private static void GUI_OnTick(GUITickEventArgs eventArgs)
{
_keys = eventArgs.Keys;
if (_renderFrameNextTick)
{
eventArgs.FrameBuffer = _frameBuffer;
eventArgs.ShouldRender = true;
_renderFrameNextTick = false;
}
if (_playSoundNextTick)
{
eventArgs.PlaySound = true;
_playSoundNextTick = false;
}
if (_emulator.Finished && !_keepOpenWhenDoneEmulating)
{
eventArgs.ShouldQuit = true;
}
if (_logPerformance)
{
_guiTickCounter++;
if (_guiPerformanceWatch.ElapsedMilliseconds >= 1000)
{
Console.WriteLine("GUI ticks per second: " + _guiTickCounter);
_guiTickCounter = 0;
_guiPerformanceWatch.Restart();
}
}
if (_debug && eventArgs.KeyDown != null)
{
if (eventArgs.KeyDown == SDL2.SDL.SDL_Keycode.SDLK_SPACE)
{
_shouldBreak = true;
}
else if (eventArgs.KeyDown == SDL2.SDL.SDL_Keycode.SDLK_F5)
{
_shouldStep = false;
_shouldBreak = false;
}
else if (eventArgs.KeyDown == SDL2.SDL.SDL_Keycode.SDLK_F10)
{
_shouldStep = true;
_shouldBreak = false;
}
}
}
public void StartLoop()
{
// Used to keep track of the time elapsed in each loop iteration. This is used to
// notify the OnTick handlers so they can update their simulation, as well as throttle
// the update loop to 60hz if needed.
var stopwatch = new Stopwatch();
// Structure used to pass data to and from the OnTick handlers. We initialize it once
// outside of the loop to avoid eating a ton of memory putting GC into a tailspin.
var tickEventArgs = new GUITickEventArgs();
tickEventArgs.Keys = GetEmptyKeyDictionary();
// The SDL event polled for in each iteration of the loop.
SDL.SDL_Event sdlEvent;
while (true)
{
stopwatch.Restart();
tickEventArgs.KeyDown = null;
while (SDL.SDL_PollEvent(out sdlEvent) != 0)
{
switch (sdlEvent.type)
{
// e.g. Command + Q
case SDL.SDL_EventType.SDL_QUIT:
// Break out of the SDL event loop, which will close the program.
return;
case SDL.SDL_EventType.SDL_KEYDOWN:
tickEventArgs.KeyDown = sdlEvent.key.keysym.sym;
UpdateKeys(tickEventArgs.Keys, sdlEvent.key.keysym.sym, true);
break;
case SDL.SDL_EventType.SDL_KEYUP:
UpdateKeys(tickEventArgs.Keys, sdlEvent.key.keysym.sym, false);
break;
}
}
// Update the event arguments that will be sent with the event handler.
tickEventArgs.ShouldRender = false;
tickEventArgs.PlaySound = false;
// Delegate out to the event handler so work can be done.
if (OnTick != null)
{
OnTick(tickEventArgs);
}
// We only want to re-render if the frame buffer has changed since last time because
// the SDL_RenderPresent method is relatively expensive and massively slows down the
// amount of opcodes (ticks) we can execute.
if (tickEventArgs.ShouldRender)
{
// Clear the screen.
SDL.SDL_SetRenderDrawColor(_renderer, 0, 0, 0, 0);
SDL.SDL_RenderClear(_renderer);
// Render screen from the updated the frame buffer.
SDL.SDL_SetRenderDrawColor(_renderer, 255, 255, 255, 255);
var frameBuffer = tickEventArgs.FrameBuffer;
// TODO: Build out a 2D array of points so we can do a single call to SDL_RenderDrawPoints here.
if (frameBuffer != null)
{
for (var x = 0; x < frameBuffer.GetLength(0); x++)
{
for (var y = 0; y < frameBuffer.GetLength(1); y++)
{
if (frameBuffer[x, y] == 1)
{
SDL.SDL_RenderDrawPoint(_renderer, x, y);
}
}
}
}
SDL.SDL_RenderPresent(_renderer);
}
// If the event handler indicated a should needs to be played, do it now.
if (tickEventArgs.PlaySound)
{
// TODO: Beep
}
// See if we need to delay to keep locked to ~ TARGET_FPS FPS.
if (stopwatch.Elapsed.TotalMilliseconds < (1000 / _targetFPS))
{
var delay = (1000 / _targetFPS) - stopwatch.Elapsed.TotalMilliseconds;
SDL.SDL_Delay((uint)delay);
}
// If the event handler indicated we should quit, then stop.
if (tickEventArgs.ShouldQuit)
{
return;
}
}
}