Yay working Lua API

Makefile

@@ -1,6 +1,6 @@
 CFLAGS += 
-LDFLAGS := -lm -lcairo -lxcb
-OBJECTS := obj/rootwindow.o obj/cairo_context.o
+LDFLAGS := -lm -lcairo -lxcb -llua
+OBJECTS := obj/common.o obj/rootwindow.o obj/cairo_context.o obj/api_draw.o
 
 livewp: lib
 	$(CC) $(CFLAGS) $(OBJECTS) src/main.c $(LDFLAGS) -o livewp

example.lua

@@ -1,11 +1,12 @@
 
-local img = assert(Image.load("/home/hkc/images/wallpapers/wallpaper.png"))
-local font = assert(Font.load("/usr/share/fonts/TTF/TerminusTTF.ttf"))
+-- local img = assert(Image.load("/home/hkc/images/wallpapers/wallpaper.png"))
+-- local font = assert(Font.load("/usr/share/fonts/TTF/TerminusTTF.ttf"))
 
-function tick()
+function tick(t)
     --           Background
-    Screen.clear(0xFF131313)
+    Draw.clear(math.floor(t * 255))
 
+--[[
     --         Color ARGB,  x,  y
     Draw.pixel(0xFFFF0000, 30, 30)
 
@@ -29,6 +30,7 @@ function tick()
 
     --          image ptr  x, y, w, h, src_x, src_y, src_w, src_h
     Draw.image(       img, 0, 0) --> Rect
+]]
 end
 
 function unload()

src/api_draw.c

@@ -0,0 +1,30 @@
+#include "common.h"
+#include "api_draw.h"
+#include <cairo/cairo.h>
+#include <lua5.3/lua.h>
+#include <lua5.3/lauxlib.h>
+
+int api_draw_clear(lua_State *L);
+
+bool loadapi_draw(lua_State *lua) {
+  const struct luaL_Reg api_draw[] = {
+    { "clear", api_draw_clear },
+  };
+  lua_newtable(lua);
+  luaL_setfuncs(lua, api_draw, 0);
+  lua_setglobal(lua, "Draw");
+  return true;
+}
+
+int api_draw_clear(lua_State *L) {
+  printf("Draw.clear()\n");
+  int color = luaL_checkinteger(L, 1);
+  printf("Draw.clear(0x%08x)\n", color);
+  cairo_t *cr = global_context.cairo_context.cairo;
+  int r = (color >> 16) & 0xFF,
+      g = (color >> 8) & 0xFF,
+      b = color & 0xFF;
+  cairo_set_source_rgb(cr, r / 255.0, g / 255.0, b / 255.0);
+  cairo_paint(cr);
+  return 0;
+}

src/api_draw.h

@@ -0,0 +1,9 @@
+#ifndef _API_DRAW_H_
+#define _API_DRAW_H_
+
+#include <lua5.3/lua.h>
+#include <stdbool.h>
+
+bool loadapi_draw(lua_State *lua);
+
+#endif

src/common.c

@@ -0,0 +1,3 @@
+#include "common.h"
+
+struct global_context global_context = { 0 };

src/common.h

@@ -0,0 +1,13 @@
+#ifndef _COMMON_H_
+#define _COMMON_H_
+
+#include <lua5.3/lua.h>
+#include "cairo_context.h"
+
+extern struct global_context {
+  lua_State *lua;
+  struct cairo_ctx cairo_context;
+  double time;
+} global_context;
+
+#endif

src/main.c

@@ -1,3 +1,7 @@
+#include <lua5.2/lualib.h>
+#include <lua5.3/lua.h>
+#include <lua5.3/luaconf.h>
+#include <lua5.3/lauxlib.h>
 #include <signal.h>
 #include <stdio.h>
 #include <math.h>
@@ -5,13 +9,14 @@
 #include <unistd.h>
 
 #include "cairo_context.h"
-
-struct cairo_ctx ctx;
+#include "common.h"
+#include "api_draw.h"
 
 volatile bool running = true;
 
 void cleanup(void) {
-  cairo_ctx_close(&ctx);
+  cairo_ctx_close(&global_context.cairo_context);
+  lua_close(global_context.lua);
 }
 
 void sighandler(int sig) {
@@ -19,21 +24,39 @@ void sighandler(int sig) {
 }
 
 int main(void) {
-  if (!cairo_ctx_create(NULL, &ctx)) {
+  if (!cairo_ctx_create(NULL, &global_context.cairo_context)) {
     fprintf(stderr, "Failed creating window or something\n");
     return EXIT_FAILURE;
   }
 
+  global_context.lua = luaL_newstate();
+  luaL_openlibs(global_context.lua);
+  loadapi_draw(global_context.lua);
+  if (luaL_dofile(global_context.lua, "example.lua") == LUA_OK) {
+    lua_pop(global_context.lua, lua_gettop(global_context.lua));
+  }
+
+
   atexit(cleanup);
   signal(SIGINT, sighandler);
 
+  cairo_t *cr = global_context.cairo_context.cairo;
   for (float t = 0.0; running; t += 1.0 / 60.0) {
-    cairo_begin(&ctx);
+    global_context.time = t;
+    cairo_begin(&global_context.cairo_context);
     {
-      cairo_set_source_rgb(ctx.cairo, 0.0, 0.5 - sin(t) * 0.5, 0.5 - cos(t) * 0.5);
-      cairo_paint(ctx.cairo);
+      lua_getglobal(global_context.lua, "tick");
+      if (lua_isfunction(global_context.lua, -1)) {
+        lua_pushnumber(global_context.lua, (lua_Number)t);
+        if (lua_pcall(global_context.lua, 1, 0, 0) == LUA_OK) {
+          lua_pop(global_context.lua, lua_gettop(global_context.lua));
+        } else {
+          printf("ERROR: %s\n", lua_tostring(global_context.lua, lua_gettop(global_context.lua)));
+          lua_pop(global_context.lua, lua_gettop(global_context.lua));
+        }
+      }
     }
-    cairo_flush(&ctx);
+    cairo_flush(&global_context.cairo_context);
     usleep(1000000 / 60.0);
   }