blittle 0.6.1

A fast little blitter
Documentation 
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#[cfg(feature = "std")]
mod from;
mod l32;
mod l8;
mod la32;
mod la8;
mod rgb8;
mod rgba32;
mod rgba8;

/// Convert from one surface's pixel type to another surface's pixel type.
pub trait PixelConverter<P: Copy + Clone + Sized + Default> {
    fn pixel_to_l8(pixel: &P) -> u8;

    fn pixel_to_la8(pixel: &P) -> [u8; 2];

    fn pixel_to_l32(pixel: &P) -> f32;

    fn pixel_to_la32(pixel: &P) -> [f32; 2];

    fn pixel_to_rgb8(pixel: &P) -> [u8; 3];

    fn pixel_to_rgba8(pixel: &P) -> [u8; 4];

    fn pixel_to_rgba32(pixel: &P) -> [f32; 4];
}

pub(crate) const fn f32_to_u8(pixel: f32) -> u8 {
    (pixel * 256.) as u8
}

/// Fast approximate u8 to f32 conversion using a lookup table.
pub(crate) const fn u8_to_f32(pixel: u8) -> f32 {
    const U8_TO_F32: [f32; 256] = [
        0.0, 0.0039216, 0.0078431, 0.0117647, 0.0156863, 0.0196078, 0.0235294, 0.027451, 0.0313725,
        0.0352941, 0.0392157, 0.0431373, 0.0470588, 0.0509804, 0.054902, 0.0588235, 0.0627451,
        0.0666667, 0.0705882, 0.0745098, 0.0784314, 0.0823529, 0.0862745, 0.0901961, 0.0941176,
        0.0980392, 0.1019608, 0.1058824, 0.1098039, 0.1137255, 0.1176471, 0.1215686, 0.1254902,
        0.1294118, 0.1333333, 0.1372549, 0.1411765, 0.145098, 0.1490196, 0.1529412, 0.1568627,
        0.1607843, 0.1647059, 0.1686275, 0.172549, 0.1764706, 0.1803922, 0.1843137, 0.1882353,
        0.1921569, 0.1960784, 0.2, 0.2039216, 0.2078431, 0.2117647, 0.2156863, 0.2196078,
        0.2235294, 0.227451, 0.2313725, 0.2352941, 0.2392157, 0.2431373, 0.2470588, 0.2509804,
        0.254902, 0.2588235, 0.2627451, 0.2666667, 0.2705882, 0.2745098, 0.2784314, 0.2823529,
        0.2862745, 0.2901961, 0.2941176, 0.2980392, 0.3019608, 0.3058824, 0.3098039, 0.3137255,
        0.3176471, 0.3215686, 0.3254902, 0.3294118, 0.3333333, 0.3372549, 0.3411765, 0.345098,
        0.3490196, 0.3529412, 0.3568627, 0.3607843, 0.3647059, 0.3686275, 0.372549, 0.3764706,
        0.3803922, 0.3843137, 0.3882353, 0.3921569, 0.3960784, 0.4, 0.4039216, 0.4078431,
        0.4117647, 0.4156863, 0.4196078, 0.4235294, 0.427451, 0.4313725, 0.4352941, 0.4392157,
        0.4431373, 0.4470588, 0.4509804, 0.454902, 0.4588235, 0.4627451, 0.4666667, 0.4705882,
        0.4745098, 0.4784314, 0.4823529, 0.4862745, 0.4901961, 0.4941176, 0.4980392, 0.5019608,
        0.5058824, 0.5098039, 0.5137255, 0.5176471, 0.5215686, 0.5254902, 0.5294118, 0.5333333,
        0.5372549, 0.5411765, 0.545098, 0.5490196, 0.5529412, 0.5568627, 0.5607843, 0.5647059,
        0.5686275, 0.572549, 0.5764706, 0.5803922, 0.5843137, 0.5882353, 0.5921569, 0.5960784, 0.6,
        0.6039216, 0.6078431, 0.6117647, 0.6156863, 0.6196078, 0.6235294, 0.627451, 0.6313725,
        0.6352941, 0.6392157, 0.6431373, 0.6470588, 0.6509804, 0.654902, 0.6588235, 0.6627451,
        0.6666667, 0.6705882, 0.6745098, 0.6784314, 0.6823529, 0.6862745, 0.6901961, 0.6941176,
        0.6980392, 0.7019608, 0.7058824, 0.7098039, 0.7137255, 0.7176471, 0.7215686, 0.7254902,
        0.7294118, 0.7333333, 0.7372549, 0.7411765, 0.745098, 0.7490196, 0.7529412, 0.7568627,
        0.7607843, 0.7647059, 0.7686275, 0.772549, 0.7764706, 0.7803922, 0.7843137, 0.7882353,
        0.7921569, 0.7960784, 0.8, 0.8039216, 0.8078431, 0.8117647, 0.8156863, 0.8196078,
        0.8235294, 0.827451, 0.8313725, 0.8352941, 0.8392157, 0.8431373, 0.8470588, 0.8509804,
        0.854902, 0.8588235, 0.8627451, 0.8666667, 0.8705882, 0.8745098, 0.8784314, 0.8823529,
        0.8862745, 0.8901961, 0.8941176, 0.8980392, 0.9019608, 0.9058824, 0.9098039, 0.9137255,
        0.9176471, 0.9215686, 0.9254902, 0.9294118, 0.9333333, 0.9372549, 0.9411765, 0.945098,
        0.9490196, 0.9529412, 0.9568627, 0.9607843, 0.9647059, 0.9686275, 0.972549, 0.9764706,
        0.9803922, 0.9843137, 0.9882353, 0.9921569, 0.9960784, 1.0,
    ];

    U8_TO_F32[pixel as usize]
}

pub(crate) const fn grayscale(r: u8, g: u8, b: u8) -> f32 {
    (u8_to_f32(r) + u8_to_f32(g) + u8_to_f32(b)) / 3.
}