Really basic implementation of SDL2.

Plus a crappy rectangle to prove that our vm screen code is working in
principle. (It will be removed shortly.)

CMakeLists.txt

@@ -6,11 +6,12 @@ project(erc)
 include(sources.cmake)
 
 if(APPLE)
-	set(opengl_library /System/Library/Frameworks/OpenGL.framework)
+	set(sdl_library /Library/Frameworks/SDL2.framework)
+	set(sdl_headers /Library/Frameworks/SDL2.framework/Headers)
 endif()
 
-if(NOT opengl_library)
-	message(FATAL_ERROR "This CMake file is not yet educated as to where OpenGL resides on your platform. Sorry!")
+if(NOT sdl_library)
+	message(FATAL_ERROR "This CMake file is not yet educated as to where SDL2 resides on your platform. Sorry!")
 endif()
 
 foreach(src ${erc_sources})
@@ -19,7 +20,7 @@ foreach(src ${erc_sources})
 endforeach(src)
 
 # our header files
-include_directories(include /usr/local/include)
+include_directories(include /usr/local/include ${sdl_headers})
 
 link_directories(/usr/local/lib)
 
@@ -27,4 +28,4 @@ link_directories(/usr/local/lib)
 add_executable(erc ${sources} src/main.c)
 
 # Graphics
-target_link_libraries(erc)
+target_link_libraries(erc ${sdl_library})

include/vm_screen.h

@@ -2,6 +2,7 @@
 #define _VM_SCREEN_H_
 
 #include <stdbool.h>
+#include <SDL.h>
 
 #define VM_SCREEN_DEFWIDTH 800
 #define VM_SCREEN_DEFHEIGHT 600
@@ -15,13 +16,14 @@
     vm_screen_draw_rect(screen, xpos, ypos, 1, 1)
 
 typedef struct {
-    /*
-     * These form the components of an RGBA composite color. 
-     */
-    int color_red;
-    int color_green;
-    int color_blue;
-    int color_alpha;
+    SDL_Window *window;
+    SDL_Renderer *render;
+    SDL_Rect rect;
+
+    int xcoords;
+    int ycoords;
+
+    int scale;
 } vm_screen;
 
 extern int vm_screen_add_window(vm_screen *);
@@ -32,6 +34,6 @@ extern bool vm_screen_active(vm_screen *);
 extern void vm_screen_draw_rect(vm_screen *, int, int, int, int);
 extern void vm_screen_free(vm_screen *);
 extern vm_screen *vm_screen_create();
-extern void vm_screen_set_color(vm_screen *, int, int, int, int);
+extern void vm_screen_set_color(vm_screen *, uint8_t, uint8_t, uint8_t, uint8_t);
 
 #endif

src/main.c

@@ -45,7 +45,10 @@ init(int argc, char **argv)
     // We're literally using stdout in this heavy phase of development.
     log_open(stdout);
 
-    vm_screen_init();
+    if (vm_screen_init() != OK) {
+        fprintf(stderr, "Couldn't initialize video\n");
+        exit(1);
+    }
 }
 
 /*
@@ -94,7 +97,7 @@ main(int argc, char **argv)
         exit(1);
     }
 
-    screen = vm_screen_create();
+    screen = vm_screen_create(320, 240, 2);
     if (screen == NULL) {
         fprintf(stderr, "Screen creation failed!\n");
         exit(1);
@@ -106,6 +109,8 @@ main(int argc, char **argv)
     }
 
     while (vm_screen_active(screen)) {
+        vm_screen_set_color(screen, 255, 0, 0, 255);
+        vm_screen_draw_rect(screen, 50, 50, 20, 20);
         vm_screen_refresh(screen);
     }
 

src/vm_screen.c

@@ -15,19 +15,25 @@
 int
 vm_screen_init()
 {
+    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+        log_critical("Could not initialize video: %s", SDL_GetError());
+        return ERR_GFXINIT;
+    }
+
     return OK;
 }
 
 void
 vm_screen_finish()
 {
+    SDL_Quit();
 }
 
 /*
  * Return a new screen. We also set the color to black.
  */
 vm_screen *
-vm_screen_create()
+vm_screen_create(int xcoords, int ycoords, int scale)
 {
     vm_screen *screen;
 
@@ -37,13 +43,35 @@ vm_screen_create()
         exit(1);
     }
 
-    vm_screen_set_color(screen, 0, 0, 0, 0);
+    screen->xcoords = xcoords;
+    screen->ycoords = ycoords;
+    screen->scale = scale;
+
+    screen->window = NULL;
+    screen->render = NULL;
+    screen->rect.x = 0;
+    screen->rect.y = 0;
+    screen->rect.w = 0;
+    screen->rect.h = 0;
+
     return screen;
 }
 
 int
 vm_screen_add_window(vm_screen *screen)
 {
+    SDL_CreateWindowAndRenderer(screen->xcoords * screen->scale,
+                                screen->ycoords * screen->scale,
+                                0, &screen->window, &screen->render);
+
+    if (screen->window == NULL || screen->render == NULL) {
+        log_critical("Could not create window: %s", SDL_GetError());
+        return ERR_GFXINIT;
+    }
+
+    vm_screen_set_color(screen, 0, 0, 0, 0);
+    SDL_RenderClear(screen->render);
+
     return OK;
 }
 
@@ -53,18 +81,28 @@ vm_screen_add_window(vm_screen *screen)
 void
 vm_screen_free(vm_screen *screen)
 {
+    SDL_DestroyRenderer(screen->render);
+    SDL_DestroyWindow(screen->window);
     free(screen);
 }
 
 bool
 vm_screen_active(vm_screen *screen)
 {
+    static int counter = 5;
+
+    if (counter--) {
+        return true;
+    }
+
     return false;
 }
 
 void
 vm_screen_refresh(vm_screen *screen)
 {
+    SDL_RenderPresent(screen->render);
+    SDL_Delay(2000);
 }
 
 /*
@@ -72,15 +110,12 @@ vm_screen_refresh(vm_screen *screen)
  */
 void
 vm_screen_set_color(vm_screen *screen,
-                    int red,
-                    int green,
-                    int blue,
-                    int alpha)
+                    uint8_t red,
+                    uint8_t green,
+                    uint8_t blue,
+                    uint8_t alpha)
 {
-    screen->color_red = red;
-    screen->color_green = green;
-    screen->color_blue = blue;
-    screen->color_alpha = alpha;
+    SDL_SetRenderDrawColor(screen->render, red, green, blue, alpha);
 }
 
 /*
@@ -94,5 +129,13 @@ vm_screen_draw_rect(vm_screen *screen,
                     int xsize,
                     int ysize)
 {
-    // FIXME: NOOP
+    // We need to scale the position and sizes, since the presumption is
+    // that we are plotting based on the literal x and y coordinates in
+    // the screen.
+    screen->rect.x = xpos * screen->scale;
+    screen->rect.y = ypos * screen->scale;
+    screen->rect.w = xsize * screen->scale;
+    screen->rect.h = ysize * screen->scale;
+
+    SDL_RenderFillRect(screen->render, &screen->rect);
 }