From e95810990284f194b191480d728ae67502ee6da2 Mon Sep 17 00:00:00 2001
From: Jim O'Donnell <james.odonnell@dtc.ox.ac.uk>
Date: Sat, 23 Nov 2024 18:16:18 +0000
Subject: [PATCH] fix(lib-classifier): canvas context for SVG drawing tools

Make sure that `SVGContext.canvas` is a reference to the SVG `rect` element that's used as a drawing canvas, so that creating new drawing marks and editing existing marks both use the same screen CTM when calculating the pointer position.

This fixes a bug in Firefox where the `draggable` decorator doesn't correctly track the active pointer, in the context of a zoomed SVG image.
---
 .../InteractionLayer/InteractionLayer.js      | 86 +++++++++----------
 .../SingleImageViewer/SingleImageViewer.js    |  5 +-
 2 files changed, 44 insertions(+), 47 deletions(-)

diff --git a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/InteractionLayer/InteractionLayer.js b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/InteractionLayer/InteractionLayer.js
index 1ec9ee978b7..5eb561b3766 100644
--- a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/InteractionLayer/InteractionLayer.js
+++ b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/InteractionLayer/InteractionLayer.js
@@ -1,7 +1,9 @@
 import cuid from 'cuid'
 import PropTypes from 'prop-types'
-import { useRef, useState } from 'react';
+import { useContext, useRef, useState } from 'react';
 import styled, { css } from 'styled-components'
+
+import SVGContext from '@plugins/drawingTools/shared/SVGContext'
 import DrawingToolMarks from './components/DrawingToolMarks'
 import TranscribedLines from './components/TranscribedLines'
 import SubTaskPopup from './components/SubTaskPopup'
@@ -24,6 +26,38 @@ function cancelEvent(event) {
   event.stopPropagation()
 }
 
+function createPoint(event) {
+  const { clientX, clientY } = event
+  // SVG 2 uses DOMPoint
+  if (window.DOMPointReadOnly) {
+    return new DOMPointReadOnly(clientX, clientY)
+  }
+  // jsdom doesn't support SVG
+  return {
+    x: clientX,
+    y: clientY
+  }
+}
+
+function getEventOffset(event, canvas) {
+  const svgPoint = createPoint(event)
+  const svgEventOffset = svgPoint.matrixTransform
+    ? svgPoint.matrixTransform(canvas.getScreenCTM().inverse())
+    : svgPoint
+  return svgEventOffset
+}
+
+function convertEvent(event, canvas) {
+  const svgEventOffset = getEventOffset(event, canvas)
+  const svgCoordinateEvent = {
+    type: event.type,
+    x: svgEventOffset.x,
+    y: svgEventOffset.y
+  }
+
+  return svgCoordinateEvent
+}
+
 function InteractionLayer({
   activeMark,
   activeTool,
@@ -43,7 +77,9 @@ function InteractionLayer({
   duration
 }) {
   const [creating, setCreating] = useState(false)
-  const canvas = useRef()
+  const svgContext = useContext(SVGContext)
+  const canvasRef = useRef()
+  svgContext.canvas = canvasRef.current
 
   if (creating && !activeMark) {
     setCreating(false)
@@ -54,42 +90,6 @@ function InteractionLayer({
     setActiveMark(undefined)
   }
 
-  function convertEvent(event) {
-    const type = event.type
-
-    const svgEventOffset = getEventOffset(event)
-
-    const svgCoordinateEvent = {
-      pointerId: event.pointerId,
-      type,
-      x: svgEventOffset.x,
-      y: svgEventOffset.y
-    }
-
-    return svgCoordinateEvent
-  }
-
-  function createPoint(event) {
-    const { clientX, clientY } = event
-    // SVG 2 uses DOMPoint
-    if (window.DOMPointReadOnly) {
-      return new DOMPointReadOnly(clientX, clientY)
-    }
-    // jsdom doesn't support SVG
-    return {
-      x: clientX,
-      y: clientY
-    }
-  }
-
-  function getEventOffset(event) {
-    const svgPoint = createPoint(event)
-    const svgEventOffset = svgPoint.matrixTransform
-      ? svgPoint.matrixTransform(canvas.current?.getScreenCTM().inverse())
-      : svgPoint
-    return svgEventOffset
-  }
-
   function createMark(event) {
     const timeStamp = getFixedNumber(played, 5)
     const mark = activeTool.createMark({
@@ -99,7 +99,7 @@ function InteractionLayer({
       toolIndex: activeToolIndex
     })
 
-    mark.initialPosition(convertEvent(event))
+    mark.initialPosition(convertEvent(event, canvasRef.current))
     setActiveMark(mark)
     setCreating(true)
     mark.setSubTaskVisibility(false)
@@ -124,7 +124,7 @@ function InteractionLayer({
     }
 
     if (creating) {
-      activeTool?.handlePointerDown?.(convertEvent(event), activeMark)
+      activeTool?.handlePointerDown?.(convertEvent(event, canvasRef.current), activeMark)
       if (activeMark.finished) onFinish(event)
       return true
     }
@@ -136,7 +136,7 @@ function InteractionLayer({
   function onPointerMove(event) {
     cancelEvent(event)
     if (creating) {
-      activeTool?.handlePointerMove?.(convertEvent(event), activeMark)
+      activeTool?.handlePointerMove?.(convertEvent(event, canvasRef.current), activeMark)
     }
   }
 
@@ -149,7 +149,7 @@ function InteractionLayer({
   function onPointerUp(event) {
     cancelEvent(event)
     if (creating) {
-      activeTool?.handlePointerUp?.(convertEvent(event), activeMark)
+      activeTool?.handlePointerUp?.(convertEvent(event, canvasRef.current), activeMark)
       if (activeMark.finished) onFinish(event)
     }
   }
@@ -165,7 +165,7 @@ function InteractionLayer({
   return (
     <>
       <DrawingCanvas
-        ref={canvas}
+        ref={canvasRef}
         disabled={disabled || move}
         pointerEvents={move ? 'none' : 'all'}
         width={width}
diff --git a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/SingleImageViewer/SingleImageViewer.js b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/SingleImageViewer/SingleImageViewer.js
index 6829d078a2c..b8d2547abef 100644
--- a/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/SingleImageViewer/SingleImageViewer.js
+++ b/packages/lib-classifier/src/components/Classifier/components/SubjectViewer/components/SingleImageViewer/SingleImageViewer.js
@@ -34,12 +34,10 @@ function SingleImageViewer({
   zoomControlFn = null,
   zooming = false
 }) {
-  const canvasLayer = useRef()
-  const canvas = canvasLayer.current
   const transform = `rotate(${rotate} ${width / 2} ${height / 2})`
 
   return (
-    <SVGContext.Provider value={{ canvas, viewBox, rotate, width, height }}>
+    <SVGContext.Provider value={{ viewBox, rotate, width, height }}>
       {zoomControlFn && (
         <ZoomControlButton
           onClick={zoomControlFn}
@@ -68,7 +66,6 @@ function SingleImageViewer({
             transform={transform}
           >
             <SVGImageCanvas
-              ref={canvasLayer}
               viewBox={viewBox}
             >
               {children}