs):
+        if key.hand is None:
+            if key == layout.spacebar or abs(hand_sign) <= 0.02:
+                key.hand = '*'
+            else:
+                key.hand = 'L' if hand_sign < 0.0 else 'R'
+
+    lines = []
+    lines.append('#ifdef CHORDAL_HOLD')
+    line = ('__attribute__((weak)) const char chordal_hold_layout[MATRIX_ROWS][MATRIX_COLS] PROGMEM = ' + layout_name + '(')
+
+    x_prev = None
+    for key in layout.keys:
+        if x_prev is None or key.x < x_prev:
+            lines.append(line)
+            line = '  '
+        line += f"'{key.hand}', "
+        x_prev = key.x
+
+    lines.append(line[:-2])
+    lines.append(');')
+    lines.append('#endif')
 
     return lines
 
@@ -101,10 +227,11 @@ def generate_keyboard_c(cli):
     kb_info_json = info_json(cli.args.keyboard)
 
     # Build the layouts.h file.
-    keyboard_h_lines = [GPL2_HEADER_C_LIKE, GENERATED_HEADER_C_LIKE, '#include QMK_KEYBOARD_H', '']
+    keyboard_c_lines = [GPL2_HEADER_C_LIKE, GENERATED_HEADER_C_LIKE, '#include QMK_KEYBOARD_H', '']
 
-    keyboard_h_lines.extend(_gen_led_configs(kb_info_json))
-    keyboard_h_lines.extend(_gen_matrix_mask(kb_info_json))
+    keyboard_c_lines.extend(_gen_led_configs(kb_info_json))
+    keyboard_c_lines.extend(_gen_matrix_mask(kb_info_json))
+    keyboard_c_lines.extend(_gen_chordal_hold_layout(kb_info_json))
 
     # Show the results
-    dump_lines(cli.args.output, keyboard_h_lines, cli.args.quiet)
+    dump_lines(cli.args.output, keyboard_c_lines, cli.args.quiet)