refactor(canvas): name the 1.3 fontHeight ratio and dedupe renderer Props

Three small cleanups on top of the KonvaObject split:

- The 1.3 ZPL-fontHeight to CSS-fontSize ratio is now a named export
  (ZPL_FONT_HEIGHT_TO_CSS_RATIO) used by textPositionTransforms and
  the text/serial render paths in KonvaObjectInner. Same number,
  no longer a magic literal sprinkled across files.
- BarcodeObject was redeclaring the renderer Props interface
  structurally identical to KonvaObjectProps. Drop the duplicate
  and import the shared one.
- konvaObjectProps.ts docstring updated: LineObject/ImageObject now
  receive the narrowed obj from the dispatcher (no internal cast)
  while BarcodeObject and KonvaObjectInner still narrow internally.

Author: u8array

src/components/Canvas/BarcodeObject.tsx

@@ -2,10 +2,9 @@ import React, { useCallback, useRef } from "react";
 import bwipjs from "bwip-js/browser";
 import { Image as KImage, Group, Rect, Text } from "react-konva";
 import type Konva from "konva";
-import type { LabelObject } from "../../registry";
 import { BARCODE_1D_TYPES, ObjectRegistry } from "../../registry";
-import type { ObjectChanges } from "../../store/labelStore";
 import { dotsToPx, pxToDots } from "../../lib/coordinates";
+import type { KonvaObjectProps } from "./konvaObjectProps";
 import {
   buildBwipOptions,
   getDisplaySize,
@@ -23,17 +22,6 @@ import {
   EAN_UPC_TYPES,
 } from "./bwipConstants";
 
-interface Props {
-  obj: LabelObject;
-  scale: number;
-  dpmm: number;
-  offsetX: number;
-  offsetY: number;
-  isSelected: boolean;
-  onSelect: (addToSelection: boolean) => void;
-  onChange: (changes: ObjectChanges) => void;
-  snap: (dots: number) => number;
-}
 export function BarcodeObject({
   obj,
   scale,
@@ -44,7 +32,7 @@ export function BarcodeObject({
   onSelect,
   onChange,
   snap,
-}: Props) {
+}: KonvaObjectProps) {
   const groupRef = useRef<Konva.Group>(null);
   const textRef = useRef<Konva.Text>(null);
 

src/components/Canvas/KonvaObject.tsx

@@ -6,7 +6,11 @@ import { LineObject } from "./LineObject";
 import { ImageObject } from "./ImageObject";
 import type Konva from "konva";
 import { dotsToPx, pxToDots } from "../../lib/coordinates";
-import { objectToDisplay, displayToObject } from "./textPositionTransforms";
+import {
+  objectToDisplay,
+  displayToObject,
+  ZPL_FONT_HEIGHT_TO_CSS_RATIO,
+} from "./textPositionTransforms";
 import type { KonvaObjectProps } from "./konvaObjectProps";
 
 type Props = KonvaObjectProps;
@@ -106,7 +110,10 @@ function KonvaObjectInner({
 
   if (obj.type === "text") {
     const p = obj.props;
-    const fontSize = Math.max(dotsToPx(p.fontHeight, scale, dpmm) / 1.3, 6);
+    const fontSize = Math.max(
+      dotsToPx(p.fontHeight, scale, dpmm) / ZPL_FONT_HEIGHT_TO_CSS_RATIO,
+      6,
+    );
     const fontFamily = p.printerFontName
       ? (getFontFamily(p.printerFontName) ?? "'Roboto Condensed', sans-serif")
       : "'Roboto Condensed', sans-serif";
@@ -179,7 +186,10 @@ function KonvaObjectInner({
 
   if (obj.type === "serial") {
     const p = obj.props;
-    const fontSize = Math.max(dotsToPx(p.fontHeight, scale, dpmm) / 1.3, 6);
+    const fontSize = Math.max(
+      dotsToPx(p.fontHeight, scale, dpmm) / ZPL_FONT_HEIGHT_TO_CSS_RATIO,
+      6,
+    );
     const zplRotationDeg: Record<typeof p.rotation, number> = {
       N: 0,
       R: 90,

src/components/Canvas/konvaObjectProps.ts

@@ -2,8 +2,11 @@ import type { LabelObject } from "../../registry";
 import type { ObjectChanges } from "../../store/labelStore";
 
 /** Shared props for the per-type renderers under KonvaObject (LineObject,
- *  ImageObject, BarcodeObject, KonvaObjectInner). The dispatcher hands
- *  the wide LabelObject down; each renderer narrows internally. */
+ *  ImageObject, BarcodeObject, KonvaObjectInner). LineObject and
+ *  ImageObject re-narrow `obj` at the type level via `Omit & { obj: ... }`
+ *  and the dispatcher passes the narrowed value explicitly; BarcodeObject
+ *  and KonvaObjectInner currently take the wide LabelObject and narrow
+ *  internally. */
 export interface KonvaObjectProps {
   obj: LabelObject;
   scale: number;

src/components/Canvas/textPositionTransforms.ts

@@ -24,12 +24,18 @@ interface TextLikeProps {
 /** 15 dots empirical canvas/ZPL alignment offset for rotated text. */
 const ROTATION_OFFSET_DOTS = 15;
 
+/** Ratio between ZPL fontHeight (cap-height) and CSS/Konva fontSize
+ *  (em-height) for Roboto Condensed Bold. Empirical: divide ZPL
+ *  fontHeight by this to get the Konva-rendered height in dots, or to
+ *  derive the Konva fontSize. Lives here because it appears in both
+ *  the FT baseline math and the text/serial render paths. */
+export const ZPL_FONT_HEIGHT_TO_CSS_RATIO = 1.3;
+
 function ftBaselineDelta(props: TextLikeProps): { dx: number; dy: number } {
   // For R/I/B the Konva anchor sits at the far end of the rendered
-  // glyph, so we use the actual rendered height (fontHeight / 1.3).
-  // For N the anchor is at the top, so we shift up by the full ZPL
-  // fontHeight.
-  const renderedH = props.fontHeight / 1.3;
+  // glyph, so we use the actual rendered height. For N the anchor is
+  // at the top, so we shift up by the full ZPL fontHeight.
+  const renderedH = props.fontHeight / ZPL_FONT_HEIGHT_TO_CSS_RATIO;
   switch (props.rotation) {
     case 'N': return { dx: 0, dy: -props.fontHeight };
     case 'R': return { dx: renderedH, dy: 0 };