config: add tweak.render-timer option

This can be set to 'none' (the default), 'osd', 'log' or 'both'.

When 'osd' is enabled, we'll render the frame rendering time to a
sub-surface after each frame.

When 'log' is enabled, the frame rendering time is logged on stderr.

CHANGELOG.md

@@ -30,6 +30,7 @@
   (https://codeberg.org/dnkl/foot/issues/54).
 * **colors.selection-foreground** and **colors.selection-background**
   options to `footrc`.
+* **tweak.render-timer** option to `footrc`.
 
 
 ### Deprecated

config.c

@@ -975,7 +975,29 @@ parse_section_tweak(
     const char *key, const char *value, struct config *conf,
     const char *path, unsigned lineno)
 {
-    if (strcmp(key, "delayed-render-lower") == 0) {
+    if (strcmp(key, "render-timer") == 0) {
+        if (strcmp(value, "none") == 0) {
+            conf->tweak.render_timer_osd = false;
+            conf->tweak.render_timer_log = false;
+        } else if (strcmp(value, "osd") == 0) {
+            conf->tweak.render_timer_osd = true;
+            conf->tweak.render_timer_log = false;
+        } else if (strcmp(value, "log") == 0) {
+            conf->tweak.render_timer_osd = false;
+            conf->tweak.render_timer_log = true;
+        } else if (strcmp(value, "both") == 0) {
+            conf->tweak.render_timer_osd = true;
+            conf->tweak.render_timer_log = true;
+        } else {
+            LOG_AND_NOTIFY_ERR(
+                "%s:%d: [tweak]: %s: invalid 'render-timer' value, "
+                "expected one of 'none', 'osd', 'log' or 'both'",
+                path, lineno, value);
+            return false;
+        }
+    }
+
+    else if (strcmp(key, "delayed-render-lower") == 0) {
         unsigned long ns;
         if (!str_to_ulong(value, 10, &ns)) {
             LOG_AND_NOTIFY_ERR("%s:%d: expected an integer, got '%s'", path, lineno, value);
@@ -1291,6 +1313,8 @@ config_load(struct config *conf, const char *conf_path, bool errors_are_fatal)
             .delayed_render_lower_ns = 500000,         /* 0.5ms */
             .delayed_render_upper_ns = 16666666 / 2,   /* half a frame period (60Hz) */
             .max_shm_pool_size = 512 * 1024 * 1024,
+            .render_timer_osd = false,
+            .render_timer_log = false,
         },
 
         .notifications = tll_init(),

config.h

@@ -127,6 +127,8 @@ struct config {
     bool hold_at_exit;
 
     struct {
+        bool render_timer_osd;
+        bool render_timer_log;
         uint64_t delayed_render_lower_ns;
         uint64_t delayed_render_upper_ns;
         off_t max_shm_pool_size;

doc/footrc.5.scd

@@ -400,6 +400,12 @@ foot.
 When reporting bugs, please mention if, and to what, you have changed
 any of these options.
 
+*render-timer*
+	Enables a frame rendering timer, that prints the time it takes to
+	render each frame, in microseconds, either on-screen, to stderr,
+	or both. Valid values are *none*, *osd*, *log* and
+	*both*. Default: _none_.
+
 *delayed-render-lower*, *delayed-render-upper*
 	These two values control the timeouts (in nanoseconds) that are
 	used to mitigate screen flicker caused by clients writing large,

render.c

@@ -24,7 +24,6 @@
 #include "util.h"
 #include "xmalloc.h"
 
-#define TIME_FRAME_RENDERING 0
 #define TIME_SCROLL_DAMAGE 0
 
 struct renderer {
@@ -1300,6 +1299,54 @@ render_csd(struct terminal *term)
     render_csd_title(term);
 }
 
+static void
+render_osd(struct terminal *term,
+           struct wl_surface *surf, struct wl_subsurface *sub_surf,
+           struct buffer *buf,
+           const wchar_t *text, uint32_t _fg, uint32_t _bg,
+           unsigned width, unsigned height, unsigned x, unsigned y)
+{
+    pixman_color_t bg = color_hex_to_pixman(_bg);
+    pixman_image_fill_rectangles(
+        PIXMAN_OP_SRC, buf->pix[0], &bg, 1,
+        &(pixman_rectangle16_t){0, 0, width, height});
+
+    struct fcft_font *font = term->fonts[0];
+    pixman_color_t fg = color_hex_to_pixman(_fg);
+
+    for (size_t i = 0; i < wcslen(text); i++) {
+        const struct fcft_glyph *glyph = fcft_glyph_rasterize(
+            font, text[i], term->font_subpixel);
+
+        if (glyph == NULL)
+            continue;
+
+        pixman_image_t *src = pixman_image_create_solid_fill(&fg);
+        pixman_image_composite32(
+            PIXMAN_OP_OVER, src, glyph->pix, buf->pix[0], 0, 0, 0, 0,
+            x + glyph->x, y + font_baseline(term) - glyph->y,
+            glyph->width, glyph->height);
+        pixman_image_unref(src);
+
+        x += term->cell_width;
+    }
+
+    quirk_weston_subsurface_desync_on(sub_surf);
+    wl_surface_attach(surf, buf->wl_buf, 0, 0);
+    wl_surface_damage_buffer(surf, 0, 0, width, height);
+    wl_surface_set_buffer_scale(surf, term->scale);
+
+    struct wl_region *region = wl_compositor_create_region(term->wl->compositor);
+    if (region != NULL) {
+        wl_region_add(region, 0, 0, width, height);
+        wl_surface_set_opaque_region(surf, region);
+        wl_region_destroy(region);
+    }
+
+    wl_surface_commit(surf);
+    quirk_weston_subsurface_desync_off(sub_surf);
+}
+
 static void
 render_scrollback_position(struct terminal *term)
 {
@@ -1402,35 +1449,6 @@ render_scrollback_position(struct terminal *term)
     struct buffer *buf = shm_get_buffer(
         term->wl->shm, width, height, cookie, false, 1);
 
-    pixman_color_t bg = color_hex_to_pixman(term->colors.table[8 + 4]);
-    pixman_image_fill_rectangles(
-        PIXMAN_OP_SRC, buf->pix[0], &bg, 1,
-        &(pixman_rectangle16_t){0, 0, width, height});
-
-    struct fcft_font *font = term->fonts[0];
-    pixman_color_t fg = color_hex_to_pixman(term->colors.table[0]);
-
-    /* Sub-surface relative coordinates */
-    unsigned x = width - margin - wcslen(text) * term->cell_width;
-    const unsigned y = margin;
-
-    for (size_t i = 0; i < wcslen(text); i++) {
-        const struct fcft_glyph *glyph = fcft_glyph_rasterize(
-            font, text[i], term->font_subpixel);
-
-        if (glyph == NULL)
-            continue;
-
-        pixman_image_t *src = pixman_image_create_solid_fill(&fg);
-        pixman_image_composite32(
-            PIXMAN_OP_OVER, src, glyph->pix, buf->pix[0], 0, 0, 0, 0,
-            x + glyph->x, y + font_baseline(term) - glyph->y,
-            glyph->width, glyph->height);
-        pixman_image_unref(src);
-
-        x += term->cell_width;
-    }
-
     /* *Where* to render - parent relative coordinates */
     int surf_top = 0;
     switch (term->conf->scrollback.indicator.position) {
@@ -1452,24 +1470,44 @@ render_scrollback_position(struct terminal *term)
     }
     }
 
-    quirk_weston_subsurface_desync_on(win->scrollback_indicator_sub_surface);
     wl_subsurface_set_position(
         win->scrollback_indicator_sub_surface,
         (term->width - margin - width) / scale,
         (term->margins.top + surf_top) / scale);
-    wl_surface_attach(win->scrollback_indicator_surface, buf->wl_buf, 0, 0);
-    wl_surface_damage_buffer(win->scrollback_indicator_surface, 0, 0, width, height);
-    wl_surface_set_buffer_scale(win->scrollback_indicator_surface, scale);
 
-    struct wl_region *region = wl_compositor_create_region(wayl->compositor);
+    render_osd(
-    if (region != NULL) {
+        term,
-        wl_region_add(region, 0, 0, width, height);
+        win->scrollback_indicator_surface, win->scrollback_indicator_sub_surface,
-        wl_surface_set_opaque_region(win->scrollback_indicator_surface, region);
+        buf, text,
-        wl_region_destroy(region);
+        term->colors.table[0], term->colors.table[8 + 4],
-    }
+        width, height, width - margin - wcslen(text) * term->cell_width, margin);
 
-    wl_surface_commit(win->scrollback_indicator_surface);
+}
-    quirk_weston_subsurface_desync_off(win->scrollback_indicator_sub_surface);
+
+static void
+render_render_timer(struct terminal *term, struct timeval render_time)
+{
+    struct wl_window *win = term->window;
+
+    wchar_t text[256];
+    double usecs = render_time.tv_sec * 1000000 + render_time.tv_usec;
+    swprintf(text, sizeof(text), L"%.2f µs", usecs);
+
+    const int cell_count = wcslen(text);
+    const int margin = 3 * term->scale;
+    const int width = 2 * margin + cell_count * term->cell_width;
+    const int height = 2 * margin + term->cell_height;
+
+    unsigned long cookie = shm_cookie_render_timer(term);
+    struct buffer *buf = shm_get_buffer(
+        term->wl->shm, width, height, cookie, false, 1);
+
+    render_osd(
+        term,
+        win->render_timer_surface, win->render_timer_sub_surface,
+        buf, text,
+        term->colors.table[0], term->colors.table[8 + 1],
+        width, height, margin, margin);
 }
 
 static void frame_callback(
@@ -1485,10 +1523,9 @@ grid_render(struct terminal *term)
     if (term->is_shutting_down)
         return;
 
-#if TIME_FRAME_RENDERING
     struct timeval start_time;
-    gettimeofday(&start_time, NULL);
+    if (term->conf->tweak.render_timer_osd || term->conf->tweak.render_timer_log)
-#endif
+        gettimeofday(&start_time, NULL);
 
     assert(term->width > 0);
     assert(term->height > 0);
@@ -1725,15 +1762,21 @@ grid_render(struct terminal *term)
     quirk_kde_damage_before_attach(term->window->surface);
     wl_surface_commit(term->window->surface);
 
-#if TIME_FRAME_RENDERING
+    if (term->conf->tweak.render_timer_osd || term->conf->tweak.render_timer_log) {
-    struct timeval end_time;
+        struct timeval end_time;
-    gettimeofday(&end_time, NULL);
+        gettimeofday(&end_time, NULL);
 
-    struct timeval render_time;
+        struct timeval render_time;
-    timersub(&end_time, &start_time, &render_time);
+        timersub(&end_time, &start_time, &render_time);
-    LOG_INFO("frame rendered in %lds %ldus",
+
-             render_time.tv_sec, render_time.tv_usec);
+        if (term->conf->tweak.render_timer_log) {
-#endif
+            LOG_INFO("frame rendered in %lds %ld µs",
+                     render_time.tv_sec, render_time.tv_usec);
+        }
+
+        if (term->conf->tweak.render_timer_osd)
+            render_render_timer(term, render_time);
+    }
 }
 
 static void

shm.h

@@ -50,4 +50,5 @@ struct terminal;
 static inline unsigned long shm_cookie_grid(const struct terminal *term) { return (unsigned long)((uintptr_t)term + 0); }
 static inline unsigned long shm_cookie_search(const struct terminal *term) { return (unsigned long)((uintptr_t)term + 1); }
 static inline unsigned long shm_cookie_scrollback_indicator(const struct terminal *term) { return (unsigned long)(uintptr_t)term + 2; }
-static inline unsigned long shm_cookie_csd(const struct terminal *term, int n) { return (unsigned long)((uintptr_t)term + 3 + (n)); }
+static inline unsigned long shm_cookie_render_timer(const struct terminal *term) { return (unsigned long)(uintptr_t)term + 3; }
+static inline unsigned long shm_cookie_csd(const struct terminal *term, int n) { return (unsigned long)((uintptr_t)term + 4 + (n)); }

wayland.c

@@ -1197,6 +1197,20 @@ wayl_win_init(struct terminal *term)
     }
 
     wl_surface_commit(win->surface);
+
+    if (conf->tweak.render_timer_osd) {
+        win->render_timer_surface = wl_compositor_create_surface(wayl->compositor);
+        if (win->render_timer_surface == NULL) {
+            LOG_ERR("failed to create render timer surface");
+            goto out;
+        }
+        win->render_timer_sub_surface = wl_subcompositor_get_subsurface(
+            wayl->sub_compositor, win->render_timer_surface, win->surface);
+        wl_subsurface_set_sync(win->render_timer_sub_surface);
+        wl_surface_set_user_data(win->render_timer_surface, win);
+        wl_subsurface_set_position(win->render_timer_sub_surface, 10, 10);
+        wl_surface_commit(win->render_timer_surface);
+    }
     return win;
 
 out:
@@ -1223,6 +1237,11 @@ wayl_win_destroy(struct wl_window *win)
      * nor mouse focus).
      */
 
+    if (win->render_timer_surface != NULL) {
+        wl_surface_attach(win->render_timer_surface, NULL, 0, 0);
+        wl_surface_commit(win->render_timer_surface);
+    }
+
     if (win->scrollback_indicator_surface != NULL) {
         wl_surface_attach(win->scrollback_indicator_surface, NULL, 0, 0);
         wl_surface_commit(win->scrollback_indicator_surface);
@@ -1252,6 +1271,10 @@ wayl_win_destroy(struct wl_window *win)
     tll_free(win->on_outputs);
 
     csd_destroy(win);
+    if (win->render_timer_sub_surface != NULL)
+        wl_subsurface_destroy(win->render_timer_sub_surface);
+    if (win->render_timer_surface != NULL)
+        wl_surface_destroy(win->render_timer_surface);
     if (win->scrollback_indicator_sub_surface != NULL)
         wl_subsurface_destroy(win->scrollback_indicator_sub_surface);
     if (win->scrollback_indicator_surface != NULL)

wayland.h

@@ -280,6 +280,9 @@ struct wl_window {
     struct wl_surface *scrollback_indicator_surface;
     struct wl_subsurface *scrollback_indicator_sub_surface;
 
+    struct wl_surface *render_timer_surface;
+    struct wl_subsurface *render_timer_sub_surface;
+
     struct wl_callback *frame_callback;
 
     tll(const struct monitor *) on_outputs; /* Outputs we're mapped on */