From 6c5315f0b1bf77773fc0ff24c14881d812ff8f02 Mon Sep 17 00:00:00 2001
From: kooriookami <38392315+kooriookami@users.noreply.github.com>
Date: Sun, 31 Jan 2021 02:43:49 -0600
Subject: [PATCH] feat(Sticky): support sticky to bottom (#7979)

---
 src/sticky/README.md                          |  10 +
 src/sticky/README.zh-CN.md                    |  12 ++
 src/sticky/demo/index.vue                     |  11 ++
 src/sticky/index.less                         |   3 -
 src/sticky/index.tsx                          |  93 +++++----
 .../test/__snapshots__/demo.spec.js.snap      |  18 ++
 .../test/__snapshots__/index.spec.js.snap     |  58 ++++--
 src/sticky/test/index.spec.js                 | 176 ++++++++++++++++--
 8 files changed, 314 insertions(+), 67 deletions(-)

diff --git a/src/sticky/README.md b/src/sticky/README.md
index ecf138340..b96ba64ff 100644
--- a/src/sticky/README.md
+++ b/src/sticky/README.md
@@ -38,6 +38,14 @@ app.use(Sticky);
 </div>
 ```
 
+### Offset Bottom
+
+```html
+<van-sticky :offset-bottom="50" position="bottom">
+  <van-button type="primary">Offset Bottom</van-button>
+</van-sticky>
+```
+
 ```js
 export default {
   setup() {
@@ -54,6 +62,8 @@ export default {
 | Attribute | Description | Type | Default |
 | --- | --- | --- | --- |
 | offset-top | Offset top, supports `px` `vw` `vh` `rem` unit, default `px` | _number \| string_ | `0` |
+| offset-bottom | Offset bottom, supports `px` `vw` `vh` `rem` unit, default `px` | _number \| string_ | `0` |
+| position | Offset position, supports `top` `bottom` | _string_ | `top` |
 | z-index | z-index when sticky | _number \| string_ | `99` |
 | container | Container DOM | _Element_ | - |
 
diff --git a/src/sticky/README.zh-CN.md b/src/sticky/README.zh-CN.md
index 031bb30bc..a80e8f018 100644
--- a/src/sticky/README.zh-CN.md
+++ b/src/sticky/README.zh-CN.md
@@ -48,6 +48,16 @@ app.use(Sticky);
 </div>
 ```
 
+### 吸底距离
+
+通过 `offset-bottom` 属性可以设置组件在吸底时与底部的距离。通过 `position` 属性控制吸附位置，默认值为 `top`。
+
+```html
+<van-sticky :offset-bottom="50" position="bottom">
+  <van-button type="primary">吸底距离</van-button>
+</van-sticky>
+```
+
 ```js
 export default {
   setup() {
@@ -64,6 +74,8 @@ export default {
 | 参数 | 说明 | 类型 | 默认值 |
 | --- | --- | --- | --- |
 | offset-top | 吸顶时与顶部的距离，支持 `px` `vw` `vh` `rem` 单位，默认 `px` | _number \| string_ | `0` |
+| offset-bottom | 吸底时与底部的距离，支持 `px` `vw` `vh` `rem` 单位，默认 `px` | _number \| string_ | `0` |
+| position | 吸附位置，支持 `top` `bottom` | _string_ | `top` |
 | z-index | 吸顶时的 z-index | _number \| string_ | `99` |
 | container | 容器对应的 HTML 节点 | _Element_ | - |
 
diff --git a/src/sticky/demo/index.vue b/src/sticky/demo/index.vue
index 9f0ad7f78..4ca62a1a8 100644
--- a/src/sticky/demo/index.vue
+++ b/src/sticky/demo/index.vue
@@ -24,6 +24,15 @@
       </van-sticky>
     </div>
   </demo-block>
+
+  <demo-block :title="t('offsetBottom')">
+    <div style="height: 200px"></div>
+    <van-sticky :offset-bottom="50" position="bottom">
+      <van-button type="primary" style="margin-left: 15px">
+        {{ t('offsetBottom') }}
+      </van-button>
+    </van-sticky>
+  </demo-block>
 </template>
 
 <script lang="ts">
@@ -33,10 +42,12 @@ import { useTranslate } from '@demo/use-translate';
 const i18n = {
   'zh-CN': {
     offsetTop: '吸顶距离',
+    offsetBottom: '吸底距离',
     setContainer: '指定容器',
   },
   'en-US': {
     offsetTop: 'Offset Top',
+    offsetBottom: 'Offset Bottom',
     setContainer: 'Set Container',
   },
 };
diff --git a/src/sticky/index.less b/src/sticky/index.less
index c849d8bb5..bb42f52b6 100644
--- a/src/sticky/index.less
+++ b/src/sticky/index.less
@@ -3,9 +3,6 @@
 .van-sticky {
   &--fixed {
     position: fixed;
-    top: 0;
-    right: 0;
-    left: 0;
     z-index: @sticky-z-index;
   }
 }
diff --git a/src/sticky/index.tsx b/src/sticky/index.tsx
index 72e40e7f2..3493ceabe 100644
--- a/src/sticky/index.tsx
+++ b/src/sticky/index.tsx
@@ -1,20 +1,16 @@
-import { ref, reactive, computed, CSSProperties } from 'vue';
+import { computed, CSSProperties, PropType, reactive, ref } from 'vue';
 
 // Utils
-import {
-  isHidden,
-  unitToPx,
-  getScrollTop,
-  getElementTop,
-  createNamespace,
-} from '../utils';
+import { createNamespace, getScrollTop, isHidden, unitToPx } from '../utils';
 
 // Composition
-import { useScrollParent, useEventListener } from '@vant/use';
+import { useEventListener, useScrollParent } from '@vant/use';
 import { useVisibilityChange } from '../composables/use-visibility-change';
 
 const [createComponent, bem] = createNamespace('sticky');
 
+export type Position = 'top' | 'bottom';
+
 export default createComponent({
   props: {
     zIndex: [Number, String],
@@ -23,6 +19,14 @@ export default createComponent({
       type: [Number, String],
       default: 0,
     },
+    offsetBottom: {
+      type: [Number, String],
+      default: 0,
+    },
+    position: {
+      type: String as PropType<Position>,
+      default: 'top',
+    },
   },
 
   emits: ['scroll'],
@@ -33,24 +37,31 @@ export default createComponent({
 
     const state = reactive({
       fixed: false,
-      height: 0,
+      height: 0, // root 高度
+      width: 0, // root 宽度
+      clientHeight: 0, // documentElement clientHeight
       transform: 0,
     });
 
     const offsetTop = computed(() => unitToPx(props.offsetTop));
+    const offsetBottom = computed(() => unitToPx(props.offsetBottom));
 
     const style = computed<CSSProperties | undefined>(() => {
       if (!state.fixed) {
         return;
       }
 
-      const top = offsetTop.value ? `${offsetTop.value}px` : undefined;
+      const top = offsetTop.value ? `${offsetTop.value}px` : 0;
+      const bottom = offsetBottom.value ? `${offsetBottom.value}px` : 0;
       const transform = state.transform
         ? `translate3d(0, ${state.transform}px, 0)`
         : undefined;
 
       return {
-        top,
+        height: `${state.height}px`,
+        width: `${state.width}px`,
+        top: props.position === 'top' ? top : undefined,
+        bottom: props.position === 'bottom' ? bottom : undefined,
         zIndex: props.zIndex !== undefined ? +props.zIndex : undefined,
         transform,
       };
@@ -68,38 +79,43 @@ export default createComponent({
         return;
       }
 
-      state.height = root.value.offsetHeight;
-
       const { container } = props;
+      const rootRect = root.value.getBoundingClientRect();
+      const containerRect = container?.getBoundingClientRect();
+      state.height = rootRect.height;
+      state.width = rootRect.width;
+      state.clientHeight = document.documentElement.clientHeight;
+
       const scrollTop = getScrollTop(window);
-      const topToPageTop = getElementTop(root.value);
 
       // The sticky component should be kept inside the container element
-      if (container) {
-        const bottomToPageTop = topToPageTop + container.offsetHeight;
 
-        if (scrollTop + offsetTop.value + state.height > bottomToPageTop) {
-          const distanceToBottom = state.height + scrollTop - bottomToPageTop;
-
-          if (distanceToBottom < state.height) {
-            state.fixed = true;
-            state.transform = -(distanceToBottom + offsetTop.value);
-          } else {
-            state.fixed = false;
-          }
-
-          emitScrollEvent(scrollTop);
-          return;
+      if (props.position === 'top') {
+        if (container) {
+          const difference =
+            containerRect.bottom - offsetTop.value - state.height;
+          state.fixed =
+            offsetTop.value > rootRect.top && containerRect.bottom > 0;
+          state.transform = difference < 0 ? difference : 0;
+        } else {
+          state.fixed = offsetTop.value > rootRect.top;
+        }
+      } else if (props.position === 'bottom') {
+        if (container) {
+          const difference =
+            state.clientHeight -
+            containerRect.top -
+            offsetBottom.value -
+            state.height;
+          state.fixed =
+            state.clientHeight - offsetBottom.value < rootRect.bottom &&
+            state.clientHeight > containerRect.top;
+          state.transform = difference < 0 ? -difference : 0;
+        } else {
+          state.fixed =
+            state.clientHeight - offsetBottom.value < rootRect.bottom;
         }
       }
-
-      if (scrollTop + offsetTop.value > topToPageTop) {
-        state.fixed = true;
-        state.transform = 0;
-      } else {
-        state.fixed = false;
-      }
-
       emitScrollEvent(scrollTop);
     };
 
@@ -107,9 +123,10 @@ export default createComponent({
     useVisibilityChange(root, onScroll);
 
     return () => {
-      const { fixed, height } = state;
+      const { fixed, height, width } = state;
       const rootStyle: CSSProperties = {
         height: fixed ? `${height}px` : undefined,
+        width: fixed ? `${width}px` : undefined,
       };
 
       return (
diff --git a/src/sticky/test/__snapshots__/demo.spec.js.snap b/src/sticky/test/__snapshots__/demo.spec.js.snap
index e4be9e114..ba324a25b 100644
--- a/src/sticky/test/__snapshots__/demo.spec.js.snap
+++ b/src/sticky/test/__snapshots__/demo.spec.js.snap
@@ -51,4 +51,22 @@ exports[`should render demo and match snapshot 1`] = `
     </div>
   </div>
 </div>
+<div>
+  <div style="height: 200px;">
+  </div>
+  <div>
+    <div class="van-sticky">
+      <button type="button"
+              class="van-button van-button--primary van-button--normal"
+              style="margin-left: 15px;"
+      >
+        <div class="van-button__content">
+          <span class="van-button__text">
+            Offset Bottom
+          </span>
+        </div>
+      </button>
+    </div>
+  </div>
+</div>
 `;
diff --git a/src/sticky/test/__snapshots__/index.spec.js.snap b/src/sticky/test/__snapshots__/index.spec.js.snap
index 4e14c31cb..4eda15bc1 100644
--- a/src/sticky/test/__snapshots__/index.spec.js.snap
+++ b/src/sticky/test/__snapshots__/index.spec.js.snap
@@ -30,11 +30,39 @@ exports[`should allow to using offset-top prop with vw unit 1`] = `
 </div>
 `;
 
-exports[`should sticky inside container when using container prop 1`] = `
-<div style="height: 20px;">
-  <div style="height: 10px;">
+exports[`should sticky inside container bottom when using container prop 1`] = `
+<div style="margin-top: 640px;">
+  <div style="height: 150px;">
+  </div>
+  <div style="height: 44px; width: 88px;">
     <div class="van-sticky van-sticky--fixed"
-         style="transform: translate3d(0, -5px, 0);"
+         style="height: 44px; width: 88px; bottom: 0px;"
+    >
+      Content
+    </div>
+  </div>
+</div>
+`;
+
+exports[`should sticky inside container bottom when using container prop 2`] = `
+<div style="margin-top: 640px;">
+  <div style="height: 150px;">
+  </div>
+  <div style="height: 44px; width: 88px;">
+    <div class="van-sticky van-sticky--fixed"
+         style="height: 44px; width: 88px; bottom: 0px; transform: translate3d(0, 24px, 0);"
+    >
+      Content
+    </div>
+  </div>
+</div>
+`;
+
+exports[`should sticky inside container when using container prop 1`] = `
+<div style="height: 150px;">
+  <div style="height: 44px; width: 88px;">
+    <div class="van-sticky van-sticky--fixed"
+         style="height: 44px; width: 88px; top: 0px;"
     >
       Content
     </div>
@@ -43,26 +71,32 @@ exports[`should sticky inside container when using container prop 1`] = `
 `;
 
 exports[`should sticky inside container when using container prop 2`] = `
-<div style="height: 20px;">
-  <div style="height: 10px;">
-    <div class="van-sticky">
+<div style="height: 150px;">
+  <div style="height: 44px; width: 88px;">
+    <div class="van-sticky van-sticky--fixed"
+         style="height: 44px; width: 88px; top: 0px; transform: translate3d(0, -14px, 0);"
+    >
       Content
     </div>
   </div>
 </div>
 `;
 
-exports[`should sticky to top after scrolling 1`] = `
+exports[`should sticky to bottom after scrolling 1`] = `
 <div style="height: 10px;">
-  <div class="van-sticky">
+  <div class="van-sticky van-sticky--fixed"
+       style="bottom: 10px;"
+  >
     Content
   </div>
 </div>
 `;
 
-exports[`should sticky to top after scrolling 2`] = `
+exports[`should sticky to top after scrolling 1`] = `
 <div style="height: 10px;">
-  <div class="van-sticky van-sticky--fixed">
+  <div class="van-sticky van-sticky--fixed"
+       style="top: 0px;"
+  >
     Content
   </div>
 </div>
@@ -71,7 +105,7 @@ exports[`should sticky to top after scrolling 2`] = `
 exports[`should update z-index when using z-index prop 1`] = `
 <div style="height: 10px;">
   <div class="van-sticky van-sticky--fixed"
-       style="z-index: 0;"
+       style="top: 0px; z-index: 0;"
   >
     Content
   </div>
diff --git a/src/sticky/test/index.spec.js b/src/sticky/test/index.spec.js
index 06762145d..2471acd47 100644
--- a/src/sticky/test/index.spec.js
+++ b/src/sticky/test/index.spec.js
@@ -1,19 +1,51 @@
 import { nextTick, ref } from 'vue';
-import { mount, mockScrollTop } from '../../../test';
+import { mockScrollTop, mount } from '../../../test';
 import Sticky from '..';
 
+Object.defineProperty(window.HTMLElement.prototype, 'clientHeight', {
+  value: 640,
+});
+
 test('should sticky to top after scrolling', async () => {
   const wrapper = mount({
     render() {
       return <Sticky style="height: 10px;">Content</Sticky>;
     },
   });
-
-  expect(wrapper.html()).toMatchSnapshot();
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: -90,
+    });
 
   await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
+
+  mockStickyRect.mockRestore();
+});
+
+test('should sticky to bottom after scrolling', async () => {
+  const wrapper = mount({
+    render() {
+      return (
+        <Sticky style="height: 10px;" offsetBottom={10} position="bottom">
+          Content
+        </Sticky>
+      );
+    },
+  });
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: 640,
+      bottom: 650,
+    });
+
   await mockScrollTop(0);
+  expect(wrapper.html()).toMatchSnapshot();
+
+  mockStickyRect.mockRestore();
 });
 
 test('should update z-index when using z-index prop', async () => {
@@ -27,25 +59,41 @@ test('should update z-index when using z-index prop', async () => {
     },
   });
 
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: -90,
+    });
+
   await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
-  await mockScrollTop(0);
+
+  mockStickyRect.mockRestore();
 });
 
 test('should add offset top when using offset-top prop', async () => {
   const wrapper = mount({
     render() {
       return (
-        <Sticky style="height: 10px;" offsetTop={10}>
+        <Sticky style="height: 10px;" offsetTop={10} position="top">
           Content
         </Sticky>
       );
     },
   });
 
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: -90,
+    });
+
   await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
-  await mockScrollTop(0);
+
+  mockStickyRect.mockRestore();
 });
 
 test('should allow to using offset-top prop with rem unit', async () => {
@@ -63,10 +111,17 @@ test('should allow to using offset-top prop with rem unit', async () => {
     },
   });
 
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: -90,
+    });
+
   await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
 
-  await mockScrollTop(0);
+  mockStickyRect.mockRestore();
   window.getComputedStyle = originGetComputedStyle;
 });
 
@@ -83,9 +138,17 @@ test('should allow to using offset-top prop with vw unit', async () => {
     },
   });
 
+  const mockStickyRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: -90,
+    });
+
   await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
-  await mockScrollTop(0);
+
+  mockStickyRect.mockRestore();
 });
 
 test('should not trigger scroll event when hidden', () => {
@@ -114,8 +177,8 @@ test('should sticky inside container when using container prop', async () => {
     },
     render() {
       return (
-        <div ref="container" style="height: 20px;">
-          <Sticky ref="sticky" style="height: 10px;" container={this.container}>
+        <div ref="container" style="height: 150px;">
+          <Sticky ref="sticky" style="height: 44px;" container={this.container}>
             Content
           </Sticky>
         </div>
@@ -123,12 +186,97 @@ test('should sticky inside container when using container prop', async () => {
     },
   });
 
-  await nextTick();
-  await mockScrollTop(15);
+  const mockStickyRect = jest
+    .spyOn(wrapper.element.firstElementChild, 'getBoundingClientRect')
+    .mockReturnValue({
+      height: 44,
+      width: 88,
+      top: -100,
+      bottom: -56,
+    });
+  const mockContainerRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: -100,
+      bottom: 50,
+    });
+
+  await mockScrollTop(100);
   expect(wrapper.html()).toMatchSnapshot();
-  await mockScrollTop(25);
+
+  mockStickyRect.mockReturnValue({
+    height: 44,
+    width: 88,
+    top: -120,
+    bottom: -76,
+  });
+  mockContainerRect.mockReturnValue({
+    top: -120,
+    bottom: 30,
+  });
+  await mockScrollTop(120);
   expect(wrapper.html()).toMatchSnapshot();
-  await mockScrollTop(0);
+  mockContainerRect.mockRestore();
+  mockStickyRect.mockRestore();
+});
+
+test('should sticky inside container bottom when using container prop', async () => {
+  const wrapper = mount({
+    setup() {
+      const container = ref();
+      return {
+        container,
+      };
+    },
+    render() {
+      return (
+        <div ref="container" style="margin-top: 640px">
+          <div style="height: 150px" />
+          <Sticky
+            ref="sticky"
+            style="height: 44px;"
+            container={this.container}
+            position="bottom"
+          >
+            Content
+          </Sticky>
+        </div>
+      );
+    },
+  });
+
+  const mockStickyRect = jest
+    .spyOn(wrapper.element.children[1], 'getBoundingClientRect')
+    .mockReturnValue({
+      height: 44,
+      width: 88,
+      top: 690,
+      bottom: 734,
+    });
+  const mockContainerRect = jest
+    .spyOn(wrapper.element, 'getBoundingClientRect')
+    .mockReturnValue({
+      top: 540,
+      bottom: 734,
+    });
+
+  await mockScrollTop(100);
+  expect(wrapper.html()).toMatchSnapshot();
+
+  mockStickyRect.mockReturnValue({
+    height: 44,
+    width: 88,
+    top: 770,
+    bottom: 814,
+  });
+  mockContainerRect.mockReturnValue({
+    top: 620,
+    bottom: 814,
+  });
+  await mockScrollTop(20);
+  expect(wrapper.html()).toMatchSnapshot();
+  mockContainerRect.mockRestore();
+  mockStickyRect.mockRestore();
 });
 
 test('should emit scroll event when visibility changed', async () => {