103 lines
2.2 KiB
JavaScript
103 lines
2.2 KiB
JavaScript
/**
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* @module ol/ImageCanvas
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*/
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import {inherits} from './index.js';
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import ImageBase from './ImageBase.js';
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import ImageState from './ImageState.js';
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/**
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* A function that is called to trigger asynchronous canvas drawing. It is
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* called with a "done" callback that should be called when drawing is done.
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* If any error occurs during drawing, the "done" callback should be called with
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* that error.
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*
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* @typedef {function(function(Error))} Loader
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*/
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/**
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* @constructor
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* @extends {module:ol/ImageBase}
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* @param {module:ol/extent~Extent} extent Extent.
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* @param {number} resolution Resolution.
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* @param {number} pixelRatio Pixel ratio.
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* @param {HTMLCanvasElement} canvas Canvas.
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* @param {module:ol/ImageCanvas~Loader=} opt_loader Optional loader function to
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* support asynchronous canvas drawing.
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*/
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const ImageCanvas = function(extent, resolution, pixelRatio, canvas, opt_loader) {
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/**
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* Optional canvas loader function.
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* @type {?module:ol/ImageCanvas~Loader}
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* @private
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*/
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this.loader_ = opt_loader !== undefined ? opt_loader : null;
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const state = opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
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ImageBase.call(this, extent, resolution, pixelRatio, state);
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/**
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* @private
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* @type {HTMLCanvasElement}
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*/
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this.canvas_ = canvas;
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/**
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* @private
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* @type {Error}
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*/
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this.error_ = null;
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};
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inherits(ImageCanvas, ImageBase);
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/**
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* Get any error associated with asynchronous rendering.
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* @return {Error} Any error that occurred during rendering.
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*/
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ImageCanvas.prototype.getError = function() {
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return this.error_;
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};
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/**
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* Handle async drawing complete.
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* @param {Error} err Any error during drawing.
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* @private
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*/
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ImageCanvas.prototype.handleLoad_ = function(err) {
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if (err) {
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this.error_ = err;
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this.state = ImageState.ERROR;
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} else {
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this.state = ImageState.LOADED;
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}
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this.changed();
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};
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/**
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* @inheritDoc
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*/
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ImageCanvas.prototype.load = function() {
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if (this.state == ImageState.IDLE) {
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this.state = ImageState.LOADING;
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this.changed();
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this.loader_(this.handleLoad_.bind(this));
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}
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};
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/**
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* @return {HTMLCanvasElement} Canvas element.
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*/
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ImageCanvas.prototype.getImage = function() {
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return this.canvas_;
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};
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export default ImageCanvas;
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