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The library was designed to create aesthetic, animated (so far only linear) charts based on a given input. The main assumptions of the library were to create smooth transitions between subsequent data sets. For this reason, we have discovered a shortage of existing libraries related to the charts. The current package was created as part of the Rainbow.me project and for this reason it was not designed as a complete and comprehensive solution for displaying various types of charts. However, we will be now using more charts in the whole application, so we believe that the number of functionalities in the application will gradually grow.
Additionally, we are open to new Pull Requests. We want this library to become popular and complete thanks to community activity.
It’s a part of the Rainbow.me project.
The library has been released in a production-ready version. We use it inside the Rainbow.me project so it’s verified for use in production. However, it relies on React Native Reanimated 2.0 in the alpha version thus it might not work perfectly. Test it deeply before using it. Until the stable release of Reanimated, I think it’s worth not marking this library as stable. Although the library works with Reanimated without any changes, we faced a few issues related to our (quite advanced) usage of the library. Thus we made some hacks we’re not very proud of and it’s for 99% something you should not do. However, if you see some crashes, you may try one of our hacks.
There’re a few things left to make it polished regarding linear charts:
ChartProvider
and ChartPath
have been split for two components to separated responsibilities of providing data and displaying charts. I’m still not sure if it’s a good move so we can decide to move some props from one to another or connect them inside one component.springConfig
and timingConfig
)yarn add @rainbow-me/animated-charts
npm i @rainbow-me/animated-charts
yarn add react-native-haptic-feedback
npm i react-native-haptic-feedback
The library is verified on 2.0.0-alpha.6
version of reanimated.
Using TurboModules might have an impact on your current development flow and most likely you don’t want to decrease your DX. Since we’re not using reanimated in other places in the app, we made some tweaks to disable charts in development mode with compilation macros on iOS. You can find it here
Also, because we’re using libraries which currently do not support reanimated 2, we patched exports in reanimated
Furthermore, we found few differences in how the Animated
module works with and without TurboModules support, so we made a trick to fallback to the not-TM version of Animated.
Most likely, you don’t need any of those patches.
We made a generic example to show briefly what’s possible to achieve with this library. A Real-life example is available inside Rainbow!
In order to run an example clone this repo and navigate to Example
then:
yarn && cd ios && pod install && cd ..
react-native run-android
react-native run-ios
The library has been designed to provide as much flexibility as possible with the component-based API for easy integration with existing applications.
import React from 'react';
import {Dimensions, View} from 'react-native';
import {ChartDot, ChartPath, ChartPathProvider, monotoneCubicInterpolation} from '@rainbow-me/animated-charts';
export const {width: SIZE} = Dimensions.get('window');
export const data = [
{x: 1453075200, y: 1.47}, {x: 1453161600, y: 1.37},
{x: 1453248000, y: 1.53}, {x: 1453334400, y: 1.54},
{x: 1453420800, y: 1.52}, {x: 1453507200, y: 2.03},
{x: 1453593600, y: 2.10}, {x: 1453680000, y: 2.50},
{x: 1453766400, y: 2.30}, {x: 1453852800, y: 2.42},
{x: 1453939200, y: 2.55}, {x: 1454025600, y: 2.41},
{x: 1454112000, y: 2.43}, {x: 1454198400, y: 2.20},
];
const points = monotoneCubicInterpolation(data)(40);
const BasicExample = () => (
<View style={{ backgroundColor: 'black' }}>
<ChartPathProvider data={{ points, smoothingStrategy: 'bezier' }}>
<ChartPath height={SIZE / 2} stroke="yellow" width={SIZE} />
<ChartDot style={{ backgroundColor: 'blue' }} />
</ChartPathProvider>
</View>
);
The code above generates the chart below:
The whole chart’s structure has to be wrapped with ChartProvider
. It’s responsible for data managing and itself does not have a visual impact on the layout. Under the hood, it uses context API to simplify manipulation with other components. The rule is to use one data series for each wrapper.
Prop name | type | default / obligatory | description |
---|---|---|---|
softMargin |
number |
0 |
While scrubbing the chart touching edges of the screen you may want make points on the edges more accessible. With softMargin it’s possible to access points on edges doubling the speed of scrubbing beyond this margin. |
enableHaptics |
boolean |
false |
On pressing in/out on the chart it might be expected to make haptic feedback. It will happen with enableHaptics set to true and react-native-haptic-feedback installed |
data |
`{ points: [Point], nativePoints: [Point], smoothingStrategy?: ‘bezier’ | ‘simple’ | ‘complex’, smoothingFactor }` |
springConfig |
object | {damping: 15, mass: 1, stiffness: 600} |
Object defining the spring animation. This spring is used for a dot’s scale. |
timingFeedbackConfig |
object | {duration: 80} |
Object defining the timing animation. timingFeedbackConfig is used for a path’s opacity and width. |
timingAnimationConfig |
object | {duration: 300} |
Object defining the timing animation. timingAnimationConfig is used for the transition between chart’s data. |
data
is an array containing points to be displayed. A Point
is an object containing x
and y
as a number.nativeData
is an array of points that will not be drawn. However, if you used some strategy of interpolating data or simplifying you might want to present data slightly different from the real one. Then if you’d like labels to be fully correct you may want to provide real data before adjusting them.smoothingStrategy
. While presenting points path can be drawn with different approaches.
smoothingStrategy
is not provided (or set to any other value but for listed here), connects points using linear interpolation.bezier
strategy connects points with a bezier path inspired by d3 shape. It’s not parametrized by smoothingFactor
.complex
strategy uses approach explained here using cubic splines. It’s parametrized by smoothingFactor
.simple
strategy is a bit simplified complex
strategy using quadratic splines. It’s parametrized by smoothingFactor
.smoothingFactor
. Is a value from 0
to 1
defining how smooth a presentation should be. 0
means no smoothing, and it’s the default. smoothingFactor
has an impact if smoothingStrategy
is simple
or complex
.This component is used for showing the path itself.
Prop name | type | default / obligatory | description |
---|---|---|---|
disableSmoothingWhileTransitioning |
number |
false |
Although smoothing is not complex computing, it might impact performance in some low-end devices so while having a big set of data it might be worth disable smoothing while transitioning. |
height |
number |
obligatory | Height od the SVG canvas |
width |
number |
obligatory | Width od the SVG canvas |
strokeWidth |
number |
1 |
Width of the path. |
strokeWidthSelected |
number |
1 |
Width of the path selected. |
gestureEnabled |
boolean |
true |
Defines if interaction with the chart should be allowed or not |
longPressGestureHandlerProps |
object |
{maxDist: 100000, minDurationMs: 0, shouldCancelWhenOutside: false} |
Under the hood we’re using LongPressGestureHandler for handling interactions. It’s recommended to not override its props. However, it might be useful while interacting with another GH. |
selectedOpacity |
number |
0.7 |
Target opacity of the path while touching the chart. |
…rest | object |
{} |
Props applied to SVG Path. |
Component for displaying the dot for scrubbing on the chart.
Prop name | type | default | description |
---|---|---|---|
size |
number |
10 |
Size of the dot. |
…props | object |
{} |
Rest of the props applied to Reanimated.View including style |
&
ChartXLabelLabels are useful while moving finger through the chart to show the exact value in given point.
Prop name | type | default | description |
---|---|---|---|
format |
reanimated worklet | a => a |
Worklet for formatting data from the chart. It can be useful when your data is a timestamp or currency. |
…props | object |
{} |
Rest of the props applied to TextInput including style |
TODO
TODO
It’s not essential in the library, but we have decided to include a lot of helpers we are (or we were) using for displaying charts.
We have two interpolators which share the most of the API: bSplineInterpolation
and monotoneCubicInterpolation
.
import { bSplineInterpolation as interpolator } from '@rainbow-me/animated-charts';
// import { monotoneCubicInterpolation as interpolator } from '@rainbow-me/animated-charts';
const interpolatedData = interpolator(data)(80, true, false);
Code above generates 80 equidistant points from given dataset. Interpolator (monotoneCubicInterpolation
or bSplineInterpolation
) returns generator. Generator accepts 3 arguments: range
, includeExtremes
, removePointsSurroundingExtremes
.
range
is the number of points of the output.
includeExtremes
. If it’s vital to include extremes in the output, set to true. However, the data might not be fully equidistant.
removePointsSurroundingExtremes
. Makes sense only if includeExtremes
set to true
. When disabled, it might be possible that extremes look very “pointy”. To get rid of this, you can remove points surrounding extremes. E.g.
removePointsSurroundingExtremes = false
o---------o----Min--o---------o---------o---------o---------o
removePointsSurroundingExtremes = true
o--------------Min------------o---------o---------o---------o
bSplineInterpolation(data, degree = 3)
bSplineInterpolation
is inspired by victorian lib and uses B-spline interpolation of a given degree
.
monotoneCubicInterpolation(data, degree = 3)
This curve is inspired by d3 shape. "Produces a cubic spline that preserves monotonicity in y, assuming monotonicity in x, as proposed by Steffen in A simple method for monotonic interpolation in one dimension: “a smooth curve with continuous first-order derivatives that passes through any given set of data points without spurious oscillations. Local extrema can occur only at grid points where they are given by the data, but not in between two adjacent grid points.”
simplifyData(data, pickRange = 10, includeExtremes = true)
This helper takes only one point per pickRange
. Might be useful for very dense data. If it’s important, it’s possible to include extremes with the includeExtremes
flag. E.g.
pickRange = 3, includeExtremes = true
X are equidistant in this case
Y:0 1 7 2 -3 0 1 2
S----------o----------E----------X----------E----------o----------X----------o----------S
X
- points picked because index%3=0
S
– the first and the last points are always included.
E
– extremes.
Author: rainbow-me
Source Code: https://github.com/rainbow-me/react-native-animated-charts
#react-native #react #mobile-apps