| /* |
| * Copyright 2019 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.ui.core.demos.gestures |
| |
| import androidx.compose.Composable |
| import androidx.compose.state |
| import androidx.ui.core.Alignment |
| import androidx.ui.core.DensityAmbient |
| import androidx.ui.core.Direction |
| import androidx.ui.core.Modifier |
| import androidx.ui.core.gesture.DragObserver |
| import androidx.ui.core.gesture.dragGestureFilter |
| import androidx.compose.foundation.Box |
| import androidx.compose.foundation.Text |
| import androidx.ui.graphics.Color |
| import androidx.compose.foundation.layout.Column |
| import androidx.compose.foundation.layout.fillMaxSize |
| import androidx.compose.foundation.layout.offset |
| import androidx.compose.foundation.layout.preferredSize |
| import androidx.compose.foundation.layout.wrapContentSize |
| import androidx.ui.geometry.Offset |
| import androidx.ui.unit.dp |
| |
| /** |
| * Simple [dragGestureFilter] demo. |
| */ |
| @Composable |
| fun DragGestureFilterDemo() { |
| |
| val verticalColor = Color(0xfff44336) |
| val horizontalColor = Color(0xff2196f3) |
| |
| val offset = state { Offset.Zero } |
| val canStartVertically = state { true } |
| |
| val dragObserver = |
| if (canStartVertically.value) { |
| object : DragObserver { |
| override fun onDrag(dragDistance: Offset): Offset { |
| offset.value = |
| Offset(x = offset.value.x, y = offset.value.y + dragDistance.y) |
| return dragDistance |
| } |
| |
| override fun onStop(velocity: Offset) { |
| canStartVertically.value = !canStartVertically.value |
| super.onStop(velocity) |
| } |
| } |
| } else { |
| object : DragObserver { |
| override fun onDrag(dragDistance: Offset): Offset { |
| offset.value = |
| Offset(x = offset.value.x + dragDistance.x, y = offset.value.y) |
| return dragDistance |
| } |
| |
| override fun onStop(velocity: Offset) { |
| canStartVertically.value = !canStartVertically.value |
| super.onStop(velocity) |
| } |
| } |
| } |
| |
| val canDrag = |
| if (canStartVertically.value) { |
| { direction: Direction -> |
| when (direction) { |
| Direction.DOWN -> true |
| Direction.UP -> true |
| else -> false |
| } |
| } |
| } else { |
| { direction: Direction -> |
| when (direction) { |
| Direction.LEFT -> true |
| Direction.RIGHT -> true |
| else -> false |
| } |
| } |
| } |
| |
| val color = |
| if (canStartVertically.value) { |
| verticalColor |
| } else { |
| horizontalColor |
| } |
| |
| val (offsetX, offsetY) = |
| with(DensityAmbient.current) { offset.value.x.toDp() to offset.value.y.toDp() } |
| |
| Column { |
| Text( |
| "Demonstrates standard dragging (when a slop has to be exceeded before dragging can " + |
| "start) and customization of the direction in which dragging can occur." |
| ) |
| Text( |
| "When the box is blue, it can only be dragged horizontally. When the box is red, it" + |
| " can only be dragged vertically." |
| ) |
| Box( |
| Modifier.offset(offsetX, offsetY) |
| .fillMaxSize() |
| .wrapContentSize(Alignment.Center) |
| .preferredSize(192.dp) |
| .dragGestureFilter(dragObserver, canDrag), |
| backgroundColor = color |
| ) |
| } |
| } |