tiny.filigree.font.model

1const std = @import("std");23pub const FontError = error{4    InvalidFont,5    MissingTable,6    UnsupportedCmap,7    InvalidCmap,8    InvalidKern,9    InvalidGsub,10    InvalidGpos,11    InvalidGdef,12    InvalidVariations,13};1415pub const Tag = u32;1617pub fn tag(comptime name: []const u8) Tag {18    if (name.len != 4) @compileError("OpenType tags are four bytes");19    return (@as(u32, name[0]) << 24) |20        (@as(u32, name[1]) << 16) |21        (@as(u32, name[2]) << 8) |22        @as(u32, name[3]);23}2425pub const GlyphClass = enum {26    unknown,27    base,28    ligature,29    mark,30    component,31};3233pub const LigatureCaret = struct {34    coordinate: i16,35    synthesized: bool = false,36};3738pub const defaultScriptTag: Tag = tag("DFLT");3940pub const FeatureRange = struct {41    start: u32 = 0,42    end: u32 = std.math.maxInt(u32),43};4445pub const FeatureSetting = struct {46    tag: Tag,47    value: u32 = 1,48    source: ?FeatureRange = null,49};5051pub const VariationAxis = struct {52    tag: Tag,53    min_value: i32,54    default_value: i32,55    max_value: i32,56    flags: u16 = 0,57    name_id: u16 = 0,58};5960pub const VariationSetting = struct {61    tag: Tag,62    value: f32,63};6465pub const NormalizedVariation = struct {66    tag: Tag,67    value: i16,68};6970pub const LayoutSelection = struct {71    script: Tag = defaultScriptTag,72    script_tags: []const Tag = &.{},73    language: ?Tag = null,74    features: []const FeatureSetting = &.{},75    variations: []const VariationSetting = &.{},76    vertical: bool = false,77    right_to_left: bool = false,78};7980pub fn featureEnabled(selection: LayoutSelection, feature_tag: Tag, default_on: bool, source: ?FeatureRange) bool {81    var enabled = default_on;82    for (selection.features) |setting| {83        if (setting.tag != feature_tag) continue;84        if (!featureSettingApplies(setting, source)) continue;85        enabled = setting.value != 0;86    }87    return enabled;88}8990pub fn fixed16ToFloat(value: i32) f32 {91    return @as(f32, @floatFromInt(value)) / 65536.0;92}9394fn featureSettingApplies(setting: FeatureSetting, source: ?FeatureRange) bool {95    const setting_source = setting.source orelse return true;96    const lookup_source = source orelse return false;97    return setting_source.start < lookup_source.end and lookup_source.start < setting_source.end;98}99100pub const noGposVariationIndex: u32 = std.math.maxInt(u32);101102pub const GsubSubstitution = struct {103    glyph_id: u32,104    component_count: u16,105    replacement_count: u16 = 1,106    replacement_glyphs_offset: usize = 0,107    target_offset: usize = 0,108    skip_count: usize = 0,109};110111pub const GposValueAdjustment = struct {112    x_placement: i32 = 0,113    y_placement: i32 = 0,114    x_advance: i32 = 0,115    y_advance: i32 = 0,116    x_placement_variation: u32 = noGposVariationIndex,117    y_placement_variation: u32 = noGposVariationIndex,118    x_advance_variation: u32 = noGposVariationIndex,119    y_advance_variation: u32 = noGposVariationIndex,120121    pub fn isZero(self: GposValueAdjustment) bool {122        return self.x_placement == 0 and123            self.y_placement == 0 and124            self.x_advance == 0 and125            self.y_advance == 0 and126            self.x_placement_variation == noGposVariationIndex and127            self.y_placement_variation == noGposVariationIndex and128            self.x_advance_variation == noGposVariationIndex and129            self.y_advance_variation == noGposVariationIndex;130    }131132    pub fn withVariations(self: GposValueAdjustment, face: anytype, settings: []const VariationSetting) GposValueAdjustment {133        return .{134            .x_placement = face.gposVariationValue(self.x_placement, settings, self.x_placement_variation),135            .y_placement = face.gposVariationValue(self.y_placement, settings, self.y_placement_variation),136            .x_advance = face.gposVariationValue(self.x_advance, settings, self.x_advance_variation),137            .y_advance = face.gposVariationValue(self.y_advance, settings, self.y_advance_variation),138        };139    }140141    pub fn add(self: *GposValueAdjustment, other: GposValueAdjustment) void {142        self.x_placement += other.x_placement;143        self.y_placement += other.y_placement;144        self.x_advance += other.x_advance;145        self.y_advance += other.y_advance;146        self.x_placement_variation = mergeGposVariationIndex(self.x_placement_variation, other.x_placement_variation);147        self.y_placement_variation = mergeGposVariationIndex(self.y_placement_variation, other.y_placement_variation);148        self.x_advance_variation = mergeGposVariationIndex(self.x_advance_variation, other.x_advance_variation);149        self.y_advance_variation = mergeGposVariationIndex(self.y_advance_variation, other.y_advance_variation);150    }151};152153pub const GposPairAdjustment = struct {154    left: GposValueAdjustment = .{},155    right: GposValueAdjustment = .{},156157    pub fn isZero(self: GposPairAdjustment) bool {158        return self.left.isZero() and self.right.isZero();159    }160161    pub fn add(self: *GposPairAdjustment, other: GposPairAdjustment) void {162        self.left.add(other.left);163        self.right.add(other.right);164    }165};166167pub const GposPairAdjustmentBefore = struct {168    adjustment: GposPairAdjustment = .{},169    left_offset: usize = 0,170171    pub fn isZero(self: GposPairAdjustmentBefore) bool {172        return self.adjustment.isZero();173    }174};175176pub const GposContextualPairAdjustment = struct {177    adjustment: GposPairAdjustment = .{},178    target_offset: usize = 0,179    skip_count: usize = 0,180181    pub fn isZero(self: GposContextualPairAdjustment) bool {182        return self.adjustment.isZero();183    }184};185186pub const GposSingleAdjustment = struct {187    adjustment: GposValueAdjustment = .{},188    target_offset: usize = 0,189    skip_count: usize = 0,190191    pub fn isZero(self: GposSingleAdjustment) bool {192        return self.adjustment.isZero();193    }194};195196pub const GposCursiveAttachment = struct {197    x_anchor_delta: i32 = 0,198    y_anchor_delta: i32 = 0,199};200201fn mergeGposVariationIndex(existing: u32, incoming: u32) u32 {202    if (incoming == noGposVariationIndex) return existing;203    if (existing == noGposVariationIndex) return incoming;204    return existing;205}206207test "tag packs OpenType tags" {208    try std.testing.expectEqual(@as(u32, 0x68656164), tag("head"));209}

1pub const model = @import("model.zig");