md_render_lib 0.1.0

// Copyright 2018-2020 Sebastian Wiesner <sebastian@swsnr.de>

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at

// 	http://www.apache.org/licenses/LICENSE-2.0

// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Terminal size.

/// The size of a text terminal.
#[derive(Debug, Copy, Clone)]
pub struct Size {
    /// The width of the terminal, in characters aka columns.
    pub width: usize,
    /// The height of the terminal, in lines.
    pub height: usize,
}

impl Default for Size {
    /// A good default size assumption for a terminal: 80x24.
    fn default() -> Size {
        Size {
            width: 80,
            height: 24,
        }
    }
}

impl Size {
    fn new(width: usize, height: usize) -> Size {
        Size { width, height }
    }

    /// Get terminal size from `$COLUMNS` and `$LINES`.
    pub fn from_env() -> Option<Size> {
        let columns = std::env::var("COLUMNS")
            .ok()
            .and_then(|value| value.parse::<usize>().ok());
        let rows = std::env::var("LINES")
            .ok()
            .and_then(|value| value.parse::<usize>().ok());

        match (columns, rows) {
            (Some(columns), Some(rows)) => Some(Size::new(columns, rows)),
            _ => None,
        }
    }

    /// Detect the terminal size.
    ///
    /// Get the terminal size from the underlying TTY, and fallback to
    /// `$COLUMNS` and `$LINES`.
    pub fn detect() -> Option<Size> {
        term_size::dimensions()
            .map(|(w, h)| Size::new(w, h))
            .or_else(Size::from_env)
    }
}