# mod.rs - source
Source of the Rust file `maplibre/src/render/tile_view_pattern/mod.rs`.

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    //! Utility for generating a tile pattern which can be used for masking.

    mod pattern;

    use std::{marker::PhantomData, mem::size_of, ops::Range};

    use cgmath::Matrix4;
    pub use pattern::{TileViewPattern, DEFAULT_TILE_VIEW_PATTERN_SIZE};

    use crate::{
        coords::{WorldTileCoords, Zoom},
        render::shaders::ShaderTileMetadata,
        tcs::{resources::ResourceQuery, world::World},
    };

    pub type WgpuTileViewPattern = TileViewPattern<wgpu::Queue, wgpu::Buffer>;

    /// If not otherwise specified, raster tiles usually are 512.0 by 512.0 pixel.
    /// In order to support 256.0 x 256.0 raster tiles 256.0 must be used.
    ///
    /// Vector tiles always have a size of 512.0.
    pub const DEFAULT_TILE_SIZE: f64 = 512.0;

    /// This defines the source tile shaped from which the content for the `target` is taken.
    /// For example if the target is `(0, 0, 1)` (of [`ViewTile`]) , we might use
    /// `SourceShapes::Parent((0, 0, 0))` as source.
    /// Similarly if we have the target `(0, 0, 0)` we might use
    /// `SourceShapes::Children((0, 0, 1), (0, 1, 1), (1, 0, 1), (1, 1, 1))` as sources.
    #[derive(Debug, Clone)]
    pub enum SourceShapes {
        /// Parent tile is the source. We construct the `target` from parts of a parent.
        Parent(TileShape),
        /// Children are the source. We construct the `target` from multiple children.
        Children(Vec<TileShape>),
        /// Source and target are equal, so no need to differentiate. We render the `source` shape
        /// exactly at the `target`.
        SourceEqTarget(TileShape),
        /// No data available so nothing to render
        None,
    }

    /// Defines the `target` tile and its `source` from which data tile data comes.
    #[derive(Debug, Clone)]
    pub struct ViewTile {
        target: WorldTileCoords,
        source: SourceShapes,
    }

    impl ViewTile {
        pub fn coords(&self) -> WorldTileCoords {
            self.target
        }

        pub fn render<F>(&self, mut callback: F)
        where
            F: FnMut(&TileShape),
        {
            match &self.source {
                SourceShapes::Parent(source_shape) => callback(source_shape),
                SourceShapes::Children(source_shapes) => {
                    for shape in source_shapes {
                        callback(shape)
                    }
                }
                SourceShapes::SourceEqTarget(source_shape) => callback(source_shape),
                SourceShapes::None => {}
            }
        }
    }

    /// Defines the exact location where a specific tile on the map is rendered. It defines the shape
    /// of the tile with its location for the current zoom factor.
    #[derive(Debug, Clone)]
    pub struct TileShape {
        coords: WorldTileCoords,

        // TODO: optimization, `zoom_factor` and `transform` are no longer required if `buffer_range` is Some()
        zoom_factor: f64,
        transform: Matrix4<f64>,

        buffer_range: Option<Range<wgpu::BufferAddress>>,
    }

    impl TileShape {
        fn new(coords: WorldTileCoords, zoom: Zoom) -> Self {
            Self {
                coords,
                zoom_factor: zoom.scale_to_tile(&coords),
                transform: coords.transform_for_zoom(zoom),
                buffer_range: None,
            }
        }

        fn set_buffer_range(&mut self, index: u64) {
            const STRIDE: u64 = size_of::<ShaderTileMetadata>() as u64;
            self.buffer_range = Some(index * STRIDE..(index + 1) * STRIDE);
        }

        pub fn buffer_range(&self) -> Option<Range<wgpu::BufferAddress>> {
            self.buffer_range.clone()
        }

        pub fn coords(&self) -> WorldTileCoords {
            self.coords
        }
    }

    pub trait HasTile {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool;

        fn get_available_parent(
            &self,
            coords: WorldTileCoords,
            world: &World,
        ) -> Option<WorldTileCoords> {
            let mut current = coords;
            loop {
                if self.has_tile(current, world) {
                    return Some(current);
                } else if let Some(parent) = current.get_parent() {
                    current = parent
                } else {
                    return None;
                }
            }
        }

        fn get_available_children(
            &self,
            coords: WorldTileCoords,
            world: &World,
            search_depth: usize,
        ) -> Option<Vec<WorldTileCoords>> {
            let mut children = coords.get_children().to_vec();

            let mut output = Vec::new();

            for _ in 0..search_depth {
                let mut new_children = Vec::with_capacity(children.len() * 4);

                for child in children {
                    if self.has_tile(child, world) {
                        output.push(child);
                    } else {
                        new_children.extend(child.get_children())
                    }
                }

                children = new_children;
            }

            Some(output)
        }
    }

    impl<A: HasTile> HasTile for &A {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            A::has_tile(*self, coords, world)
        }
    }

    impl<A: HasTile> HasTile for (A,) {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            self.0.has_tile(coords, world)
        }
    }

    impl<A: HasTile, B: HasTile> HasTile for (A, B) {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            self.0.has_tile(coords, world) && self.1.has_tile(coords, world)
        }
    }

    impl<A: HasTile, B: HasTile, C: HasTile> HasTile for (A, B, C) {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            self.0.has_tile(coords, world)
                && self.1.has_tile(coords, world)
                && self.2.has_tile(coords, world)
        }
    }

    pub struct QueryHasTile<Q> {
        phantom_q: PhantomData<Q>,
    }

    impl<Q: ResourceQuery> Default for QueryHasTile<Q> {
        fn default() -> Self {
            Self {
                phantom_q: Default::default(),
            }
        }
    }

    impl<Q: ResourceQuery> HasTile for QueryHasTile<Q>
    where
        for<'a> Q::Item<'a>: HasTile,
    {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            let resources = world
                .resources
                .query::<Q>()
                .expect("resource not found for has_tile check");

            resources.has_tile(coords, world)
        }
    }

    #[derive(Default)]
    pub struct ViewTileSources {
        items: Vec<Box<dyn HasTile>>,
    }

    impl ViewTileSources {
        pub fn add<H: HasTile + 'static + Default>(&mut self) -> &mut Self {
            self.items.push(Box::<H>::default());
            self
        }

        pub fn add_resource_query<Q: ResourceQuery + 'static>(&mut self) -> &mut Self
        where
            for<'a> Q::Item<'a>: HasTile,
        {
            self.items.push(Box::new(QueryHasTile::<Q>::default()));
            self
        }

        pub fn clear(&mut self) {
            self.items.clear()
        }
    }

    impl HasTile for ViewTileSources {
        fn has_tile(&self, coords: WorldTileCoords, world: &World) -> bool {
            self.items.iter().all(|item| item.has_tile(coords, world))
        }
    }