bd028579
 易尊强
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import LRU from '../../core/LRU';
import { platformApi } from '../../core/platform';
import { ImageLike } from '../../core/types';
const globalImageCache = new LRU<CachedImageObj>(50);
type PendingWrap = {
hostEl: {dirty: () => void}
cb: (image: ImageLike, payload: any) => void
cbPayload: any
}
type CachedImageObj = {
image: ImageLike
pending: PendingWrap[]
}
export function findExistImage(newImageOrSrc: string | ImageLike): ImageLike {
if (typeof newImageOrSrc === 'string') {
const cachedImgObj = globalImageCache.get(newImageOrSrc);
return cachedImgObj && cachedImgObj.image;
}
else {
return newImageOrSrc;
}
}
/**
* Caution: User should cache loaded images, but not just count on LRU.
* Consider if required images more than LRU size, will dead loop occur?
*
* @param newImageOrSrc
* @param image Existent image.
* @param hostEl For calling `dirty`.
* @param onload params: (image, cbPayload)
* @param cbPayload Payload on cb calling.
* @return image
*/
export function createOrUpdateImage<T>(
newImageOrSrc: string | ImageLike,
image: ImageLike,
hostEl: { dirty: () => void },
onload?: (image: ImageLike, payload: T) => void,
cbPayload?: T
) {
if (!newImageOrSrc) {
return image;
}
else if (typeof newImageOrSrc === 'string') {
// Image should not be loaded repeatly.
if ((image && (image as any).__zrImageSrc === newImageOrSrc) || !hostEl) {
return image;
}
// Only when there is no existent image or existent image src
// is different, this method is responsible for load.
const cachedImgObj = globalImageCache.get(newImageOrSrc);
const pendingWrap = {hostEl: hostEl, cb: onload, cbPayload: cbPayload};
if (cachedImgObj) {
image = cachedImgObj.image;
!isImageReady(image) && cachedImgObj.pending.push(pendingWrap);
}
else {
image = platformApi.loadImage(
newImageOrSrc, imageOnLoad, imageOnLoad
);
(image as any).__zrImageSrc = newImageOrSrc;
globalImageCache.put(
newImageOrSrc,
(image as any).__cachedImgObj = {
image: image,
pending: [pendingWrap]
}
);
}
return image;
}
// newImageOrSrc is an HTMLImageElement or HTMLCanvasElement or Canvas
else {
return newImageOrSrc;
}
}
function imageOnLoad(this: any) {
const cachedImgObj = this.__cachedImgObj;
this.onload = this.onerror = this.__cachedImgObj = null;
for (let i = 0; i < cachedImgObj.pending.length; i++) {
const pendingWrap = cachedImgObj.pending[i];
const cb = pendingWrap.cb;
cb && cb(this, pendingWrap.cbPayload);
pendingWrap.hostEl.dirty();
}
cachedImgObj.pending.length = 0;
}
export function isImageReady(image: ImageLike) {
return image && image.width && image.height;
}
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