tessera-components 0.0.0

Basic components for tessera-ui, using md3e design principles.
Documentation 
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use std::{
    hash::{Hash, Hasher},
    sync::Arc,
};

use tessera_ui::{Color, DrawCommand};

/// Vertex attributes for tessellated vector geometry.
#[repr(C)]
#[derive(Clone, Copy, Debug, bytemuck::Pod, bytemuck::Zeroable)]
pub struct ImageVectorVertex {
    /// 2D position in normalized SVG viewport coordinates.
    pub position: [f32; 2],
    /// Premultiplied color for the vertex.
    pub color: Color,
}

/// Tessellated vector data ready for rendering.
#[derive(Debug, Clone)]
pub struct ImageVectorData {
    /// Width of the original SVG viewport.
    pub viewport_width: f32,
    /// Height of the original SVG viewport.
    pub viewport_height: f32,
    /// Vertex data (positions and colors).
    pub vertices: Arc<Vec<ImageVectorVertex>>,
    /// Triangle indices referencing `vertices`.
    pub indices: Arc<Vec<u32>>,
}

impl ImageVectorData {
    /// Creates vector data from raw vertices and indices.
    pub fn new(
        viewport_width: f32,
        viewport_height: f32,
        vertices: Arc<Vec<ImageVectorVertex>>,
        indices: Arc<Vec<u32>>,
    ) -> Self {
        Self {
            viewport_width,
            viewport_height,
            vertices,
            indices,
        }
    }
}

impl PartialEq for ImageVectorData {
    fn eq(&self, other: &Self) -> bool {
        self.viewport_width.to_bits() == other.viewport_width.to_bits()
            && self.viewport_height.to_bits() == other.viewport_height.to_bits()
            && Arc::ptr_eq(&self.vertices, &other.vertices)
            && Arc::ptr_eq(&self.indices, &other.indices)
    }
}

impl Eq for ImageVectorData {}

impl Hash for ImageVectorData {
    fn hash<H: Hasher>(&self, state: &mut H) {
        state.write_u32(self.viewport_width.to_bits());
        state.write_u32(self.viewport_height.to_bits());
        state.write_usize(Arc::as_ptr(&self.vertices) as usize);
        state.write_usize(Arc::as_ptr(&self.indices) as usize);
    }
}

/// Defines how the tint color is combined with the vector image.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default)]
pub enum VectorTintMode {
    /// Multiplies the tint color with the image color.
    /// This is the default behavior.
    /// Result = Image * Tint
    #[default]
    Multiply,
    /// Ignores the image's color channels, using only its alpha to mask the
    /// tint color. Result = Tint * Image.Alpha
    Solid,
}

/// Draw command for vector images.
#[derive(Debug, Clone, PartialEq)]
pub struct ImageVectorCommand {
    /// Shared vector mesh data.
    pub data: Arc<ImageVectorData>,
    /// Tint color multiplied with the mesh.
    pub tint: Color,
    /// How to apply the tint.
    pub tint_mode: VectorTintMode,
    /// Rotation in degrees.
    pub rotation: f32,
}

impl DrawCommand for ImageVectorCommand {
    fn apply_opacity(&mut self, opacity: f32) {
        self.tint = self.tint.with_alpha(self.tint.a * opacity.clamp(0.0, 1.0));
    }
}