Add font_patcher's grouped vs individual alignment

src/font/nerd_font_attributes.zig

@@ -365,9 +365,9 @@ pub fn getConstraint(cp: u21) ?Constraint {
         0xebd7...0xec06,
         0xec08...0xec0a,
         0xec0d...0xec1e,
-        0xed00...0xf018,
+        0xed00...0xf02f,
-        0xf01a...0xf02f,
         0xf031...0xf03c,
+        0xf03f,
         0xf041...0xf043,
         0xf045...0xf049,
         0xf04b...0xf050,
@@ -378,18 +378,16 @@ pub fn getConstraint(cp: u21) ?Constraint {
         0xf07c...0xf080,
         0xf082...0xf08b,
         0xf08d...0xf091,
-        0xf093...0xf09e,
+        0xf093...0xf0a0,
-        0xf0a0,
         0xf0a5...0xf0a9,
         0xf0ab...0xf0c9,
         0xf0cb...0xf0d5,
         0xf0d7...0xf0dd,
         0xf0df...0xf0e6,
         0xf0e8...0xf295,
-        0xf297...0xf2c3,
+        0xf297...0xf2c4,
         0xf2c6...0xf2ef,
-        0xf2f1...0xf305,
+        0xf2f1...0xf847,
-        0xf307...0xf847,
         0xf0001...0xf1af0,
         => .{
             .size = .fit_cover1,
@@ -670,22 +668,15 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .relative_width = 0.8008342022940563,
             .relative_x = 0.1991657977059437,
         },
-        0xf019,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
-        },
         0xf030,
         0xf03e,
+        0xf071,
+        0xf08c,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
             .relative_height = 0.8751322751322751,
             .relative_y = 0.0624338624338624,
         },
@@ -698,24 +689,13 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .relative_height = 0.7502645502645503,
             .relative_y = 0.1248677248677249,
         },
-        0xf03f,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.5554597570408116,
-            .relative_x = 0.0005406676069582,
-        },
         0xf040,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8877888683953564,
             .relative_height = 0.9992749363119733,
-            .relative_x = 0.0003164442515641,
             .relative_y = 0.0001959631589261,
         },
         0xf044,
@@ -724,37 +704,27 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9913442331878375,
             .relative_height = 0.9923123057630445,
             .relative_y = 0.0002010014265405,
         },
         0xf04a,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
-            .relative_height = 0.7506817256817256,
-            .relative_y = 0.1247354497354497,
-        },
         0xf051,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.5557122708039492,
             .relative_height = 0.7506817256817256,
             .relative_y = 0.1247354497354497,
         },
         0xf052,
+        0xf081,
+        0xf092,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8741409740917385,
             .relative_height = 0.8748851565736010,
             .relative_y = 0.0626172338785870,
         },
@@ -764,39 +734,26 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.4993711622401420,
             .relative_height = 0.8759430588185509,
             .relative_y = 0.0620882827561120,
         },
         0xf05a...0xf05b,
+        0xf0a2,
         0xf0aa,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9987423244802840,
             .relative_height = 0.9997176214776941,
             .relative_y = 0.0002010014265405,
         },
-        0xf071,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
-            .relative_height = 0.8751322751322751,
-            .relative_x = 0.0004701457451810,
-            .relative_y = 0.0624338624338624,
-        },
         0xf078,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8745600777856455,
             .relative_height = 0.4993298596163721,
             .relative_y = 0.1879786499051550,
         },
@@ -806,70 +763,25 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
             .relative_height = 0.8139763779527559,
             .relative_y = 0.0930118110236220,
         },
-        0xf081,
-        0xf092,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.8740316426933279,
-            .relative_height = 0.8748851565736010,
-            .relative_y = 0.0626172338785870,
-        },
-        0xf08c,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.7776210625293841,
-            .relative_height = 0.8751322751322751,
-            .relative_y = 0.0624338624338624,
-        },
-        0xf09f,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.5717654171704958,
-            .relative_x = 0.0006952841596131,
-        },
         0xf0a1,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.8885754583921015,
             .relative_height = 0.9303101594008066,
             .relative_y = 0.0349409448818898,
         },
-        0xf0a2,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.8749266777006549,
-            .relative_height = 0.9997176214776941,
-            .relative_x = 0.0001253913778381,
-            .relative_y = 0.0002010014265405,
-        },
         0xf0a3,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9994081526966043,
             .relative_height = 0.9998551487695376,
-            .relative_x = 0.0005918473033957,
         },
         0xf0a4,
         => .{
@@ -877,7 +789,6 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9987423244802840,
             .relative_height = 0.7500526916695081,
             .relative_y = 0.1250334663306335,
         },
@@ -887,7 +798,6 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9675646540335450,
             .relative_height = 0.8124689241215546,
             .relative_y = 0.0938253501046103,
         },
@@ -906,9 +816,7 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.7150686682199350,
             .relative_height = 0.3756613756613756,
-            .relative_x = 0.0004030632809351,
             .relative_y = 0.5708994708994709,
         },
         0xf0e7,
@@ -917,9 +825,7 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.7491243338952770,
             .relative_height = 0.9998803756692248,
-            .relative_x = 0.0006021702214782,
             .relative_y = 0.0001196243307751,
         },
         0xf296,
@@ -928,28 +834,16 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9994800427141276,
             .relative_height = 0.9627792014248586,
-            .relative_x = 0.0001795653226322,
             .relative_y = 0.0187142907131644,
         },
-        0xf2c4,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.7523272214386461,
-        },
         0xf2c5,
         => .{
             .size = .fit_cover1,
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9883117728988424,
             .relative_height = 0.8573155985489722,
-            .relative_x = 0.0004377219006858,
             .relative_y = 0.0713422007255139,
         },
         0xf2f0,
@@ -958,18 +852,9 @@ pub fn getConstraint(cp: u21) ?Constraint {
             .height = .icon,
             .align_horizontal = .center1,
             .align_vertical = .center1,
-            .relative_width = 0.9987423244802840,
             .relative_height = 0.9669226518842459,
             .relative_y = 0.0165984862232646,
         },
-        0xf306,
-        => .{
-            .size = .fit_cover1,
-            .height = .icon,
-            .align_horizontal = .center1,
-            .align_vertical = .center1,
-            .relative_width = 0.7691584391161260,
-        },
         else => null,
     };
 }

src/font/nerd_font_codegen.py

@@ -282,17 +282,23 @@ def generate_zig_switch_arms(
 
         entries |= {k: v for k, v in attributes.items() if isinstance(k, int)}
 
-        if entry["ScaleRules"] is not None and "ScaleGroups" in entry["ScaleRules"]:
+        if entry["ScaleRules"] is not None:
+            if "ScaleGroups" not in entry["ScaleRules"]:
+                raise ValueError(
+                    f"Scale rule format {entry['ScaleRules']} not implemented."
+                )
             for group in entry["ScaleRules"]["ScaleGroups"]:
                 xMin = math.inf
                 yMin = math.inf
                 xMax = -math.inf
                 yMax = -math.inf
                 individual_bounds: dict[int, tuple[int, int, int, int]] = {}
+                individual_advances: set[float] = set()
                 for cp in group:
                     if cp not in cmap:
                         continue
                     glyph = glyphs[cmap[cp]]
+                    individual_advances.add(glyph.width)
                     bounds = BoundsPen(glyphSet=glyphs)
                     glyph.draw(bounds)
                     individual_bounds[cp] = bounds.bounds
@@ -302,16 +308,32 @@ def generate_zig_switch_arms(
                     yMax = max(bounds.bounds[3], yMax)
                 group_width = xMax - xMin
                 group_height = yMax - yMin
+                group_is_monospace = (len(individual_bounds) > 1) and (
+                    len(individual_advances) == 1
+                )
                 for cp in group:
-                    if cp not in cmap or cp not in entries:
+                    if (
+                        cp not in cmap
+                        or cp not in entries
+                        # Codepoints may contribute to the bounding box of multiple groups,
+                        # but should be scaled according to the first group they are found
+                        # in. Hence, to avoid overwriting, we need to skip codepoints that
+                        # have already been assigned a scale group.
+                        or "relative_height" in entries[cp]
+                    ):
                         continue
                     this_bounds = individual_bounds[cp]
-                    this_width = this_bounds[2] - this_bounds[0]
                     this_height = this_bounds[3] - this_bounds[1]
-                    entries[cp]["relative_width"] = this_width / group_width
                     entries[cp]["relative_height"] = this_height / group_height
-                    entries[cp]["relative_x"] = (this_bounds[0] - xMin) / group_width
                     entries[cp]["relative_y"] = (this_bounds[1] - yMin) / group_height
+                    # Horizontal alignment should only be grouped if the group is monospace,
+                    # that is, if all glyphs in the group have the same advance width.
+                    if group_is_monospace:
+                        this_width = this_bounds[2] - this_bounds[0]
+                        entries[cp]["relative_width"] = this_width / group_width
+                        entries[cp]["relative_x"] = (
+                            this_bounds[0] - xMin
+                        ) / group_width
 
     del entries[0]