| /* |
| * 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.animation.demos |
| |
| import android.app.Activity |
| import android.os.Bundle |
| import android.util.Log |
| import androidx.animation.DEBUG |
| import androidx.animation.PhysicsBuilder |
| import androidx.animation.TargetAnimation |
| import androidx.animation.fling |
| import androidx.compose.Composable |
| import androidx.compose.composer |
| import androidx.compose.memo |
| import androidx.compose.state |
| import androidx.compose.unaryPlus |
| import androidx.ui.animation.animatedFloat |
| import androidx.ui.core.Draw |
| import androidx.ui.core.IntPx |
| import androidx.ui.core.Layout |
| import androidx.ui.core.PxPosition |
| import androidx.ui.core.Text |
| import androidx.ui.core.dp |
| import androidx.ui.core.gesture.RawDragGestureDetector |
| import androidx.ui.core.gesture.DragObserver |
| import androidx.ui.core.setContent |
| import androidx.ui.core.sp |
| import androidx.ui.engine.geometry.Rect |
| import androidx.ui.graphics.Color |
| import androidx.ui.layout.Column |
| import androidx.ui.layout.Padding |
| import androidx.ui.painting.Canvas |
| import androidx.ui.painting.Paint |
| import androidx.ui.text.TextStyle |
| import kotlin.math.roundToInt |
| |
| class FancyScrolling : Activity() { |
| |
| override fun onCreate(savedInstanceState: Bundle?) { |
| super.onCreate(savedInstanceState) |
| setContent { |
| FancyScrollingExample() |
| } |
| } |
| |
| @Composable |
| fun FancyScrollingExample() { |
| Column { |
| Padding(40.dp) { |
| Text("<== Scroll horizontally ==>", style = TextStyle(fontSize = 20.sp)) |
| } |
| val animScroll = +animatedFloat(0f) |
| val itemWidth = +state { 0f } |
| RawDragGestureDetector(dragObserver = object : DragObserver { |
| override fun onDrag(dragDistance: PxPosition): PxPosition { |
| // Snap to new drag position |
| animScroll.snapTo(animScroll.value + dragDistance.x.value) |
| return dragDistance |
| } |
| override fun onStop(velocity: PxPosition) { |
| |
| // Uses default decay animation to calculate where the fling will settle, |
| // and adjust that position as needed. The target animation will be used for |
| // animating to the adjusted target. |
| animScroll.fling(velocity.x.value, adjustTarget = { target -> |
| // Adjust the target position to center align the item |
| val animation = PhysicsBuilder<Float>(dampingRatio = 2.0f, stiffness = 100f) |
| var rem = target % itemWidth.value |
| if (rem < 0) { |
| rem += itemWidth.value |
| } |
| TargetAnimation((target - rem), animation) |
| }) |
| } |
| }) { |
| val children = @Composable { |
| var paint = +memo { Paint() } |
| Draw { canvas, parentSize -> |
| val width = parentSize.width.value / 2f |
| val scroll = animScroll.value + width / 2 |
| itemWidth.value = width |
| if (DEBUG) { |
| Log.w("Anim", "Drawing items with updated" + |
| " AnimatedFloat: ${animScroll.value}") |
| } |
| drawItems(canvas, scroll, width, parentSize.height.value, paint) |
| } |
| } |
| Layout(children) { _, constraints -> |
| layout(constraints.maxWidth, IntPx(1200)) {} |
| } |
| } |
| } |
| } |
| |
| private fun drawItems( |
| canvas: Canvas, |
| scrollPosition: Float, |
| width: Float, |
| height: Float, |
| paint: Paint |
| ) { |
| var startingPos = scrollPosition % width |
| if (startingPos > 0) { |
| startingPos -= width |
| } |
| var startingColorIndex = |
| ((scrollPosition - startingPos) / width).roundToInt().rem(colors.size) |
| if (startingColorIndex < 0) { |
| startingColorIndex += colors.size |
| } |
| paint.color = colors[startingColorIndex] |
| canvas.drawRect(Rect(startingPos + 10, 0f, startingPos + width - 10, |
| height), paint) |
| paint.color = colors[(startingColorIndex + colors.size - 1) % colors.size] |
| canvas.drawRect(Rect(startingPos + width + 10, 0f, startingPos + width * 2 - 10, |
| height), paint) |
| paint.color = colors[(startingColorIndex + colors.size - 2) % colors.size] |
| canvas.drawRect(Rect(startingPos + width * 2 + 10, 0f, startingPos + width * 3 - 10, |
| height), paint) |
| } |
| |
| private val colors = listOf( |
| Color(0xFFffd9d9.toInt()), |
| Color(0xFFffa3a3.toInt()), |
| Color(0xFFff7373.toInt()), |
| Color(0xFFff3b3b.toInt()), |
| Color(0xFFce0000.toInt()), |
| Color(0xFFff3b3b.toInt()), |
| Color(0xFFff7373.toInt()), |
| Color(0xFFffa3a3.toInt())) |
| } |
