DetectDragModifier now detects long-presses

The long press initiates an item drag; otherwise the view just scrolls on drag.

Author: Stypox

app/src/main/java/org/schabi/newpipe/ui/DetectDragModifier.kt

@@ -1,37 +1,75 @@
 package org.schabi.newpipe.ui
 
+import android.view.MotionEvent
 import androidx.compose.foundation.gestures.awaitEachGesture
 import androidx.compose.foundation.gestures.awaitFirstDown
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.geometry.Offset
+import androidx.compose.ui.input.pointer.PointerEventTimeoutCancellationException
+import androidx.compose.ui.input.pointer.changedToUp
+import androidx.compose.ui.input.pointer.isOutOfBounds
 import androidx.compose.ui.input.pointer.pointerInput
 import androidx.compose.ui.input.pointer.positionChange
 import androidx.compose.ui.unit.IntOffset
+import androidx.compose.ui.unit.IntSize
+import androidx.compose.ui.util.fastAll
+import androidx.compose.ui.util.fastAny
 
 /**
  * Detects a drag gesture **without** trying to filter out any misclicks. This is useful in menus
  * where items are dragged around, where the usual misclick guardrails would cause unexpected lags
- * or strange behaviors when dragging stuff around quickly. For other use cases, use
- * [androidx.compose.foundation.gestures.detectDragGestures] or
+ * or strange behaviors when dragging stuff around quickly. Also detects whether a drag gesture
+ * began with a long press or not, which can be useful to decide whether an item should be dragged
+ * around (in case of long-press) or the view should be scrolled (otherwise). For other use cases,
+ * use [androidx.compose.foundation.gestures.detectDragGestures] or
  * [androidx.compose.foundation.gestures.detectDragGesturesAfterLongPress].
  *
  * @param beginDragGesture called when the user first touches the screen (down event) with the
- * pointer position.
+ * pointer position and whether a long press was detected.
  * @param handleDragGestureChange called with the current pointer position and the difference from
  * the last position, every time the user moves the finger after [beginDragGesture] has been called.
  * @param endDragGesture called when the drag gesture finishes, after [beginDragGesture] has been
  * called.
  */
 fun Modifier.detectDragGestures(
-    beginDragGesture: (position: IntOffset) -> Unit,
+    beginDragGesture: (position: IntOffset, wasLongPressed: Boolean) -> Unit,
     handleDragGestureChange: (position: IntOffset, positionChange: Offset) -> Unit,
     endDragGesture: () -> Unit
 ): Modifier {
     return this.pointerInput(Unit) {
         awaitEachGesture {
             val down = awaitFirstDown()
+            val wasLongPressed = try {
+                // code in this branch was taken from AwaitPointerEventScope.waitForLongPress(),
+                // which unfortunately is private
+                withTimeout(viewConfiguration.longPressTimeoutMillis) {
+                    while (true) {
+                        val event = awaitPointerEvent()
+                        if (event.changes.fastAll { it.changedToUp() }) {
+                            // All pointers are up
+                            break
+                        }
+
+                        if (event.classification == MotionEvent.CLASSIFICATION_DEEP_PRESS) {
+                            return@withTimeout true
+                        }
+
+                        if (
+                            event.changes.fastAny {
+                                it.isConsumed || it.isOutOfBounds(IntSize(0, 0), extendedTouchPadding)
+                            }
+                        ) {
+                            break
+                        }
+                    }
+                    return@withTimeout false
+                }
+            } catch (_: PointerEventTimeoutCancellationException) {
+                true
+            }
+
             val pointerId = down.id
-            beginDragGesture(down.position.toIntOffset())
+            beginDragGesture(down.position.toIntOffset(), wasLongPressed)
             while (true) {
                 val change = awaitPointerEvent().changes.find { it.id == pointerId }
                 if (change == null || !change.pressed) {

app/src/main/java/org/schabi/newpipe/ui/components/menu/LongPressMenuEditor.kt

@@ -94,7 +94,7 @@ import kotlin.math.floor
 import kotlin.math.max
 import kotlin.math.min
 
-const val TAG = "LongPressMenuEditor"
+internal const val TAG = "LongPressMenuEditor"
 
 // TODO padding doesn't seem to work as expected when the list becomes scrollable?
 @Composable
@@ -166,7 +166,12 @@ fun LongPressMenuEditor(modifier: Modifier = Modifier) {
     }
 
     // this beginDragGesture() overload is only called when moving the finger (not on DPAD's Enter)
-    fun beginDragGesture(pos: IntOffset) {
+    fun beginDragGesture(pos: IntOffset, wasLongPressed: Boolean) {
+        if (!wasLongPressed) {
+            // items can be dragged around only if they are long-pressed;
+            // use the drag as scroll otherwise
+            return
+        }
         val rawItem = findItemForOffsetOrClosestInRow(pos) ?: return
         beginDragGesture(pos, rawItem)
         autoScrollSpeed = 0f
@@ -229,7 +234,8 @@ fun LongPressMenuEditor(modifier: Modifier = Modifier) {
     fun handleDragGestureChange(pos: IntOffset, posChangeForScrolling: Offset) {
         val dragItem = activeDragItem
         if (dragItem == null) {
-            // when the user clicks outside of any draggable item, let the list be scrolled
+            // when the user clicks outside of any draggable item, or if the user did not long-press
+            // on an item to begin with, let the list be scrolled
             gridState.dispatchRawDelta(-posChangeForScrolling.y)
             return
         }