[BUG] Data outside the plot area gets plotted at the edge instead of clipped

[jbncode]

When data occurs outside the plot area, it gets plotted on the edge of the plot area. I would expect it to be clipped and not visible at all. For e.g. PointSeries this can be worked around easily by removing the out-of-bounds points ahead of time, but for e.g. LineSeries it can be more problematic. The example below shows in red what plotters currently does, and the expected result in blue. Notice that even the lines within the boundary are drawn incorrectly because they connect to the shifted x=0 point.

use plotters::prelude::*;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let root = BitMapBackend::new("/tmp/test.png", (640, 480)).into_drawing_area();
    root.fill(&WHITE)?;
    let mut chart = ChartBuilder::on(&root)
        .margin(5)
        .x_label_area_size(30)
        .y_label_area_size(30)
        .build_cartesian_2d(-1f32..1f32, 0.2f32..1f32)?;

    chart.configure_mesh().draw()?;

    // Normal line plot
    chart
        .draw_series(LineSeries::new(
            (-2..=2).map(|x| x as f32 / 2.0).map(|x| (x, x * x)),
            ShapeStyle::from(RED).stroke_width(8),
        ))?;

    // Manually creating the expected result
    chart
        .draw_series(LineSeries::new(
            [(-1.0, 4.0), (-0.5, 0.25), (-f32::sqrt(0.2), 0.0)],
            ShapeStyle::from(BLUE).stroke_width(3),
        ))?;
    chart
        .draw_series(LineSeries::new(
            [(f32::sqrt(0.2), 0.0), (0.5, 0.25), (1.0, 4.0)],
            ShapeStyle::from(BLUE).stroke_width(3),
        ))?;

    root.present()?;

    Ok(())
}

[SpecificProtagonist]

The clipping happens in CoordMapper (as well as a few lines later for 3d), but I'm not sure how to fix it.

[tgross35]

Adding a note, NaN gets displayed as in infinite value and gets plotted at the edge:

NaNs should probably not be displayed at all. For contrast, Plots.jl output:

[bluenote10]

For the record, I think this issue is tracked multiple times (or at least highly related issues):

• Support clipping in DrawingBackend #622
• [BUG] Surprising plotting behavior when point is out of range. #656

[dactest]

Looks like very old bug but no one trying to fix it?