feat(Splitter): add lazy mode

components/splitter/SplitBar.tsx

@@ -4,6 +4,7 @@ import LeftOutlined from '@ant-design/icons/LeftOutlined';
 import RightOutlined from '@ant-design/icons/RightOutlined';
 import UpOutlined from '@ant-design/icons/UpOutlined';
 import classNames from 'classnames';
+import { useEvent } from 'rc-util';
 
 export interface SplitBarProps {
   index: number;
@@ -20,6 +21,8 @@ export interface SplitBarProps {
   ariaNow: number;
   ariaMin: number;
   ariaMax: number;
+  lazy?: boolean;
+  containerSize: number;
 }
 
 function getValidNumber(num: number | undefined): number {
@@ -42,12 +45,15 @@ const SplitBar: React.FC<SplitBarProps> = (props) => {
     onOffsetUpdate,
     onOffsetEnd,
     onCollapse,
+    lazy,
+    containerSize,
   } = props;
 
   const splitBarPrefixCls = `${prefixCls}-bar`;
 
   // ======================== Resize ========================
   const [startPos, setStartPos] = useState<[x: number, y: number] | null>(null);
+  const [constrainedOffset, setConstrainedOffset] = useState<[x: number, y: number] | null>(null);
 
   const onMouseDown: React.MouseEventHandler<HTMLDivElement> = (e) => {
     if (resizable && e.currentTarget) {
@@ -64,17 +70,55 @@ const SplitBar: React.FC<SplitBarProps> = (props) => {
     }
   };
 
+  // Updated constraint calculation
+  const getConstrainedOffset = (rawOffset: number) => {
+    const currentPos = (containerSize * ariaNow) / 100;
+    const newPos = currentPos + rawOffset;
+
+    // Calculate available space
+    const minAllowed = Math.max(0, (containerSize * ariaMin) / 100);
+    const maxAllowed = Math.min(containerSize, (containerSize * ariaMax) / 100);
+
+    // Constrain new position within bounds
+    const clampedPos = Math.max(minAllowed, Math.min(maxAllowed, newPos));
+    return clampedPos - currentPos;
+  };
+
+  const handleLazyMove = useEvent((offsetX: number, offsetY: number) => {
+    const constrainedOffsetValue = getConstrainedOffset(vertical ? offsetY : offsetX);
+    setConstrainedOffset(vertical ? [0, constrainedOffsetValue] : [constrainedOffsetValue, 0]);
+  });
+
+  const handleLazyEnd = useEvent(() => {
+    const constrainedOffsetValue = getConstrainedOffset(
+      vertical ? (constrainedOffset?.[1] ?? 0) : (constrainedOffset?.[0] ?? 0),
+    );
+    onOffsetUpdate(
+      index,
+      vertical ? 0 : constrainedOffsetValue,
+      vertical ? constrainedOffsetValue : 0,
+    );
+    setConstrainedOffset(null);
+  });
+
   React.useEffect(() => {
     if (startPos) {
       const onMouseMove = (e: MouseEvent) => {
         const { pageX, pageY } = e;
         const offsetX = pageX - startPos[0];
         const offsetY = pageY - startPos[1];
 
-        onOffsetUpdate(index, offsetX, offsetY);
+        if (lazy) {
+          handleLazyMove(offsetX, offsetY);
+        } else {
+          onOffsetUpdate(index, offsetX, offsetY);
+        }
       };
 
       const onMouseUp = () => {
+        if (lazy) {
+          handleLazyEnd();
+        }
         setStartPos(null);
         onOffsetEnd();
       };
@@ -85,11 +129,18 @@ const SplitBar: React.FC<SplitBarProps> = (props) => {
           const offsetX = touch.pageX - startPos[0];
           const offsetY = touch.pageY - startPos[1];
 
-          onOffsetUpdate(index, offsetX, offsetY);
+          if (lazy) {
+            handleLazyMove(offsetX, offsetY);
+          } else {
+            onOffsetUpdate(index, offsetX, offsetY);
+          }
         }
       };
 
       const handleTouchEnd = () => {
+        if (lazy) {
+          handleLazyEnd();
+        }
         setStartPos(null);
         onOffsetEnd();
       };
@@ -106,7 +157,12 @@ const SplitBar: React.FC<SplitBarProps> = (props) => {
         window.removeEventListener('touchend', handleTouchEnd);
       };
     }
-  }, [startPos]);
+  }, [startPos, lazy, vertical, index, containerSize, ariaNow, ariaMin, ariaMax]);
+
+  const transformStyle = {
+    [`--${splitBarPrefixCls}-preview-translate-x`]: `${constrainedOffset?.[0] ?? 0}px`,
+    [`--${splitBarPrefixCls}-preview-translate-y`]: `${constrainedOffset?.[1] ?? 0}px`,
+  };
 
   // ======================== Render ========================
   const StartIcon = vertical ? UpOutlined : LeftOutlined;
@@ -120,6 +176,15 @@ const SplitBar: React.FC<SplitBarProps> = (props) => {
       aria-valuemin={getValidNumber(ariaMin)}
       aria-valuemax={getValidNumber(ariaMax)}
     >
+      {lazy && (
+        <div
+          className={classNames(`${splitBarPrefixCls}-preview`, {
+            [`${splitBarPrefixCls}-preview-active`]: !!constrainedOffset,
+          })}
+          style={transformStyle}
+        />
+      )}
+
       <div
         className={classNames(`${splitBarPrefixCls}-dragger`, {
           [`${splitBarPrefixCls}-dragger-disabled`]: !resizable,

components/splitter/Splitter.tsx

@@ -28,6 +28,7 @@ const Splitter: React.FC<React.PropsWithChildren<SplitterProps>> = (props) => {
     onResizeStart,
     onResize,
     onResizeEnd,
+    lazy,
   } = props;
 
   const { getPrefixCls, direction, splitter } = React.useContext(ConfigContext);
@@ -170,6 +171,7 @@ const Splitter: React.FC<React.PropsWithChildren<SplitterProps>> = (props) => {
 
             splitBar = (
               <SplitBar
+                lazy={lazy}
                 index={idx}
                 active={movingIndex === idx}
                 prefixCls={prefixCls}
@@ -190,6 +192,7 @@ const Splitter: React.FC<React.PropsWithChildren<SplitterProps>> = (props) => {
                 }}
                 onOffsetEnd={onInternalResizeEnd}
                 onCollapse={onInternalCollapse}
+                containerSize={containerSize || 0}
               />
             );
           }

components/splitter/__tests__/__snapshots__/demo-extend.test.ts.snap

@@ -562,6 +562,128 @@ exports[`renders components/splitter/demo/group.tsx extend context correctly 1`]
 
 exports[`renders components/splitter/demo/group.tsx extend context correctly 2`] = `[]`;
 
+exports[`renders components/splitter/demo/lazy.tsx extend context correctly 1`] = `
+<div
+  class="ant-space ant-space-vertical ant-space-gap-row-small ant-space-gap-col-small"
+  style="width: 100%;"
+>
+  <div
+    class="ant-space-item"
+  >
+    <div
+      class="ant-splitter ant-splitter-horizontal"
+      style="height: 200px; box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);"
+    >
+      <div
+        class="ant-splitter-panel"
+        style="flex-basis: 40%; flex-grow: 0;"
+      >
+        <div
+          class="ant-flex ant-flex-align-center ant-flex-justify-center"
+          style="height: 100%;"
+        >
+          <h5
+            class="ant-typography ant-typography-secondary"
+            style="white-space: nowrap;"
+          >
+            First
+          </h5>
+        </div>
+      </div>
+      <div
+        aria-valuemax="0"
+        aria-valuemin="0"
+        aria-valuenow="40"
+        class="ant-splitter-bar"
+        role="separator"
+      >
+        <div
+          class="ant-splitter-bar-preview"
+          style="--ant-splitter-bar-preview-translate-x: 0px; --ant-splitter-bar-preview-translate-y: 0px;"
+        />
+        <div
+          class="ant-splitter-bar-dragger ant-splitter-bar-dragger-disabled"
+        />
+      </div>
+      <div
+        class="ant-splitter-panel"
+        style="flex-basis: auto; flex-grow: 1;"
+      >
+        <div
+          class="ant-flex ant-flex-align-center ant-flex-justify-center"
+          style="height: 100%;"
+        >
+          <h5
+            class="ant-typography ant-typography-secondary"
+            style="white-space: nowrap;"
+          >
+            Second
+          </h5>
+        </div>
+      </div>
+    </div>
+  </div>
+  <div
+    class="ant-space-item"
+  >
+    <div
+      class="ant-splitter ant-splitter-vertical"
+      style="height: 200px; box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);"
+    >
+      <div
+        class="ant-splitter-panel"
+        style="flex-basis: 40%; flex-grow: 0;"
+      >
+        <div
+          class="ant-flex ant-flex-align-center ant-flex-justify-center"
+          style="height: 100%;"
+        >
+          <h5
+            class="ant-typography ant-typography-secondary"
+            style="white-space: nowrap;"
+          >
+            First
+          </h5>
+        </div>
+      </div>
+      <div
+        aria-valuemax="0"
+        aria-valuemin="0"
+        aria-valuenow="40"
+        class="ant-splitter-bar"
+        role="separator"
+      >
+        <div
+          class="ant-splitter-bar-preview"
+          style="--ant-splitter-bar-preview-translate-x: 0px; --ant-splitter-bar-preview-translate-y: 0px;"
+        />
+        <div
+          class="ant-splitter-bar-dragger ant-splitter-bar-dragger-disabled"
+        />
+      </div>
+      <div
+        class="ant-splitter-panel"
+        style="flex-basis: auto; flex-grow: 1;"
+      >
+        <div
+          class="ant-flex ant-flex-align-center ant-flex-justify-center"
+          style="height: 100%;"
+        >
+          <h5
+            class="ant-typography ant-typography-secondary"
+            style="white-space: nowrap;"
+          >
+            Second
+          </h5>
+        </div>
+      </div>
+    </div>
+  </div>
+</div>
+`;
+
+exports[`renders components/splitter/demo/lazy.tsx extend context correctly 2`] = `[]`;
+
 exports[`renders components/splitter/demo/multiple.tsx extend context correctly 1`] = `
 <div
   class="ant-splitter ant-splitter-horizontal"