Skip generation increment in background_images() when paths unchanged

Author: Copilot

kitty/options/to-c.h

@@ -178,15 +178,25 @@ free_background_images(Options *opts) {
 
 static inline void
 background_images(PyObject *src, Options *opts) {
-    free_background_images(opts);
     static unsigned generation = 0;
+    size_t new_count = (PyTuple_Check(src) && PyTuple_GET_SIZE(src) > 0) ? (size_t)PyTuple_GET_SIZE(src) : 0;
+    if (new_count == opts->background_images.count && opts->background_images.paths) {
+        bool changed = false;
+        for (size_t i = 0; i < new_count; i++) {
+            const char *p = PyUnicode_AsUTF8(PyTuple_GET_ITEM(src, i));
+            if (!p || !opts->background_images.paths[i] || strcmp(p, opts->background_images.paths[i]) != 0) { changed = true; break; }
+        }
+        if (!changed) return;
+    }
+    free_background_images(opts);
     opts->background_images.generation = ++generation;
-    if (!PyTuple_Check(src) || PyTuple_GET_SIZE(src) == 0) return;
-    opts->background_images.paths = calloc(PyTuple_GET_SIZE(src), sizeof(opts->background_images.paths[0]));
+    if (!new_count) return;
+    opts->background_images.paths = calloc(new_count, sizeof(opts->background_images.paths[0]));
     if (opts->background_images.paths) {
-        opts->background_images.count = PyTuple_GET_SIZE(src);
-        for (size_t i = 0; i < opts->background_images.count; i++) opts->background_images.paths[i] = strdup(
-                PyUnicode_AsUTF8(PyTuple_GET_ITEM(src, i)));
+        opts->background_images.count = new_count;
+        for (size_t i = 0; i < opts->background_images.count; i++) {
+            opts->background_images.paths[i] = strdup(PyUnicode_AsUTF8(PyTuple_GET_ITEM(src, i)));
+        }
     }
 }
 

kitty/state.c

@@ -226,6 +226,7 @@ ensure_background_images_generation(bool release_texture) {
     if (global_state.background_images.generation == OPT(background_images).generation) return;
     free_global_background_images(release_texture);
     global_state.background_images.generation = OPT(background_images).generation;
+    global_state.background_images.entries_attempted = 0;
     if (OPT(background_images).count) {
         global_state.background_images.images = calloc(
                 OPT(background_images).count, sizeof(global_state.background_images.images[0]));
@@ -238,12 +239,11 @@ static unsigned bg_image_id_counter = 0;
 static BackgroundImage*
 global_background_image(size_t idx) {
     ensure_background_images_generation(true);
-    while (global_state.background_images.count <= idx && OPT(background_images).count) {
-        RAII_ALLOC(char, path, OPT(background_images).paths[0]);  // transfer ownership
-        remove_i_from_array(OPT(background_images.paths), 0, OPT(background_images).count);
+    while (global_state.background_images.count <= idx && global_state.background_images.entries_attempted < OPT(background_images).count) {
+        size_t j = global_state.background_images.entries_attempted++;
         BackgroundImage *img = calloc(1, sizeof(BackgroundImage));
         if (!img) fatal("Out of memory");
-        if (image_path_to_bitmap(path, &img->bitmap, &img->width, &img->height, &img->mmap_size)) {
+        if (image_path_to_bitmap(OPT(background_images).paths[j], &img->bitmap, &img->width, &img->height, &img->mmap_size)) {
             if (send_bgimage_to_gpu(OPT(background_image_layout), img)) {
                 img->refcnt++;
                 img->id = ++bg_image_id_counter;
@@ -273,7 +273,7 @@ increment_bg_image_idx(size_t idx, int delta) {
     }
     if ((unsigned)abs(delta) <= idx) return idx + delta;
     // wrap to last image, which means we need to load all
-    global_background_image(global_state.background_images.count + OPT(background_images).count + 1);
+    if (OPT(background_images).count > 0) global_background_image(OPT(background_images).count - 1);
     return global_state.background_images.count ? global_state.background_images.count - 1 : 0;
 }
 
@@ -1417,6 +1417,12 @@ pyset_background_image(PyObject *self UNUSED, PyObject *args, PyObject *kw) {
             }
             global_state.background_images.images[0] = bgimage;
             bgimage->refcnt++;
+            if (OPT(background_images).count > 0) {
+                free(OPT(background_images).paths[0]);
+                char *new_path = strdup(path);
+                if (!new_path) fatal("Out of memory");
+                OPT(background_images).paths[0] = new_path;
+            }
         } else free_global_background_images(true);
         OPT(background_image_layout) = layout;
         if (pylinear && pylinear != Py_None) convert_from_python_background_image_linear(pylinear, &global_state.opts);

kitty/state.h

@@ -95,7 +95,8 @@ typedef struct Options {
 
     char *default_window_logo;
     struct {
-        char **paths; size_t count;
+        char **paths;
+        size_t count;
         unsigned generation;
     } background_images;
     BackgroundImageLayout background_image_layout;
@@ -470,7 +471,7 @@ typedef struct GlobalState {
     PyObject *boss;
     struct {
         BackgroundImage **images;
-        size_t count;
+        size_t count, entries_attempted;
         unsigned generation;
     } background_images;
     OSWindow *os_windows;