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qgis-rs

Working with Layers

Working with Layers

This guide covers accessing and working with vector and raster layers in QGIS projects.

Accessing Layers

let project = Project::open("map.qgs")?;


// By name
let layer = project.layer("buildings")?;


// By ID
let layer = project.layer_by_id("buildings_abc123")?;


// All layers
let layers = project.layers();
for layer in layers {
    println!("{}: {:?}", layer.name(), layer.layer_type());
}

Vector Layers

Feature Iteration

let vector = layer.as_vector()?;


for feature in vector.features() {
    println!("id={} geom={:?}", feature.id(), feature.geometry());
    println!("name={}", feature.get("name")?);
    println!("height={}", feature.get("height")?);
}

Filtering

use qgis_render::{FeatureRequest, Expression, Extent};


let request = FeatureRequest::new()
    .filter(Expression::gt("height", 50))
    .bounding_box(Extent::new(14.0, 50.0, 15.0, 51.0))
    .select(["name", "height"])
    .limit(1000);


for feature in vector.features_with(request) {
    println!("{}: {}m", feature.get("name")?, feature.get("height")?);
}

Feature Count

let total = vector.feature_count();
let filtered = vector.count_with(request)?;

Raster Layers

let raster = layer.as_raster()?;


println!("bands={}", raster.band_count());
println!("size={}x{}", raster.width(), raster.height());


let block = raster.read_block(1, extent, 256, 256)?;

Geometry Operations

let geom = feature.geometry();


// Properties
geom.area()
geom.length()
geom.centroid()
geom.bounding_box()


// Operations
geom.buffer(10.0)
geom.simplify(0.01)
geom.intersection(&other)
geom.union(&other)
geom.contains(&point)
geom.distance(&other)

Next Steps