141 lines
4.6 KiB
JavaScript
141 lines
4.6 KiB
JavaScript
import { VantComponent } from '../common/component';
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const ROOT_ELEMENT = '.van-sticky';
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VantComponent({
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props: {
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zIndex: {
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type: Number,
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value: 99
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},
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offsetTop: {
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type: Number,
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value: 0,
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observer: 'observeContent'
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},
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disabled: {
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type: Boolean,
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observer(value) {
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if (!this.mounted) {
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return;
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}
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value ? this.disconnectObserver() : this.initObserver();
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}
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},
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container: {
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type: null,
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observer(target) {
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if (typeof target !== 'function' || !this.data.height) {
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return;
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}
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this.observeContainer();
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}
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}
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},
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data: {
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wrapStyle: '',
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containerStyle: ''
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},
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methods: {
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setStyle() {
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const { offsetTop, height, fixed, zIndex } = this.data;
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if (fixed) {
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this.setData({
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wrapStyle: `top: ${offsetTop}px;`,
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containerStyle: `height: ${height}px; z-index: ${zIndex};`
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});
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}
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else {
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this.setData({
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wrapStyle: '',
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containerStyle: ''
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});
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}
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},
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getContainerRect() {
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const nodesRef = this.data.container();
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return new Promise(resolve => nodesRef.boundingClientRect(resolve).exec());
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},
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initObserver() {
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this.disconnectObserver();
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this.getRect(ROOT_ELEMENT).then((rect) => {
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this.setData({ height: rect.height });
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wx.nextTick(() => {
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this.observeContent();
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this.observeContainer();
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});
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});
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},
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disconnectObserver(observerName) {
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if (observerName) {
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const observer = this[observerName];
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observer && observer.disconnect();
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}
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else {
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this.contentObserver && this.contentObserver.disconnect();
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this.containerObserver && this.containerObserver.disconnect();
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}
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},
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observeContent() {
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const { offsetTop } = this.data;
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this.disconnectObserver('contentObserver');
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const contentObserver = this.createIntersectionObserver({
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thresholds: [0, 1]
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});
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this.contentObserver = contentObserver;
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contentObserver.relativeToViewport({ top: -offsetTop });
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contentObserver.observe(ROOT_ELEMENT, res => {
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if (this.data.disabled) {
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return;
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}
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this.setFixed(res.boundingClientRect.top);
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});
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},
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observeContainer() {
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if (typeof this.data.container !== 'function') {
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return;
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}
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const { height } = this.data;
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this.getContainerRect().then((rect) => {
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this.containerHeight = rect.height;
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this.disconnectObserver('containerObserver');
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const containerObserver = this.createIntersectionObserver({
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thresholds: [0, 1]
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});
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this.containerObserver = containerObserver;
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containerObserver.relativeToViewport({
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top: this.containerHeight - height
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});
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containerObserver.observe(ROOT_ELEMENT, res => {
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if (this.data.disabled) {
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return;
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}
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this.setFixed(res.boundingClientRect.top);
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});
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});
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},
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setFixed(top) {
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const { offsetTop, height } = this.data;
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const { containerHeight } = this;
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const fixed = containerHeight && height
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? top > height - containerHeight && top < offsetTop
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: top < offsetTop;
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this.$emit('scroll', {
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scrollTop: top,
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isFixed: fixed
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});
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this.setData({ fixed });
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wx.nextTick(() => {
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this.setStyle();
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});
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}
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},
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mounted() {
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this.mounted = true;
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if (!this.data.disabled) {
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this.initObserver();
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}
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},
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destroyed() {
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this.disconnectObserver();
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}
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});
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