New Layer#getFeatures method with fast hit detection for VectorLayer

This commit is contained in:
Andreas Hocevar
2019-09-26 19:55:14 +02:00
parent 057cc92716
commit 315695eeb8
13 changed files with 429 additions and 31 deletions

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@@ -0,0 +1,15 @@
---
layout: example.html
title: Vector Layer Hit Detection
shortdesc: Example of hit detection on a countries vector layer with country information.
docs: >
The countries are loaded from a GeoJSON file. Information about countries is
on hover and click is retrieved using the layer's `getFeatures()` method. For
vector layers, this function resolves with an array of only the topmost
feature. It uses a very efficient hit detection algorithm, at the cost of
accuracy. For pixel exact hit detection, when performance is not a concern,
use the map's `getFeaturesAtPixel()` or `forEachFeatureAtPixel()` methods.
tags: "vector, geojson, click, hover, hit detection"
---
<div id="map" class="map"></div>
<div id="info">&nbsp;</div>

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@@ -0,0 +1,113 @@
import Map from '../src/ol/Map.js';
import View from '../src/ol/View.js';
import GeoJSON from '../src/ol/format/GeoJSON.js';
import VectorLayer from '../src/ol/layer/Vector.js';
import VectorSource from '../src/ol/source/Vector.js';
import {Fill, Stroke, Style, Text} from '../src/ol/style.js';
const style = new Style({
fill: new Fill({
color: 'rgba(255, 255, 255, 0.6)'
}),
stroke: new Stroke({
color: '#319FD3',
width: 1
}),
text: new Text({
font: '12px Calibri,sans-serif',
fill: new Fill({
color: '#000'
}),
stroke: new Stroke({
color: '#fff',
width: 3
})
})
});
const vectorLayer = new VectorLayer({
source: new VectorSource({
url: 'data/geojson/countries.geojson',
format: new GeoJSON()
}),
style: function(feature) {
style.getText().setText(feature.get('name'));
return style;
}
});
const map = new Map({
layers: [vectorLayer],
target: 'map',
view: new View({
center: [0, 0],
zoom: 1
})
});
const highlightStyle = new Style({
stroke: new Stroke({
color: '#f00',
width: 1
}),
fill: new Fill({
color: 'rgba(255,0,0,0.1)'
}),
text: new Text({
font: '12px Calibri,sans-serif',
fill: new Fill({
color: '#000'
}),
stroke: new Stroke({
color: '#f00',
width: 3
})
})
});
const featureOverlay = new VectorLayer({
source: new VectorSource(),
map: map,
style: function(feature) {
highlightStyle.getText().setText(feature.get('name'));
return highlightStyle;
}
});
let highlight;
const displayFeatureInfo = function(pixel) {
vectorLayer.getFeatures(pixel).then(function(features) {
const feature = features.length ? features[0] : undefined;
const info = document.getElementById('info');
if (features.length) {
info.innerHTML = feature.getId() + ': ' + feature.get('name');
} else {
info.innerHTML = '&nbsp;';
}
if (feature !== highlight) {
if (highlight) {
featureOverlay.getSource().removeFeature(highlight);
}
if (feature) {
featureOverlay.getSource().addFeature(feature);
}
highlight = feature;
}
});
};
map.on('pointermove', function(evt) {
if (evt.dragging) {
return;
}
const pixel = map.getEventPixel(evt.originalEvent);
displayFeatureInfo(pixel);
});
map.on('click', function(evt) {
displayFeatureInfo(evt.pixel);
});

View File

@@ -135,6 +135,24 @@ class BaseVectorLayer extends Layer {
return this.declutter_;
}
/**
* Get the topmost feature that intersects the given pixel on the viewport. Returns a promise
* that resolves with an array of features. The array will either contain the topmost feature
* when a hit was detected, or it will be empty.
*
* The hit detection algorithm used for this method is optimized for performance, but is less
* accurate than the one used in {@link import("../PluggableMap.js").default#getFeaturesAtPixel}: Text
* is not considered, and icons are only represented by their bounding box instead of the exact
* image.
*
* @param {import("../pixel.js").Pixel} pixel Pixel.
* @return {Promise<Array<import("../Feature").default>>} Promise that resolves with an array of features.
* @api
*/
getFeatures(pixel) {
return super.getFeatures(pixel);
}
/**
* @return {number|undefined} Render buffer.
*/

View File

@@ -192,6 +192,15 @@ class Layer extends BaseLayer {
this.changed();
}
/**
* @param {import("../pixel").Pixel} pixel Pixel.
* @return {Promise<Array<import("../Feature").default>>} Promise that resolves with
* an array of features.
*/
getFeatures(pixel) {
return this.renderer_.getFeatures(pixel);
}
/**
* In charge to manage the rendering of the layer. One layer type is
* bounded with one layer renderer.

View File

@@ -438,6 +438,13 @@ class CanvasImmediateRenderer extends VectorContext {
this.setTextStyle(style.getText());
}
/**
* @param {import("../../transform.js").Transform} transform Transform.
*/
setTransform(transform) {
this.transform_ = transform;
}
/**
* Render a geometry into the canvas. Call
* {@link module:ol/render/canvas/Immediate#setStyle} first to set the rendering style.

View File

@@ -30,6 +30,16 @@ class LayerRenderer extends Observable {
}
/**
* Asynchronous layer level hit detection.
* @param {import("../pixel.js").Pixel} pixel Pixel.
* @return {Promise<Array<import("../Feature").default>>} Promise that resolves with
* an array of features.
*/
getFeatures(pixel) {
return abstract();
}
/**
* Determine whether render should be called.
* @abstract

View File

@@ -213,23 +213,24 @@ class CanvasLayerRenderer extends LayerRenderer {
/**
* Creates a transform for rendering to an element that will be rotated after rendering.
* @param {import("../../PluggableMap.js").FrameState} frameState Frame state.
* @param {import("../../coordinate.js").Coordinate} center Center.
* @param {number} resolution Resolution.
* @param {number} rotation Rotation.
* @param {number} pixelRatio Pixel ratio.
* @param {number} width Width of the rendered element (in pixels).
* @param {number} height Height of the rendered element (in pixels).
* @param {number} offsetX Offset on the x-axis in view coordinates.
* @protected
* @return {!import("../../transform.js").Transform} Transform.
*/
getRenderTransform(frameState, width, height, offsetX) {
const viewState = frameState.viewState;
const pixelRatio = frameState.pixelRatio;
getRenderTransform(center, resolution, rotation, pixelRatio, width, height, offsetX) {
const dx1 = width / 2;
const dy1 = height / 2;
const sx = pixelRatio / viewState.resolution;
const sx = pixelRatio / resolution;
const sy = -sx;
const dx2 = -viewState.center[0] + offsetX;
const dy2 = -viewState.center[1];
return composeTransform(this.tempTransform_, dx1, dy1, sx, sy, -viewState.rotation, dx2, dy2);
const dx2 = -center[0] + offsetX;
const dy2 = -center[1];
return composeTransform(this.tempTransform_, dx1, dy1, sx, sy, -rotation, dx2, dy2);
}
/**

View File

@@ -9,7 +9,13 @@ import CanvasBuilderGroup from '../../render/canvas/BuilderGroup.js';
import ExecutorGroup, {replayDeclutter} from '../../render/canvas/ExecutorGroup.js';
import CanvasLayerRenderer from './Layer.js';
import {defaultOrder as defaultRenderOrder, getTolerance as getRenderTolerance, getSquaredTolerance as getSquaredRenderTolerance, renderFeature} from '../vector.js';
import {toString as transformToString, makeScale, makeInverse} from '../../transform.js';
import {toString as transformToString, makeScale, makeInverse, apply} from '../../transform.js';
import {createCanvasContext2D} from '../../dom.js';
import CanvasImmediateRenderer from '../../render/canvas/Immediate.js';
import {Icon} from '../../style.js';
import IconAnchorUnits from '../../style/IconAnchorUnits.js';
import GeometryType from '../../geom/GeometryType.js';
import {numberSafeCompareFunction} from '../../array.js';
/**
* @classdesc
@@ -28,6 +34,10 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
/** @private */
this.boundHandleStyleImageChange_ = this.handleStyleImageChange_.bind(this);
/**
* @type {boolean}
*/
this.animatingOrInteracting_;
/**
* @private
@@ -35,6 +45,16 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
*/
this.dirty_ = false;
/**
* @type {ImageData}
*/
this.hitDetectionImageData_ = null;
/**
* @type {Array<import("../../Feature.js").default>}
*/
this.renderedFeatures_ = null;
/**
* @private
* @type {number}
@@ -53,6 +73,24 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
*/
this.renderedExtent_ = createEmpty();
/**
* @private
* @type {number}
*/
this.renderedRotation_;
/**
* @private
* @type {import("../../coordinate").Coordinate}
*/
this.renderedCenter_ = null;
/**
* @private
* @type {import("../../proj/Projection").default}
*/
this.renderedProjection_ = null;
/**
* @private
* @type {function(import("../../Feature.js").default, import("../../Feature.js").default): number|null}
@@ -124,6 +162,8 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
const extent = frameState.extent;
const viewState = frameState.viewState;
const center = viewState.center;
const resolution = viewState.resolution;
const projection = viewState.projection;
const rotation = viewState.rotation;
const projectionExtent = projection.getExtent();
@@ -143,7 +183,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
const viewHints = frameState.viewHints;
const snapToPixel = !(viewHints[ViewHint.ANIMATING] || viewHints[ViewHint.INTERACTING]);
const transform = this.getRenderTransform(frameState, width, height, 0);
const transform = this.getRenderTransform(center, resolution, rotation, pixelRatio, width, height, 0);
const declutterReplays = this.getLayer().getDeclutter() ? {} : null;
replayGroup.execute(context, transform, rotation, snapToPixel, undefined, declutterReplays);
@@ -155,7 +195,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
while (startX < projectionExtent[0]) {
--world;
offsetX = worldWidth * world;
const transform = this.getRenderTransform(frameState, width, height, offsetX);
const transform = this.getRenderTransform(center, resolution, rotation, pixelRatio, width, height, offsetX);
replayGroup.execute(context, transform, rotation, snapToPixel, undefined, declutterReplays);
startX += worldWidth;
}
@@ -164,7 +204,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
while (startX > projectionExtent[2]) {
++world;
offsetX = worldWidth * world;
const transform = this.getRenderTransform(frameState, width, height, offsetX);
const transform = this.getRenderTransform(center, resolution, rotation, pixelRatio, width, height, offsetX);
replayGroup.execute(context, transform, rotation, snapToPixel, undefined, declutterReplays);
startX -= worldWidth;
}
@@ -190,6 +230,175 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
return this.container;
}
/**
* @private
*/
createHitDetectionImageData_() {
const features = this.renderedFeatures_;
const layer = this.getLayer();
const resolution = this.renderedResolution_;
const size = [this.context.canvas.width, this.context.canvas.height];
apply(this.pixelTransform, size);
const width = size[0] / 2;
const height = size[1] / 2;
const context = createCanvasContext2D(width, height);
context.imageSmoothingEnabled = false;
const canvas = context.canvas;
const styleFunction = layer.getStyleFunction();
const center = this.renderedCenter_;
const rotation = this.renderedRotation_;
const projection = this.renderedProjection_;
const extent = this.renderedExtent_;
const transforms = [];
transforms.push(this.getRenderTransform(center, resolution, rotation, 0.5, width, height, 0).slice());
const source = layer.getSource();
const projectionExtent = projection.getExtent();
if (source.getWrapX() && projection.canWrapX() && !containsExtent(projectionExtent, extent)) {
let startX = extent[0];
const worldWidth = getWidth(projectionExtent);
let world = 0;
let offsetX;
while (startX < projectionExtent[0]) {
--world;
offsetX = worldWidth * world;
transforms.push(this.getRenderTransform(center, resolution, rotation, 0.5, width, height, offsetX).slice());
startX += worldWidth;
}
world = 0;
startX = extent[2];
while (startX > projectionExtent[2]) {
++world;
offsetX = worldWidth * world;
transforms.push(this.getRenderTransform(center, resolution, rotation, 0.5, width, height, offsetX).slice());
startX -= worldWidth;
}
}
const renderer = new CanvasImmediateRenderer(context, 0.5, extent, null, rotation);
const featureCount = features.length;
// Stretch hit detection index to use the whole available color range
const indexFactor = Math.ceil((256 * 256 * 256) / featureCount);
const featuresByZIndex = {};
for (let i = 0; i < featureCount; ++i) {
const feature = features[i];
const featureStyleFunction = feature.getStyleFunction() || styleFunction;
let styles = featureStyleFunction(feature, resolution);
if (!Array.isArray(styles)) {
styles = [styles];
}
const index = i * indexFactor;
const color = '#' + ('000000' + index.toString(16)).slice(-6);
for (let j = 0, jj = styles.length; j < jj; ++j) {
const originalStyle = styles[j];
const style = originalStyle.clone();
const fill = style.getFill();
if (fill) {
fill.setColor(color);
}
const stroke = style.getStroke();
if (stroke) {
stroke.setColor(color);
}
style.setText(undefined);
const image = originalStyle.getImage();
if (image) {
const imgSize = image.getImageSize();
const imgContext = createCanvasContext2D(imgSize[0], imgSize[1]);
imgContext.fillStyle = color;
const img = imgContext.canvas;
imgContext.fillRect(0, 0, img.width, img.height);
const width = imgSize ? imgSize[0] : img.width;
const height = imgSize ? imgSize[1] : img.height;
const iconContext = createCanvasContext2D(width, height);
iconContext.drawImage(img, 0, 0);
style.setImage(new Icon({
img: img,
imgSize: imgSize,
anchor: image.getAnchor(),
anchorXUnits: IconAnchorUnits.PIXELS,
anchorYUnits: IconAnchorUnits.PIXELS,
offset: image.getOrigin(),
size: image.getSize(),
opacity: image.getOpacity(),
scale: image.getScale(),
rotation: image.getRotation(),
rotateWithView: image.getRotateWithView()
}));
}
const zIndex = Number(style.getZIndex());
let byGeometryType = featuresByZIndex[zIndex];
if (!byGeometryType) {
byGeometryType = featuresByZIndex[zIndex] = {};
byGeometryType[GeometryType.POLYGON] = [];
byGeometryType[GeometryType.CIRCLE] = [];
byGeometryType[GeometryType.LINE_STRING] = [];
byGeometryType[GeometryType.POINT] = [];
}
const geometry = style.getGeometryFunction()(feature);
if (geometry && intersectsExtent(extent, geometry.getExtent())) {
byGeometryType[geometry.getType().replace('Multi', '')].push(geometry, style);
}
}
}
const zIndexKeys = Object.keys(featuresByZIndex).map(Number).sort(numberSafeCompareFunction);
for (let i = 0, ii = zIndexKeys.length; i < ii; ++i) {
const byGeometryType = featuresByZIndex[zIndexKeys[i]];
for (const type in byGeometryType) {
const geomAndStyle = byGeometryType[type];
for (let j = 0, jj = geomAndStyle.length; j < jj; j += 2) {
renderer.setStyle(geomAndStyle[j + 1]);
for (let k = 0, kk = transforms.length; k < kk; ++k) {
renderer.setTransform(transforms[k]);
renderer.drawGeometry(geomAndStyle[j]);
}
}
}
}
this.hitDetectionImageData_ = context.getImageData(0, 0, canvas.width, canvas.height);
}
/**
* @param {import("../../pixel").Pixel} pixel Pixel.
* @return {Array<import("../../Feature").default>} features Features.
*/
hitDetect_(pixel) {
const renderPixel = apply(this.pixelTransform, pixel.slice());
const features = this.renderedFeatures_;
const imageData = this.hitDetectionImageData_;
const resultFeatures = [];
if (imageData) {
const index = (Math.round(renderPixel[0]) + Math.round(renderPixel[1]) * imageData.width) * 4;
const r = imageData.data[index];
const g = imageData.data[index + 1];
const b = imageData.data[index + 2];
const a = imageData.data[index + 3];
if (a === 255) {
const i = b + (256 * (g + (256 * r)));
const indexFactor = Math.ceil((256 * 256 * 256) / features.length);
if (i % indexFactor === 0) {
resultFeatures.push(features[i / indexFactor]);
}
}
}
return resultFeatures;
}
/**
* @inheritDoc
*/
getFeatures(pixel) {
return new Promise(function(resolve, reject) {
if (!this.hitDetectionImageData_ && !this.animatingOrInteracting_) {
requestAnimationFrame(function() {
this.createHitDetectionImageData_();
resolve(this.hitDetect_(pixel));
}.bind(this));
} else {
resolve(this.hitDetect_(pixel));
}
}.bind(this));
}
/**
* @inheritDoc
*/
@@ -253,8 +462,10 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
if (!this.dirty_ && (!updateWhileAnimating && animating) ||
(!updateWhileInteracting && interacting)) {
this.animatingOrInteracting_ = true;
return true;
}
this.animatingOrInteracting_ = false;
const frameStateExtent = frameState.extent;
const viewState = frameState.viewState;
@@ -269,6 +480,7 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
vectorLayerRenderOrder = defaultRenderOrder;
}
const center = viewState.center.slice();
const extent = buffer(frameStateExtent,
vectorLayerRenderBuffer * resolution);
const projectionExtent = viewState.projection.getExtent();
@@ -284,6 +496,8 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
const gutter = Math.max(getWidth(extent) / 2, worldWidth);
extent[0] = projectionExtent[0] - gutter;
extent[2] = projectionExtent[2] + gutter;
const worldsAway = Math.floor((center[0] - projectionExtent[0]) / worldWidth);
center[0] -= (worldsAway * worldWidth);
}
if (!this.dirty_ &&
@@ -334,23 +548,15 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
}.bind(this);
const userExtent = toUserExtent(extent, projection);
/** @type {Array<import("../../Feature.js").default>} */
const features = vectorSource.getFeaturesInExtent(userExtent);
if (vectorLayerRenderOrder) {
/** @type {Array<import("../../Feature.js").default>} */
const features = [];
vectorSource.forEachFeatureInExtent(userExtent,
/**
* @param {import("../../Feature.js").default} feature Feature.
*/
function(feature) {
features.push(feature);
});
features.sort(vectorLayerRenderOrder);
for (let i = 0, ii = features.length; i < ii; ++i) {
render(features[i]);
}
} else {
vectorSource.forEachFeatureInExtent(userExtent, render);
}
for (let i = 0, ii = features.length; i < ii; ++i) {
render(features[i]);
}
this.renderedFeatures_ = features;
const replayGroupInstructions = replayGroup.finish();
const executorGroup = new ExecutorGroup(extent, resolution,
@@ -361,7 +567,11 @@ class CanvasVectorLayerRenderer extends CanvasLayerRenderer {
this.renderedRevision_ = vectorLayerRevision;
this.renderedRenderOrder_ = vectorLayerRenderOrder;
this.renderedExtent_ = extent;
this.renderedRotation_ = viewState.rotation;
this.renderedCenter_ = center;
this.renderedProjection_ = projection;
this.replayGroup_ = executorGroup;
this.hitDetectionImageData_ = null;
this.replayGroupChanged = true;
return true;

View File

@@ -428,7 +428,10 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
const declutterReplays = layer.getDeclutter() ? {} : null;
const replayTypes = VECTOR_REPLAYS[renderMode];
const pixelRatio = frameState.pixelRatio;
const rotation = frameState.viewState.rotation;
const viewState = frameState.viewState;
const center = viewState.center;
const resolution = viewState.resolution;
const rotation = viewState.rotation;
const size = frameState.size;
// set forward and inverse pixel transforms
@@ -462,7 +465,7 @@ class CanvasVectorTileLayerRenderer extends CanvasTileLayerRenderer {
const tileCoord = tile.tileCoord;
const tileExtent = tileGrid.getTileCoordExtent(tile.wrappedTileCoord);
const worldOffset = tileGrid.getTileCoordExtent(tileCoord, this.tmpExtent)[0] - tileExtent[0];
const transform = this.getRenderTransform(frameState, width, height, worldOffset);
const transform = this.getRenderTransform(center, resolution, rotation, pixelRatio, width, height, worldOffset);
const executorGroups = tile.executorGroups[getUid(layer)];
let clipped = false;
for (let t = 0, tt = executorGroups.length; t < tt; ++t) {

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@@ -675,14 +675,21 @@ class VectorSource extends Source {
* all features intersecting the given extent in random order (so it may include
* features whose geometries do not intersect the extent).
*
* This method is not available when the source is configured with
* `useSpatialIndex` set to `false`.
* When `useSpatialIndex` is set to false, this method will return all
* features.
*
* @param {import("../extent.js").Extent} extent Extent.
* @return {Array<import("../Feature.js").default<Geometry>>} Features.
* @api
*/
getFeaturesInExtent(extent) {
return this.featuresRtree_.getInExtent(extent);
if (this.featuresRtree_) {
return this.featuresRtree_.getInExtent(extent);
} else if (this.featuresCollection_) {
return this.featuresCollection_.getArray();
} else {
return [];
}
}

View File

@@ -40,6 +40,7 @@ describe('ol/renderer/canvas/VectorImageLayer', function() {
extent: extent,
viewHints: [],
viewState: {
center: [0, 0],
projection: projection,
resolution: 1,
rotation: 0

View File

@@ -208,6 +208,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
const frameState = {
layerStatesArray: [{}],
viewState: {
center: [0, 0],
resolution: 1,
rotation: 0
}
@@ -234,6 +235,7 @@ describe('ol.renderer.canvas.VectorLayer', function() {
frameState = {
viewHints: [],
viewState: {
center: [0, 0],
projection: projection,
resolution: 1,
rotation: 0

View File

@@ -22,6 +22,7 @@ import VectorTileRenderType from '../../../../../src/ol/layer/VectorTileRenderTy
import {getUid} from '../../../../../src/ol/util.js';
import TileLayer from '../../../../../src/ol/layer/Tile.js';
import XYZ from '../../../../../src/ol/source/XYZ.js';
import {create} from '../../../../../src/ol/transform.js';
describe('ol.renderer.canvas.VectorTileLayer', function() {
@@ -262,6 +263,7 @@ describe('ol.renderer.canvas.VectorTileLayer', function() {
layerIndex: 0,
extent: proj.getExtent(),
pixelRatio: 1,
pixelToCoordinateTransform: create(),
time: Date.now(),
viewHints: [],
viewState: {