implemented DisplaySDL

DisplaySDL.cpp

@@ -0,0 +1,77 @@
+#include "DisplaySDL.hpp"
+
+#include <stdexcept>
+
+DisplaySDL::DisplaySDL(int w, int h, uint32_t fgColor, uint32_t bgColor) {
+  // Create SDL Window
+  mpWindow = SDL_CreateWindow(
+    "ChocoChip-8",
+    SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
+    w, h,
+    0
+  );
+  if(mpWindow == NULL) {
+    throw std::runtime_error(SDL_GetError());
+  }
+
+  // Convert our foreground/background colors to the format expected by SDL
+  SDL_PixelFormat *fmt = SDL_AllocFormat(SDL_GetWindowPixelFormat(mpWindow));
+  mFgColor = SDL_MapRGB(
+      fmt,
+      (fgColor & 0x00FF0000) >> 16,
+      (fgColor & 0x0000FF00) >> 8,
+      (fgColor & 0x000000FF)
+  );
+  mBgColor = SDL_MapRGB(
+      fmt,
+      (bgColor & 0x00FF0000) >> 16,
+      (bgColor & 0x0000FF00) >> 8,
+      (bgColor & 0x000000FF)
+  );
+  SDL_FreeFormat(fmt);
+};
+
+DisplaySDL::~DisplaySDL() {
+  SDL_DestroyWindow(mpWindow);
+}
+
+void DisplaySDL::updateWindow() const {
+  SDL_Surface *pSurface = SDL_GetWindowSurface(mpWindow);
+  SDL_LockSurface(pSurface);
+
+  int fx, fy; // ChocoChip8 Framebuffer coordinates
+  int sx, sy; // SDL Surface coordinates
+  int lx, ly; // Last-used ChocoChip8 Framebuffer coordinates
+  Uint32 lc;  // Last-used SDL color
+  
+  // Fill the entire SDL surface, one pixel at a time
+  lx = -1;
+  ly = -1;
+  for(sy = 0; sy < pSurface->h; sy++) {
+    for(sx = 0; sx < pSurface->w; sx++) {
+      // Map SDL surface coordinates to Chocochip8 Framebuffer coordinates
+      fx = sx * (double(chocochip8::gcWidth) / pSurface->w);
+      fy = sy * (double(chocochip8::gcHeight) / pSurface->h);
+
+      // Reuse color if this screen pixel maps to the same ChocoChip8 pixel as the last
+      if(fx != lx || fy != ly) {
+        lx = fx;
+        ly = ly;
+        // Read Chocochip8 Framebuffer and choose appropriate color,
+        // note that the MSB of an scanline's bitset is the leftmost pixel.
+        lc = (mpFramebuffer->at(fy)[(chocochip8::gcWidth - 1) - fx] ? mFgColor : mBgColor);
+      }
+
+      // Convert (x, y) indexes into SDL Surface pixel array index
+      Uint32 *pPixel = static_cast<Uint32*>(static_cast<void*>(
+          static_cast<char*>(pSurface->pixels)
+          + sy * pSurface->pitch
+          + sx * pSurface->format->BytesPerPixel
+      ));
+      *pPixel = lc;
+    }
+  }
+
+  SDL_UnlockSurface(pSurface);
+  SDL_UpdateWindowSurface(mpWindow);
+}