add key delay to options menu

fcore/constants.sml

@@ -42,4 +42,6 @@ struct
   val moveBatY = 2
 
   val moveProjectileBy = 11
+
+  val keyDelay = 0.3
 end

fcore/options/options-type.sml

@@ -10,7 +10,7 @@ sig
   | SAVE_BUTTON
   | CANCEL_BUTTON
 
-  type options_type = {focus: focus}
+  type options_type = {focus: focus, lastUpPress: real, lastDownPress: real}
 
   val initial: options_type
 end
@@ -27,7 +27,7 @@ struct
   | SAVE_BUTTON
   | CANCEL_BUTTON
 
-  type options_type = {focus: focus}
+  type options_type = {focus: focus, lastUpPress: real, lastDownPress: real}
 
-  val initial = {focus = LEFT_KEY}
+  val initial = {focus = LEFT_KEY, lastUpPress = 0.0, lastDownPress = 0.0}
 end

fcore/options/options-update.sml

@@ -2,42 +2,94 @@ structure OptionsUpdate =
 struct
   open OptionsType
 
-  fun default (options, userKeys) =
+  fun default (options: OptionsType.options_type, userKeys) =
+    let
+      val {focus, ...} = options
+      (* `default` function is called when no keys are pressed
+       * so set up pressed/down pressed both to 0
+       * as neither is being pressed. *)
+      val options = {focus = focus, lastUpPress = 0.0, lastDownPress = 0.0}
+    in
       {mode = GameType.OPTIONS options, userKeys = userKeys}
+    end
 
-  fun withFocus (newFocus, userKeys) =
+  fun moveFocusUp (options, newFocus, userKeys, time) =
-    {mode = GameType.OPTIONS {focus = newFocus}, userKeys = userKeys}
+    let
+      val {focus, lastUpPress, ...} = options
+      (* only switch to newFocus if it is time for key delay to be triggered.
+       * We set lastDownPress to 0 because up is currently being pressed instead
+       * so we don't want to a key delay for down. *)
+      val options =
+        if lastUpPress + Constants.keyDelay <= time then
+          {focus = newFocus, lastUpPress = time, lastDownPress = 0.0}
+        else
+          {focus = focus, lastUpPress = lastUpPress, lastDownPress = 0.0}
+    in
+      {mode = GameType.OPTIONS options, userKeys = userKeys}
+    end
+
+  fun moveFocusDown (options, newFocus, userKeys, time) =
+    let
+      val {focus, lastDownPress, ...} = options
+      val options =
+        if lastDownPress + Constants.keyDelay <= time then
+          {focus = newFocus, lastUpPress = 0.0, lastDownPress = time}
+        else
+          {focus = focus, lastUpPress = 0.0, lastDownPress = lastDownPress}
+    in
+      {mode = GameType.OPTIONS options, userKeys = userKeys}
+    end
 
   fun update (options, input: FrameInputType.t, userKeys, time) =
     case #focus options of
       LEFT_KEY =>
-        if #downHeld input then withFocus (RIGHT_KEY, userKeys)
+        if #downHeld input then
-        else default (options, userKeys)
+          moveFocusDown (options, RIGHT_KEY, userKeys, time)
+        else
+          default (options, userKeys)
     | RIGHT_KEY =>
-        if #upHeld input then withFocus (LEFT_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (UP_KEY, userKeys)
+          moveFocusUp (options, LEFT_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, UP_KEY, userKeys, time)
+        else
+          default (options, userKeys)
     | UP_KEY =>
-        if #upHeld input then withFocus (RIGHT_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (DOWN_KEY, userKeys)
+          moveFocusUp (options, RIGHT_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, DOWN_KEY, userKeys, time)
+        else
+          default (options, userKeys)
     | DOWN_KEY =>
-        if #upHeld input then withFocus (UP_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (JUMP_KEY, userKeys)
+          moveFocusUp (options, UP_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, JUMP_KEY, userKeys, time)
+        else
+          default (options, userKeys)
     | JUMP_KEY =>
-        if #upHeld input then withFocus (DOWN_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (ATTACK_KEY, userKeys)
+          moveFocusUp (options, DOWN_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, ATTACK_KEY, userKeys, time)
+        else
+          default (options, userKeys)
     | ATTACK_KEY =>
-        if #upHeld input then withFocus (JUMP_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (SAVE_BUTTON, userKeys)
+          moveFocusUp (options, JUMP_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, SAVE_BUTTON, userKeys, time)
+        else
+          default (options, userKeys)
     | SAVE_BUTTON =>
-        if #upHeld input then withFocus (ATTACK_KEY, userKeys)
+        if #upHeld input then
-        else if #downHeld input then withFocus (CANCEL_BUTTON, userKeys)
+          moveFocusUp (options, ATTACK_KEY, userKeys, time)
-        else default (options, userKeys)
+        else if #downHeld input then
+          moveFocusDown (options, CANCEL_BUTTON, userKeys, time)
+        else
+          default (options, userKeys)
     | CANCEL_BUTTON =>
-        if #upHeld input then withFocus (SAVE_BUTTON, userKeys)
+        if #upHeld input then moveFocusUp (options, SAVE_BUTTON, userKeys, time)
         else default (options, userKeys)
 end