Files
openlayers/src/ol/render.js
2019-05-22 16:47:23 +02:00

134 lines
4.7 KiB
JavaScript

/**
* @module ol/render
*/
import {DEVICE_PIXEL_RATIO} from './has.js';
import {
apply as applyTransform,
create as createTransform,
multiply as multiplyTransform,
scale as scaleTransform
} from './transform.js';
import CanvasImmediateRenderer from './render/canvas/Immediate.js';
/**
* @typedef {Object} State
* @property {CanvasRenderingContext2D} context Canvas context that the layer is being rendered to.
* @property {import("./Feature.js").FeatureLike} feature
* @property {import("./geom/SimpleGeometry.js").default} geometry
* @property {number} pixelRatio Pixel ratio used by the layer renderer.
* @property {number} resolution Resolution that the render batch was created and optimized for.
* This is not the view's resolution that is being rendered.
* @property {number} rotation Rotation of the rendered layer in radians.
*/
/**
* A function to be used when sorting features before rendering.
* It takes two instances of {@link module:ol/Feature} or
* {@link module:ol/render/Feature} and returns a `{number}`.
*
* @typedef {function(import("./Feature.js").FeatureLike, import("./Feature.js").FeatureLike):number} OrderFunction
*/
/**
* @typedef {Object} ToContextOptions
* @property {import("./size.js").Size} [size] Desired size of the canvas in css
* pixels. When provided, both canvas and css size will be set according to the
* `pixelRatio`. If not provided, the current canvas and css sizes will not be
* altered.
* @property {number} [pixelRatio=window.devicePixelRatio] Pixel ratio (canvas
* pixel to css pixel ratio) for the canvas.
*/
/**
* Binds a Canvas Immediate API to a canvas context, to allow drawing geometries
* to the context's canvas.
*
* The units for geometry coordinates are css pixels relative to the top left
* corner of the canvas element.
* ```js
* import {toContext} from 'ol/render';
* import Fill from 'ol/style/Fill';
* import Polygon from 'ol/geom/Polygon';
*
* var canvas = document.createElement('canvas');
* var render = toContext(canvas.getContext('2d'),
* { size: [100, 100] });
* render.setFillStrokeStyle(new Fill({ color: blue }));
* render.drawPolygon(
* new Polygon([[[0, 0], [100, 100], [100, 0], [0, 0]]]));
* ```
*
* @param {CanvasRenderingContext2D} context Canvas context.
* @param {ToContextOptions=} opt_options Options.
* @return {CanvasImmediateRenderer} Canvas Immediate.
* @api
*/
export function toContext(context, opt_options) {
const canvas = context.canvas;
const options = opt_options ? opt_options : {};
const pixelRatio = options.pixelRatio || DEVICE_PIXEL_RATIO;
const size = options.size;
if (size) {
canvas.width = size[0] * pixelRatio;
canvas.height = size[1] * pixelRatio;
canvas.style.width = size[0] + 'px';
canvas.style.height = size[1] + 'px';
}
const extent = [0, 0, canvas.width, canvas.height];
const transform = scaleTransform(createTransform(), pixelRatio, pixelRatio);
return new CanvasImmediateRenderer(context, pixelRatio, extent, transform, 0);
}
/**
* Gets a vector context for drawing to the event's canvas.
* @param {import("./render/Event.js").default} event Render event.
* @returns {CanvasImmediateRenderer} Vector context.
* @api
*/
export function getVectorContext(event) {
const frameState = event.frameState;
const transform = multiplyTransform(event.inversePixelTransform.slice(), frameState.coordinateToPixelTransform);
return new CanvasImmediateRenderer(
event.context, frameState.pixelRatio, frameState.extent, transform,
frameState.viewState.rotation);
}
/**
* Gets the pixel of the event's canvas context from the map viewport's CSS pixel.
* @param {import("./render/Event.js").default} event Render event.
* @param {import("./pixel.js").Pixel} pixel CSS pixel relative to the top-left
* corner of the map viewport.
* @returns {import("./pixel.js").Pixel} Pixel on the event's canvas context.
* @api
*/
export function getRenderPixel(event, pixel) {
const result = pixel.slice(0);
applyTransform(event.inversePixelTransform.slice(), result);
return result;
}
/**
* @param {import("./PluggableMap.js").FrameState} frameState Frame state.
* @param {?} declutterTree Declutter tree.
* @returns {?} Declutter tree.
*/
export function renderDeclutterItems(frameState, declutterTree) {
if (declutterTree) {
declutterTree.clear();
}
const items = frameState.declutterItems;
for (let z = items.length - 1; z >= 0; --z) {
const item = items[z];
const zIndexItems = item.items;
for (let i = 0, ii = zIndexItems.length; i < ii; i += 3) {
declutterTree = zIndexItems[i].renderDeclutter(zIndexItems[i + 1], zIndexItems[i + 2], item.opacity, declutterTree);
}
}
items.length = 0;
return declutterTree;
}