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, 113 insertions, 0 deletions

diff --git a/src/main/c/simple_minifb.c b/src/main/c/simple_minifb.c
new file mode 100644
index 00000000..34663e2e
--- /dev/null
+++ b/src/main/c/simple_minifb.c
@@ -0,0 +1,113 @@
+#include "simple_graphics.h"
+#include <MiniFB.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#ifdef _WIN32
+#include <windows.h>
+#else
+#include <errno.h>
+#include <time.h>
+#endif
+
+// One fixed-size window for now. No Simple pointer survives a native call:
+// MiniFB retains its last draw buffer for OS repaint events, so copy it here.
+static struct mfb_window *window;
+static uint32_t *frame;
+static uint32_t width, height;
+
+// The C-only build never installs the upstream C++ callback wrappers.
+void release_cpp_stub(struct mfb_window *unused) { (void)unused; }
+
+static void close_window(void) {
+    if (window) {
+        mfb_close(window);             // Requests close.
+        mfb_update_events(window);     // Actually destroys the window.
+        window = NULL;
+    }
+    free(frame);
+    frame = NULL;
+}
+
+static int32_t open_window(const char *title, uint32_t w, uint32_t h) {
+    if (window || !w || !h || w > UINT32_MAX / 4 ||
+        (uint64_t)w * h > UINT32_MAX || (uint64_t)w * h > SIZE_MAX / 4) {
+        fprintf(stderr, "Simple graphics: invalid dimensions or a window is already open.\n");
+        return -1;
+    }
+    frame = calloc((size_t)w * h, sizeof(*frame));
+    if (!frame) {
+        fprintf(stderr, "Simple graphics: cannot allocate the display buffer.\n");
+        return -1;
+    }
+    window = mfb_open(title, w, h);
+    if (!window) {
+        fprintf(stderr, "Simple graphics: MiniFB could not open a window (is a graphical display available?).\n");
+        close_window();
+        return -1;
+    }
+    width = w;
+    height = h;
+    return 0;
+}
+
+static int32_t status(mfb_update_state state) {
+    if (state == MFB_STATE_OK) return 0;
+    if (state == MFB_STATE_EXIT) {
+        window = NULL; // MiniFB has already destroyed it.
+        close_window();
+        return 1;
+    }
+    fprintf(stderr, "Simple graphics: MiniFB update failed (%d).\n", state);
+    close_window();
+    return -1;
+}
+
+static int32_t present(const uint32_t *pixels, uint32_t count) {
+    if (!window) return 1;
+    if (!pixels || count != (uint64_t)width * height) {
+        fprintf(stderr, "Simple graphics: pixel array length must equal width * height.\n");
+        return -1;
+    }
+    memcpy(frame, pixels, (size_t)count * sizeof(*frame));
+    return status(mfb_update_ex(window, frame, width, height));
+}
+
+static int32_t poll_events(int32_t wait) {
+    if (!window) return 1;
+    if (wait) {
+        // mfb_wait_sync returns false for both destruction and errors that
+        // leave the window alive. Use a short OS wait, then the status-bearing
+        // event API, so we know whether the window still needs destruction.
+#ifdef _WIN32
+        Sleep(17);
+#else
+        struct timespec delay = {0, 16666667};
+        while (nanosleep(&delay, &delay) < 0) {
+            if (errno != EINTR) {
+                perror("Simple graphics: event wait");
+                close_window();
+                return -1;
+            }
+        }
+#endif
+    }
+    return status(mfb_update_events(window));
+}
+static int32_t mouse_x(void) { return window ? mfb_get_mouse_x(window) : 0; }
+static int32_t mouse_y(void) { return window ? mfb_get_mouse_y(window) : 0; }
+static int32_t button(int32_t b) {
+    return window && b >= 0 && b < 8 ? mfb_get_mouse_button_buffer(window)[b] != 0 : 0;
+}
+static int32_t key(int32_t k) {
+    return window && k >= 0 && k <= MFB_KB_KEY_LAST ? mfb_get_key_buffer(window)[k] != 0 : 0;
+}
+
+static const struct simple_graphics_api api = {
+    SIMPLE_GRAPHICS_VERSION, open_window, present, poll_events,
+    mouse_x, mouse_y, button, key, close_window
+};
+#ifdef _WIN32
+__declspec(dllexport)
+#endif
+const struct simple_graphics_api *simple_minifb_api(void) { return &api; }