fix(pdf): scaling and font styles consistency

Closes #146

src/App.scss

@@ -121,6 +121,16 @@ input {
   object-fit: contain; /* Ensure the image fits within the container */
 }
 
+// Consistent styling for every file mark
+// Reverts some of the design defaults for font
+.file-mark {
+  font-family: Arial;
+  font-size: 16px;
+  font-weight: normal;
+  color: black;
+  letter-spacing: normal;
+}
+
 [data-dev='true'] {
   .image-wrapper {
     // outline: 1px solid #ccc; /* Optional: for visual debugging */

src/components/DrawPDFFields/style.module.scss

@@ -23,10 +23,6 @@
   justify-content: center;
   align-items: center;
 
-  font-family: Arial;
-  font-size: 16px;
-  font-weight: normal;
-
   &.nonEditable {
     cursor: default;
     visibility: hidden;

src/components/PDFView/PdfMarkItem.tsx

@@ -1,6 +1,6 @@
 import { CurrentUserMark } from '../../types/mark.ts'
 import styles from '../DrawPDFFields/style.module.scss'
-import { FONT_TYPE, inPx } from '../../utils/pdf.ts'
+import { FONT_SIZE, FONT_TYPE, inPx } from '../../utils/pdf.ts'
 
 interface PdfMarkItemProps {
   userMark: CurrentUserMark
@@ -26,13 +26,14 @@ const PdfMarkItem = ({
   return (
     <div
       onClick={handleClick}
-      className={`${styles.drawingRectangle} ${isEdited() && styles.edited}`}
+      className={`file-mark ${styles.drawingRectangle} ${isEdited() && styles.edited}`}
       style={{
         left: inPx(location.left),
         top: inPx(location.top),
         width: inPx(location.width),
         height: inPx(location.height),
-        fontFamily: FONT_TYPE
+        fontFamily: FONT_TYPE,
+        fontSize: inPx(FONT_SIZE)
       }}
     >
       {getMarkValue()}

src/pages/verify/index.tsx

@@ -29,6 +29,8 @@ import axios from 'axios'
 import {
   addMarks,
   convertToPdfBlob,
+  FONT_SIZE,
+  FONT_TYPE,
   groupMarksByFileNamePage,
   inPx
 } from '../../utils/pdf.ts'
@@ -105,13 +107,15 @@ const SlimPdfView = ({
                       {marks.map((m) => {
                         return (
                           <div
-                            className={styles.mark}
+                            className={`file-mark ${styles.mark}`}
                             key={m.id}
                             style={{
                               left: inPx(m.location.left),
                               top: inPx(m.location.top),
                               width: inPx(m.location.width),
-                              height: inPx(m.location.height)
+                              height: inPx(m.location.height),
+                              fontFamily: FONT_TYPE,
+                              fontSize: inPx(FONT_SIZE)
                             }}
                           >
                             {m.value}
@@ -427,7 +431,7 @@ export const VerifyPage = () => {
     for (const [fileName, file] of Object.entries(files)) {
       if (file.isPdf) {
         // Draw marks into PDF file and generate a brand new blob
-        const pages = await addMarks(file, marksByPage[fileName])
+        const pages = await addMarks(file, file.pages!, marksByPage[fileName])
         const blob = await convertToPdfBlob(pages)
         zip.file(`files/${fileName}`, blob)
       } else {

src/pages/verify/style.module.scss

@@ -61,6 +61,6 @@
 
 [data-dev='true'] {
   .mark {
-    border: 1px dotted black;
+    outline: 1px dotted black;
   }
 }

src/types/drawing.ts

@@ -10,6 +10,7 @@ export interface MouseState {
 
 export interface PdfPage {
   image: string
+  scale: number
   drawnFields: DrawnField[]
 }
 

src/utils/file.ts

@@ -22,7 +22,11 @@ export const getZipWithFiles = async (
   for (const [fileName, file] of Object.entries(files)) {
     if (file.isPdf) {
       // Handle PDF Files
-      const pages = await addMarks(file, marksByFileNamePage[fileName])
+      const pages = await addMarks(
+        file,
+        file.pages!,
+        marksByFileNamePage[fileName]
+      )
       const blob = await convertToPdfBlob(pages)
       zip.file(`files/${fileName}`, blob)
     } else {

src/utils/pdf.ts

@@ -8,11 +8,16 @@ PDFJS.GlobalWorkerOptions.workerSrc = new URL(
   import.meta.url
 ).toString()
 
+/**
+ * Default width of the rendered element on the website
+ * @constant {number}
+ */
+export const DEFAULT_VIEWPORT_WIDTH = 550
 /**
  * Scale between the PDF page's natural size and rendered size
  * @constant {number}
  */
-export const SCALE: number = 3
+export const DEFAULT_SCALE: number = 1
 /**
  * Defined font size used when generating a PDF. Currently it is difficult to fully
  * correlate font size used at the time of filling in / drawing on the PDF
@@ -20,7 +25,7 @@ export const SCALE: number = 3
  * This should be fixed going forward.
  * Switching to PDF-Lib will most likely make this problem redundant.
  */
-export const FONT_SIZE: number = 40
+export const FONT_SIZE: number = 16
 /**
  * Current font type used when generating a PDF.
  */
@@ -72,28 +77,30 @@ export const readPdf = (file: File): Promise<string | ArrayBuffer> => {
 export const pdfToImages = async (
   data: string | ArrayBuffer
 ): Promise<PdfPage[]> => {
-  const images: string[] = []
+  const pages: PdfPage[] = []
   const pdf = await PDFJS.getDocument(data).promise
   const canvas = document.createElement('canvas')
 
   for (let i = 0; i < pdf.numPages; i++) {
     const page = await pdf.getPage(i + 1)
-    const viewport = page.getViewport({ scale: SCALE })
+
+    const originalViewport = page.getViewport({ scale: 1 })
+    const scale = originalViewport.width / DEFAULT_VIEWPORT_WIDTH
+
+    const viewport = page.getViewport({ scale })
     const context = canvas.getContext('2d')
     canvas.height = viewport.height
     canvas.width = viewport.width
+
     await page.render({ canvasContext: context!, viewport: viewport }).promise
-    images.push(canvas.toDataURL())
+    pages.push({
+      image: canvas.toDataURL(),
+      scale,
+      drawnFields: []
+    })
   }
 
-  return Promise.resolve(
-    images.map((image) => {
-      return {
-        image,
-        drawnFields: []
-      }
-    })
-  )
+  return pages
 }
 
 /**
@@ -103,6 +110,7 @@ export const pdfToImages = async (
  */
 export const addMarks = async (
   file: File,
+  pages: PdfPage[],
   marksPerPage: { [key: string]: Mark[] }
 ) => {
   const p = await readPdf(file)
@@ -113,34 +121,39 @@ export const addMarks = async (
 
   for (let i = 0; i < pdf.numPages; i++) {
     const page = await pdf.getPage(i + 1)
-    const viewport = page.getViewport({ scale: SCALE })
+    const viewport = page.getViewport({ scale: 1 })
     const context = canvas.getContext('2d')
     canvas.height = viewport.height
     canvas.width = viewport.width
-    await page.render({ canvasContext: context!, viewport: viewport }).promise
+    if (context) {
+      await page.render({ canvasContext: context, viewport: viewport }).promise
 
-    if (marksPerPage && Object.hasOwn(marksPerPage, i))
-      marksPerPage[i]?.forEach((mark) => draw(mark, context!))
+      if (marksPerPage && Object.hasOwn(marksPerPage, i)) {
+        marksPerPage[i]?.forEach((mark) => draw(mark, context, pages[i].scale))
+      }
 
-    images.push(canvas.toDataURL())
+      images.push(canvas.toDataURL())
+    }
   }
 
-  return Promise.resolve(images)
+  canvas.remove()
+
+  return images
 }
 
 /**
  * Utility to scale mark in line with the PDF-to-PNG scale
  */
-export const scaleMark = (mark: Mark): Mark => {
+export const scaleMark = (mark: Mark, scale: number): Mark => {
   const { location } = mark
   return {
     ...mark,
     location: {
       ...location,
-      width: location.width * SCALE,
-      height: location.height * SCALE,
-      left: location.left * SCALE,
-      top: location.top * SCALE
+      width: location.width * scale,
+      height: location.height * scale,
+      left: location.left * scale,
+      top: location.top * scale
     }
   }
 }
@@ -156,15 +169,21 @@ export const hasValue = (mark: Mark): boolean => !!mark.value
  * @param mark to be drawn
  * @param ctx a Canvas representation of a specific PDF Page
  */
-export const draw = (mark: Mark, ctx: CanvasRenderingContext2D) => {
-  const { location } = mark
+export const draw = (
+  mark: Mark,
+  ctx: CanvasRenderingContext2D,
+  scale: number
+) => {
+  const { location } = scaleMark(mark, scale)
 
-  ctx!.font = FONT_SIZE + 'px ' + FONT_TYPE
-  ctx!.fillStyle = 'black'
-  const textMetrics = ctx!.measureText(mark.value!)
+  ctx.font = scale * FONT_SIZE + 'px ' + FONT_TYPE
+  ctx.fillStyle = 'black'
+  const textMetrics = ctx.measureText(mark.value!)
+  const textHeight =
+    textMetrics.actualBoundingBoxAscent + textMetrics.actualBoundingBoxDescent
   const textX = location.left + (location.width - textMetrics.width) / 2
-  const textY = location.top + (location.height + parseInt(ctx!.font)) / 2
-  ctx!.fillText(mark.value!, textX, textY)
+  const textY = location.top + (location.height + textHeight) / 2
+  ctx.fillText(mark.value!, textX, textY)
 }
 
 /**
@@ -194,13 +213,11 @@ export const convertToPdfBlob = async (
 /**
  * @param marks - an array of Marks
  * @function hasValue removes any Mark without a property
- * @function scaleMark scales remaining marks in line with SCALE
  * @function byPage groups remaining Marks by their page marks.location.page
  */
 export const groupMarksByFileNamePage = (marks: Mark[]) => {
   return marks
     .filter(hasValue)
-    .map(scaleMark)
     .reduce<{ [fileName: string]: { [page: number]: Mark[] } }>(byPage, {})
 }