Function draw_fps_overlay

rustcv-camera/examples/resolution_bench.rs:154–192

Draw FPS and resolution label overlay. 绘制 FPS 和分辨率标签叠加。

(buf: &mut [u32], stride: usize, fps: f64, label: &str)

/// Draw FPS and resolution label overlay.
/// 绘制 FPS 和分辨率标签叠加。
fn draw_fps_overlay(buf: &mut [u32], stride: usize, fps: f64, label: &str) {
    let text = format!("{} FPS:{:.1}", label, fps);
    let scale = 2;
    let x0 = 8;
    let y0 = 8;

    // Black background.
    // 黑色背景。
    let text_w = text.len() * 6 * scale;
    let text_h = 7 * scale;
    for dy in 0..text_h + 4 {
        for dx in 0..text_w + 8 {
            let px = x0 + dx - 2;
            let py = y0 + dy - 2;
            if py < buf.len() / stride && px < stride {
                buf[py * stride + px] = 0x00000000;
            }
        }
    }

    for (ci, ch) in text.chars().enumerate() {
        let glyph = char_glyph(ch);
        for (row, &glyph_row) in glyph.iter().enumerate() {
            for col in 0..5 {
                if glyph_row & (1 << (4 - col)) != 0 {
                    for sy in 0..scale {
                        for sx in 0..scale {
                            let px = x0 + ci * 6 * scale + col * scale + sx;
                            let py = y0 + row * scale + sy;
                            if py < buf.len() / stride && px < stride {
                                buf[py * stride + px] = 0x0000FF00; // green
                            }
                        }
                    }
                }
            }
        }
    }
}

fn char_glyph(ch: char) -> [u8; 7] {
    match ch {