[ion/simulator] Add a runtime "--headless" option

We probably can ditch the static headless version

ion/src/simulator/shared/keyboard.cpp

@@ -39,6 +39,11 @@ namespace Ion {
 namespace Keyboard {
 
 State scan() {
+  State state = sKeyboardState;
+
+  if (Simulator::Window::isHeadless()) {
+    return state;
+  }
   // We need to tell SDL to get new state from the host OS
   SDL_PumpEvents();
 
@@ -48,7 +53,6 @@ State scan() {
   // Grab this opportunity to refresh the display if needed
   Simulator::Window::refresh();
 
-  State state = sKeyboardState;
 #if !EPSILON_SDL_SCREEN_ONLY
   // Register a key for the mouse, if any
   Key k = Simulator::Layout::getHighlightedKey();
@@ -65,6 +69,7 @@ State scan() {
       state.setKey(pair.key());
     }
   }
+
   return state;
 }
 

ion/src/simulator/shared/main.cpp

@@ -1,6 +1,7 @@
 #include "haptics.h"
 #include "journal.h"
 #include "platform.h"
+#include "random.h"
 #include "telemetry.h"
 #include "window.h"
 #include <vector>
@@ -85,19 +86,26 @@ int main(int argc, char * argv[]) {
   }
 #endif
 
+  bool headless = args.popFlag("--headless");
+
   using namespace Ion::Simulator;
-  Journal::init();
+  Random::init();
+  if (!headless) {
+    Journal::init();
 #if EPSILON_TELEMETRY
-  Telemetry::init();
+    Telemetry::init();
 #endif
-  Window::init();
-  Haptics::init();
+    Window::init();
+    Haptics::init();
+  }
   ion_main(args.argc(), args.argv());
-  Haptics::shutdown();
-  Window::quit();
+  if (!headless) {
+    Haptics::shutdown();
+    Window::quit();
 #if EPSILON_TELEMETRY
-  Telemetry::shutdown();
+    Telemetry::shutdown();
 #endif
+  }
 
   return 0;
 }

ion/src/simulator/shared/window.cpp

@@ -2,7 +2,6 @@
 #include "display.h"
 #include "layout.h"
 #include "platform.h"
-#include "random.h"
 
 #include <assert.h>
 #include <ion.h>
@@ -19,14 +18,16 @@ static bool sNeedsRefresh = false;
 static SDL_Rect sScreenRect;
 #endif
 
+bool isHeadless() {
+  return sWindow == nullptr;
+}
+
 void init() {
   if (SDL_Init(SDL_INIT_VIDEO) != 0) {
     SDL_Log("Could not init video");
     return;
   }
 
-  Random::init();
-
   sWindow = SDL_CreateWindow(
     "Epsilon",
     SDL_WINDOWPOS_CENTERED,
@@ -67,6 +68,9 @@ void init() {
 }
 
 void relayout() {
+  if (isHeadless()) {
+    return;
+  }
   int windowWidth = 0;
   int windowHeight = 0;
   SDL_GetWindowSize(sWindow, &windowWidth, &windowHeight);
@@ -89,7 +93,7 @@ void setNeedsRefresh() {
 }
 
 void refresh() {
-  if (!sNeedsRefresh) {
+  if (!sNeedsRefresh || isHeadless()) {
     return;
   }
   sNeedsRefresh = false;
@@ -112,11 +116,15 @@ void refresh() {
 }
 
 void quit() {
+  if (isHeadless()) {
+    return;
+  }
 #if !EPSILON_SDL_SCREEN_ONLY
   Layout::quit();
 #endif
   Display::quit();
   SDL_DestroyWindow(sWindow);
+  sWindow = nullptr;
   SDL_Quit();
 }
 

ion/src/simulator/shared/window.h

@@ -8,6 +8,8 @@ namespace Window {
 void init();
 void quit();
 
+bool isHeadless();
+
 void setNeedsRefresh();
 void refresh();
 void relayout();