160 lines
3.7 KiB
JavaScript
160 lines
3.7 KiB
JavaScript
/**
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* @module ol/Image
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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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import {listenOnce, unlistenByKey} from './events.js';
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import EventType from './events/EventType.js';
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import {getHeight} from './extent.js';
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/**
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* A function that takes an {@link module:ol/Image~Image} for the image and a
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* `{string}` for the src as arguments. It is supposed to make it so the
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* underlying image {@link module:ol/Image~Image#getImage} is assigned the
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* content specified by the src. If not specified, the default is
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*
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* function(image, src) {
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* image.getImage().src = src;
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* }
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*
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* Providing a custom `imageLoadFunction` can be useful to load images with
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* post requests or - in general - through XHR requests, where the src of the
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* image element would be set to a data URI when the content is loaded.
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*
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* @typedef {function(module:ol/Image~Image, string)} LoadFunction
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* @api
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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|undefined} resolution Resolution.
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* @param {number} pixelRatio Pixel ratio.
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* @param {string} src Image source URI.
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* @param {?string} crossOrigin Cross origin.
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* @param {module:ol/Image~LoadFunction} imageLoadFunction Image load function.
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*/
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const ImageWrapper = function(extent, resolution, pixelRatio, src, crossOrigin, imageLoadFunction) {
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ImageBase.call(this, extent, resolution, pixelRatio, ImageState.IDLE);
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/**
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* @private
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* @type {string}
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*/
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this.src_ = src;
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/**
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* @private
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* @type {HTMLCanvasElement|Image|HTMLVideoElement}
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*/
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this.image_ = new Image();
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if (crossOrigin !== null) {
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this.image_.crossOrigin = crossOrigin;
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}
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/**
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* @private
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* @type {Array.<module:ol/events~EventsKey>}
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*/
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this.imageListenerKeys_ = null;
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/**
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* @protected
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* @type {module:ol/ImageState}
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*/
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this.state = ImageState.IDLE;
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/**
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* @private
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* @type {module:ol/Image~LoadFunction}
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*/
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this.imageLoadFunction_ = imageLoadFunction;
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};
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inherits(ImageWrapper, ImageBase);
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/**
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* @inheritDoc
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* @api
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*/
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ImageWrapper.prototype.getImage = function() {
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return this.image_;
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};
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/**
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* Tracks loading or read errors.
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*
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* @private
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*/
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ImageWrapper.prototype.handleImageError_ = function() {
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this.state = ImageState.ERROR;
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this.unlistenImage_();
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this.changed();
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};
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/**
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* Tracks successful image load.
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*
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* @private
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*/
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ImageWrapper.prototype.handleImageLoad_ = function() {
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if (this.resolution === undefined) {
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this.resolution = getHeight(this.extent) / this.image_.height;
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}
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this.state = ImageState.LOADED;
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this.unlistenImage_();
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this.changed();
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};
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/**
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* Load the image or retry if loading previously failed.
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* Loading is taken care of by the tile queue, and calling this method is
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* only needed for preloading or for reloading in case of an error.
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* @override
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* @api
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*/
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ImageWrapper.prototype.load = function() {
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if (this.state == ImageState.IDLE || this.state == ImageState.ERROR) {
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this.state = ImageState.LOADING;
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this.changed();
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this.imageListenerKeys_ = [
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listenOnce(this.image_, EventType.ERROR,
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this.handleImageError_, this),
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listenOnce(this.image_, EventType.LOAD,
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this.handleImageLoad_, this)
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];
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this.imageLoadFunction_(this, this.src_);
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}
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};
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/**
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* @param {HTMLCanvasElement|Image|HTMLVideoElement} image Image.
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*/
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ImageWrapper.prototype.setImage = function(image) {
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this.image_ = image;
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};
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/**
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* Discards event handlers which listen for load completion or errors.
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*
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* @private
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*/
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ImageWrapper.prototype.unlistenImage_ = function() {
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this.imageListenerKeys_.forEach(unlistenByKey);
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this.imageListenerKeys_ = null;
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};
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export default ImageWrapper;
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