Batch frequent Marked Text edit commands

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/platform/IOSSkikoInput.uikit.kt

@@ -16,7 +16,6 @@
 
 package androidx.compose.ui.platform
 
-import androidx.compose.ui.geometry.Offset
 import androidx.compose.ui.unit.DpOffset
 
 internal interface IOSSkikoInput {
@@ -27,6 +26,16 @@ internal interface IOSSkikoInput {
 
     fun endFloatingCursor()
 
+    /**
+     * Delays all edit commands until [endEditBatch] is being called.
+     */
+    fun beginEditBatch()
+
+    /**
+     * Performs all editing commands, starting from the [beginEditBatch] call.
+     */
+    fun endEditBatch()
+
     /**
      * A Boolean value that indicates whether the text-entry object has any text.
      * https://developer.apple.com/documentation/uikit/uikeyinput/1614457-hastext
@@ -116,23 +125,4 @@ internal interface IOSSkikoInput {
      * Returned value must be in range between 0 and length of text (inclusive).
      */
     fun positionFromPosition(position: Long, offset: Long): Long
-
-    object Empty : IOSSkikoInput {
-        override fun beginFloatingCursor(offset: DpOffset) = Unit
-        override fun updateFloatingCursor(offset: DpOffset)  = Unit
-        override fun endFloatingCursor()  = Unit
-        override fun hasText(): Boolean = false
-        override fun insertText(text: String) = Unit
-        override fun deleteBackward() = Unit
-        override fun endOfDocument(): Long = 0L
-        override fun getSelectedTextRange(): IntRange? = null
-        override fun setSelectedTextRange(range: IntRange?) = Unit
-        override fun selectAll() = Unit
-        override fun textInRange(range: IntRange): String = ""
-        override fun replaceRange(range: IntRange, text: String) = Unit
-        override fun setMarkedText(markedText: String?, selectedRange: IntRange) = Unit
-        override fun markedTextRange(): IntRange? = null
-        override fun unmarkText() = Unit
-        override fun positionFromPosition(position: Long, offset: Long): Long = 0
-    }
 }

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/platform/UIKitTextInputService.uikit.kt

@@ -162,6 +162,7 @@ internal class UIKitTextInputService(
     }
 
     override fun stopInput() {
+        flushEditCommandsIfNeeded(force = true)
         currentInput = null
         _tempCurrentInputSession = null
         currentImeOptions = null
@@ -263,10 +264,27 @@ internal class UIKitTextInputService(
         return event.type == KeyEventType.KeyDown
     }
 
+    private val editCommandsBatch = mutableListOf<EditCommand>()
+    private var editBatchDepth: Int = 0
+        set(value) {
+            field = value
+            flushEditCommandsIfNeeded()
+        }
+
     private fun sendEditCommand(vararg commands: EditCommand) {
-        val commandList = commands.toList()
-        _tempCurrentInputSession?.apply(commandList)
-        currentInput?.onEditCommand?.invoke(commandList)
+        _tempCurrentInputSession?.apply(commands.toList())
+
+        editCommandsBatch.addAll(commands)
+        flushEditCommandsIfNeeded()
+    }
+
+    fun flushEditCommandsIfNeeded(force: Boolean = false) {
+        if ((force || editBatchDepth == 0) && editCommandsBatch.isNotEmpty()) {
+            val commandList = editCommandsBatch.toList()
+            editCommandsBatch.clear()
+
+            currentInput?.onEditCommand?.invoke(commandList)
+        }
     }
 
     private fun getCursorPos(): Int? {
@@ -395,6 +413,14 @@ internal class UIKitTextInputService(
             floatingCursorTranslation = null
         }
 
+        override fun beginEditBatch() {
+            editBatchDepth++
+        }
+
+        override fun endEditBatch() {
+            editBatchDepth--
+        }
+
         /**
          * A Boolean value that indicates whether the text-entry object has any text.
          * https://developer.apple.com/documentation/uikit/uikeyinput/1614457-hastext

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/scene/ComposeSceneMediator.uikit.kt

@@ -466,6 +466,7 @@ internal class ComposeSceneMediator(
     }
 
     fun render(canvas: Canvas, nanoTime: Long) {
+        textInputService.flushEditCommandsIfNeeded(force = true)
         scene.render(canvas, nanoTime)
     }
 

compose/ui/ui/src/uikitMain/kotlin/androidx/compose/ui/window/IntermediateTextInputUIView.uikit.kt

@@ -29,6 +29,8 @@ import kotlin.time.DurationUnit
 import kotlinx.cinterop.CValue
 import kotlinx.cinterop.readValue
 import kotlinx.cinterop.useContents
+import kotlinx.coroutines.MainScope
+import kotlinx.coroutines.launch
 import platform.CoreGraphics.CGPoint
 import platform.CoreGraphics.CGRect
 import platform.CoreGraphics.CGRectMake
@@ -47,6 +49,7 @@ import platform.UIKit.UIEvent
 import platform.UIKit.UIKeyInputProtocol
 import platform.UIKit.UIKeyboardAppearance
 import platform.UIKit.UIKeyboardType
+import platform.UIKit.UIPress
 import platform.UIKit.UIPressesEvent
 import platform.UIKit.UIReturnKeyType
 import platform.UIKit.UITextAutocapitalizationType
@@ -66,7 +69,6 @@ import platform.UIKit.UITextRange
 import platform.UIKit.UITextSelectionRect
 import platform.UIKit.UITextStorageDirection
 import platform.UIKit.UIView
-import platform.UIKit.UIPress
 import platform.darwin.NSInteger
 
 private val NoOpOnKeyboardPresses: (Set<*>) -> Unit = {}
@@ -88,6 +90,8 @@ internal class IntermediateTextInputUIView(
             }
         }
 
+    private val mainScope = MainScope()
+
     /**
      * Callback to handle keyboard presses. The parameter is a [Set] of [UIPress] objects.
      * Erasure happens due to K/N not supporting Obj-C lightweight generics.
@@ -233,7 +237,18 @@ internal class IntermediateTextInputUIView(
             location.toInt() to length.toInt()
         }
         val relativeTextRange = locationRelative until locationRelative + lengthRelative
-        input?.setMarkedText(markedText, relativeTextRange)
+
+        // Due to iOS specifics, [setMarkedText] can be called several times in a row. Batching
+        // helps to avoid text input problems, when Composables use parameters set during
+        // recomposition instead of the current ones. Example:
+        // 1. State "1" -> TextField(text = "1")
+        // 2. setMarkedText "12" -> Not equal to TextField(text = "1") -> State "12"
+        // 3. setMarkedText "1" -> Equal to TextField(text = "1") -> State remains "12"
+        // scene.render() - Recomposes TextField
+        // 4. State "12" -> TextField(text = "12") - Invalid state. Should be TextField(text = "1")
+        input?.withBatch {
+            input?.setMarkedText(markedText, relativeTextRange)
+        }
     }
 
     /**
@@ -496,6 +511,14 @@ internal class IntermediateTextInputUIView(
     fun resetOnKeyboardPressesCallback() {
         onKeyboardPresses = NoOpOnKeyboardPresses
     }
+
+    private fun IOSSkikoInput.withBatch(update: () -> Unit) {
+        beginEditBatch()
+        update()
+        mainScope.launch {
+            endEditBatch()
+        }
+    }
 }
 
 private class IntermediateTextPosition(val position: Long = 0) : UITextPosition()