forked from zhurui/management
88 lines
2.7 KiB
JavaScript
88 lines
2.7 KiB
JavaScript
var LRU = require("../../core/LRU");
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var globalImageCache = new LRU(50);
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/**
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* @param {string|HTMLImageElement|HTMLCanvasElement|Canvas} newImageOrSrc
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* @return {HTMLImageElement|HTMLCanvasElement|Canvas} image
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*/
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function findExistImage(newImageOrSrc) {
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if (typeof newImageOrSrc === 'string') {
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var cachedImgObj = globalImageCache.get(newImageOrSrc);
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return cachedImgObj && cachedImgObj.image;
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} else {
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return newImageOrSrc;
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}
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}
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/**
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* Caution: User should cache loaded images, but not just count on LRU.
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* Consider if required images more than LRU size, will dead loop occur?
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*
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* @param {string|HTMLImageElement|HTMLCanvasElement|Canvas} newImageOrSrc
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* @param {HTMLImageElement|HTMLCanvasElement|Canvas} image Existent image.
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* @param {module:zrender/Element} [hostEl] For calling `dirty`.
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* @param {Function} [cb] params: (image, cbPayload)
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* @param {Object} [cbPayload] Payload on cb calling.
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* @return {HTMLImageElement|HTMLCanvasElement|Canvas} image
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*/
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function createOrUpdateImage(newImageOrSrc, image, hostEl, cb, cbPayload) {
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if (!newImageOrSrc) {
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return image;
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} else if (typeof newImageOrSrc === 'string') {
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// Image should not be loaded repeatly.
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if (image && image.__zrImageSrc === newImageOrSrc || !hostEl) {
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return image;
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} // Only when there is no existent image or existent image src
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// is different, this method is responsible for load.
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var cachedImgObj = globalImageCache.get(newImageOrSrc);
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var pendingWrap = {
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hostEl: hostEl,
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cb: cb,
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cbPayload: cbPayload
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};
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if (cachedImgObj) {
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image = cachedImgObj.image;
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!isImageReady(image) && cachedImgObj.pending.push(pendingWrap);
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} else {
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image = new Image();
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image.onload = image.onerror = imageOnLoad;
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globalImageCache.put(newImageOrSrc, image.__cachedImgObj = {
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image: image,
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pending: [pendingWrap]
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});
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image.src = image.__zrImageSrc = newImageOrSrc;
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}
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return image;
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} // newImageOrSrc is an HTMLImageElement or HTMLCanvasElement or Canvas
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else {
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return newImageOrSrc;
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}
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}
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function imageOnLoad() {
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var cachedImgObj = this.__cachedImgObj;
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this.onload = this.onerror = this.__cachedImgObj = null;
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for (var i = 0; i < cachedImgObj.pending.length; i++) {
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var pendingWrap = cachedImgObj.pending[i];
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var cb = pendingWrap.cb;
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cb && cb(this, pendingWrap.cbPayload);
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pendingWrap.hostEl.dirty();
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}
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cachedImgObj.pending.length = 0;
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}
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function isImageReady(image) {
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return image && image.width && image.height;
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}
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exports.findExistImage = findExistImage;
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exports.createOrUpdateImage = createOrUpdateImage;
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exports.isImageReady = isImageReady; |