Implement TextFieldScrollState and TextFieldScrollbarAdapter (#384)

JetBrains · Jan 26, 2023 · 125f049 · 125f049
1 parent c7220b0
commit 125f049
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Showing 7 changed files with 769 additions and 34 deletions.
diff --git a/...dation/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/CoreTextField.kt b/...dation/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/CoreTextField.kt
@@ -190,7 +190,8 @@ internal fun CoreTextField(
     enabled: Boolean = true,
     readOnly: Boolean = false,
     decorationBox: @Composable (innerTextField: @Composable () -> Unit) -> Unit =
-        @Composable { innerTextField -> innerTextField() }
+        @Composable { innerTextField -> innerTextField() },
+    textScrollerPosition: TextFieldScrollerPosition? = null,
 ) {
     val focusRequester = FocusRequester()
 
@@ -205,10 +206,20 @@ internal fun CoreTextField(
     // Scroll state
     val singleLine = maxLines == 1 && !softWrap && imeOptions.singleLine
     val orientation = if (singleLine) Orientation.Horizontal else Orientation.Vertical
-    val scrollerPosition = rememberSaveable(
+    val scrollerPosition = textScrollerPosition ?: rememberSaveable(
         orientation,
         saver = TextFieldScrollerPosition.Saver
     ) { TextFieldScrollerPosition(orientation) }
+    if (scrollerPosition.orientation != orientation){
+        throw IllegalArgumentException(
+            "Mismatching scroller orientation; " + (
+                if (orientation == Orientation.Vertical)
+                    "only single-line, non-wrap text fields can scroll horizontally"
+                else
+                    "single-line, non-wrap text fields can only scroll horizontally"
+                )
+        )
+    }
 
     // State
     val transformedText = remember(value, visualTransformation) {

diff --git a/...tion/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/TextFieldScroll.kt b/...tion/foundation/src/commonMain/kotlin/androidx/compose/foundation/text/TextFieldScroll.kt
@@ -246,6 +246,12 @@ internal class TextFieldScrollerPosition(
     var maximum by mutableStateOf(0f)
         private set
 
+    /**
+     * Size of the visible part, on the scrollable axis, in pixels.
+     */
+    var viewportSize by mutableStateOf(0)
+        private set
+
     /**
      * Keeps the cursor position before a new symbol has been typed or the text field has been
      * dragged. We check it to understand if the [offset] needs to be updated.
@@ -279,6 +285,7 @@ internal class TextFieldScrollerPosition(
             previousCursorRect = cursorRect
         }
         offset = offset.coerceIn(0f, difference)
+        viewportSize = containerSize
     }
 
     /*@VisibleForTesting*/

diff --git a/...dation/foundation/src/desktopMain/kotlin/androidx/compose/foundation/Scrollbar.desktop.kt b/...dation/foundation/src/desktopMain/kotlin/androidx/compose/foundation/Scrollbar.desktop.kt
@@ -29,10 +29,12 @@ import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.lazy.grid.LazyGridState
 import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.foundation.text.TextFieldScrollState
 import androidx.compose.foundation.v2.LazyGridScrollbarAdapter
 import androidx.compose.foundation.v2.LazyListScrollbarAdapter
 import androidx.compose.foundation.v2.ScrollableScrollbarAdapter
 import androidx.compose.foundation.v2.SliderAdapter
+import androidx.compose.foundation.v2.TextFieldScrollbarAdapter
 import androidx.compose.foundation.v2.maxScrollOffset
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocal
@@ -569,8 +571,6 @@ fun OldScrollbarAdapter(
  *
  * [scrollState] is instance of [LazyListState] which is used by scrollable component
  *
- * Scrollbar size and position will be dynamically changed on the current visible content.
- *
  * Example:
  *     Box(Modifier.fillMaxSize()) {
  *         val state = rememberLazyListState()
@@ -634,6 +634,19 @@ fun rememberScrollbarAdapter(
     ScrollbarAdapter(scrollState)
 }
 
+/**
+ * Create and [remember] [androidx.compose.foundation.v2.ScrollbarAdapter] for text field with
+ * the given instance of [TextFieldScrollState].
+ */
+@ExperimentalFoundationApi
+@JvmName("rememberScrollbarAdapter2")
+@Composable
+fun rememberScrollbarAdapter(
+    scrollState: TextFieldScrollState,
+): androidx.compose.foundation.v2.ScrollbarAdapter = remember(scrollState) {
+    ScrollbarAdapter(scrollState)
+}
+
 /**
  * ScrollbarAdapter for Modifier.verticalScroll and Modifier.horizontalScroll
  *
@@ -663,8 +676,6 @@ fun ScrollbarAdapter(
  *
  * [scrollState] is instance of [LazyListState] which is used by scrollable component
  *
- * Scrollbar size and position will be dynamically changed on the current visible content.
- *
  * Example:
  *     Box(Modifier.fillMaxSize()) {
  *         val state = rememberLazyListState()
@@ -689,8 +700,6 @@ fun ScrollbarAdapter(
  *
  * [scrollState] is instance of [LazyGridState] which is used by scrollable component
  *
- * Scrollbar size and position will be dynamically changed on the current visible content.
- *
  * Example:
  *     Box(Modifier.fillMaxSize()) {
  *         val state = rememberLazyGridState()
@@ -710,6 +719,35 @@ fun ScrollbarAdapter(
     scrollState: LazyGridState
 ): androidx.compose.foundation.v2.ScrollbarAdapter = LazyGridScrollbarAdapter(scrollState)
 
+/**
+ * ScrollbarAdapter for text fields.
+ *
+ * [scrollState] is instance of [TextFieldScrollState] which is used by scrollable component
+ *
+ * Example:
+ *     Box(Modifier.fillMaxSize()) {
+ *         val scrollState = rememberTextFieldVerticalScrollState()
+ *
+ *         BasicTextField(
+ *             value = ...,
+ *             onValueChange = ...,
+ *             scrollState = state
+ *         ) {
+ *             ...
+ *         }
+ *
+ *         VerticalScrollbar(
+ *             adapter = rememberScrollbarAdapter(scrollState)
+ *             modifier = Modifier.align(Alignment.CenterEnd).fillMaxHeight(),
+ *         )
+ *     }
+ */
+@ExperimentalFoundationApi
+@JvmName("ScrollbarAdapter2")
+fun ScrollbarAdapter(
+    scrollState: TextFieldScrollState
+): androidx.compose.foundation.v2.ScrollbarAdapter = TextFieldScrollbarAdapter(scrollState)
+
 /**
  * Defines how to scroll the scrollable component
  */