| /* |
| * Copyright 2022 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package androidx.compose.foundation.newtext.text.copypasta.selection |
| |
| import androidx.compose.foundation.gestures.awaitEachGesture |
| import androidx.compose.foundation.gestures.drag |
| import androidx.compose.ui.geometry.Offset |
| import androidx.compose.ui.input.pointer.AwaitPointerEventScope |
| import androidx.compose.ui.input.pointer.PointerEvent |
| import androidx.compose.ui.input.pointer.PointerEventPass |
| import androidx.compose.ui.input.pointer.PointerInputChange |
| import androidx.compose.ui.input.pointer.PointerInputScope |
| import androidx.compose.ui.input.pointer.PointerType |
| import androidx.compose.ui.input.pointer.changedToDown |
| import androidx.compose.ui.input.pointer.isPrimaryPressed |
| import androidx.compose.ui.input.pointer.isShiftPressed |
| import androidx.compose.ui.platform.ViewConfiguration |
| import androidx.compose.ui.util.fastAll |
| |
| // * Without shift it starts the new selection from the scratch. |
| // * With shift expand / shrink existed selection. |
| // * Click sets start and end of the selection, but shift click only the end of |
| // selection. |
| // * The specific case of it when selection is collapsed, but the same logic is |
| // applied for not collapsed selection too. |
| internal interface MouseSelectionObserver { |
| // on start of shift click. if returns true event will be consumed |
| fun onExtend(downPosition: Offset): Boolean |
| // on drag after shift click. if returns true event will be consumed |
| fun onExtendDrag(dragPosition: Offset): Boolean |
| |
| // if returns true event will be consumed |
| fun onStart(downPosition: Offset, adjustment: SelectionAdjustment): Boolean |
| fun onDrag(dragPosition: Offset, adjustment: SelectionAdjustment): Boolean |
| } |
| |
| // Distance in pixels between consecutive click positions to be considered them as clicks sequence |
| internal const val ClicksSlop = 100.0 |
| |
| private class ClicksCounter( |
| private val viewConfiguration: ViewConfiguration |
| ) { |
| var clicks = 0 |
| var prevClick: PointerInputChange? = null |
| fun update(event: PointerEvent) { |
| val currentPrevClick = prevClick |
| val newClick = event.changes[0] |
| if (currentPrevClick != null && |
| timeIsTolerable(currentPrevClick, newClick) && |
| positionIsTolerable(currentPrevClick, newClick) |
| ) { |
| clicks += 1 |
| } else { |
| clicks = 1 |
| } |
| prevClick = newClick |
| } |
| |
| fun timeIsTolerable(prevClick: PointerInputChange, newClick: PointerInputChange): Boolean { |
| val diff = newClick.uptimeMillis - prevClick.uptimeMillis |
| return diff < viewConfiguration.doubleTapTimeoutMillis |
| } |
| |
| fun positionIsTolerable(prevClick: PointerInputChange, newClick: PointerInputChange): Boolean { |
| val diff = newClick.position - prevClick.position |
| return diff.getDistance() < ClicksSlop |
| } |
| } |
| |
| internal suspend fun PointerInputScope.mouseSelectionDetector( |
| observer: MouseSelectionObserver |
| ) { |
| awaitEachGesture { |
| val clicksCounter = ClicksCounter(viewConfiguration) |
| while (true) { |
| val down: PointerEvent = awaitMouseEventDown() |
| clicksCounter.update(down) |
| val downChange = down.changes[0] |
| if (down.keyboardModifiers.isShiftPressed) { |
| val started = observer.onExtend(downChange.position) |
| if (started) { |
| downChange.consume() |
| drag(downChange.id) { |
| if (observer.onExtendDrag(it.position)) { |
| it.consume() |
| } |
| } |
| } |
| } else { |
| val selectionMode = when (clicksCounter.clicks) { |
| 1 -> SelectionAdjustment.None |
| 2 -> SelectionAdjustment.Word |
| else -> SelectionAdjustment.Paragraph |
| } |
| val started = observer.onStart(downChange.position, selectionMode) |
| if (started) { |
| downChange.consume() |
| drag(downChange.id) { |
| if (observer.onDrag(it.position, selectionMode)) { |
| it.consume() |
| } |
| } |
| } |
| } |
| } |
| } |
| } |
| |
| private suspend fun AwaitPointerEventScope.awaitMouseEventDown(): PointerEvent { |
| var event: PointerEvent |
| do { |
| event = awaitPointerEvent(PointerEventPass.Main) |
| } while ( |
| !( |
| event.buttons.isPrimaryPressed && event.changes.fastAll { |
| it.type == PointerType.Mouse && it.changedToDown() |
| } |
| ) |
| ) |
| return event |
| } |
