Simple timer app inspired by Newton's Cradle. Created in Jetpack Compose for #AndroidDevChallenge.

The goal was to create something simple yet playful to demonstrate (and evaluate) capabilities of Jetpack Compose.
The result is a (up to) 1 minute timer trying to recreate Newton's Cradle.

Some highlights and links to code:

• Drawing first ball trajectory and hint animation to setup the timer:
  • Usage of drawArc with dashPathEffect and animated clipPath - code
• Playful way of setting up timer by dragging first ball. Timer starts as soon as you lift your finger up:
  • Usage of pointerInput and detectDragGestures - code
• Smooth transitioning between states:
  • Configuration mode and started mode - code
• Swinging animation is controlling animation from ViewModel and can be paused/resumed:
  • TargetBasedAnimation + update loop in a Coroutine - code
• Trying to recreate gravitational swing with hit rebound and colliding balls:
  • Custom Easing and many parameters - code
• Shadows are blurred and scaled down if ball is swinging higher from the ground:
  • Brush.radialGradient and transformations using graphicsLayer - code
• Playing hit sounds when balls collide, synchronized with animation.
• Swinging amplitude and hit sound volume decrease with time, reaching 0 at the end of the timer.
• Timer's display is styled with two font sizes and colors. Also font size adjusts to the available space:
  • Using AnnotatedString.Builder - code
• Animated change between dark and light mode.
• Support for both portrait and landscape orientations.

Copyright 2020 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

    https://www.apache.org/licenses/LICENSE-2.0

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distributed under the License is distributed on an "AS IS" BASIS,
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