Fine-tune markup drawing

This adjusts markup color slightly for the dark display, makes it fully
opaque, alternates the squiggly line between grammar and spelling
mistakes to visualize one-word-two-mistake-types, paints most important
mistakes last/on top etc.

All to make the markup as visible as possible.

service.js

@@ -371,13 +371,19 @@ class BesService {
     if (match.highlights.length === 0) return
     const dpr = window.devicePixelRatio
     this.ctx.lineWidth = 2 * dpr // Use 2 for clearer visibility
+    let amplitude = 0
     const ruleId = match.match.rule.id
-    this.ctx.strokeStyle = ruleId.startsWith('MORFOLOGIK_RULE')
-      ? 'rgba(0, 123, 255, 0.8)'
-      : 'rgba(255, 115, 0, 0.8)'
-    this.ctx.fillStyle = ruleId.startsWith('MORFOLOGIK_RULE')
-      ? 'rgba(0, 123, 255, 0.8)'
-      : 'rgba(255, 115, 0, 0.8)'
+    if (ruleId.startsWith('MORFOLOGIK_RULE')) {
+      const styles = window.getComputedStyle(this.highlightSpelling)
+      this.ctx.strokeStyle = styles.color
+      this.ctx.fillStyle = styles.color
+      amplitude = -1
+    } else {
+      const styles = window.getComputedStyle(this.highlightGrammar)
+      this.ctx.strokeStyle = styles.color
+      this.ctx.fillStyle = styles.color
+      amplitude = 1
+    }
     let markerY1, markerY2
     switch (this.markupStyle) {
       case 'lector':
@@ -681,7 +687,7 @@ class BesService {
           const x2 = rect.right
           const y = rect.bottom
           const scale = (rect.bottom - rect.top) / 18
-          this.drawAttentionRequired(x1, x2, y, scale)
+          this.drawAttentionRequired(x1, x2, y, amplitude, scale)
         }
 
         markerY1 = Math.min(...match.highlights.map(rect => rect.top))
@@ -865,17 +871,18 @@ class BesService {
    * @param {Number} x1 Sign left [px]
    * @param {Number} x2 Sign right [px]
    * @param {Number} y Sign baseline [px]
+   * @param {Number} amplitude Sign amplitude [px]
    * @param {Number} scale Sign scale
    */
-  drawAttentionRequired(x1, x2, y, scale) {
+  drawAttentionRequired(x1, x2, y, amplitude, scale) {
     const dpr = window.devicePixelRatio
     this.ctx.beginPath()
-    this.ctx.moveTo(x1 * dpr, (y - scale) * dpr)
+    this.ctx.moveTo(x1 * dpr, (y - amplitude * scale) * dpr)
     for (let x = x1; ; ) {
       if (x >= x2) break
-      this.ctx.lineTo((x += 2 * scale) * dpr, (y + scale) * dpr)
+      this.ctx.lineTo((x += 2 * scale) * dpr, (y + amplitude * scale) * dpr)
       if (x >= x2) break
-      this.ctx.lineTo((x += 2 * scale) * dpr, (y - scale) * dpr)
+      this.ctx.lineTo((x += 2 * scale) * dpr, (y - amplitude * scale) * dpr)
     }
     this.ctx.stroke()
   }
@@ -972,7 +979,16 @@ class BesService {
     this.ctx = this.canvasPanel.getContext('2d')
     this.ctx.scale(1, 1)
 
+    this.highlightSpelling = document.createElement('div')
+    this.highlightSpelling.classList.add('bes-highlight-placeholder')
+    this.highlightSpelling.classList.add('bes-highlight-spelling')
+    this.highlightGrammar = document.createElement('div')
+    this.highlightGrammar.classList.add('bes-highlight-placeholder')
+    this.highlightGrammar.classList.add('bes-highlight-grammar')
+
     this.correctionPanel.appendChild(this.scrollPanel)
+    this.correctionPanel.appendChild(this.highlightSpelling)
+    this.correctionPanel.appendChild(this.highlightGrammar)
     this.scrollPanel.appendChild(this.canvasPanel)
     this.textElement.parentElement.insertBefore(
       this.correctionPanel,
@@ -1066,8 +1082,8 @@ class BesService {
       el.classList.add('bes-highlight-rect')
       el.classList.add(
         match.match.rule.id.startsWith('MORFOLOGIK_RULE')
-          ? 'bes-highlight-spelling-rect'
-          : 'bes-highlight-grammar-rect'
+          ? 'bes-highlight-spelling'
+          : 'bes-highlight-grammar'
       )
       el.style.left = `${rect.x + canvasPanelRect.x + window.scrollX}px`
       el.style.top = `${rect.y + canvasPanelRect.y + window.scrollY}px`
@@ -1107,7 +1123,9 @@ class BesService {
   redrawAllMistakeMarkup() {
     this.ctx.clearRect(0, 0, this.canvasPanel.width, this.canvasPanel.height)
     this.results.forEach(result => {
-      result.matches.forEach(match => this.drawMistakeMarkup(match))
+      // Most important matches are first, we want to draw them last => iterate in reverse.
+      for (let i = result.matches.length; i-- > 0; )
+        this.drawMistakeMarkup(result.matches[i])
     })
   }
 
@@ -1263,9 +1281,11 @@ class BesTreeService extends BesService {
                     ),
                     match: match
                   }
-                  this.drawMistakeMarkup(m)
                   matches.push(m)
                 })
+                // Most important matches are first, we want to draw them last => iterate in reverse.
+                for (let i = matches.length; i-- > 0; )
+                  this.drawMistakeMarkup(matches[i])
                 this.markProofed(node, matches)
                 this.onProofingProgress(matches.length)
               })
@@ -2052,9 +2072,11 @@ class BesPlainTextService extends BesService {
                 ),
                 match: match
               }
-              this.drawMistakeMarkup(m)
               matches.push(m)
             })
+            // Most important matches are first, we want to draw them last => iterate in reverse.
+            for (let i = matches.length; i-- > 0; )
+              this.drawMistakeMarkup(matches[i])
             this.markProofed(paragraphRange, matches)
             this.onProofingProgress(matches.length)
           })