Add speculative typing latency parameter

projector-client-common/src/jsMain/kotlin/org/jetbrains/projector/client/common/misc/ParamsProvider.kt

@@ -66,6 +66,7 @@ actual object ParamsProvider {
   private const val DEFAULT_REPAINT_INTERVAL_MS = 333
   private const val DEFAULT_IMAGE_CACHE_SIZE_CHARS = 5_000_000
   private const val DEFAULT_BLOCK_CLOSING = true
+  private const val DEFAULT_SPECULATIVE_TYPING_LATENCY = 0
 
   val SYSTEM_SCALING_RATIO
     get() = window.devicePixelRatio  // get every time because it can be changed
@@ -101,6 +102,7 @@ actual object ParamsProvider {
   actual val IMAGE_CACHE_SIZE_CHARS: Int
   val BLOCK_CLOSING: Boolean
   val LAYOUT_TYPE: LayoutType
+  val SPECULATIVE_TYPING_LATENCY: Int
   val SCALING_RATIO: Double
     get() = SYSTEM_SCALING_RATIO * USER_SCALING_RATIO
 
@@ -162,6 +164,7 @@ actual object ParamsProvider {
         "frAzerty" -> LayoutType.FR_AZERTY
         else -> LayoutType.JS_DEFAULT
       }
+      SPECULATIVE_TYPING_LATENCY = searchParams.get("speculativeTypingLatency")?.toIntOrNull() ?: DEFAULT_SPECULATIVE_TYPING_LATENCY
     }
   }
 

projector-client-web/README.md

@@ -66,6 +66,7 @@ Name | Type | Default value | Description
 `cacheSize` | Int | `5M` | Set size of cache for images in Chars.
 `blockClosing` | Boolean | `true` | Enable blocking of accidental closing of the web page
 `relayServerId` | String? | Not present | Identifier of Projector server to connect to for relay connection. Warning: Static files must be accessed via https when relay is used.
+`speculativeTypingLatency` | Int | `0` | Sets latency before key press event is sent to server if speculative symbol for the event was drawn.
 
 ## Shortcuts
 - `Ctrl + F10` prints statistics to the browser console. Example:  

projector-client-web/src/main/kotlin/org/jetbrains/projector/client/web/speculative/Typing.kt

@@ -39,7 +39,7 @@ sealed class Typing {
 
   abstract fun removeSpeculativeImage()
 
-  abstract fun addEventChar(event: ClientKeyPressEvent)
+  abstract fun addEventChar(event: ClientKeyPressEvent): Boolean
 
   abstract fun dispose()
 
@@ -53,8 +53,8 @@ sealed class Typing {
       // do nothing
     }
 
-    override fun addEventChar(event: ClientKeyPressEvent) {
-      // do nothing
+    override fun addEventChar(event: ClientKeyPressEvent): Boolean {
+      return false
     }
 
     override fun dispose() {
@@ -124,14 +124,14 @@ sealed class Typing {
              || event.char.category.fromOtherUnicodeGroup
     }
 
-    override fun addEventChar(event: ClientKeyPressEvent) {
-      if (shouldSkipEvent(event)) return
+    override fun addEventChar(event: ClientKeyPressEvent): Boolean {
+      if (shouldSkipEvent(event)) return false
 
-      val currentCarets = carets as? ServerCaretInfoChangedEvent.CaretInfoChange.Carets ?: return
+      val currentCarets = carets as? ServerCaretInfoChangedEvent.CaretInfoChange.Carets ?: return false
 
-      val canvas = canvasByIdGetter(currentCarets.editorWindowId) ?: return
+      val canvas = canvasByIdGetter(currentCarets.editorWindowId) ?: return false
 
-      val firstCaretLocation = currentCarets.caretInfoList.firstOrNull()?.locationInWindow ?: return  // todo: support multiple carets
+      val firstCaretLocation = currentCarets.caretInfoList.firstOrNull()?.locationInWindow ?: return false  // todo: support multiple carets
 
       ensureSpeculativeCanvasSize(canvas)
 
@@ -182,6 +182,8 @@ sealed class Typing {
 
       speculativeCanvasImage.style.display = "block"
       canvas.style.display = "none"
+
+      return true
     }
 
     private fun ensureSpeculativeCanvasSize(canvas: HTMLCanvasElement) {

projector-client-web/src/main/kotlin/org/jetbrains/projector/client/web/state/ClientState.kt

@@ -508,12 +508,25 @@ sealed class ClientState {
       is ClientAction.AddEvent -> {
         val event = action.event
 
+        fun addEvent() {
+          eventsToSend.add(event)
+          messagingPolicy.onAddEvent()
+        }
+
+        var latency = 0
+
         if (event is ClientKeyPressEvent) {
-          typing.addEventChar(event)
+          val added = typing.addEventChar(event)
+          if (added) {
+            latency = ParamsProvider.SPECULATIVE_TYPING_LATENCY
+          }
         }
 
-        eventsToSend.add(event)
-        messagingPolicy.onAddEvent()
+        if (latency > 0) {
+          window.setTimeout(::addEvent, latency)
+        } else {
+          addEvent()
+        }
 
         this
       }