penpot/render-wasm/src/wasm/fills.rs

use macros::{wasm_error, ToJs};

use crate::mem;
use crate::shapes;
use crate::with_current_shape_mut;

mod gradient;
mod image;
mod solid;

const RAW_FILL_DATA_SIZE: usize = std::mem::size_of::<RawFillData>();

#[repr(C, u8, align(4))]
#[derive(Debug, PartialEq, Clone, Copy, ToJs)]
#[allow(dead_code)]
pub enum RawFillData {
    Solid(solid::RawSolidData) = 0x00,
    Linear(gradient::RawGradientData) = 0x01,
    Radial(gradient::RawGradientData) = 0x02,
    Image(image::RawImageFillData) = 0x03,
}

impl From<RawFillData> for shapes::Fill {
    fn from(fill_data: RawFillData) -> Self {
        match fill_data {
            RawFillData::Solid(solid_fill_data) => shapes::Fill::Solid(solid_fill_data.into()),
            RawFillData::Linear(linear_fill_data) => {
                shapes::Fill::LinearGradient(linear_fill_data.into())
            }
            RawFillData::Radial(radial_fill_data) => {
                shapes::Fill::RadialGradient(radial_fill_data.into())
            }
            RawFillData::Image(image_fill_data) => shapes::Fill::Image(image_fill_data.into()),
        }
    }
}

impl TryFrom<&shapes::Fill> for RawFillData {
    type Error = String;

    fn try_from(fill: &shapes::Fill) -> Result<Self, Self::Error> {
        match fill {
            shapes::Fill::Solid(shapes::SolidColor(color)) => {
                Ok(RawFillData::Solid(solid::RawSolidData {
                    color: ((color.a() as u32) << 24)
                        | ((color.r() as u32) << 16)
                        | ((color.g() as u32) << 8)
                        | (color.b() as u32),
                }))
            }
            shapes::Fill::LinearGradient(linear_gradient) => Ok(RawFillData::Linear(
                gradient::RawGradientData::from(linear_gradient),
            )),
            shapes::Fill::RadialGradient(radial_gradient) => Ok(RawFillData::Radial(
                gradient::RawGradientData::from(radial_gradient),
            )),
            shapes::Fill::Image(image_fill) => Ok(RawFillData::Image(
                image::RawImageFillData::from(image_fill),
            )),
        }
    }
}

impl From<[u8; RAW_FILL_DATA_SIZE]> for RawFillData {
    fn from(bytes: [u8; RAW_FILL_DATA_SIZE]) -> Self {
        unsafe { std::mem::transmute(bytes) }
    }
}

impl From<RawFillData> for [u8; RAW_FILL_DATA_SIZE] {
    fn from(fill_data: RawFillData) -> Self {
        unsafe { std::mem::transmute(fill_data) }
    }
}

impl TryFrom<&[u8]> for RawFillData {
    type Error = String;
    fn try_from(bytes: &[u8]) -> Result<Self, Self::Error> {
        let data: [u8; RAW_FILL_DATA_SIZE] = bytes
            .get(0..RAW_FILL_DATA_SIZE)
            .and_then(|slice| slice.try_into().ok())
            .ok_or("Invalid fill data".to_string())?;
        Ok(RawFillData::from(data))
    }
}

// FIXME: return Result
pub fn read_fills_from_bytes(buffer: &[u8], num_fills: usize) -> Vec<shapes::Fill> {
    buffer
        .chunks_exact(RAW_FILL_DATA_SIZE)
        .take(num_fills)
        .map(|bytes| {
            RawFillData::try_from(bytes)
                .expect("Invalid fill data")
                .into()
        })
        .collect()
}

#[no_mangle]
#[wasm_error]
pub extern "C" fn set_shape_fills() -> Result<()> {
    with_current_shape_mut!(state, |shape: &mut Shape| {
        let bytes = mem::bytes();
        // The first byte contains the actual number of fills
        let num_fills = bytes.first().copied().unwrap_or(0) as usize;
        // Skip the first 4 bytes (header with fill count) and parse only the actual fills
        let fills = read_fills_from_bytes(&bytes[4..], num_fills);
        shape.set_fills(fills);
        mem::free_bytes()?;
    });
    Ok(())
}

#[no_mangle]
pub extern "C" fn add_shape_fill() {
    with_current_shape_mut!(state, |shape: &mut Shape| {
        let bytes = mem::bytes();
        let raw_fill = RawFillData::try_from(&bytes[..]).expect("Invalid fill data");
        shape.add_fill(raw_fill.into());
    });
}

#[no_mangle]
pub extern "C" fn clear_shape_fills() {
    with_current_shape_mut!(state, |shape: &mut Shape| {
        shape.clear_fills();
    });
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_raw_fill_data_layout() {
        assert_eq!(
            std::mem::size_of::<RawFillData>(),
            4 + std::mem::size_of::<gradient::RawGradientData>()
        );
        assert_eq!(std::mem::align_of::<RawFillData>(), 4);
    }

    #[test]
    fn test_raw_fill_data_from_bytes_to_solid_fill() {
        let mut bytes = vec![0x00; std::mem::size_of::<RawFillData>()];
        bytes[0] = 0x00;
        bytes[4..8].copy_from_slice(&0xfffabada_u32.to_le_bytes());

        let raw_fill = RawFillData::try_from(&bytes[..]);

        assert!(raw_fill.is_ok());
        assert_eq!(
            raw_fill.unwrap(),
            RawFillData::Solid(solid::RawSolidData { color: 0xfffabada })
        );
    }

    #[test]
    fn test_gradient_fill_round_trip() {
        let gradient = shapes::Gradient::new(
            (0.0, 0.5),
            (1.0, 0.5),
            0x80,
            0.25,
            &[
                (shapes::Color::from(0xfffabada), 0.0),
                (shapes::Color::from(0xff00ff00), 1.0),
            ],
        );

        let fill = shapes::Fill::LinearGradient(gradient.clone());
        let raw_fill = RawFillData::try_from(&fill).expect("gradient must be serializable");
        let bytes = <[u8; RAW_FILL_DATA_SIZE]>::from(raw_fill);

        assert_eq!(bytes[0], 0x01);
        assert_eq!(shapes::Fill::from(RawFillData::from(bytes)), fill);
    }

    #[test]
    fn test_image_fill_round_trip() {
        let image_fill = shapes::ImageFill::new(crate::uuid::Uuid::nil(), 0x80, 300, 200, true);
        let fill = shapes::Fill::Image(image_fill);
        let raw_fill = RawFillData::try_from(&fill).expect("image fill must be serializable");
        let bytes = <[u8; RAW_FILL_DATA_SIZE]>::from(raw_fill);

        assert_eq!(bytes[0], 0x03);
        assert_eq!(shapes::Fill::from(RawFillData::from(bytes)), fill);
    }
}