Originally posted by **manuelarte** September 8, 2024
Hi, I would like to run the example of the graphs but instead of writing to a file, get the buffer so I can send the image. This is what I changed
```rust
use plotters::prelude::*;
const OUT_FILE_NAME: &str = "plotters-doc-data/sample.png";
fn main() -> Result, Box> {
let width = 1024;
let height = 768;
let mut buffer = vec![0; (width as usize) * (height as usize) * 3];
{
let root_area =
BitMapBackend::with_buffer(&mut buffer, (width , height )).into_drawing_area();
root_area.fill(&WHITE)?;
let root_area = root_area.titled("Image Title", ("sans-serif", 60))?;
let (upper, lower) = root_area.split_vertically(512);
let x_axis = (-3.4f32..3.4).step(0.1);
let mut cc = ChartBuilder::on(&upper)
.margin(5)
.set_all_label_area_size(50)
.caption("Sine and Cosine", ("sans-serif", 40))
.build_cartesian_2d(-3.4f32..3.4, -1.2f32..1.2f32)?;
cc.configure_mesh()
.x_labels(20)
.y_labels(10)
.disable_mesh()
.x_label_formatter(&|v| format!("{:.1}", v))
.y_label_formatter(&|v| format!("{:.1}", v))
.draw()?;
cc.draw_series(LineSeries::new(x_axis.values().map(|x| (x, x.sin())), &RED))?
.label("Sine")
.legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], RED));
cc.draw_series(LineSeries::new(
x_axis.values().map(|x| (x, x.cos())),
&BLUE,
))?
.label("Cosine")
.legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], BLUE));
cc.configure_series_labels().border_style(BLACK).draw()?;
/*
// It's possible to use a existing pointing element
cc.draw_series(PointSeries::<_, _, Circle<_>>::new(
(-3.0f32..2.1f32).step(1.0).values().map(|x| (x, x.sin())),
5,
Into::::into(&RGBColor(255,0,0)).filled(),
))?;*/
// Otherwise you can use a function to construct your pointing element yourself
cc.draw_series(PointSeries::of_element(
(-3.0f32..2.1f32).step(1.0).values().map(|x| (x, x.sin())),
5,
ShapeStyle::from(&RED).filled(),
&|coord, size, style| {
EmptyElement::at(coord)
+ Circle::new((0, 0), size, style)
+ Text::new(format!("{:?}", coord), (0, 15), ("sans-serif", 15))
},
))?;
let drawing_areas = lower.split_evenly((1, 2));
for (drawing_area, idx) in drawing_areas.iter().zip(1..) {
let mut cc = ChartBuilder::on(drawing_area)
.x_label_area_size(30)
.y_label_area_size(30)
.margin_right(20)
.caption(format!("y = x^{}", 1 + 2 * idx), ("sans-serif", 40))
.build_cartesian_2d(-1f32..1f32, -1f32..1f32)?;
cc.configure_mesh()
.x_labels(5)
.y_labels(3)
.max_light_lines(4)
.draw()?;
cc.draw_series(LineSeries::new(
(-1f32..1f32)
.step(0.01)
.values()
.map(|x| (x, x.powf(idx as f32 * 2.0 + 1.0))),
&BLUE,
))?;
}
// To avoid the IO failure being ignored silently, we manually call the present function
root_area.present().expect("Unable to write result to file, please make sure 'plotters-doc-data' dir exists under current dir");
}
Ok(buffer)
}
#[test]
fn entry_point() {
let buffer = main().unwrap()
let image = image::RgbImage::from_raw(input.width, input.height, buffer.clone()).unwrap();
let path = format!("{}/{}", OUT_DIRECTORY, "graphs.png".to_string());
image.save(&Path::new(path.as_str()))?;
println!("Result has been saved to {}", OUT_DIRECTORY);
}
```
But I get a weird image (with the graphs overlapping), not the graphs, any idea what I am doing wrong? I have very similar code with the histogram and it works.
Discussed in https://github.com/orgs/plotters-rs/discussions/635