[python/turtle] Turtle::m_drawn is false if sandbox not displayed

This way, Turtle::draw() and erase() are more symetrical and no not
perform themselves if the turtle is already drawn / erased.

python/port/mod/turtle/modturtle.cpp

@@ -11,6 +11,10 @@ void modturtle_gc_collect() {
   gc_collect_root((void **)&sTurtle, sizeof(Turtle));
 }
 
+void modturtle_view_did_disappear() {
+  sTurtle.viewDidDisappear();
+}
+
 mp_obj_t modturtle___init__() {
   sTurtle = Turtle();
   /* Note: we don't even bother writing a destructor for Turtle because this

python/port/mod/turtle/modturtle.h

@@ -2,6 +2,7 @@
 
 mp_obj_t modturtle___init__();
 void modturtle_gc_collect();
+void modturtle_view_did_disappear();
 
 mp_obj_t modturtle_reset();
 

python/port/mod/turtle/turtle.cpp

@@ -166,6 +166,10 @@ void Turtle::setColor(const char * color) {
   }
 }
 
+void Turtle::viewDidDisappear() {
+  m_drawn = false;
+}
+
 // Private functions
 
 void Turtle::setHeadingPrivate(mp_float_t angle) {
@@ -225,7 +229,7 @@ KDRect Turtle::iconRect() const {
 bool Turtle::draw(bool force) {
   MicroPython::ExecutionEnvironment::currentExecutionEnvironment()->displaySandbox();
 
-  if ((m_speed > 0 || force) && m_visible && hasUnderneathPixelBuffer()) {
+  if ((m_speed > 0 || force) && m_visible && !m_drawn && hasUnderneathPixelBuffer()) {
     KDContext * ctx = KDIonContext::sharedContext();
 
     // Get the pixels underneath the turtle
@@ -322,8 +326,8 @@ bool Turtle::dot(mp_float_t x, mp_float_t y) {
 }
 
 void Turtle::drawPaw(PawType type, PawPosition pos) {
-  assert(!m_drawn && m_underneathPixelBuffer != nullptr);
-
+  assert(!m_drawn);
+  assert(m_underneathPixelBuffer != nullptr);
   KDCoordinate pawOffset = 5;
   constexpr float crawlOffset = 0.6f;
   constexpr float angles[] = {M_PI_2/2, M_PI_2+M_PI_2/2, -M_PI_2-M_PI_2/2, -M_PI_2/2};

python/port/mod/turtle/turtle.h

@@ -72,6 +72,9 @@ public:
     m_color = KDColor::RGB888(r, g, b);
   }
   void setColor(const char * color);
+
+  void viewDidDisappear();
+
 private:
   static constexpr mp_float_t k_headingOffset = M_PI_2;
   static constexpr mp_float_t k_headingScale = M_PI / 180;

python/port/port.cpp

@@ -24,11 +24,6 @@ extern "C" {
 static MicroPython::ScriptProvider * sScriptProvider = nullptr;
 static MicroPython::ExecutionEnvironment * sCurrentExecutionEnvironment = nullptr;
 
-MicroPython::ExecutionEnvironment::ExecutionEnvironment() :
-  m_sandboxIsDisplayed(false)
-{
-}
-
 MicroPython::ExecutionEnvironment * MicroPython::ExecutionEnvironment::currentExecutionEnvironment() {
   return sCurrentExecutionEnvironment;
 }
@@ -90,6 +85,13 @@ void MicroPython::ExecutionEnvironment::interrupt() {
   mp_keyboard_interrupt();
 }
 
+void MicroPython::ExecutionEnvironment::setSandboxIsDisplayed(bool display) {
+  if (m_sandboxIsDisplayed && !display) {
+    modturtle_view_did_disappear();
+  }
+  m_sandboxIsDisplayed = display;
+}
+
 extern "C" {
   extern const void * _stack_start;
   extern const void * _stack_end;

python/port/port.h

@@ -14,7 +14,7 @@ public:
 
 class ExecutionEnvironment {
 public:
-  ExecutionEnvironment();
+  ExecutionEnvironment() : m_sandboxIsDisplayed(false) {}
   static ExecutionEnvironment * currentExecutionEnvironment();
   void runCode(const char * );
   virtual const char * inputText(const char * prompt) { return nullptr; }
@@ -22,7 +22,10 @@ public:
   virtual void resetSandbox() {}
   virtual void printText(const char * text, size_t length) {}
   void interrupt();
+  void setSandboxIsDisplayed(bool display);
 protected:
+  bool sandboxIsDisplayed() const { return m_sandboxIsDisplayed; }
+private:
   bool m_sandboxIsDisplayed;
 };