Chapter 31: Software Drawing and Graphical Gameslinear-chapter31linear

Co-authored-by: Hsiang-Ying Fu <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: fuhsnn <66062782+fuhsnn@users.noreply.github.com>
Co-authored-by: Symious <14933944+symious@users.noreply.github.com>
Co-authored-by: Jun Kawasaki <jun784@gmail.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 60 insertions, 0 deletions

diff --git a/src/main/c/simple_graphics.c b/src/main/c/simple_graphics.c
new file mode 100644
index 00000000..41073470
--- /dev/null
+++ b/src/main/c/simple_graphics.c
@@ -0,0 +1,60 @@
+#include "simple_graphics.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <dlfcn.h>
+
+// No MiniFB headers or link dependency in the default runtime. Cygwin's
+// dlopen also loads native Windows DLLs; both use the x64 Windows C ABI.
+static const struct simple_graphics_api *api;
+static void *library;
+
+static int load_graphics(void) {
+    // Explicitly disabling graphics also makes headless tests deterministic.
+    const char *path = getenv("SIMPLE_MINIFB");
+    if (path && strcmp(path, "off") == 0) {
+        fprintf(stderr, "Simple graphics: disabled (SIMPLE_MINIFB=off).\n");
+        return -1;
+    }
+    if (api) return 0;
+    if (!path || !*path) {
+        fprintf(stderr, "Simple graphics: MiniFB backend not configured. "
+                "Run make graphics, then set SIMPLE_MINIFB to the backend library's full path.\n");
+        return -1;
+    }
+    library = dlopen(path, RTLD_NOW | RTLD_LOCAL);
+    if (!library) {
+        fprintf(stderr, "Simple graphics: cannot load MiniFB backend '%s': %s\n", path, dlerror());
+        return -1;
+    }
+    const struct simple_graphics_api *(*get_api)(void) =
+        (const struct simple_graphics_api *(*)(void))dlsym(library, "simple_minifb_api");
+    const struct simple_graphics_api *candidate = get_api ? get_api() : NULL;
+    if (!candidate || candidate->version != SIMPLE_GRAPHICS_VERSION ||
+        !candidate->open || !candidate->present || !candidate->poll ||
+        !candidate->mouse_x || !candidate->mouse_y || !candidate->button ||
+        !candidate->key || !candidate->close) {
+        fprintf(stderr, "Simple graphics: incompatible MiniFB backend '%s'. Rebuild with make graphics.\n", path);
+        dlclose(library);
+        library = NULL;
+        return -1;
+    }
+    api = candidate;
+    // Keep the library loaded until process exit; its window callbacks may
+    // still be registered. Closing a window releases its native resources.
+    atexit(api->close);
+    return 0;
+}
+
+int32_t simple_gfx_open(const char *title, uint32_t width, uint32_t height) {
+    return load_graphics() ? -1 : api->open(title, width, height);
+}
+int32_t simple_gfx_present(const uint32_t *pixels, uint32_t count) {
+    return api ? api->present(pixels, count) : -1;
+}
+int32_t simple_gfx_poll(int32_t wait) { return api ? api->poll(wait) : -1; }
+int32_t simple_gfx_mouse_x(void) { return api ? api->mouse_x() : 0; }
+int32_t simple_gfx_mouse_y(void) { return api ? api->mouse_y() : 0; }
+int32_t simple_gfx_button(int32_t button) { return api ? api->button(button) : 0; }
+int32_t simple_gfx_key(int32_t key) { return api ? api->key(key) : 0; }
+int32_t simple_gfx_close(void) { if (api) api->close(); return 0; }