@shopify/flash-list
Version:
FlashList is a more performant FlatList replacement
108 lines • 5.63 kB
JavaScript
;
Object.defineProperty(exports, "__esModule", { value: true });
var tslib_1 = require("tslib");
var ViewabilityHelper_1 = tslib_1.__importDefault(require("./ViewabilityHelper"));
/**
* Manager for viewability tracking. It holds multiple viewability callback pairs and keeps them updated.
*/
var ViewabilityManager = /** @class */ (function () {
function ViewabilityManager(flashListRef) {
var _this = this;
var _a;
this.viewabilityHelpers = [];
this.hasInteracted = false;
this.dispose = function () {
_this.viewabilityHelpers.forEach(function (viewabilityHelper) {
return viewabilityHelper.dispose();
});
};
this.onVisibleIndicesChanged = function (all) {
_this.updateViewableItems(all);
};
this.recordInteraction = function () {
if (_this.hasInteracted) {
return;
}
_this.hasInteracted = true;
_this.viewabilityHelpers.forEach(function (viewabilityHelper) {
viewabilityHelper.hasInteracted = true;
});
_this.updateViewableItems();
};
this.updateViewableItems = function (newViewableIndices) {
var _a, _b;
var listSize = (_a = _this.flashListRef.getWindowSize()) !== null && _a !== void 0 ? _a : _this.flashListRef.props.estimatedListSize;
if (listSize === undefined || !_this.shouldListenToVisibleIndices) {
return;
}
var scrollOffset = ((_b = _this.flashListRef.getAbsoluteLastScrollOffset()) !== null && _b !== void 0 ? _b : 0) -
_this.flashListRef.firstItemOffset;
_this.viewabilityHelpers.forEach(function (viewabilityHelper) {
var _a;
viewabilityHelper.updateViewableItems((_a = _this.flashListRef.props.horizontal) !== null && _a !== void 0 ? _a : false, scrollOffset, listSize, function (index) { return _this.flashListRef.getLayout(index); }, newViewableIndices);
});
};
this.recomputeViewableItems = function () {
_this.viewabilityHelpers.forEach(function (viewabilityHelper) {
return viewabilityHelper.clearLastReportedViewableIndices();
});
_this.updateViewableItems();
};
/**
* Creates a new `ViewabilityHelper` instance with `onViewableItemsChanged` callback and `ViewabilityConfig`
* @returns `ViewabilityHelper` instance
*/
this.createViewabilityHelper = function (viewabilityConfig, onViewableItemsChanged) {
var mapViewToken = function (index, isViewable) {
var _a;
var item = (_a = _this.flashListRef.props.data) === null || _a === void 0 ? void 0 : _a[index];
var key = item === undefined || _this.flashListRef.props.keyExtractor === undefined
? index.toString()
: _this.flashListRef.props.keyExtractor(item, index);
return {
index: index,
isViewable: isViewable,
item: item,
key: key,
timestamp: Date.now(),
};
};
return new ViewabilityHelper_1.default(viewabilityConfig, function (indices, newlyVisibleIndices, newlyNonvisibleIndices) {
onViewableItemsChanged === null || onViewableItemsChanged === void 0 ? void 0 : onViewableItemsChanged({
viewableItems: indices.map(function (index) { return mapViewToken(index, true); }),
changed: tslib_1.__spreadArray(tslib_1.__spreadArray([], tslib_1.__read(newlyVisibleIndices.map(function (index) { return mapViewToken(index, true); })), false), tslib_1.__read(newlyNonvisibleIndices.map(function (index) {
return mapViewToken(index, false);
})), false),
});
});
};
this.flashListRef = flashListRef;
if (flashListRef.props.onViewableItemsChanged !== null &&
flashListRef.props.onViewableItemsChanged !== undefined) {
this.viewabilityHelpers.push(this.createViewabilityHelper(flashListRef.props.viewabilityConfig, function (info) {
var _a, _b;
(_b = (_a = flashListRef.props).onViewableItemsChanged) === null || _b === void 0 ? void 0 : _b.call(_a, info);
}));
}
((_a = flashListRef.props.viewabilityConfigCallbackPairs) !== null && _a !== void 0 ? _a : []).forEach(function (pair, index) {
_this.viewabilityHelpers.push(_this.createViewabilityHelper(pair.viewabilityConfig, function (info) {
var _a, _b;
var callback = (_b = (_a = flashListRef.props.viewabilityConfigCallbackPairs) === null || _a === void 0 ? void 0 : _a[index]) === null || _b === void 0 ? void 0 : _b.onViewableItemsChanged;
callback === null || callback === void 0 ? void 0 : callback(info);
}));
});
}
Object.defineProperty(ViewabilityManager.prototype, "shouldListenToVisibleIndices", {
/**
* @returns true if the viewability manager has any viewability callback pairs registered.
*/
get: function () {
return this.viewabilityHelpers.length > 0;
},
enumerable: false,
configurable: true
});
return ViewabilityManager;
}());
exports.default = ViewabilityManager;
//# sourceMappingURL=ViewabilityManager.js.map