[chore] Refactor STTextViewController to reduce duplication (#185)

### Description

Fixed a few UI bugs by reducing overlap between loadView and reloadUI
and calling reloadUI from loadView. These include...
- There were some areas where the theme background was not getting
applied.
- The currently selected line was not getting a background in the ruler
view until changing a setting which called reloadUI.

Now loadView calls reloadUI which allows us to reduce code duplication

### Related Issues

- n/a

### Checklist

<!--- Add things that are not yet implemented above -->
- [x] I read and understood the [contributing
guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md)
as well as the [code of
conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots

n/a

Sources/CodeEditTextView/Controller/STTextViewController+Lifecycle.swift

@@ -9,62 +9,39 @@ import AppKit
 import STTextView
 
 extension STTextViewController {
-    // swiftlint:disable:next function_body_length
     public override func loadView() {
         textView = STTextView()
 
         let scrollView = CEScrollView()
         scrollView.translatesAutoresizingMaskIntoConstraints = false
         scrollView.hasVerticalScroller = true
         scrollView.documentView = textView
-        scrollView.drawsBackground = useThemeBackground
         scrollView.automaticallyAdjustsContentInsets = contentInsets == nil
-        if let contentInsets = contentInsets {
-            scrollView.contentInsets = contentInsets
-        }
 
         rulerView = STLineNumberRulerView(textView: textView, scrollView: scrollView)
-        rulerView.backgroundColor = useThemeBackground ? theme.background : .clear
-        rulerView.textColor = .secondaryLabelColor
         rulerView.drawSeparator = false
         rulerView.baselineOffset = baselineOffset
-        rulerView.font = rulerFont
-        rulerView.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
-        ? NSColor.quaternaryLabelColor
-        : NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
-        rulerView.rulerInsets = STRulerInsets(leading: rulerFont.pointSize * 1.6, trailing: 8)
         rulerView.allowsMarkers = false
-
-        if self.isEditable == false {
-            rulerView.selectedLineTextColor = nil
-            rulerView.selectedLineHighlightColor = theme.background
-        }
+        rulerView.backgroundColor = .clear
+        rulerView.textColor = .secondaryLabelColor
 
         scrollView.verticalRulerView = rulerView
         scrollView.rulersVisible = true
 
         textView.typingAttributes = attributesFor(nil)
         textView.defaultParagraphStyle = self.paragraphStyle
         textView.font = self.font
-        textView.textColor = theme.text
-        textView.backgroundColor = useThemeBackground ? theme.background : .clear
-        textView.insertionPointColor = theme.insertionPoint
         textView.insertionPointWidth = 1.0
-        textView.selectionBackgroundColor = theme.selection
-        textView.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
-        ? NSColor.quaternaryLabelColor
-        : NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
+        textView.backgroundColor = .clear
+
         textView.string = self.text.wrappedValue
-        textView.isEditable = self.isEditable
-        textView.highlightSelectedLine = true
         textView.allowsUndo = true
         textView.setupMenus()
         textView.delegate = self
-        textView.highlightSelectedLine = self.isEditable
 
         scrollView.documentView = textView
-
         scrollView.translatesAutoresizingMaskIntoConstraints = false
+        scrollView.backgroundColor = useThemeBackground ? theme.background : .clear
 
         self.view = scrollView
 
@@ -80,6 +57,7 @@ extension STTextViewController {
             return event
         }
 
+        reloadUI()
         setUpHighlighter()
         setHighlightProvider(self.highlightProvider)
         setUpTextFormation()

Sources/CodeEditTextView/Controller/STTextViewController.swift

@@ -187,28 +187,29 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
 
     /// Reloads the UI to apply changes to ``STTextViewController/font``, ``STTextViewController/theme``, ...
     internal func reloadUI() {
-        textView?.textColor = theme.text
-        textView.backgroundColor = useThemeBackground ? theme.background : .clear
-        textView?.insertionPointColor = theme.insertionPoint
-        textView?.selectionBackgroundColor = theme.selection
-        textView?.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
+        textView.textColor = theme.text
+        textView.insertionPointColor = theme.insertionPoint
+        textView.selectionBackgroundColor = theme.selection
+        textView.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
             ? NSColor.quaternaryLabelColor
             : NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
-        textView?.isEditable = isEditable
+        textView.isEditable = isEditable
         textView.highlightSelectedLine = isEditable
-        textView?.typingAttributes = attributesFor(nil)
+        textView.typingAttributes = attributesFor(nil)
         paragraphStyle = generateParagraphStyle()
-        textView?.defaultParagraphStyle = paragraphStyle
+        textView.defaultParagraphStyle = paragraphStyle
 
-        rulerView?.backgroundColor = useThemeBackground ? theme.background : .clear
-        rulerView?.separatorColor = theme.invisibles
-        rulerView?.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
+        rulerView.selectedLineHighlightColor = useThemeBackground ? theme.lineHighlight : systemAppearance == .darkAqua
             ? NSColor.quaternaryLabelColor
             : NSColor.selectedTextBackgroundColor.withSystemEffect(.disabled)
-        rulerView?.baselineOffset = baselineOffset
+        rulerView.baselineOffset = baselineOffset
         rulerView.highlightSelectedLine = isEditable
-        rulerView?.rulerInsets = STRulerInsets(leading: rulerFont.pointSize * 1.6, trailing: 8)
-        rulerView?.font = rulerFont
+        rulerView.rulerInsets = STRulerInsets(leading: rulerFont.pointSize * 1.6, trailing: 8)
+        rulerView.font = rulerFont
+        if self.isEditable == false {
+            rulerView.selectedLineTextColor = nil
+            rulerView.selectedLineHighlightColor = .clear
+        }
 
         if let scrollView = view as? NSScrollView {
             scrollView.drawsBackground = useThemeBackground