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