[code] Avoid init/deinit-ing uPy in each editor redraw

apps/code/editor_controller.cpp

@@ -53,6 +53,7 @@ void EditorController::didBecomeFirstResponder() {
 }
 
 void EditorController::viewWillAppear() {
+  m_editorView.loadSyntaxHighlighter();
   m_editorView.setCursorLocation(strlen(m_editorView.text()));
 }
 
@@ -60,6 +61,7 @@ void EditorController::viewDidDisappear() {
   m_menuController->scriptContentEditionDidFinish();
   delete[] m_areaBuffer;
   m_areaBuffer = nullptr;
+  m_editorView.unloadSyntaxHighlighter();
 }
 
 bool EditorController::textAreaDidReceiveEvent(TextArea * textArea, Ion::Events::Event event) {

apps/code/editor_view.h

@@ -12,15 +12,15 @@ public:
   void setTextAreaDelegate(TextAreaDelegate * delegate) {
     m_textArea.setDelegate(delegate);
   }
-  const char * text() const {
-    return m_textArea.text();
-  }
+  const char * text() const { return m_textArea.text(); }
   void setText(char * textBuffer, size_t textBufferSize) {
     m_textArea.setText(textBuffer, textBufferSize);
   }
   bool setCursorLocation(int location) {
     return m_textArea.setCursorLocation(location);
   }
+  void loadSyntaxHighlighter() { m_textArea.loadSyntaxHighlighter(); };
+  void unloadSyntaxHighlighter() { m_textArea.unloadSyntaxHighlighter(); };
   void scrollViewDidChangeOffset(ScrollViewDataSource * scrollViewDataSource) override;
   void didBecomeFirstResponder() override;
 private:

apps/code/python_text_area.cpp

@@ -58,15 +58,19 @@ static inline int TokenLength(mp_lexer_t * lex) {
   }
 }
 
-PythonTextArea::ContentView::ContentView(KDText::FontSize fontSize) :
-  TextArea::ContentView(fontSize)
-{
+void PythonTextArea::ContentView::loadSyntaxHighlighter() {
+  assert(m_pythonHeap == nullptr);
   m_pythonHeap = static_cast<char *>(malloc(k_pythonHeapSize));
+  if (m_pythonHeap != nullptr) {
+    MicroPython::init(m_pythonHeap, m_pythonHeap + k_pythonHeapSize);
+  }
 }
 
-PythonTextArea::ContentView::~ContentView() {
-  if (m_pythonHeap) {
+void PythonTextArea::ContentView::unloadSyntaxHighlighter() {
+  if (m_pythonHeap != nullptr) {
+    MicroPython::deinit();
     free(m_pythonHeap);
+    m_pythonHeap = nullptr;
   }
 }
 
@@ -85,7 +89,7 @@ void PythonTextArea::ContentView::clearRect(KDContext * ctx, KDRect rect) const
 void PythonTextArea::ContentView::drawLine(KDContext * ctx, int line, const char * text, size_t length, int fromColumn, int toColumn) const {
   LOG_DRAW("Drawing \"%.*s\"\n", length, text);
 
-  if (!m_pythonHeap) {
+  if (m_pythonHeap == nullptr) {
     drawStringAt(
       ctx,
       line,
@@ -98,8 +102,6 @@ void PythonTextArea::ContentView::drawLine(KDContext * ctx, int line, const char
     return;
   }
 
-  MicroPython::init(m_pythonHeap, m_pythonHeap + k_pythonHeapSize);
-
   nlr_buf_t nlr;
   if (nlr_push(&nlr) == 0) {
     /* We're using the MicroPython lexer to do syntax highlighting on a per-line
@@ -151,8 +153,6 @@ void PythonTextArea::ContentView::drawLine(KDContext * ctx, int line, const char
     mp_lexer_free(lex);
     nlr_pop();
   }
-
-  MicroPython::deinit();
 }
 
 KDRect PythonTextArea::ContentView::dirtyRectFromCursorPosition(size_t index, bool lineBreak) const {

apps/code/python_text_area.h

@@ -12,11 +12,18 @@ public:
     m_contentView(fontSize)
   {
   }
+  void loadSyntaxHighlighter() { m_contentView.loadSyntaxHighlighter(); }
+  void unloadSyntaxHighlighter() { m_contentView.unloadSyntaxHighlighter(); }
 protected:
   class ContentView : public TextArea::ContentView {
   public:
-    ContentView(KDText::FontSize fontSize);
-    ~ContentView();
+    ContentView(KDText::FontSize fontSize) :
+      TextArea::ContentView(fontSize),
+      m_pythonHeap(nullptr)
+    {
+    }
+    void loadSyntaxHighlighter();
+    void unloadSyntaxHighlighter();
     void clearRect(KDContext * ctx, KDRect rect) const override;
     void drawLine(KDContext * ctx, int line, const char * text, size_t length, int fromColumn, int toColumn) const override;
     KDRect dirtyRectFromCursorPosition(size_t index, bool lineBreak) const override;
@@ -27,7 +34,6 @@ protected:
 private:
   const ContentView * nonEditableContentView() const override { return &m_contentView; }
   ContentView m_contentView;
-  char * m_pythonHeap;
 };
 
 }