From bec575505537847cd8b128182bf9f81c7ac01319 Mon Sep 17 00:00:00 2001
From: James Magahern <james@magahern.com>
Date: Sun, 27 Jan 2019 22:45:02 -0800
Subject: Animate with easing function

---
 src/animation.c | 14 +++++++++++++-
 src/animation.h | 11 +++++++----
 src/render.c    | 10 +++-------
 3 files changed, 23 insertions(+), 12 deletions(-)

diff --git a/src/animation.c b/src/animation.c
index ecefb97..0ec403b 100644
--- a/src/animation.c
+++ b/src/animation.c
@@ -11,6 +11,11 @@
  * Easing functions
  */
 
+double anim_identity(double p)
+{
+    return p;
+}
+
 double anim_qubic_ease_out(double p)
 {
 	double f = (p - 1.0);
@@ -35,13 +40,20 @@ anim_time_interval_t anim_now()
     return (ms / 1000.0);
 }
 
-double anim_progress(animation_t *anim, const double duration)
+double anim_progress_ease(animation_t *anim, const double duration, AnimationEasingFunc easing_f)
 {
     const anim_time_interval_t now = anim_now();
     double progress = (now - anim->start_time) / duration;
+    progress = easing_f(progress);
+
     return (anim->direction == IN) ? progress : (1.0 - progress);
 }
 
+double anim_progress(animation_t *anim, const double duration)
+{
+    return anim_progress_ease(anim, duration, anim_identity);
+}
+
 bool anim_complete(animation_t *anim, const double progress)
 {
    return (anim->direction == IN) ? progress >= 1.0 : progress <= 0.0;
diff --git a/src/animation.h b/src/animation.h
index 54adb70..e51771d 100644
--- a/src/animation.h
+++ b/src/animation.h
@@ -70,14 +70,17 @@ typedef struct {
 // returns current time as anim_time_interval_t
 anim_time_interval_t anim_now();
 
+// Easing functions
+typedef double(*AnimationEasingFunc)(double in);
+double anim_identity(double p);
+double anim_qubic_ease_out(double p);
+double anim_quad_ease_out(double p);
+
 // Returns normalized progress based on start time of `anim` and `duration`
 double anim_progress(animation_t *anim, const double duration);
+double anim_progress_ease(animation_t *anim, const double duration, AnimationEasingFunc easing_func);
 
 // Returns true if `anim` is complete depending on direction
 bool anim_complete(animation_t *anim, const double progress);
 
-// Easing functions
-double anim_qubic_ease_out(double p);
-double anim_quad_ease_out(double p);
-
 
diff --git a/src/render.c b/src/render.c
index b6a70d4..ab1e701 100644
--- a/src/render.c
+++ b/src/render.c
@@ -47,7 +47,7 @@ static void update_single_animation(saver_state_t *state, animation_t *anim)
         if (ca->cursor_animating) {
             if (!state->is_processing) {
                 const double fade_duration = 0.5;
-                double progress = anim_progress(anim, fade_duration);
+                const double progress = anim_progress(anim, fade_duration);
 
                 state->cursor_opacity = progress;
 
@@ -64,9 +64,7 @@ static void update_single_animation(saver_state_t *state, animation_t *anim)
     // Logo animation
     else if (anim->type == ALogoAnimation) {
         const double logo_duration = 0.6;
-
-        double progress = anim_progress(anim, logo_duration);
-        progress = anim_qubic_ease_out(progress);
+        const double progress = anim_progress_ease(anim, logo_duration, anim_qubic_ease_out);
 
         state->logo_fill_progress = progress;
         state->password_opacity = progress;
@@ -77,9 +75,7 @@ static void update_single_animation(saver_state_t *state, animation_t *anim)
     // Background red flash animation
     else if (anim->type == ARedFlashAnimation) {
         const double duration = 0.1;
-
-        double progress = anim_progress(anim, duration);
-        progress = anim_qubic_ease_out(progress);
+        const double progress = anim_progress_ease(anim, duration, anim_qubic_ease_out);
 
         bool completed = false;
         if (anim_complete(anim, progress)) {
-- 
cgit v1.2.3