Add graph background color argument

[daniel-eh]

The background color for the canvas is hard coded to MaterialTheme.colors.surface

Just add an optional argument to the LineGraph composable for the graph background color, then set the bgColor variable in the composable to be equal to this argument. You can default it to the surface color if you wish and make it optional.

[thsaravana]

True, the background color of LineGraph is set to MaterialTheme.colors.surface. But it is by no means hard coded. MaterialTheme.colors.surface picks up the surface color set in the app's theme. In the sample app, you will notice that this is Grey50 mentioned in PlotTheme. You can override the color there. Or if you prefer to handle this as an isolated case, then you can always use ThemeOverlays like how it is done in LineGraph4.kt. This keeps the API clean and sticks to the principle of Theme driving the color, shape and typography.

[JesusM]

True, the background color of LineGraph is set to MaterialTheme.colors.surface. But it is by no means hard coded. MaterialTheme.colors.surface picks up the surface color set in the app's theme. In the sample app, you will notice that this is Grey50 mentioned in PlotTheme. You can override the color there. Or if you prefer to handle this as an isolated case, then you can always use ThemeOverlays like how it is done in LineGraph4.kt. This keeps the API clean and sticks to the principle of Theme driving the color, shape and typography.

Wether I agree with keeping the library with a clean API, it's also true that most of material-related compose components provide some sort of personalisation. Taking LineGraph component as an example, I guess you could keep a clean API and allow personalisation moving the bgColor to a parameter with a default value based on material theme, something like this:

@Composable
fun LineGraph(
    plot: LinePlot,
    modifier: Modifier = Modifier,
    bgColor: Color = MaterialTheme.colors.surface,
    onSelectionStart: () -> Unit = {},
    onSelectionEnd: () -> Unit = {},
    onSelection: ((Float, List<DataPoint>) -> Unit)? = null
)