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Improve scaling code a bit #152

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Aug 8, 2023
Merged

Improve scaling code a bit #152

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8 changes: 5 additions & 3 deletions geozero/src/mvt/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -38,8 +38,9 @@ pub(crate) mod conversion {
right: f64,
top: f64,
) -> Result<tile::Feature>;
/// Convert to MVT geometry with geometries in tile coordinate space.
fn to_mvt_raw(&self) -> Result<tile::Feature>;

/// Convert to MVT geometry with geometries in unmodified tile coordinate space.
fn to_mvt_unscaled(&self) -> Result<tile::Feature>;
}

impl<T: GeozeroGeometry> ToMvt for T {
Expand All @@ -55,7 +56,8 @@ pub(crate) mod conversion {
self.process_geom(&mut mvt)?;
Ok(mvt.feature)
}
fn to_mvt_raw(&self) -> Result<tile::Feature> {

fn to_mvt_unscaled(&self) -> Result<tile::Feature> {
let mut mvt = MvtWriter::default();
self.process_geom(&mut mvt)?;
Ok(mvt.feature)
Expand Down
70 changes: 28 additions & 42 deletions geozero/src/mvt/mvt_writer.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,37 +9,41 @@ use crate::GeomProcessor;
use super::mvt_error::MvtError;

/// Generator for MVT geometry type.
#[derive(Default, Debug)]
pub struct MvtWriter {
pub(crate) feature: tile::Feature,
tile_size: Option<f64>,
// Tile extent
// Extent, 0 for unscaled
extent: i32,
// Scale geometry to bounds
left: f64,
bottom: f64,
right: f64,
top: f64,
x_multiplier: f64,
y_multiplier: f64,
// Writer state
last_x: i32,
last_y: i32,
line_state: LineState,
is_multiline: bool,
}

#[derive(PartialEq)]
#[derive(Default, Debug, PartialEq)]
enum LineState {
#[default]
None,
// Issue LineTo command after first point
Line(usize),
Ring(usize),
}

impl MvtWriter {
pub fn new(tile_size: u32, left: f64, bottom: f64, right: f64, top: f64) -> MvtWriter {
pub fn new(extent: u32, left: f64, bottom: f64, right: f64, top: f64) -> MvtWriter {
assert_ne!(extent, 0);
MvtWriter {
tile_size: Some(tile_size as f64),
extent: extent as i32,
left,
bottom,
right,
top,
x_multiplier: (extent as f64) / (right - left),
y_multiplier: (extent as f64) / (top - bottom),
..Default::default()
}
}
Expand All @@ -58,23 +62,6 @@ impl MvtWriter {
}
}

impl Default for MvtWriter {
fn default() -> Self {
Self {
feature: tile::Feature::default(),
tile_size: None,
left: 0.0,
bottom: 0.0,
right: 0.0,
top: 0.0,
last_x: 0,
last_y: 0,
line_state: LineState::None,
is_multiline: false,
}
}
}

impl GeomProcessor for MvtWriter {
fn xy(&mut self, x_coord: f64, y_coord: f64, idx: usize) -> Result<()> {
// Omit last coord of ring (emit ClosePath instead)
Expand All @@ -85,17 +72,16 @@ impl GeomProcessor for MvtWriter {
};

if !last_ring_coord {
let x: i32;
let mut y: i32;
if let Some(tile_size) = self.tile_size {
x = ((x_coord - self.left) * tile_size / (self.right - self.left)) as i32;
y = ((y_coord - self.bottom) * tile_size / (self.top - self.bottom)) as i32;
y = (tile_size as i32).saturating_sub(y); // reverse_y only?
let (x, y) = if self.extent != 0 {
// scale to tile coordinate space
let x = ((x_coord - self.left) * self.x_multiplier) as i32;
let y = ((y_coord - self.bottom) * self.y_multiplier) as i32;
// Y is stored as reversed
(x, self.extent.saturating_sub(y))
} else {
// unscaled
x = x_coord as i32;
y = y_coord as i32;
}
(x_coord as i32, y_coord as i32)
};
self.feature
.geometry
.push(ParameterInteger::from(x.saturating_sub(self.last_x)));
Expand Down Expand Up @@ -415,21 +401,21 @@ mod test {
#[test]
fn point_geom() {
let geojson = GeoJson(r#"{"type": "Point", "coordinates": [25, 17]}"#);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(mvt.geometry, [9, 50, 34]);
}

#[test]
fn multipoint_geom() {
let geojson = GeoJson(r#"{"type": "MultiPoint", "coordinates": [[5, 7], [3, 2]]}"#);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(mvt.geometry, [17, 10, 14, 3, 9]);
}

#[test]
fn line_geom() {
let geojson = GeoJson(r#"{"type": "LineString", "coordinates": [[2,2], [2,10], [10,10]]}"#);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(mvt.geometry, [9, 4, 4, 18, 0, 16, 16, 0]);
}

Expand All @@ -438,7 +424,7 @@ mod test {
let geojson = GeoJson(
r#"{"type": "MultiLineString", "coordinates": [[[2,2], [2,10], [10,10]],[[1,1],[3,5]]]}"#,
);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(
mvt.geometry,
[9, 4, 4, 18, 0, 16, 16, 0, 9, 17, 17, 10, 4, 8]
Expand All @@ -449,7 +435,7 @@ mod test {
fn polygon_geom() {
let geojson =
GeoJson(r#"{"type": "Polygon", "coordinates": [[[3, 6], [8, 12], [20, 34], [3, 6]]]}"#);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(mvt.geometry, [9, 6, 12, 18, 10, 12, 24, 44, 15]);
}

Expand All @@ -472,7 +458,7 @@ mod test {
]
}"#;
let geojson = GeoJson(geojson);
let mvt = geojson.to_mvt_raw().unwrap();
let mvt = geojson.to_mvt_unscaled().unwrap();
assert_eq!(
mvt.geometry,
[
Expand All @@ -485,7 +471,7 @@ mod test {
#[cfg(feature = "with-geo")]
fn geo_screen_coords_to_mvt() -> Result<()> {
let geo: geo_types::Geometry<f64> = geo_types::Point::new(25.0, 17.0).into();
let mvt = geo.to_mvt_raw()?;
let mvt = geo.to_mvt_unscaled()?;
assert_eq!(mvt.geometry, [9, 50, 34]);
Ok(())
}
Expand Down
2 changes: 1 addition & 1 deletion geozero/tests/mvt.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,7 +11,7 @@ use std::sync::Mutex;
#[test]
fn geo_screen_coords_to_mvt() {
let geo: geo_types::Geometry<f64> = geo_types::Point::new(25.0, 17.0).into();
let mvt = geo.to_mvt_raw().unwrap();
let mvt = geo.to_mvt_unscaled().unwrap();
assert_eq!(mvt.geometry, [9, 50, 34]);
}

Expand Down