Question

使用image包，我可以创建一个ImageBuffer然后放一个像素并保存它：

let mut img = ImageBuffer::new(100, 100);
img.put_pixel(50, 50);

let ref mut fout = File::create(&Path::new("test.png")).unwrap();
let _ = ImageRgb8(img).save(fout, PNG);

我想设置背景颜色（默认为黑色）。我可以迭代像素并在每个像素上放置相同颜色的像素，但我不确定它是最好的方式（看起来有点过分）。我想我错过了什么。

Answer 1

如果您继续阅读文档，则会找到ImageBuffer::from_pixel：

fn from_pixel(width: u32,
              height: u32,
              pixel: P)
              -> ImageBuffer<P, Vec<P::Subpixel>>

通过复制像素构建新的ImageBuffer

Answer 2

您可以使用from_pixel和from_fn方法构建具有自定义背景的缓冲区。

这是我的一个项目中的一个例子，我在背景上投下阴影。

enum Grace {
    /// How much "grace" time have passed, in percents.
    Good (f32),
    Picked,
    Delayed,
    Closed,
    /// Closed by GM without player making a choice.
    Miss}

impl Grace {
    fn from_time (opened: i64, now: i64) -> Grace {
        let delta = now - (opened + 7200);  // First two hours are "free".
        if delta <= 0 {return Grace::Good (0.0)}
        let percent = (delta * 100) as f32 / time::Duration::hours (24) .num_seconds() as f32;
        if percent <= 100.0 {Grace::Good (percent)} else {Grace::Delayed}}}

let mut ib = ImageBuffer::from_fn (600, 24, |x, y| Rgba (match grace {
    Grace::Picked | Grace::Closed => [200, 200, 255, (255 * y / 24) as u8],
    Grace::Good (pc) => [pc as u8, (70 + (130 * x / 600)) as u8, 0, (255 * y / 24) as u8],
    Grace::Delayed => [(70 + (130 * x / 600)) as u8, (70 + (130 * x / 600)) as u8, 0, (255 * y / 24) as u8],
    Grace::Miss => [(70 + (130 * x / 600)) as u8, 0, 0, (255 * y / 24) as u8]}));

有没有办法在`image :: ImageBuffer`上设置背景颜色？

2 个答案: