✨(component): [dropdown]下拉面板位置自适应

package/component/src/component/cascader/index.less

@@ -42,6 +42,6 @@
   background-color: var(--global-checked-color);
   color: white;
 }
-.layui-cascader.layui-dropdown-up > dl {
-  min-width: unset;
-}
+// .layui-cascader.layui-dropdown-up > dl {
+//   min-width: unset;
+// }

package/component/src/component/cascader/index.vue

@@ -1,5 +1,5 @@
 <template>
-  <lay-dropdown class="layui-cascader" ref="dropdownRef">
+  <lay-dropdown class="layui-cascader" ref="dropdownRef"  :autoFitMinWidth="false">
     <lay-input
       v-model="displayValue"
       readonly

package/component/src/component/dropdown/index.less

@@ -6,9 +6,7 @@
 .layui-dropdown dl {
   display: none;
   position: absolute;
-  margin-top: 2px;
   z-index: 899;
-  min-width: 100%;
   background-color: #fff;
   box-sizing: border-box;
   border: 1px solid #e4e7ed;

package/component/src/component/dropdown/index.vue

@@ -6,37 +6,50 @@ export default {
 
 <script setup lang="ts">
 import "./index.less";
-import { provide, ref } from "vue";
-import { onClickOutside } from "@vueuse/core";
-import { DropdownTrigger } from "./interface";
+import { CSSProperties, nextTick, provide, ref, shallowRef, watch, watchEffect } from "vue";
+import { onClickOutside, useWindowSize } from "@vueuse/core";
+import { DropdownTrigger, dropdownPlacement } from "./interface";
 
 export interface LayDropdownProps {
   trigger?: DropdownTrigger;
+  placement?: dropdownPlacement;
   disabled?: boolean;
+  autoFitPlacement?: boolean;
+  autoFitWidth?: boolean;
+  autoFitMinWidth?: boolean; 
 }
 
 const props = withDefaults(defineProps<LayDropdownProps>(), {
   trigger: "click",
   disabled: false,
+  placement: 'bottom-left',
+  autoFitPlacement: true,
+  autoFitMinWidth: true,
+  autoFitWidth: false,
 });
 
+const dropdownRef = shallowRef<null | HTMLElement>();
+const contentRef = shallowRef<null | HTMLElement>();
+const contentStyle = ref<CSSProperties>({});
+const { width: windowWidth, height: windowHeight } = useWindowSize();
 const openState = ref(false);
-const dropdownRef = ref<null | HTMLElement>();
+const contentSpace = 2;
+
 const emit = defineEmits(["open", "hide"]);
 
 onClickOutside(dropdownRef, () => {
-  openState.value = false;
+  changeVisible(false)
 });
 
 const open = (): void => {
   if (props.disabled == false) {
-    openState.value = true;
+    changeVisible(true);
     emit("open");
   }
 };
 
 const hide = (): void => {
-  openState.value = false;
+  changeVisible(false);
   emit("hide");
 };
 
@@ -49,26 +62,172 @@ const toggle = (): void => {
     }
 };
 
+const changeVisible = (visible: boolean) => {
+  if (visible === openState.value) {
+    return;
+  }
+  openState.value = visible;
+  nextTick(() => {
+    updateContentStyle();
+  });
+}
+
+const updateContentStyle = () => {
+  if (!dropdownRef.value || !contentRef.value){
+    return
+  }
+  const triggerRect = dropdownRef.value.getBoundingClientRect()
+  const contentRect = contentRef.value.getBoundingClientRect()
+  const { style } = getContentStyle(
+    props.placement, 
+    triggerRect, 
+    contentRect, 
+    {autoFitPlacement: props.autoFitPlacement}
+  );
+
+  if (props.autoFitMinWidth) {
+    style.minWidth = `${triggerRect.width}px`;
+  } 
+  if (props.autoFitWidth) {
+    style.width = `${triggerRect.width}px`;
+  }
+  
+  contentStyle.value = style
+}
+
+const getContentStyle = (
+  placement: dropdownPlacement,
+  triggerRect: DOMRect,
+  contentRect: DOMRect,
+  {
+    autoFitPlacement = false,
+    customStyle = {}
+  }: {
+    autoFitPlacement?: boolean;
+    customStyle?: CSSProperties;
+  } = {}
+) => {
+  let { top, left } = getContentOffset(placement, triggerRect, contentRect)
+  if(autoFitPlacement){
+    const { top: fitTop, left: fitLeft } = getFitPlacement(top, left, placement, triggerRect, contentRect)
+    top = fitTop;
+    left = fitLeft;
+  }
+  const style = {
+    top: `${top}px`,
+    left: `${left}px`,
+    ...customStyle,
+  }
+  return {
+    style
+  }
+}
+
+const getFitPlacement = (
+  top: number, 
+  left: number, 
+  placement: dropdownPlacement,
+  triggerRect: DOMRect,
+  contentRect: DOMRect
+) => {
+  // 溢出屏幕底部
+  if (triggerRect.bottom + contentRect.height > windowHeight.value) {
+    top = -contentRect.height - contentSpace
+  }
+  // 溢出屏幕顶部
+  if (triggerRect.top - contentRect.height < 0) {
+    top = triggerRect.height + contentSpace
+  }
+  if(["bottom-right", "top-right"].includes(placement) ){
+    // 溢出屏幕左边
+    const contentRectLeft = triggerRect.left - (contentRect.width - triggerRect.width)
+    if (contentRectLeft < 0) {
+      left = left + (0 - contentRectLeft)
+    }
+  }
+
+  if(["bottom-left", "top-left"].includes(placement)){
+    // 溢出屏幕右边
+    const contentRectRight = triggerRect.right + (contentRect.width - triggerRect.width)
+    if (contentRectRight > windowWidth.value) {
+      left = left - (contentRectRight - windowWidth.value)
+    }
+  }
+
+  if(["bottom", "top"].includes(placement)){
+    const contentRectLeft = triggerRect.left - (contentRect.width - triggerRect.width) / 2
+    const contentRectRight = triggerRect.right + (contentRect.width - triggerRect.width) / 2
+    // 溢出屏幕左边
+    if (contentRectLeft < 0) {
+      left = left + (0 - contentRectLeft)
+    }
+    // 溢出屏幕右边
+    if (contentRectRight > windowWidth.value) {
+      left = left - (contentRectRight - windowWidth.value)
+    }
+  }
+  return {
+    top,
+    left
+  }
+}
+
+const getContentOffset = (
+  placement: dropdownPlacement,
+  triggerRect: DOMRect, 
+  contentRect: DOMRect
+) => {
+  switch (placement) {
+    case "top":
+      return {
+        top: -contentRect.height - contentSpace,
+        left: -(contentRect.width - triggerRect.width) / 2
+      }
+    case "top-left":
+      return {
+        top: -contentRect.height - contentSpace,
+        left: 0
+      }
+    case "top-right":
+      return {
+        top: -contentRect.height - contentSpace,
+        left: -(contentRect.width - triggerRect.width)
+      }
+    case "bottom":
+      return {
+        top: triggerRect.height + contentSpace,
+        left: -(contentRect.width - triggerRect.width) / 2
+      }
+    case "bottom-left":
+      return {
+        top: triggerRect.height + contentSpace,
+        left: 0
+      }
+    case "bottom-right":
+      return {
+        top: triggerRect.height + contentSpace,
+        left: -(contentRect.width - triggerRect.width)
+      }
+    default:
+      return {
+        left: 0,
+        top: 0,
+      };
+  }
+}
+
 provide("openState", openState);
 
 defineExpose({ open, hide, toggle });
 </script>
 
 <template>
-  <div
-    ref="dropdownRef"
-    class="layui-dropdown"
-    @mouseenter="trigger == 'hover' && open()"
-    @mouseleave="trigger == 'hover' && hide()"
-    :class="{ 'layui-dropdown-up': openState }"
-  >
-    <div
-      @click="trigger == 'click' && toggle()"
-      @contextmenu.prevent="trigger == 'contextMenu' && toggle()"
-    >
+  <div ref="dropdownRef" class="layui-dropdown" @mouseenter="trigger == 'hover' && open()"
+    @mouseleave="trigger == 'hover' && hide()" :class="{ 'layui-dropdown-up': openState }">
+    <div @click="trigger == 'click' && toggle()" @contextmenu.prevent="trigger == 'contextMenu' && toggle()">
       <slot></slot>
     </div>
-    <dl class="layui-anim layui-anim-upbit">
+    <dl ref="contentRef" class="layui-anim layui-anim-upbit" :style="contentStyle">
       <slot name="content"></slot>
     </dl>
   </div>

package/component/src/component/dropdown/interface.ts

@@ -1 +1,2 @@
 export type DropdownTrigger = "click" | "hover" | "contextMenu";
+export type dropdownPlacement = 'top' | 'top-left' | 'top-right' | 'bottom' | 'bottom-left' | 'bottom-right';