| /* |
| * 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.Layout |
| import androidx.ui.core.Modifier |
| import androidx.ui.core.gesture.rawScaleGestureFilter |
| import androidx.ui.core.gesture.RawScaleObserver |
| import androidx.compose.foundation.Text |
| import androidx.compose.foundation.background |
| import androidx.compose.ui.graphics.Color |
| import androidx.compose.foundation.layout.Column |
| import androidx.compose.foundation.layout.wrapContentSize |
| import kotlin.math.roundToInt |
| |
| /** |
| * Demo app created to study some complex interactions of multiple DragGestureDetectors. |
| */ |
| @Composable |
| fun NestedScalingDemo() { |
| Column { |
| Text("Demonstrates nested scaling.") |
| Text("As of now, this works the same way that nested scrolling does. There is a scaling " + |
| "region inside another scaling region. If you scale the inner region far " + |
| "enough, it will actually stop scaling and the outer region will scale instead. " + |
| "Or you can just scale the outer region (Scale out to get started)") |
| Layout( |
| children = { |
| Scalable(.66666666f, Color(0xFFffeb3b.toInt())) { |
| Scalable(.5f, Color(0xFF4caf50.toInt())) {} |
| } |
| }) { measurables, constraints -> |
| val placeable = measurables.first().measure(constraints) |
| |
| layout(constraints.maxWidth, constraints.maxHeight) { |
| placeable.place( |
| (constraints.maxWidth - placeable.width) / 2, |
| (constraints.maxHeight - placeable.height) / 2 |
| ) |
| } |
| } |
| } |
| } |
| |
| @Composable |
| private fun Scalable( |
| minPercent: Float, |
| color: Color, |
| children: @Composable () -> Unit |
| ) { |
| |
| val currentPercent = state { 1f } |
| |
| val outerScaleObserver = object : RawScaleObserver { |
| override fun onScale(scaleFactor: Float): Float { |
| val oldSize = currentPercent.value |
| currentPercent.value = oldSize * scaleFactor |
| if (currentPercent.value < minPercent) { |
| currentPercent.value = minPercent |
| } else if (currentPercent.value > 1f) { |
| currentPercent.value = 1f |
| } |
| return currentPercent.value / oldSize |
| } |
| } |
| |
| Layout( |
| children = children, |
| modifier = Modifier.wrapContentSize(Alignment.Center) |
| .rawScaleGestureFilter(outerScaleObserver) |
| .background(color = color), |
| measureBlock = { measurables, constraints -> |
| val newConstraints = |
| constraints.copy( |
| maxWidth = (constraints.maxWidth * currentPercent.value).roundToInt(), |
| maxHeight = (constraints.maxHeight * currentPercent.value).roundToInt(), |
| minWidth = 0, |
| minHeight = 0 |
| ) |
| |
| val placeable = if (measurables.isNotEmpty()) { |
| measurables.first().measure(newConstraints) |
| } else { |
| null |
| } |
| |
| layout(newConstraints.maxWidth, newConstraints.maxHeight) { |
| placeable?.place( |
| (newConstraints.maxWidth - placeable.width) / 2, |
| (newConstraints.maxHeight - placeable.height) / 2 |
| ) |
| } |
| }) |
| } |