Newton’s Timer

Workflow result

📜 Description

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

💡 Motivation and Context

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 clipPathcode
  • Playful way of setting up timer by dragging first ball. Timer starts as soon as you lift your finger up:
    • Usage of pointerInput and detectDragGesturescode
  • 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 graphicsLayercode
  • 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.Buildercode
  • Animated change between dark and light mode.
  • Support for both portrait and landscape orientations.

📸 Screenshots


Copyright 2020 The Android Open Source Project

Licensed under the Apache License, Version 2.0 (the "License");
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