Cache out of view thumbnails in the background

commands.c

@@ -126,7 +126,7 @@ bool cg_reload_image(arg_t a)
 		load_image(fileidx);
 	} else {
 		win_set_cursor(&win, CURSOR_WATCH);
-		if (!tns_load(&tns, fileidx, true)) {
+		if (!tns_load(&tns, fileidx, true, false)) {
 			remove_file(fileidx, false);
 			tns.dirty = true;
 		}

main.c

@@ -385,7 +385,10 @@ void update_info(void)
 	r->p = r->buf;
 	if (mode == MODE_THUMB) {
 		if (tns.loadnext < tns.end) {
-			bar_put(l, "Loading... %0*d", fw, MAX(tns.loadnext, 1));
+			bar_put(l, "Loading... %0*d", fw, tns.loadnext + 1);
+			ow_info = false;
+		} else if (tns.initnext < filecnt) {
+			bar_put(l, "Caching... %0*d", fw, tns.initnext + 1);
 			ow_info = false;
 		} else {
 			ow_info = true;
@@ -453,7 +456,7 @@ void reset_cursor(void)
 			}
 		}
 	} else {
-		if (tns.loadnext < tns.end)
+		if (tns.loadnext < tns.end || tns.initnext < filecnt)
 			cursor = CURSOR_WATCH;
 		else
 			cursor = CURSOR_ARROW;
@@ -694,26 +697,29 @@ void run(void)
 	int xfd;
 	fd_set fds;
 	struct timeval timeout;
-	bool discard, load_thumb, to_set;
+	bool discard, init_thumb, load_thumb, to_set;
 	XEvent ev, nextev;
 
 	while (true) {
 		to_set = check_timeouts(&timeout);
+		init_thumb = mode == MODE_THUMB && tns.initnext < filecnt;
 		load_thumb = mode == MODE_THUMB && tns.loadnext < tns.end;
 
-		if ((load_thumb || to_set || info.fd != -1) &&
+		if ((init_thumb || load_thumb || to_set || info.fd != -1) &&
 		    XPending(win.env.dpy) == 0)
 		{
 			if (load_thumb) {
 				set_timeout(redraw, TO_REDRAW_THUMBS, false);
-				if (!tns_load(&tns, tns.loadnext, false)) {
+				if (!tns_load(&tns, tns.loadnext, false, false)) {
 					remove_file(tns.loadnext, false);
 					tns.dirty = true;
 				}
-				while (tns.loadnext < tns.end && tns.thumbs[tns.loadnext].im != NULL)
-					tns.loadnext++;
 				if (tns.loadnext >= tns.end)
 					redraw();
+			} else if (init_thumb) {
+				set_timeout(redraw, TO_REDRAW_THUMBS, false);
+				if (!tns_load(&tns, tns.initnext, false, true))
+					remove_file(tns.initnext, false);
 			} else {
 				xfd = ConnectionNumber(win.env.dpy);
 				FD_ZERO(&fds);
@@ -899,8 +905,8 @@ int main(int argc, char **argv)
 	if (options->thumb_mode) {
 		mode = MODE_THUMB;
 		tns_init(&tns, files, &filecnt, &fileidx, &win);
-		while (!tns_load(&tns, 0, false))
-			remove_file(0, false);
+		while (!tns_load(&tns, fileidx, false, false))
+			remove_file(fileidx, false);
 	} else {
 		mode = MODE_IMAGE;
 		tns.thumbs = NULL;

thumbs.c

@@ -152,7 +152,7 @@ void tns_clean_cache(tns_t *tns)
 }
 
 
-void tns_init(tns_t *tns, const fileinfo_t *files, const int *cnt, int *sel,
+void tns_init(tns_t *tns, fileinfo_t *files, const int *cnt, int *sel,
               win_t *win)
 {
 	int len;
@@ -169,7 +169,8 @@ void tns_init(tns_t *tns, const fileinfo_t *files, const int *cnt, int *sel,
 	}
 	tns->files = files;
 	tns->cnt = cnt;
-	tns->loadnext = tns->first = tns->end = tns->r_first = tns->r_end = 0;
+	tns->initnext = tns->loadnext = 0;
+	tns->first = tns->end = tns->r_first = tns->r_end = 0;
 	tns->sel = sel;
 	tns->win = win;
 	tns->dirty = false;
@@ -237,7 +238,7 @@ Imlib_Image tns_scale_down(Imlib_Image im, int dim)
 	return im;
 }
 
-bool tns_load(tns_t *tns, int n, bool force)
+bool tns_load(tns_t *tns, int n, bool force, bool cache_only)
 {
 	int w, h;
 	int maxwh = thumb_sizes[ARRLEN(thumb_sizes)-1];
@@ -245,8 +246,8 @@ bool tns_load(tns_t *tns, int n, bool force)
 	char *cfile;
 	float zw, zh;
 	thumb_t *t;
+	fileinfo_t *file;
 	Imlib_Image im = NULL;
-	const fileinfo_t *file;
 
 	if (tns == NULL || tns->thumbs == NULL)
 		return false;
@@ -261,6 +262,7 @@ bool tns_load(tns_t *tns, int n, bool force)
 	if (t->im != NULL) {
 		imlib_context_set_image(t->im);
 		imlib_free_image();
+		t->im = NULL;
 	}
 
 	if (!force) {
@@ -345,10 +347,10 @@ bool tns_load(tns_t *tns, int n, bool force)
 			warn("could not open image: %s", file->name);
 		return false;
 	}
+	imlib_context_set_image(im);
 
 	if (!cache_hit) {
 #if HAVE_LIBEXIF
-		imlib_context_set_image(im);
 		exif_auto_orientate(file);
 #endif
 		im = tns_scale_down(im, maxwh);
@@ -357,12 +359,22 @@ bool tns_load(tns_t *tns, int n, bool force)
 			tns_cache_write(im, file->path, true);
 	}
 
-	t->im = tns_scale_down(im, thumb_sizes[tns->zl]);
-	imlib_context_set_image(t->im);
-	t->w = imlib_image_get_width();
-	t->h = imlib_image_get_height();
+	if (cache_only) {
+		imlib_free_image_and_decache();
+	} else {
+		t->im = tns_scale_down(im, thumb_sizes[tns->zl]);
+		imlib_context_set_image(t->im);
+		t->w = imlib_image_get_width();
+		t->h = imlib_image_get_height();
+		tns->dirty = true;
+	}
+	file->flags |= FF_TN_INIT;
+
+	if (n == tns->initnext)
+		while (++tns->initnext < *tns->cnt && ((++file)->flags & FF_TN_INIT));
+	if (n == tns->loadnext && !cache_only)
+		while (++tns->loadnext < tns->end && (++t)->im != NULL);
 
-	tns->dirty = true;
 	return true;
 }
 

thumbs.h

@@ -34,10 +34,11 @@ typedef struct {
 } thumb_t;
 
 typedef struct {
-	const fileinfo_t *files;
+	fileinfo_t *files;
 	thumb_t *thumbs;
 	const int *cnt;
 	int *sel;
+	int initnext;
 	int loadnext;
 	int first, end;
 	int r_first, r_end;
@@ -56,10 +57,10 @@ typedef struct {
 
 void tns_clean_cache(tns_t*);
 
-void tns_init(tns_t*, const fileinfo_t*, const int*, int*, win_t*);
+void tns_init(tns_t*, fileinfo_t*, const int*, int*, win_t*);
 void tns_free(tns_t*);
 
-bool tns_load(tns_t*, int, bool);
+bool tns_load(tns_t*, int, bool, bool);
 void tns_unload(tns_t*, int);
 
 void tns_render(tns_t*);

types.h

@@ -65,8 +65,9 @@ typedef enum {
 } cursor_t;
 
 typedef enum {
-	FF_WARN = 1,
-	FF_MARK = 2
+	FF_WARN    = 1,
+	FF_MARK    = 2,
+	FF_TN_INIT = 4
 } fileflags_t;
 
 typedef struct {