Allow controlling the easing curves used for the visual bell

docs/changelog.rst

@@ -96,6 +96,8 @@ Detailed list of changes
 
 - Add support for in-band window resize notifications (:iss:`7642`)
 
+- Allow controlling the easing curves used for :opt:`visual_bell_duration`
+
 0.35.2 [2024-06-22]
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 

docs/glossary.rst

@@ -58,7 +58,8 @@ Glossary
       Commonly used easing functions are :code:`linear` for a constant rate
       animation and :code:`ease-in-out` for an animation that starts slow,
       becomes fast in the middle and ends slowly. These are used to control
-      various animations in kitty, such as :opt:`cursor_blink_interval`.
+      various animations in kitty, such as :opt:`cursor_blink_interval` and
+      :opt:`visual_bell_duration`.
 
 .. _env_vars:
 

kitty/cleanup.h

@@ -18,6 +18,7 @@ typedef enum {
     FONTCONFIG_CLEANUP_FUNC,
     FREETYPE_CLEANUP_FUNC,
     SYSTEMD_CLEANUP_FUNC,
+    SHADERS_CLEANUP_FUNC,
 
     NUM_CLEANUP_FUNCS
 } AtExitCleanupFunc;

kitty/options/definition.py

@@ -897,10 +897,16 @@
     )
 
 opt('visual_bell_duration', '0.0',
-    option_type='positive_float', ctype='time',
+    option_type='visual_bell_duration', ctype='!visual_bell_duration',
     long_text='''
 The visual bell duration (in seconds). Flash the screen when a bell occurs for
-the specified number of seconds. Set to zero to disable.
+the specified number of seconds. Set to zero to disable. The flash is animated, fading
+in and out over the specified duration. The :term:`easing function` used for the fading can be controlled.
+For example, :code:`2.0 linear` will casuse the flash to fade in and out linearly. The default
+if unspecified is to use :code:`ease-in-out` which fades slowly at the start, middle and end.
+You can specify different easing functions for the fade-in and fade-out parts, like this:
+:code:`2.0 ease-in linear`. kitty
+supports all the :link:`CSS easing functions <https://developer.mozilla.org/en-US/docs/Web/CSS/easing-function>`.
 '''
     )
 

kitty/options/parse.py

@@ -19,7 +19,8 @@
     tab_activity_symbol, tab_bar_edge, tab_bar_margin_height, tab_bar_min_tabs, tab_fade,
     tab_font_style, tab_separator, tab_title_template, titlebar_color, to_cursor_shape,
     to_cursor_unfocused_shape, to_font_size, to_layout_names, to_modifiers, url_prefixes, url_style,
-    visual_window_select_characters, window_border_width, window_logo_scale, window_size
+    visual_bell_duration, visual_window_select_characters, window_border_width, window_logo_scale,
+    window_size
 )
 
 
@@ -1353,7 +1354,7 @@ def visual_bell_color(self, val: str, ans: typing.Dict[str, typing.Any]) -> None
         ans['visual_bell_color'] = to_color_or_none(val)
 
     def visual_bell_duration(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
-        ans['visual_bell_duration'] = positive_float(val)
+        ans['visual_bell_duration'] = visual_bell_duration(val)
 
     def visual_window_select_characters(self, val: str, ans: typing.Dict[str, typing.Any]) -> None:
         ans['visual_window_select_characters'] = visual_window_select_characters(val)

kitty/options/to-c-generated.h

@@ -488,7 +488,7 @@ convert_from_opts_enable_audio_bell(PyObject *py_opts, Options *opts) {
 
 static void
 convert_from_python_visual_bell_duration(PyObject *val, Options *opts) {
-    opts->visual_bell_duration = parse_s_double_to_monotonic_t(val);
+    visual_bell_duration(val, opts);
 }
 
 static void

kitty/options/to-c.h

@@ -156,20 +156,31 @@ add_easing_function(Animation *a, PyObject *e, double y_at_start, double y_at_en
 #undef G
 }
 
+#define parse_animation(duration, name, start, end) \
+    opts->duration = parse_s_double_to_monotonic_t(PyTuple_GET_ITEM(src, 0)); \
+    opts->animation.name = free_animation(opts->animation.name); \
+    if (PyObject_IsTrue(PyTuple_GET_ITEM(src, 1)) && (opts->animation.name = alloc_animation()) != NULL) { \
+        add_easing_function(opts->animation.name, PyTuple_GET_ITEM(src, 1), start, end); \
+        if (PyObject_IsTrue(PyTuple_GET_ITEM(src, 2))) { \
+            add_easing_function(opts->animation.name, PyTuple_GET_ITEM(src, 2), end, start); \
+        } else { \
+            add_easing_function(opts->animation.name, PyTuple_GET_ITEM(src, 1), end, start); \
+        } \
+    } \
+
 static inline void
 cursor_blink_interval(PyObject *src, Options *opts) {
-    opts->cursor_blink_interval = parse_s_double_to_monotonic_t(PyTuple_GET_ITEM(src, 0));
-    opts->animation.cursor = free_animation(opts->animation.cursor);
-    if (PyObject_IsTrue(PyTuple_GET_ITEM(src, 1)) && (opts->animation.cursor = alloc_animation()) != NULL) {
-        add_easing_function(opts->animation.cursor, PyTuple_GET_ITEM(src, 1), 1, 0);
-        if (PyObject_IsTrue(PyTuple_GET_ITEM(src, 2))) {
-            add_easing_function(opts->animation.cursor, PyTuple_GET_ITEM(src, 2), 0, 1);
-        } else {
-            add_easing_function(opts->animation.cursor, PyTuple_GET_ITEM(src, 1), 0, 1);
-        }
-    }
+    parse_animation(cursor_blink_interval, cursor, 1, 0);
 }
 
+static inline void
+visual_bell_duration(PyObject *src, Options *opts) {
+    parse_animation(visual_bell_duration, visual_bell, 0, 1);
+}
+
+#undef parse_animation
+
+
 static void
 parse_font_mod_size(PyObject *val, float *sz, AdjustmentUnit *unit) {
     PyObject *mv = PyObject_GetAttrString(val, "mod_value");

kitty/options/types.py

@@ -612,7 +612,7 @@ class Options:
     url_prefixes: typing.Tuple[str, ...] = ('file', 'ftp', 'ftps', 'gemini', 'git', 'gopher', 'http', 'https', 'irc', 'ircs', 'kitty', 'mailto', 'news', 'sftp', 'ssh')
     url_style: int = 3
     visual_bell_color: typing.Optional[kitty.fast_data_types.Color] = None
-    visual_bell_duration: float = 0
+    visual_bell_duration: typing.Tuple[float, kitty.options.utils.EasingFunction, kitty.options.utils.EasingFunction] = (0.0, kitty.options.utils.EasingFunction(), kitty.options.utils.EasingFunction())
     visual_window_select_characters: str = '1234567890ABCDEFGHIJKLMNOPQRSTUVWXYZ'
     wayland_enable_ime: bool = True
     wayland_titlebar_color: int = 0

kitty/options/utils.py

@@ -1493,8 +1493,7 @@ def steps(cls, params: str) -> 'EasingFunction':
         return cls(type='steps', jump_type=jump_type, num_steps=n)
 
 
-def cursor_blink_interval(spec: str) -> Tuple[float, EasingFunction, EasingFunction]:
-    interval: float = -1
+def parse_animation(spec: str, interval: float = -1.) -> Tuple[float, EasingFunction, EasingFunction]:
     with suppress(Exception):
         interval = float(spec)
         return interval, EasingFunction(), EasingFunction()
@@ -1540,6 +1539,14 @@ def parse_func(func_name: str, params: str) -> None:
     return interval, m[0], m[1]
 
 
+def cursor_blink_interval(spec: str) -> Tuple[float, EasingFunction, EasingFunction]:
+    return parse_animation(spec)
+
+
+def visual_bell_duration(spec: str) -> Tuple[float, EasingFunction, EasingFunction]:
+    return parse_animation(spec, interval=0.)
+
+
 def deprecated_hide_window_decorations_aliases(key: str, val: str, ans: Dict[str, Any]) -> None:
     if not hasattr(deprecated_hide_window_decorations_aliases, key):
         setattr(deprecated_hide_window_decorations_aliases, key, True)

kitty/shaders.c

@@ -7,6 +7,7 @@
 
 #include "fonts.h"
 #include "gl.h"
+#include "cleanup.h"
 #include "colors.h"
 #include <stddef.h>
 #include "window_logo.h"
@@ -973,31 +974,23 @@ send_cell_data_to_gpu(ssize_t vao_idx, GLfloat xstart, GLfloat ystart, GLfloat d
     return changed;
 }
 
-static float
-ease_out_cubic(float phase) {
-    return 1.0f - powf(1.0f - phase, 3.0f);
-}
-
-static float
-ease_in_out_cubic(float phase) {
-    return phase < 0.5f ?
-        4.0f * powf(phase, 3.0f) :
-        1.0f - powf(-2.0f * phase + 2.0f, 3.0f) / 2.0f;
-}
-
-static float
-visual_bell_intensity(float phase) {
-    static const float peak = 0.2f;
-    const float fade = 1.0f - peak;
-    return phase < peak ? ease_out_cubic(phase / peak) : ease_in_out_cubic((1.0f - phase) / fade);
-}
+static Animation *default_visual_bell_animation = NULL;
 
 static float
 get_visual_bell_intensity(Screen *screen) {
     if (screen->start_visual_bell_at > 0) {
-        monotonic_t progress = monotonic() - screen->start_visual_bell_at;
-        monotonic_t duration = OPT(visual_bell_duration);
-        if (progress <= duration) return visual_bell_intensity((float)progress / duration);
+        if (!default_visual_bell_animation) {
+            default_visual_bell_animation = alloc_animation();
+            if (!default_visual_bell_animation) fatal("Out of memory");
+            add_cubic_bezier_animation(default_visual_bell_animation, 0, 1, 0.42, 0, 0.58, 1);
+            add_cubic_bezier_animation(default_visual_bell_animation, 1, 0, 0.42, 0, 0.58, 1);
+        }
+        const monotonic_t progress = monotonic() - screen->start_visual_bell_at;
+        const monotonic_t duration = OPT(visual_bell_duration) / 2;
+        if (progress <= duration) {
+            Animation *a = animation_is_valid(OPT(animation.visual_bell)) ? OPT(animation.visual_bell) : default_visual_bell_animation;
+            return (float)apply_easing_curve(a, progress / (double)duration, duration);
+        }
         screen->start_visual_bell_at = 0;
     }
     return 0.0f;
@@ -1244,6 +1237,11 @@ static PyMethodDef module_methods[] = {
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 
+static void
+finalize(void) {
+    default_visual_bell_animation = free_animation(default_visual_bell_animation);
+}
+
 bool
 init_shaders(PyObject *module) {
 #define C(x) if (PyModule_AddIntConstant(module, #x, x) != 0) { PyErr_NoMemory(); return false; }
@@ -1277,6 +1275,7 @@ init_shaders(PyObject *module) {
 
 #undef C
     if (PyModule_AddFunctions(module, module_methods) != 0) return false;
+    register_at_exit_cleanup_func(SHADERS_CLEANUP_FUNC, finalize);
     return true;
 }
 // }}}

kitty/state.c

@@ -1463,6 +1463,7 @@ finalize(void) {
 #undef F
     Py_CLEAR(options_object);
     free_animation(OPT(animation.cursor));
+    free_animation(OPT(animation.visual_bell));
     // we leak the texture here since it is not guaranteed
     // that freeing the texture will work during shutdown and
     // the GPU driver should take care of it when the OpenGL context is

kitty/state.h

@@ -119,7 +119,7 @@ typedef struct {
             hb_feature_t *features;
         } *entries;
     } font_features;
-    struct { Animation *cursor; } animation;
+    struct { Animation *cursor, *visual_bell; } animation;
 } Options;
 
 typedef struct WindowLogoRenderData {