Dispaly a sine wave graph to the screen

// A program to plot a sine wave using the plotters library 
// and display it in a window using minifb
// by Rich from https://maths.earth/

use plotters::prelude::*;
use minifb::{Key, Window, WindowOptions};
use std::f64::consts::PI;

fn main() {
    // Define the range and step size for the sine wave
    let x_range = (0..1000).map(|i| i as f64 * 0.01).collect::>();
    let y_values: Vec = x_range.iter().map(|&x| (x * 2.0 * PI).sin()).collect();

    // Plot the sine wave to a PNG file
    plot_sine_wave(&x_range, &y_values).expect("Failed to plot sine wave");

    // Display the sine wave in a window
    display_graph_in_window().expect("Failed to display graph in window");
}

// Function to plot the sine wave using the plotters library
fn plot_sine_wave(x_values: &Vec, y_values: &Vec) -> Result<(), Box> {
    // Create a drawing area for the graph
    let root_area = BitMapBackend::new("sine_wave.png", (640, 480)).into_drawing_area();
    root_area.fill(&WHITE)?; // Fill the background with white color

    // Build the chart with specified configurations
    let mut chart = ChartBuilder::on(&root_area)
        .caption("Sine Wave", ("sans-serif", 50).into_font()) // Title of the chart
        .margin(10) // Margin around the chart
        .x_label_area_size(30) // Space allocated for x-axis labels
        .y_label_area_size(30) // Space allocated for y-axis labels
        .build_cartesian_2d(
            x_values.first().cloned().unwrap()..x_values.last().cloned().unwrap(), // X-axis range
            -1.0..1.0, // Y-axis range
        )?;

    chart.configure_mesh().draw()?; // Draw the mesh (grid lines and labels)

    // Plot the sine wave as a line series
    chart.draw_series(LineSeries::new(
        x_values.iter().zip(y_values.iter()).map(|(&x, &y)| (x, y)), // Data points
        &BLUE, // Line color
    ))?
    .label("Sine Wave") // Label for the legend
    .legend(|(x, y)| PathElement::new(vec![(x, y), (x + 20, y)], &BLUE)); // Legend styling

    // Configure and draw the series labels (legend box)
    chart.configure_series_labels()
        .background_style(&WHITE.mix(0.8)) // Background style of the legend box
        .border_style(&BLACK) // Border style of the legend box
        .draw()?;

    root_area.present()?; // Save the chart to the PNG file
    println!("Sine wave has been saved to sine_wave.png");

    Ok(())
}

// Function to display the graph in a window using minifb
fn display_graph_in_window() -> Result<(), Box> {
    // Load the PNG file and convert it to an RGBA buffer
    let img = image::open("sine_wave.png")?.to_rgba8(); // Open the image file
    let (width, height) = img.dimensions(); // Get the dimensions of the image
    let buffer: Vec = img
        .pixels()
        .map(|p| {
            let [r, g, b, _] = p.0; // Extract the red, green, and blue components
            ((r as u32) << 16) | ((g as u32) << 8) | (b as u32) // Combine them into a single u32 value
        })
        .collect();

    // Create a window to display the image
    let mut window = Window::new(
        "Sine Wave - ESC to exit", // Window title
        width as usize, // Window width
        height as usize, // Window height
        WindowOptions::default(), // Default window options
    )?;

    // Update the window with the buffer content and check for the ESC key press
    while window.is_open() && !window.is_key_down(Key::Escape) {
		// Update the window with the image buffer
        window.update_with_buffer(&buffer, width as usize, height as usize)?; 
    }

    Ok(())
}                

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[package]
name = "graph"
version = "0.1.0"
edition = "2021"

[dependencies]
plotters = "0.3.1"
plotters-backend = "0.3.1"
minifb = "0.15.0"
image = "0.23.14"

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