Manually ports tgstation/tgstation#74428 due to merge conflicts

code/datums/chatmessage.dm

@@ -4,6 +4,8 @@
 #define CHAT_MESSAGE_LIFESPAN 5 SECONDS
 /// How long the chat message's end of life fading animation will occur for
 #define CHAT_MESSAGE_EOL_FADE 0.7 SECONDS
+/// Grace period for fade before we actually delete the chat message
+#define CHAT_MESSAGE_GRACE_PERIOD (0.2 SECONDS)
 /// Factor of how much the message index (number of messages) will account to exponential decay
 #define CHAT_MESSAGE_EXP_DECAY 0.7
 /// Factor of how much height will account to exponential decay
@@ -50,10 +52,10 @@
 	var/datum/chatmessage/prev
 	/// The current index used for adjusting the layer of each sequential chat message such that recent messages will overlay older ones
 	var/static/current_z_idx = 0
-	/// Contains ID of assigned timer for end_of_life fading event
-	var/fadertimer = null
-	/// States if end_of_life is being executed
-	var/isFading = FALSE
+	/// When we started animating the message
+	var/animate_start = 0
+	/// Our animation lifespan, how long this message will last
+	var/animate_lifespan = 0
 
 /**
  * Constructs a chat message overlay
@@ -77,6 +79,8 @@
 	INVOKE_ASYNC(src, .proc/generate_image, text, target, owner, language, extra_classes, lifespan)
 
 /datum/chatmessage/Destroy()
+	if(REALTIMEOFDAY < animate_start + animate_lifespan)
+		stack_trace("Del'd before we finished fading, with [(animate_start + animate_lifespan) - REALTIMEOFDAY] time left")
 	if (owned_by)
 		if (owned_by.seen_messages)
 			LAZYREMOVEASSOC(owned_by.seen_messages, message_loc, src)
@@ -184,6 +188,7 @@
 ///necessary because after that call the proc can resume at the end of the tick and cause overtime.
 /datum/chatmessage/proc/finish_image_generation(mheight, atom/target, mob/owner, complete_text, lifespan)
 
+	var/rough_time = REALTIMEOFDAY
 	approx_lines = max(1, mheight / CHAT_MESSAGE_APPROX_LHEIGHT)
 
 	// Translate any existing messages upwards, apply exponential decay factors to timers
@@ -192,19 +197,33 @@
 		var/idx = 1
 		var/combined_height = approx_lines
 		for(var/datum/chatmessage/m as anything in owned_by.seen_messages[message_loc])
-			animate(m.message, pixel_y = m.message.pixel_y + mheight, time = CHAT_MESSAGE_SPAWN_TIME)
+
 			combined_height += m.approx_lines
 
+			var/time_spent = rough_time - m.animate_start
+			var/time_before_fade = m.animate_lifespan - CHAT_MESSAGE_EOL_FADE
+
 			// When choosing to update the remaining time we have to be careful not to update the
 			// scheduled time once the EOL has been executed.
-			if (!m.isFading)
-				var/sched_remaining = timeleft(m.fadertimer, SSrunechat)
-				var/remaining_time = max(0, (sched_remaining) * (CHAT_MESSAGE_EXP_DECAY ** idx++) * (CHAT_MESSAGE_HEIGHT_DECAY ** combined_height))
-				if (remaining_time)
-					deltimer(m.fadertimer, SSrunechat)
-					m.fadertimer = addtimer(CALLBACK(m, .proc/end_of_life), remaining_time, TIMER_STOPPABLE|TIMER_DELETE_ME, SSrunechat)
-				else
-					m.end_of_life()
+			if (time_spent >= time_before_fade)
+				animate(m.message, pixel_y = m.message.pixel_y + mheight, time = CHAT_MESSAGE_SPAWN_TIME, flags = ANIMATION_PARALLEL)
+				continue
+
+			var/remaining_time = time_before_fade * (CHAT_MESSAGE_EXP_DECAY ** idx++) * (CHAT_MESSAGE_HEIGHT_DECAY ** combined_height)
+			// Ensure we don't accidentially spike alpha up or something silly like that
+			m.message.alpha = m.get_current_alpha(time_spent)
+			if (remaining_time > 0)
+				// Stay faded in for a while, then
+				animate(m.message, alpha = 255, remaining_time)
+				// Fade out
+				animate(alpha = 0, time = CHAT_MESSAGE_EOL_FADE)
+				m.animate_lifespan = remaining_time + CHAT_MESSAGE_EOL_FADE
+			else
+				// Your time has come my son
+				animate(alpha = 0, time = CHAT_MESSAGE_EOL_FADE)
+			// We run this after the alpha animate, because we don't want to interrup it, but also don't want to block it by running first
+			// Sooo instead we do this. bit messy but it fuckin works
+			animate(m.message, pixel_y = m.message.pixel_y + mheight, time = CHAT_MESSAGE_SPAWN_TIME, flags = ANIMATION_PARALLEL)
 
 	// Reset z index if relevant
 	if (current_z_idx >= CHAT_LAYER_MAX_Z)
@@ -222,26 +241,32 @@
 	message.maptext_x = (CHAT_MESSAGE_WIDTH - owner.bound_width) * -0.5
 	message.maptext = MAPTEXT(complete_text)
 
+	animate_start = rough_time
+	animate_lifespan = lifespan
+
 	// View the message
 	LAZYADDASSOCLIST(owned_by.seen_messages, message_loc, src)
 	owned_by.images |= message
 	animate(message, alpha = 255, time = CHAT_MESSAGE_SPAWN_TIME)
 
-	// Register with the runechat SS to handle EOL and destruction
-	var/duration = lifespan - CHAT_MESSAGE_EOL_FADE
-	fadertimer = addtimer(CALLBACK(src, .proc/end_of_life), duration, TIMER_STOPPABLE|TIMER_DELETE_ME, SSrunechat)
+	var/time_before_fade = lifespan - CHAT_MESSAGE_SPAWN_TIME - CHAT_MESSAGE_EOL_FADE
+	// Stay faded in
+	animate(alpha = 255, time = time_before_fade)
+	// Fade out
+	animate(alpha = 0, time = CHAT_MESSAGE_EOL_FADE)
 
-/**
- * Applies final animations to overlay CHAT_MESSAGE_EOL_FADE deciseconds prior to message deletion,
- * sets timer for scheduling deletion
- *
- * Arguments:
- * * fadetime - The amount of time to animate the message's fadeout for
- */
-/datum/chatmessage/proc/end_of_life(fadetime = CHAT_MESSAGE_EOL_FADE)
-	isFading = TRUE
-	animate(message, alpha = 0, time = fadetime, flags = ANIMATION_PARALLEL)
-	addtimer(CALLBACK(GLOBAL_PROC, /proc/qdel, src), fadetime, TIMER_DELETE_ME, SSrunechat)
+	// Register with the runechat SS to handle destruction
+	addtimer(CALLBACK(GLOBAL_PROC, .proc/qdel, src), lifespan + CHAT_MESSAGE_GRACE_PERIOD, TIMER_DELETE_ME, SSrunechat)
+
+/datum/chatmessage/proc/get_current_alpha(time_spent)
+	if(time_spent < CHAT_MESSAGE_SPAWN_TIME)
+		return (time_spent / CHAT_MESSAGE_SPAWN_TIME) * 255
+
+	var/time_before_fade = animate_lifespan - CHAT_MESSAGE_EOL_FADE
+	if(time_spent <= time_before_fade)
+		return 255
+
+	return (1 - ((time_spent - time_before_fade) / CHAT_MESSAGE_EOL_FADE)) * 255
 
 /**
  * Creates a message overlay at a defined location for a given speaker
@@ -331,6 +356,7 @@
 #undef CHAT_MESSAGE_SPAWN_TIME
 #undef CHAT_MESSAGE_LIFESPAN
 #undef CHAT_MESSAGE_EOL_FADE
+#undef CHAT_MESSAGE_GRACE_PERIOD
 #undef CHAT_MESSAGE_EXP_DECAY
 #undef CHAT_MESSAGE_HEIGHT_DECAY
 #undef CHAT_MESSAGE_APPROX_LHEIGHT