refactor(Sticky): refactor component with page scroll (#2950)

fix #2651, fix #2418

packages/mixins/page-scroll.ts

@@ -0,0 +1,42 @@
+type IPageScrollOption = WechatMiniprogram.Page.IPageScrollOption;
+type Scroller = (event: IPageScrollOption) => void;
+type TrivialInstance = WechatMiniprogram.Page.TrivialInstance & {
+  vanPageScroller?: Scroller[];
+};
+
+function getCurrentPage(): TrivialInstance {
+  const pages = getCurrentPages();
+  return pages[pages.length - 1] || ({} as TrivialInstance);
+}
+
+function onPageScroll(event: IPageScrollOption) {
+  const { vanPageScroller = [] } = getCurrentPage();
+
+  vanPageScroller.forEach((scroller: Scroller) => {
+    if (typeof scroller === 'function') {
+      scroller(event);
+    }
+  });
+}
+
+export const pageScrollMixin = (scroller: Scroller) =>
+  Behavior({
+    attached() {
+      const page = getCurrentPage();
+
+      if (Array.isArray(page.vanPageScroller)) {
+        page.vanPageScroller.push(scroller.bind(this));
+      } else {
+        page.vanPageScroller = [page.onPageScroll, scroller.bind(this)];
+      }
+
+      page.onPageScroll = onPageScroll;
+    },
+
+    detached() {
+      const page = getCurrentPage();
+      page.vanPageScroller = (page.vanPageScroller || []).filter(
+        item => item !== scroller
+      );
+    }
+  });

packages/sticky/index.ts

@@ -1,7 +1,10 @@
 import { VantComponent } from '../common/component';
+import { pageScrollMixin } from '../mixins/page-scroll';
 
 const ROOT_ELEMENT = '.van-sticky';
 
+type BoundingClientRect = WechatMiniprogram.BoundingClientRectCallbackResult;
+
 VantComponent({
   props: {
     zIndex: {
@@ -11,163 +14,106 @@ VantComponent({
     offsetTop: {
       type: Number,
       value: 0,
-      observer: 'observeContent'
+      observer: 'onScroll'
     },
     disabled: {
       type: Boolean,
-      observer(value) {
-        if (!this.mounted) {
-          return;
-        }
-        value ? this.disconnectObserver() : this.initObserver();
-      }
+      observer: 'onScroll'
     },
     container: {
       type: null,
-      observer(target: () => WechatMiniprogram.NodesRef) {
-        if (typeof target !== 'function' || !this.data.height) {
-          return;
-        }
-
-        this.observeContainer();
-        this.updateFixed();
-      }
+      observer: 'onScroll'
     }
   },
 
+  mixins: [
+    pageScrollMixin(function(event) {
+      this.onScroll(event);
+    })
+  ],
+
   data: {
     height: 0,
-    fixed: false
+    fixed: false,
+    transform: 0
+  },
+
+  mounted() {
+    this.onScroll();
   },
 
   methods: {
+    onScroll({ scrollTop } = {}) {
+      const { container, offsetTop, disabled } = this.data;
+
+      if (disabled) {
+        this.setDataAfterDiff({
+          fixed: false,
+          transform: 0
+        });
+        return;
+      }
+
+      this.scrollTop = scrollTop || this.scrollTop;
+
+      if (typeof container === 'function') {
+        Promise.all([this.getRect(ROOT_ELEMENT), this.getContainerRect()]).then(
+          ([root, container]: BoundingClientRect[]) => {
+            if (offsetTop + root.height > container.height + container.top) {
+              this.setDataAfterDiff({
+                fixed: false,
+                transform: container.height - root.height
+              });
+            } else if (offsetTop >= root.top) {
+              this.setDataAfterDiff({
+                fixed: true,
+                height: root.height,
+                transform: 0
+              });
+            } else {
+              this.setDataAfterDiff({ fixed: false, transform: 0 });
+            }
+          }
+        );
+
+        return;
+      }
+
+      this.getRect(ROOT_ELEMENT).then((root: BoundingClientRect) => {
+        if (offsetTop >= root.top) {
+          this.setDataAfterDiff({ fixed: true, height: root.height });
+          this.transform = 0;
+        } else {
+          this.setDataAfterDiff({ fixed: false });
+        }
+      });
+    },
+
+    setDataAfterDiff(data) {
+      wx.nextTick(() => {
+        const diff = Object.keys(data).reduce((prev, key) => {
+          if (data[key] !== this.data[key]) {
+            prev[key] = data[key];
+          }
+
+          return prev;
+        }, {});
+
+        this.setData(diff);
+
+        this.$emit('scroll', {
+          scrollTop: this.scrollTop,
+          isFixed: data.fixed || this.data.fixed
+        });
+      });
+    },
+
     getContainerRect() {
       const nodesRef: WechatMiniprogram.NodesRef = this.data.container();
 
       return new Promise(resolve =>
         nodesRef.boundingClientRect(resolve).exec()
       );
-    },
-
-    initObserver() {
-      this.disconnectObserver();
-
-      this.getRect(ROOT_ELEMENT).then(
-        (rect: WechatMiniprogram.BoundingClientRectCallbackResult) => {
-          this.setData({ height: rect.height });
-
-          wx.nextTick(() => {
-            this.observeContent();
-            this.observeContainer();
-          });
-        }
-      );
-    },
-
-    updateFixed() {
-      Promise.all([this.getRect(ROOT_ELEMENT), this.getContainerRect()]).then(
-        ([
-          content,
-          container
-        ]: WechatMiniprogram.BoundingClientRectCallbackResult[]) => {
-          this.setData({ height: content.height });
-          this.containerHeight = container.height;
-
-          wx.nextTick(() => {
-            this.setFixed(content.top);
-          });
-        }
-      );
-    },
-
-    disconnectObserver(observerName?: string) {
-      if (observerName) {
-        const observer: WechatMiniprogram.IntersectionObserver = 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: [0.9, 1]
-      });
-      contentObserver.relativeToViewport({ top: -offsetTop });
-      contentObserver.observe(ROOT_ELEMENT, res => {
-        if (this.data.disabled) {
-          return;
-        }
-
-        this.setFixed(res.boundingClientRect.top);
-      });
-
-      this.contentObserver = contentObserver;
-    },
-
-    observeContainer() {
-      if (typeof this.data.container !== 'function') {
-        return;
-      }
-
-      const { height } = this.data;
-
-      this.getContainerRect().then(
-        (rect: WechatMiniprogram.BoundingClientRectCallbackResult) => {
-          this.containerHeight = rect.height;
-
-          this.disconnectObserver('containerObserver');
-          const containerObserver = this.createIntersectionObserver({
-            thresholds: [0.9, 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 });
     }
-  },
-
-  mounted() {
-    this.mounted = true;
-
-    if (!this.data.disabled) {
-      this.initObserver();
-    }
-  },
-
-  destroyed() {
-    this.disconnectObserver();
   }
 });

packages/sticky/index.wxml

@@ -2,7 +2,7 @@
 <wxs src="./index.wxs" module="computed" />
 
 <view class="custom-class van-sticky" style="{{ computed.containerStyle({ fixed, height, zIndex }) }}">
-  <view class="{{ utils.bem('sticky-wrap', { fixed }) }}" style="{{ computed.wrapStyle({ fixed, offsetTop }) }}">
+  <view class="{{ utils.bem('sticky-wrap', { fixed }) }}" style="{{ computed.wrapStyle({ fixed, offsetTop, transform, zIndex }) }}">
     <slot />
   </view>
 </view>

packages/sticky/index.wxs

@@ -1,18 +1,34 @@
 /* eslint-disable */
 function wrapStyle(data) {
-  if (data.fixed) {
-    return 'top: ' + data.offsetTop + 'px;';
+  var style = '';
+
+  if (data.transform) {
+    style += 'transform: translate3d(0, ' + data.transform + 'px, 0);';
   }
 
-  return '';
+  if (data.fixed) {
+    style += 'top: ' + data.offsetTop + 'px;';
+  }
+
+  if (data.zIndex) {
+    style += 'z-index: ' + data.zIndex + ';';
+  }
+
+  return style;
 }
 
 function containerStyle(data) {
+  var style = '';
+
   if (data.fixed) {
-    return 'height: ' + data.height + 'px; z-index: ' + data.zIndex + ';';
+    style += 'height: ' + data.height + 'px;';
   }
 
-  return '';
+  if (data.zIndex) {
+    style += 'z-index: ' + data.zIndex + ';';
+  }
+
+  return style;
 }
 
 module.exports = {