| /* |
| * 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.Modifier |
| import androidx.ui.core.gesture.DragObserver |
| import androidx.ui.core.gesture.ScaleObserver |
| import androidx.ui.core.gesture.dragGestureFilter |
| import androidx.ui.core.gesture.scaleGestureFilter |
| import androidx.ui.core.gesture.tapGestureFilter |
| import androidx.compose.foundation.Box |
| import androidx.compose.foundation.Text |
| 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.compose.ui.geometry.Offset |
| import androidx.ui.unit.dp |
| |
| /** |
| * Simple demo that shows off how [dragGestureFilter] and [scaleGestureFilter] automatically |
| * interoperate. |
| */ |
| @Composable |
| fun DragAndScaleGestureFilterDemo() { |
| val size = state { 200.dp } |
| val offset = state { Offset.Zero } |
| val dragInScale = state { false } |
| |
| val scaleObserver = object : ScaleObserver { |
| override fun onScale(scaleFactor: Float) { |
| size.value *= scaleFactor |
| } |
| } |
| |
| val dragObserver = object : DragObserver { |
| override fun onDrag(dragDistance: Offset): Offset { |
| offset.value += dragDistance |
| return dragDistance |
| } |
| } |
| |
| val onRelease: (Offset) -> Unit = { |
| dragInScale.value = !dragInScale.value |
| } |
| |
| val gestures = |
| if (dragInScale.value) { |
| Modifier |
| .scaleGestureFilter(scaleObserver) |
| .dragGestureFilter(dragObserver) |
| .tapGestureFilter(onRelease) |
| } else { |
| Modifier |
| .dragGestureFilter(dragObserver) |
| .scaleGestureFilter(scaleObserver) |
| .tapGestureFilter(onRelease) |
| } |
| |
| val color = |
| if (dragInScale.value) { |
| Red |
| } else { |
| Blue |
| } |
| |
| val (offsetX, offsetY) = |
| with(DensityAmbient.current) { offset.value.x.toDp() to offset.value.y.toDp() } |
| |
| Column { |
| Text("Demonstrates combining dragging with scaling.") |
| Text("Drag and scale around. Play with how slop works for both dragging and scaling. Tap" + |
| " on the box to flip the order of scaling and dragging. The behavior is always " + |
| "the same because the 2 gesture filters are completely orthogonal.") |
| Box( |
| Modifier.fillMaxSize() |
| .wrapContentSize(Alignment.Center) |
| .offset(offsetX, offsetY) |
| .preferredSize(size.value) |
| .plus(gestures), |
| backgroundColor = color |
| ) |
| } |
| } |