一、前言

        我们要用rust 生成二维码，但是rust 自带的库里面。没有手动设置白边的参数。遂有了下文

use anyhow::{anyhow, Result};
use image::{DynamicImage, EncodableLayout, GenericImageView, ImageBuffer, Luma};
use qrcode::{EcLevel, QrCode, Version};



#[tokio::main]
pub async fn main() -> Result<()> {
    // 生成二维码
    const QUIET_ZONE_PIXELS: u32 = 8; // 留白像素
                                      // 生成二维码
    let qr_code = QrCode::new("fuckworld".as_bytes())?;


    // 创建二维码裸图 不带白边
    let qr_image = qr_code
        .render::<image::Luma<u8>>()
        .quiet_zone(false)
        .build();
    let qr_image = image::DynamicImage::ImageLuma8(qr_image);

    let with_white_w = qr_image.width() + 2 * QUIET_ZONE_PIXELS;
    let with_white_h = qr_image.height() + 2 * QUIET_ZONE_PIXELS;

    // 手动创建一个画布
    let mut padded = image::ImageBuffer::<image::Luma<u8>, Vec<u8>>::from_pixel(
        with_white_w,
        with_white_h,
        image::Luma([255u8]),
    );
    image::imageops::replace(
        &mut padded,
        &qr_image.to_luma8(),
        QUIET_ZONE_PIXELS as i64,
        QUIET_ZONE_PIXELS as i64,
    );


    let (screen_width, screen_height) = (800, 1280);
    // let (screen_width, screen_height) = (300, 1280);
    
    // 根据屏幕大小调整
    let min_len = screen_width.min(screen_height);
    let width = (min_len * 5) / 16;

    let padded_img = DynamicImage::ImageLuma8(padded);

    // 调整大小
    let qr_image = padded_img.resize_exact(
        width + 30,
        width + 30 ,
        image::imageops::FilterType::Lanczos3,
    );

    let output_path = "device_qr.png";
    qr_image
        .save(output_path)
        .map_err(|e| anyhow!("Failed to save QR image: {}", e))?;

    Ok(())
}

qrcode = "0.14.0"
image = { version = "0.25", features = ["png", "jpeg", "gif", "bmp"] }