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Allows for other apps to render accessible audio charts
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app Songbird Mar 13, 2020
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Songbird Charts

This is a demo app with audio charts rendering and functionality. Allows for other apps to render accessible audio charts. To see it in action, please build the demo app on your device or emulator. You can also try it out on the Yahoo Finance Android app on the Play Store, that uses this library to make audio charts available.

Charts such as stocks, sports scores and political polls are still almost impossible to use for people with visual impairment. The quick summary of thousands or more data points charts are meant for is virtually not usable for about 300 million people worldwide and for users on a voice interface. This is a first step towards changing that.

Demo video here is a demo video of audio charts in action

Table of Contents


This project embodies Verizon Media's commitment to accessibility and to going above and beyond in making our products accessible to all. What started as a conversation about the state of charts for users with visual impairment led to an initial prototype, several user stidies and finally, this solution presenting primarily visual information with music and haptics. We realize that this problem is bigger than financial graphs are also hoping to see where the open source community takes this approach and applies it to interfaces such as voice, web etc. The tones are played in Hz. This is largely a reference implementation and we'll try to review pull requests as we can. We are however not sure of the SLAs yet. Thank you!


If you've never used git before, please take a moment to familiarize yourself with what it is and how it works. To install this project, you'll need to have git installed and set up on your local dev environment.


It's as easy as adding this view to your XML file:


Initializing it with a AudioChartViewModel and a ScrubCallback:


And act on that chart object to have it do whatever you need (more details below):


Don't forget to dispose when you're done:




Plays each chart point's tone in succession


Notifies SongbirdChartView to dispose of any disposables to avoid memory leaks


val contentDescription: String

The summary content description for the chart view, not applied on it's own. You can use this in your own view wherever it fits best. The sample uses it in the toolbar.

val benchmark: Double

The value that represents the dotted benchmark line that goes horizontally across the chart

val chartDataPoints: List

The chart data points

val priceHint: Int

Price hint for the price labels renderd in the y-axis (e.g. priceHint of 2.0 will render 100.00)

val showXAxis: Boolean = true

Displays x-axis with timestamps. True by default

val xAxisLabels: List = listOf()

The XAxisLabels to be displayed if showXAxis is true

val showYAxis: Boolean = true

Displays y-axis with highestPointValue, lowestPointValue, benchmark value, and the last value in the list. True by default

@ColorRes val fillColor: Int

The color of the gradient below the chart line

@ColorRes val strokeColor: Int

The color of the chart line itself

@ColorRes val benchmarkColor: Int = R.color.chart_line

The color of the dotted benchmark line


val value: Double

The value of this point

val timestamp: Long

The timestamp of this point in milliseconds

val index: Int

The index of this point in the list

val onSwipeListener: (() -> Unit)

To be notified whenever the user swiped onto this point and is now focused on it in talkback mode


val index: Int

The index of this label in the list

val label: String

The timestamp converted into a string format to be displayed. Typically uses the AudioChartPointViewModel's timestamp when the index matches. It's up to you to format the timestamp to your needs.


onScrub(x: Float)

The chart has received a motion event at this rawX (one finger drag when talkback is off, two finger drag when talkback is on)

onRelease(x: Float)

The chart was being scrubbed and has now been released at this rawX


getItemIndexByWidth(context: Context, numItems: Int, x: Float): Int

context: Used to retrieve the screen width in pixels

numItems: the total number of chart points

x: rawX of the Touch MotionEvent

returns the closest index of AudioChartPointViewModel that maps to the rawX


Please refer to the file for information about how to get involved. We welcome issues, questions, and pull requests. Pull Requests are welcome.


Finance Mobile Android


This project is licensed under the terms of the Apache 2.0 open source license. Please refer to LICENSE for the full terms.

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