refactor: move mmToPix const to a common file

Author: urish

src/7segment-element.ts

@@ -1,5 +1,6 @@
 import { css, customElement, html, LitElement, property, svg } from 'lit-element';
 import { ElementPin } from './pin';
+import { mmToPix } from './utils/units';
 
 @customElement('wokwi-7segment')
 export class SevenSegmentElement extends LitElement {
@@ -42,7 +43,6 @@ export class SevenSegmentElement extends LitElement {
       const col = (n - 1) % cols;
       const row = 1 - Math.floor((n - 1) / cols);
       const xOffset = 1.27;
-      const mmToPix = 3.78;
       const x = startX + xOffset + (row ? col : cols - col - 1) * 2.54;
       const y = this.pins === 'top' ? (row ? bottomY + 1 : 1) : row ? bottomY + 2 : 0;
       return { number: n, x: x * mmToPix, y: y * mmToPix };

src/led-ring-element.ts

@@ -1,6 +1,7 @@
 import { customElement, html, LitElement, property, svg } from 'lit-element';
 import { ElementPin } from './pin';
 import { RGB } from './types/rgb';
+import { mmToPix } from './utils/units';
 
 const pinHeight = 3;
 const pcbWidth = 6;
@@ -39,7 +40,6 @@ export class LEDRingElement extends LitElement {
 
   get pinInfo(): ElementPin[] {
     const { radius } = this;
-    const mmToPix = 3.78;
     const pinSpacing = 2.54;
     const y = (radius * 2 + pinHeight) * mmToPix;
     const cx = radius * mmToPix;

src/neopixel-matrix-element.ts

@@ -1,6 +1,7 @@
 import { css, customElement, html, LitElement, property, svg } from 'lit-element';
 import { ElementPin, GND, VCC } from './pin';
 import { RGB } from './types/rgb';
+import { mmToPix } from './utils/units';
 
 const pixelWidth = 5.66;
 const pixelHeight = 5;
@@ -52,7 +53,6 @@ export class NeopixelMatrixElement extends LitElement {
 
   get pinInfo(): ElementPin[] {
     const { cols, rows, rowSpacing, colSpacing } = this;
-    const mmToPix = 3.78;
     const pinSpacing = 2.54;
     const p = pinSpacing * mmToPix;
     const cx = ((cols * (colSpacing + pixelWidth)) / 2) * mmToPix;

src/utils/units.ts

@@ -0,0 +1 @@
+export const mmToPix = 3.78;