feat: 完成四种字母描红开发

miniprogram/englishPages/shared/draw/casePairingDraw.ts

@@ -3,121 +3,128 @@ import type {
     LetterTracingData,
     TracingRow,
 } from '../generators/letter-tracing-generator';
-import { drawFourLineGrid } from './drawTools';
+import { fontFamilyOf } from '../data/fontProfiles';
+import {
+    calcLetterFontSizes,
+    drawFourLineGrid,
+    drawLetterInFourLineGrid,
+    FOUR_LINE_GRID_H,
+    type LetterFontSizes,
+} from './drawTools';
+const COLOR_BLACK = '#1a1a1a';
+const COLOR_LIGHT_RED = '#FF8E8E';
 
-const LETTER_FACE = 'Helvetica, Arial, "Segoe UI", Roboto, sans-serif';
+/** 左右大写/小写两栏之间的间距（相对行宽 + 下限，避免过窄屏过小） */
+const COLUMN_GUTTER_RATIO = 0.02;
+const COLUMN_GUTTER_MIN = 14;
 
-type CasePairingData = Extract<LetterTracingData, { mode: 'case-pairing' }>;
+/**
+ * 单栏内字母排版区域占栏宽比例（<1 则同栏字母更紧凑、字间距更小）
+ */
+const INTRA_COLUMN_LETTER_BAND_RATIO = 1;
 
+type CasePairingData = Extract<
+    LetterTracingData,
+    { mode: 'letter-tracing-case-pairing' }
+>;
+
+/**
+ * 分栏对照绘制：
+ * 四线三格横跨整页宽度，字母分左右两侧书写——
+ * 左栏大写、右栏小写（各 repetitions 个），中间留间距；同栏内字母略收紧。
+ * 每侧第一个字母黑色，后续浅红色。
+ */
 export default class CasePairingDraw extends BaseDrawService {
+    private letterSizes: LetterFontSizes =
+        calcLetterFontSizes(FOUR_LINE_GRID_H);
+
     async draw(data: CasePairingData) {
         this.prepareDraw();
         await this.drawHeaderAndDivider();
-        this.drawContent(data.leftVisualRows, data.rightVisualRows);
+        this.drawContent(data.leftRows, data.rightRows);
         this.drawPrintFooter();
     }
 
-    private drawContent(
-        leftVisualRows: TracingRow[][],
-        rightVisualRows: TracingRow[][],
-    ) {
+    private drawContent(leftRows: TracingRow[], rightRows: TracingRow[]) {
         const M = 24;
-        const y0 = this.currentY + 6;
-        const bottom = this.canvasHeight - M;
-        const gapCol = 18;
-        const colW = (this.canvasWidth - M * 2 - gapCol) / 2;
-        const maxVisual = Math.max(
-            leftVisualRows.length,
-            rightVisualRows.length,
+        const lineW = this.canvasWidth - M * 2;
+        const maxR = Math.max(leftRows.length, rightRows.length);
+
+        const footerReserve = 56;
+        const availableH =
+            this.canvasHeight - this.currentY - footerReserve - 12;
+        const rowGap = Math.max(
+            4,
+            (availableH - maxR * FOUR_LINE_GRID_H) / (maxR + 1),
         );
-        const rowSlotH = Math.max(40, (bottom - y0) / maxVisual - 6);
 
-        const drawSide = (
-            blocks: TracingRow[][],
-            startX: number,
-            width: number,
-        ) => {
-            let y = y0;
-            for (const visualRow of blocks) {
-                const nSeg = visualRow.length;
-                const segGap = 6;
-                const segW = (width - (nSeg - 1) * segGap) / nSeg;
-                for (let s = 0; s < nSeg; s++) {
-                    this.drawTracingRow(
-                        visualRow[s],
-                        startX + s * (segW + segGap),
-                        y,
-                        rowSlotH,
-                        segW,
-                    );
-                }
-                y += rowSlotH + 8;
+        const y0 = this.currentY + rowGap;
+
+        const columnGutter = Math.max(
+            COLUMN_GUTTER_MIN,
+            Math.round(lineW * COLUMN_GUTTER_RATIO),
+        );
+        const halfContentW = (lineW - columnGutter) / 2;
+        const leftX = M;
+        const rightX = M + halfContentW + columnGutter;
+
+        for (let i = 0; i < maxR; i++) {
+            const y = y0 + i * (FOUR_LINE_GRID_H + rowGap);
+
+            drawFourLineGrid(this.ctx, M, y, lineW, FOUR_LINE_GRID_H);
+
+            if (i < leftRows.length) {
+                this.drawLettersInHalf(
+                    leftRows[i],
+                    leftX,
+                    y,
+                    halfContentW,
+                    INTRA_COLUMN_LETTER_BAND_RATIO,
+                );
             }
-        };
-
-        drawSide(leftVisualRows, M, colW);
-        drawSide(rightVisualRows, M + colW + gapCol, colW);
+            if (i < rightRows.length) {
+                this.drawLettersInHalf(
+                    rightRows[i],
+                    rightX,
+                    y,
+                    halfContentW,
+                    INTRA_COLUMN_LETTER_BAND_RATIO,
+                );
+            }
+        }
     }
 
-    private drawTracingRow(
+    /**
+     * 在四线三格的半侧区域内绘制字母。
+     * 第一个字母黑色，后续字母浅红色。
+     */
+    private drawLettersInHalf(
         row: TracingRow,
-        startX: number,
+        x: number,
         y: number,
-        rowH: number,
-        totalWidth: number,
+        columnW: number,
+        letterBandRatio: number,
     ) {
-        const gap = 4;
         const n = row.cells.length;
-        const cellW = n > 0 ? (totalWidth - gap * (n - 1)) / n : totalWidth;
+        if (n === 0) return;
+
+        const bandW = columnW * letterBandRatio;
+        const inset = (columnW - bandW) / 2;
+        const slotW = bandW / n;
         for (let i = 0; i < n; i++) {
-            const cx = startX + i * (cellW + gap);
-            drawFourLineGrid(this.ctx, cx, y, cellW, rowH);
             const cell = row.cells[i];
-            this.drawCharInCell(
+            const color = i === 0 ? COLOR_BLACK : COLOR_LIGHT_RED;
+            const cx = x + inset + slotW * i + slotW / 2;
+
+            drawLetterInFourLineGrid(
+                this.ctx,
                 cell.char,
                 cx,
                 y,
-                cellW,
-                rowH,
-                cell.opacity,
-                cell.isGuide,
-                cell.pairChar,
+                FOUR_LINE_GRID_H,
+                this.letterSizes,
+                { fontFamily: fontFamilyOf(this.letterSizes._profile), color },
             );
         }
     }
-
-    private drawCharInCell(
-        ch: string,
-        x: number,
-        y: number,
-        w: number,
-        h: number,
-        opacity: number,
-        bold: boolean,
-        pairChar?: string,
-    ) {
-        const ctx = this.ctx;
-        if (opacity <= 0) return;
-        ctx.save();
-        ctx.globalAlpha = opacity;
-        ctx.fillStyle = bold ? '#1a1a1a' : '#4a4a4a';
-        ctx.textAlign = 'center';
-        ctx.textBaseline = 'alphabetic';
-        const baselineY = y + h * 0.72;
-
-        if (pairChar) {
-            const fs = Math.min(h * 0.5, w * 0.22);
-            ctx.font = `${bold ? 'bold ' : ''}${fs}px ${LETTER_FACE}`;
-            const gap = fs * 0.2;
-            const totalW = fs * 2 + gap;
-            const x0 = x + w / 2 - totalW / 2;
-            ctx.fillText(ch, x0 + fs * 0.5, baselineY);
-            ctx.fillText(pairChar, x0 + fs * 1.5 + gap, baselineY);
-        } else {
-            const fontSize = Math.min(h * 0.72, w * 0.85);
-            ctx.font = `${bold ? 'bold ' : ''}${fontSize}px ${LETTER_FACE}`;
-            ctx.fillText(ch, x + w / 2, baselineY);
-        }
-        ctx.restore();
-    }
 }

miniprogram/englishPages/shared/draw/columnCompareDraw.ts

@@ -1,127 +0,0 @@
-import { BaseDrawService } from '../../../core/draw/baseDraw';
-import type {
-    LetterTracingData,
-    TracingRow,
-} from '../generators/letter-tracing-generator';
-import { fontFamilyOf } from '../data/fontProfiles';
-import {
-    calcLetterFontSizes,
-    drawFourLineGrid,
-    drawLetterInFourLineGrid,
-    FOUR_LINE_GRID_H,
-    type LetterFontSizes,
-} from './drawTools';
-const COLOR_BLACK = '#1a1a1a';
-const COLOR_LIGHT_RED = 'rgba(252, 46, 0, 0.3)';
-
-/** 左右大写/小写两栏之间的间距（相对行宽 + 下限，避免过窄屏过小） */
-const COLUMN_GUTTER_RATIO = 0.02;
-const COLUMN_GUTTER_MIN = 14;
-
-/**
- * 单栏内字母排版区域占栏宽比例（<1 则同栏字母更紧凑、字间距更小）
- */
-const INTRA_COLUMN_LETTER_BAND_RATIO = 1;
-
-type ColumnCompareData = Extract<LetterTracingData, { mode: 'column-compare' }>;
-
-/**
- * 分栏对照绘制：
- * 四线三格横跨整页宽度，字母分左右两侧书写——
- * 左栏大写、右栏小写（各 repetitions 个），中间留间距；同栏内字母略收紧。
- * 每侧第一个字母黑色，后续浅红色。
- */
-export default class ColumnCompareDraw extends BaseDrawService {
-    private letterSizes: LetterFontSizes =
-        calcLetterFontSizes(FOUR_LINE_GRID_H);
-
-    async draw(data: ColumnCompareData) {
-        this.prepareDraw();
-        await this.drawHeaderAndDivider();
-        this.drawContent(data.leftRows, data.rightRows);
-        this.drawPrintFooter();
-    }
-
-    private drawContent(leftRows: TracingRow[], rightRows: TracingRow[]) {
-        const M = 24;
-        const lineW = this.canvasWidth - M * 2;
-        const maxR = Math.max(leftRows.length, rightRows.length);
-
-        const footerReserve = 56;
-        const availableH =
-            this.canvasHeight - this.currentY - footerReserve - 12;
-        const rowGap = Math.max(
-            4,
-            (availableH - maxR * FOUR_LINE_GRID_H) / (maxR + 1),
-        );
-
-        const y0 = this.currentY + rowGap;
-
-        const columnGutter = Math.max(
-            COLUMN_GUTTER_MIN,
-            Math.round(lineW * COLUMN_GUTTER_RATIO),
-        );
-        const halfContentW = (lineW - columnGutter) / 2;
-        const leftX = M;
-        const rightX = M + halfContentW + columnGutter;
-
-        for (let i = 0; i < maxR; i++) {
-            const y = y0 + i * (FOUR_LINE_GRID_H + rowGap);
-
-            drawFourLineGrid(this.ctx, M, y, lineW, FOUR_LINE_GRID_H);
-
-            if (i < leftRows.length) {
-                this.drawLettersInHalf(
-                    leftRows[i],
-                    leftX,
-                    y,
-                    halfContentW,
-                    INTRA_COLUMN_LETTER_BAND_RATIO,
-                );
-            }
-            if (i < rightRows.length) {
-                this.drawLettersInHalf(
-                    rightRows[i],
-                    rightX,
-                    y,
-                    halfContentW,
-                    INTRA_COLUMN_LETTER_BAND_RATIO,
-                );
-            }
-        }
-    }
-
-    /**
-     * 在四线三格的半侧区域内绘制字母。
-     * 第一个字母黑色，后续字母浅红色。
-     */
-    private drawLettersInHalf(
-        row: TracingRow,
-        x: number,
-        y: number,
-        columnW: number,
-        letterBandRatio: number,
-    ) {
-        const n = row.cells.length;
-        if (n === 0) return;
-
-        const bandW = columnW * letterBandRatio;
-        const inset = (columnW - bandW) / 2;
-        const slotW = bandW / n;
-        for (let i = 0; i < n; i++) {
-            const cell = row.cells[i];
-            const color = i === 0 ? COLOR_BLACK : COLOR_LIGHT_RED;
-            const cx = x + inset + slotW * i + slotW / 2;
-
-            drawLetterInFourLineGrid(
-                this.ctx,
-                cell.char,
-                cx,
-                y,
-                FOUR_LINE_GRID_H,
-                this.letterSizes,
-                { fontFamily: fontFamilyOf(this.letterSizes._profile), color },
-            );
-        }
-    }
-}

miniprogram/englishPages/shared/draw/drawTools.ts

@@ -97,8 +97,7 @@ export function drawLetterInFourLineGrid(
         bold?: boolean;
     },
 ) {
-    const fontFamily =
-        options?.fontFamily ?? fontFamilyOf(sizes._profile);
+    const fontFamily = options?.fontFamily ?? fontFamilyOf(sizes._profile);
     const color = options?.color ?? '#1a1a1a';
     const bold = options?.bold ?? false;
 

miniprogram/englishPages/shared/draw/letterTracingDraw.ts

@@ -1,9 +1,9 @@
 import { BaseDrawService } from '../../../core/draw/baseDraw';
 import type { LetterTracingData } from '../generators/letter-tracing-generator';
-import PictureTracingDraw from './pictureTracingDraw';
+import singleLetterDraw from './singleLetterDraw';
 import CasePairingDraw from './casePairingDraw';
-import ColumnCompareDraw from './columnCompareDraw';
-import OverviewDraw from './overviewDraw';
+import TwoColumnDraw from './twoColumnDraw';
+import UpperLowerDraw from './upperLowerDraw';
 
 /**
  * 字母描红绘制分发层。
@@ -12,10 +12,10 @@ import OverviewDraw from './overviewDraw';
 export default class LetterTracingDraw extends BaseDrawService {
     async draw(data: LetterTracingData) {
         const DrawClass = {
-            'picture-tracing': PictureTracingDraw,
-            'case-pairing': CasePairingDraw,
-            'column-compare': ColumnCompareDraw,
-            overview: OverviewDraw,
+            'letter-tracing-single': singleLetterDraw,
+            'letter-tracing-upper-lower': UpperLowerDraw,
+            'letter-tracing-case-pairing': CasePairingDraw,
+            'letter-tracing-two-column': TwoColumnDraw,
         }[data.mode];
 
         const delegate = new DrawClass(this.canvas, this.ctx, this.options);

miniprogram/englishPages/shared/draw/singleLetterDraw.ts

@@ -19,23 +19,26 @@ const ACCENT_RED = 'rgba(252, 46, 0, 1)';
 const TITLE_TEXT_FONT = '14px sans-serif';
 const TITLE_ICON_GAP = 4;
 
-type PictureData = Extract<LetterTracingData, { mode: 'picture-tracing' }>;
+type SingleLetterData = Extract<
+    LetterTracingData,
+    { mode: 'letter-tracing-single' }
+>;
 
-export default class PictureTracingDraw extends BaseDrawService {
+export default class SingleLetterDraw extends BaseDrawService {
     private letterSizes: LetterFontSizes =
         calcLetterFontSizes(FOUR_LINE_GRID_H);
     private get letterFace(): string {
         return fontFamilyOf(this.letterSizes._profile);
     }
 
-    async draw(data: PictureData) {
+    async draw(data: SingleLetterData) {
         this.prepareDraw();
         await this.drawHeaderAndDivider();
         await this.drawContent(data);
         this.drawPrintFooter();
     }
 
-    private async drawContent(data: PictureData) {
+    private async drawContent(data: SingleLetterData) {
         const { teaching, highlightGrid, traceImgPath } = data;
         const ctx = this.ctx;
 
@@ -79,7 +82,7 @@ export default class PictureTracingDraw extends BaseDrawService {
             );
         }
 
-        this.drawSentence(
+        this.drawSingleLetterSentence(
             teaching.sentence,
             teaching.upper,
             TOP_X,
@@ -228,7 +231,7 @@ export default class PictureTracingDraw extends BaseDrawService {
         ctx.restore();
     }
 
-    private drawSentence(
+    private drawSingleLetterSentence(
         sentence: string,
         letter: string,
         x: number,

miniprogram/englishPages/shared/draw/twoColumnDraw.ts

@@ -0,0 +1,124 @@
+import { BaseDrawService } from '../../../core/draw/baseDraw';
+import type {
+    LetterTracingData,
+    TracingRow,
+} from '../generators/letter-tracing-generator';
+import { fontFamilyOf } from '../data/fontProfiles';
+import {
+    calcLetterFontSizes,
+    drawFourLineGrid,
+    drawLetterInFourLineGrid,
+    FOUR_LINE_GRID_H,
+    type LetterFontSizes,
+} from './drawTools';
+
+const COLOR_BLACK = '#1a1a1a';
+const COLOR_LIGHT_RED = '#FF8E8E';
+const COLUMN_GUTTER = 18;
+
+type TwoColumnData = Extract<
+    LetterTracingData,
+    { mode: 'letter-tracing-two-column' }
+>;
+
+/**
+ * 两列练习绘制：
+ * 左栏 A–M（Aa Bb … Mm）、右栏 N–Z（Nn Oo … Zz），每栏 13 行。
+ * 每行一个完整四线三格，格内绘制大小写配对字母。
+ * 第一行黑色示范，后续行浅红色渐淡。两栏间距 18px。
+ */
+export default class TwoColumnDraw extends BaseDrawService {
+    private letterSizes: LetterFontSizes =
+        calcLetterFontSizes(FOUR_LINE_GRID_H);
+
+    async draw(data: TwoColumnData) {
+        this.prepareDraw();
+        await this.drawHeaderAndDivider();
+        this.drawContent(data.leftRows, data.rightRows);
+        this.drawPrintFooter();
+    }
+
+    private drawContent(leftRows: TracingRow[], rightRows: TracingRow[]) {
+        const M = 24;
+        const lineW = this.canvasWidth - M * 2;
+        const colW = (lineW - COLUMN_GUTTER) / 2;
+        const maxR = Math.max(leftRows.length, rightRows.length);
+
+        const footerReserve = 56;
+        const availableH =
+            this.canvasHeight - this.currentY - footerReserve - 12;
+        const rowGap = Math.max(
+            4,
+            (availableH - maxR * FOUR_LINE_GRID_H) / (maxR + 1),
+        );
+        const y0 = this.currentY + rowGap;
+
+        const leftX = M;
+        const rightX = M + colW + COLUMN_GUTTER;
+
+        for (let i = 0; i < maxR; i++) {
+            const y = y0 + i * (FOUR_LINE_GRID_H + rowGap);
+
+            if (i < leftRows.length) {
+                drawFourLineGrid(this.ctx, leftX, y, colW, FOUR_LINE_GRID_H);
+                this.drawPairRow(leftRows[i], leftX, y, colW);
+            }
+            if (i < rightRows.length) {
+                drawFourLineGrid(this.ctx, rightX, y, colW, FOUR_LINE_GRID_H);
+                this.drawPairRow(rightRows[i], rightX, y, colW);
+            }
+        }
+    }
+
+    /**
+     * 在一个四线三格内绘制大小写配对（如 A a）。
+     * rowIndex=0 黑色示范，>0 浅红色。
+     * cells 里每个 cell 的 char 是大写、pairChar 是小写，
+     * 按 repetitions 排列（第一个实色 → 后续渐淡）。
+     */
+    private drawPairRow(row: TracingRow, x: number, y: number, colW: number) {
+        const fontFamily = fontFamilyOf(this.letterSizes._profile);
+        const cells = row.cells;
+        const n = cells.length;
+        if (n === 0) return;
+
+        const pairCount = n;
+        const slotW = colW / pairCount;
+
+        const pairGap = 25;
+
+        for (let i = 0; i < pairCount; i++) {
+            const cell = cells[i];
+            const color = i === 0 ? COLOR_BLACK : COLOR_LIGHT_RED;
+            const alpha = i >= pairCount - 2 ? 0.5 : 1;
+            const pairCx = x + i * slotW + slotW / 2;
+
+            this.ctx.save();
+            this.ctx.globalAlpha = alpha;
+
+            drawLetterInFourLineGrid(
+                this.ctx,
+                cell.char,
+                pairCx - pairGap / 2,
+                y,
+                FOUR_LINE_GRID_H,
+                this.letterSizes,
+                { fontFamily, color },
+            );
+
+            if (cell.pairChar) {
+                drawLetterInFourLineGrid(
+                    this.ctx,
+                    cell.pairChar,
+                    pairCx + pairGap / 2,
+                    y,
+                    FOUR_LINE_GRID_H,
+                    this.letterSizes,
+                    { fontFamily, color },
+                );
+            }
+
+            this.ctx.restore();
+        }
+    }
+}

miniprogram/englishPages/shared/draw/upperLowerDraw.ts

@@ -14,7 +14,10 @@ import {
     type LetterFontSizes,
 } from './drawTools';
 
-type OverviewData = Extract<LetterTracingData, { mode: 'overview' }>;
+type UpperLowerData = Extract<
+    LetterTracingData,
+    { mode: 'letter-tracing-upper-lower' }
+>;
 
 /** 页面左右边距（margin，px），用于排版时留白 */
 const M = 24;
@@ -40,24 +43,24 @@ const TITLE_FACE = fontFamilyOf(TITLE_PROFILE);
  * 字母总览：上区大写、下区小写；每区标题 + 4 行四线三格（7+7+6+6）。
  * 列宽按 7 列均分；后两行 6 字左对齐，与前两行逐列对齐（占前 6 列）。
  */
-export default class OverviewDraw extends BaseDrawService {
+export default class UpperLowerDraw extends BaseDrawService {
     private letterSizes: LetterFontSizes = calcLetterFontSizes(
         FOUR_LINE_GRID_H,
         DASHED_PROFILE,
     );
 
-    async draw(data: OverviewData) {
+    async draw(data: UpperLowerData) {
         this.prepareDraw();
         await Promise.allSettled([
             loadLetterFont(DASHED_PROFILE),
             loadLetterFont(TITLE_PROFILE),
         ]);
         await this.drawHeaderAndDivider();
-        this.drawOverviewBody(data.upperRows, data.lowerRows);
+        this.drawUpperLowerBody(data.upperRows, data.lowerRows);
         await this.drawPrintFooter();
     }
 
-    private drawOverviewBody(
+    private drawUpperLowerBody(
         upperRows: string[][],
         lowerRows: string[][],
     ): void {

miniprogram/englishPages/shared/generators/letter-tracing-generator.ts

@@ -3,17 +3,17 @@ import { ALPHABET_BY_LETTER, LETTERS_UPPER } from '../data/alphabet';
 /** 字母描红的布局模式（与产品文档六类练习一致） */
 export type LetterTracingMode =
     /** 1 看图识字：教学区 + 描红行（前三行大写、后三行小写） */
-    | 'picture-tracing'
+    | 'letter-tracing-single'
     /** 2 字母总览：Uppercase / Lowercase 分区，每区四行 7+7+6+6 */
-    | 'overview'
+    | 'letter-tracing-upper-lower'
     /** 3 大小写配对：左栏 A–M、右栏 N–Z，每行最多 4 组 Aa */
-    | 'case-pairing'
+    | 'letter-tracing-case-pairing'
     /** 4 分栏对照：半组字母，左栏大写、右栏小写，每行 4 个 */
-    | 'column-compare'
+    | 'letter-tracing-two-column'
     /** 5 三字母精练：每页聚焦 3 个字母，各含大写行 + 小写行 */
-    | 'triple-focus'
+    | 'letter-tracing-triple'
     /** 6 单字母逐行：每行一个字母，13 字母半表（A–M 或 N–Z） */
-    | 'single-line';
+    | 'letter-tracing-single-line';
 
 /** 字母大小写模式（部分模式不使用） */
 export type LetterCaseMode = 'upper' | 'lower' | 'both';
@@ -70,7 +70,7 @@ export interface TeachingBlock {
 
 export type LetterTracingData =
     | {
-          mode: 'picture-tracing';
+          mode: 'letter-tracing-single';
           teaching: TeachingBlock;
           highlightGrid: HighlightGrid;
           /** Trace It 区域使用的字母笔顺图路径（同 teaching.letterImgPath） */
@@ -79,17 +79,17 @@ export type LetterTracingData =
           tracingLineCount: number;
       }
     | {
-          mode: 'case-pairing';
-          leftVisualRows: TracingRow[][];
-          rightVisualRows: TracingRow[][];
-      }
-    | {
-          mode: 'column-compare';
+          mode: 'letter-tracing-case-pairing';
           leftRows: TracingRow[];
           rightRows: TracingRow[];
       }
     | {
-          mode: 'overview';
+          mode: 'letter-tracing-two-column';
+          leftRows: TracingRow[];
+          rightRows: TracingRow[];
+      }
+    | {
+          mode: 'letter-tracing-upper-lower';
           upperRows: string[][];
           lowerRows: string[][];
       };
@@ -212,7 +212,7 @@ export function generateLetterTracing(
 ): LetterTracingData {
     const { mode, repetitions, fadePattern } = config;
 
-    if (mode === 'picture-tracing') {
+    if (mode === 'letter-tracing-single') {
         const key = normalizeLetter(config.selectedLetter ?? 'A');
         const meta = ALPHABET_BY_LETTER[key] ?? ALPHABET_BY_LETTER.A;
         const upper = key;
@@ -237,7 +237,7 @@ export function generateLetterTracing(
         const highlightGrid = buildHighlightGrid(upper, 3, 6);
 
         return {
-            mode: 'picture-tracing',
+            mode: 'letter-tracing-single',
             teaching,
             highlightGrid,
             traceImgPath: letterImgPath,
@@ -245,23 +245,7 @@ export function generateLetterTracing(
         };
     }
 
-    if (mode === 'case-pairing') {
-        const leftLetters = LETTERS_UPPER.slice(0, 13);
-        const rightLetters = LETTERS_UPPER.slice(13);
-        const pack = (letters: string[]) =>
-            chunk(letters, 4).map((group) =>
-                group.map((L) =>
-                    rowForChar(L, repetitions, fadePattern, L.toLowerCase()),
-                ),
-            );
-        return {
-            mode: 'case-pairing',
-            leftVisualRows: pack(leftLetters),
-            rightVisualRows: pack(rightLetters),
-        };
-    }
-
-    if (mode === 'column-compare') {
+    if (mode === 'letter-tracing-case-pairing') {
         const half =
             config.alphabetHalf === 'N-Z'
                 ? LETTERS_UPPER.slice(13)
@@ -272,12 +256,26 @@ export function generateLetterTracing(
         const rightRows = half.map((L) =>
             rowForChar(L.toLowerCase(), repetitions, fadePattern),
         );
-        return { mode: 'column-compare', leftRows, rightRows };
+        return { mode: 'letter-tracing-case-pairing', leftRows, rightRows };
     }
 
-    // overview
+    if (mode === 'letter-tracing-two-column') {
+        const leftLetters = LETTERS_UPPER.slice(0, 13);
+        const rightLetters = LETTERS_UPPER.slice(13);
+        const toRows = (letters: string[]) =>
+            letters.map((L) =>
+                rowForChar(L, repetitions, fadePattern, L.toLowerCase()),
+            );
+        return {
+            mode: 'letter-tracing-two-column',
+            leftRows: toRows(leftLetters),
+            rightRows: toRows(rightLetters),
+        };
+    }
+
+    // letter-tracing-upper-lower
     return {
-        mode: 'overview',
+        mode: 'letter-tracing-upper-lower',
         upperRows: overviewRowsFrom([...LETTERS_UPPER]),
         lowerRows: overviewRowsFrom(LETTERS_UPPER.map((L) => L.toLowerCase())),
     };
@@ -291,7 +289,7 @@ export function mergeLetterTracingConfig(
     return {
         mode: (overrides.mode ??
             base.mode ??
-            'picture-tracing') as LetterTracingMode,
+            'letter-tracing-single') as LetterTracingMode,
         letterCase: (overrides.letterCase ??
             base.letterCase ??
             'upper') as LetterCaseMode,