components[splitePane]: Feat: Add option to hide first pane in SplitPane

components/SplitPane/demo/src/jvmMain/kotlin/org/jetbrains/compose/splitpane/demo/Main.kt

@@ -23,7 +23,9 @@ import androidx.compose.ui.graphics.SolidColor
 import androidx.compose.ui.input.pointer.PointerIcon
 import androidx.compose.ui.input.pointer.pointerHoverIcon
 import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.DpSize
 import androidx.compose.ui.unit.dp
+import androidx.compose.ui.window.WindowState
 import androidx.compose.ui.window.singleWindowApplication
 import org.jetbrains.compose.splitpane.ExperimentalSplitPaneApi
 import org.jetbrains.compose.splitpane.HorizontalSplitPane
@@ -36,8 +38,12 @@ private fun Modifier.cursorForHorizontalResize(): Modifier =
 
 @OptIn(ExperimentalSplitPaneApi::class)
 fun main() = singleWindowApplication(
+    state = WindowState(
+        size  = DpSize(800.dp, 700.dp)
+    ),
     title = "SplitPane demo"
 ) {
+
     MaterialTheme {
         val splitterState = rememberSplitPaneState()
         val hSplitterState = rememberSplitPaneState()
@@ -53,6 +59,13 @@ fun main() = singleWindowApplication(
                     Text(if (hSplitterState.moveEnabled) "Freeze H" else "Unfreeze H")
                 }
 
+                Button(onClick = { splitterState.firstVisible = !splitterState.firstVisible }) {
+                    Text(if (splitterState.firstVisible) "Hide Left Pane" else "Show Left Pane")
+                }
+                Button(onClick = { hSplitterState.firstVisible = !hSplitterState.firstVisible }) {
+                    Text(if (hSplitterState.firstVisible) "Hide Top Pane" else "Show Top Pane")
+                }
+
                 OutlinedTextField(value = delta, onValueChange = { delta = it }, label = { Text("Delta") })
                 Button(onClick = { delta.toFloatOrNull()?.let { splitterState.dispatchRawMovement(it) } }) {
                     Text("Add delta V")

components/SplitPane/library/src/commonMain/kotlin/org/jetbrains/compose/splitpane/SplitPaneDSL.kt

@@ -20,7 +20,7 @@ interface SplitPaneScope {
      * Left part, for [VerticalSplitPane] it will be Top part
      * @param minSize a minimal size of composable item.
      * For [HorizontalSplitPane] it will be minimal width, for [VerticalSplitPane] it wil be minimal Heights.
-     * In this context minimal mean that this composable item could not be smaller than specified value.
+     * In this context, minimal means that this composable item could not be smaller than the specified value.
      * @param content composable item content.
      * */
     fun first(
@@ -33,7 +33,7 @@ interface SplitPaneScope {
      * For [HorizontalSplitPane] it will be Right part, for [VerticalSplitPane] it will be Bottom part
      * @param minSize a minimal size of composable item.
      * For [HorizontalSplitPane] it will be minimal width, for [VerticalSplitPane] it wil be minimal Heights.
-     * In this context minimal mean that this composable item could not be smaller than specified value.
+     * In this context, minimal means that this composable item could not be smaller than the specified value.
      * @param content composable item content.
      * */
     fun second(
@@ -48,7 +48,7 @@ interface SplitPaneScope {
 /** Receiver scope which is used by [SplitterScope] */
 @ExperimentalSplitPaneApi
 interface HandleScope {
-    /** allow mark composable as movable handle */
+    /** allow mark composable as a movable handle */
     fun Modifier.markAsHandle(): Modifier
 }
 
@@ -65,15 +65,15 @@ interface SplitterScope {
 
     /**
      * Set up handle part, this part of splitter would be measured and placed above [visiblePart] content.
-     * Size of handle will have no effect on split pane parts (first and second) sizes.
+     * The Size of the handle will have no effect on split pane parts (first and second) sizes.
      *
-     * @param alignment alignment of handle according to [visiblePart] could be:
+     * @param alignment alignment of the handle according to [visiblePart] could be:
      * * [SplitterHandleAlignment.BEFORE] if you place handle before [visiblePart],
      * * [SplitterHandleAlignment.ABOVE] if you place handle above [visiblePart] (will be centered)
-     * * and [SplitterHandleAlignment.AFTER] if you place handle after [visiblePart].
+     * * and [SplitterHandleAlignment.AFTER] if you place the handle after [visiblePart].
      *
-     * @param content composable item content provider. Uses [HandleScope] to allow mark any provided composable part
-     * as handle.
+     * @param content composable item content provider, Uses [HandleScope] to allow marking any provided composable part
+     * as a handle.
      * [content] will be placed only if [SplitPaneState.moveEnabled] is true
      */
     fun handle(
@@ -171,7 +171,7 @@ internal class SplitPaneScopeImpl(
 }
 
 /**
- * creates a [SplitPaneState] and remembers it across composition
+ * Creates a [SplitPaneState] and remembers it across composition
  *
  * Changes to the provided initial values will **not** result in the state being recreated or
  * changed in any way if it has already been created.
@@ -183,11 +183,13 @@ internal class SplitPaneScopeImpl(
 @Composable
 fun rememberSplitPaneState(
     initialPositionPercentage: Float = 0f,
-    moveEnabled: Boolean = true
+    moveEnabled: Boolean = true,
+    firstVisible: Boolean = true
 ): SplitPaneState {
     return remember {
         SplitPaneState(
             moveEnabled = moveEnabled,
+            firstVisible = firstVisible,
             initialPositionPercentage = initialPositionPercentage
         )
     }

components/SplitPane/library/src/commonMain/kotlin/org/jetbrains/compose/splitpane/SplitPaneState.kt

@@ -8,10 +8,13 @@ import androidx.compose.runtime.setValue
 class SplitPaneState(
     initialPositionPercentage: Float,
     moveEnabled: Boolean,
+    firstVisible: Boolean = true
 ) {
 
     var moveEnabled by mutableStateOf(moveEnabled)
 
+    var firstVisible by mutableStateOf(firstVisible)
+
     private var _positionPercentage by mutableStateOf(initialPositionPercentage)
     var positionPercentage: Float
         get() = _positionPercentage

components/SplitPane/library/src/desktopMain/kotlin/org/jetbrains/compose/splitpane/DesktopSplitPane.kt

@@ -14,8 +14,8 @@ private fun Constraints.withUnconstrainedWidth() = copy(minWidth = 0, maxWidth =
 private fun Constraints.withUnconstrainedHeight() = copy(minHeight = 0, maxHeight = Constraints.Infinity)
 
 
-@OptIn(ExperimentalSplitPaneApi::class)
 @Composable
+@OptIn(ExperimentalSplitPaneApi::class)
 internal actual fun SplitPane(
     modifier: Modifier,
     isHorizontal: Boolean,
@@ -30,7 +30,7 @@ internal actual fun SplitPane(
         second?.let { Box(modifier) { it() } }
         return
     }
-    
+
     Layout(
         {
             Box {
@@ -77,8 +77,10 @@ internal actual fun SplitPane(
                 minPosition = constrainedMin
                 maxPosition = constrainedMax
 
-                val position = (constrainedMin * (1-positionPercentage) + constrainedMax * positionPercentage)
-                    .roundToInt()
+                val position =
+                    if (firstVisible) {
+                        (constrainedMin * (1 - positionPercentage) + constrainedMax * positionPercentage).roundToInt()
+                    } else 0
 
                 val firstPlaceable = firstMeasurable.measure(
                     if (isHorizontal) {
@@ -94,7 +96,7 @@ internal actual fun SplitPane(
                     }
                 )
 
-                val secondPlaceablePosition = position + splitterSize
+                val secondPlaceablePosition = if (firstVisible) position + splitterSize else 0
                 val secondAvailableSize = (maxConstraintOnMainAxis - secondPlaceablePosition).coerceAtLeast(0)
 
                 val secondPlaceable = secondMeasurable.measure(
@@ -113,7 +115,7 @@ internal actual fun SplitPane(
 
                 val handlePlaceable = handleMeasurable.measure(splitterConstraints)
                 val handleSize = handlePlaceable.valueByDirection(isHorizontal)
-                // TODO support RTL
+
                 val handlePosition = when (splitter.alignment) {
                     SplitterHandleAlignment.BEFORE -> position + splitterSize - handleSize
                     SplitterHandleAlignment.ABOVE -> position + (splitterSize - handleSize) / 2

components/SplitPane/library/src/desktopMain/kotlin/org/jetbrains/compose/splitpane/DesktopSplitter.kt

@@ -3,15 +3,13 @@ package org.jetbrains.compose.splitpane
 import androidx.compose.foundation.gestures.detectDragGestures
 import androidx.compose.foundation.layout.*
 import androidx.compose.runtime.Composable
-import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.input.pointer.*
 import androidx.compose.ui.platform.LocalLayoutDirection
 import androidx.compose.ui.unit.LayoutDirection
 import androidx.compose.ui.unit.dp
 import java.awt.Cursor
 
-@OptIn(ExperimentalComposeUiApi::class)
 private fun Modifier.cursorForHorizontalResize(isHorizontal: Boolean): Modifier =
     pointerHoverIcon(PointerIcon(Cursor(if (isHorizontal) Cursor.E_RESIZE_CURSOR else Cursor.S_RESIZE_CURSOR)))