feat(Slider): button slot add dragging param (#11946)

* feat(Slider): button slot add dragging param

* test(Slider): add test case

packages/vant/src/slider/README.md

@@ -175,11 +175,11 @@ export default {
 
 ### Slots
 
-| Name         | Description                       | SlotProps           |
-| ------------ | --------------------------------- | ------------------- |
-| button       | Custom button                     | _{ value: number }_ |
-| left-button  | Custom left button in range mode  | _{ value: number }_ |
-| right-button | Custom right button in range mode | _{ value: number }_ |
+| Name | Description | SlotProps |
+| --- | --- | --- |
+| button | Custom button | _{ value: number, dragging: boolean }_ |
+| left-button | Custom left button in range mode | _{ value: number, dragging: boolean, dragIndex?: number }_ |
+| right-button | Custom right button in range mode | _{ value: number, dragging: boolean, dragIndex?: number }_ |
 
 ### Types
 

packages/vant/src/slider/README.zh-CN.md

@@ -177,11 +177,11 @@ export default {
 
 ### Slots
 
-| 名称         | 说明                               | 参数                |
-| ------------ | ---------------------------------- | ------------------- |
-| button       | 自定义滑块按钮                     | _{ value: number }_ |
-| left-button  | 自定义左侧滑块按钮（双滑块模式下） | _{ value: number }_ |
-| right-button | 自定义右侧滑块按钮（双滑块模式下） | _{ value: number }_ |
+| 名称 | 说明 | 参数 |
+| --- | --- | --- |
+| button | 自定义滑块按钮 | _{ value: number, dragging: boolean }_ |
+| left-button | 自定义左侧滑块按钮（双滑块模式下） | _{ value: number, dragging: boolean, dragIndex?: number }_ |
+| right-button | 自定义右侧滑块按钮（双滑块模式下） | _{ value: number, dragging: boolean, dragIndex?: number }_ |
 
 ### 类型定义
 

packages/vant/src/slider/Slider.tsx

@@ -273,15 +273,23 @@ export default defineComponent({
     };
 
     const renderButtonContent = (value: number, index?: 0 | 1) => {
+      const dragging = dragStatus.value === 'dragging';
+
       if (typeof index === 'number') {
         const slot = slots[index === 0 ? 'left-button' : 'right-button'];
+        let dragIndex;
+
+        if (dragging && Array.isArray(current)) {
+          dragIndex = current[0] > current[1] ? buttonIndex ^ 1 : buttonIndex;
+        }
+
         if (slot) {
-          return slot({ value });
+          return slot({ value, dragging, dragIndex });
         }
       }
 
       if (slots.button) {
-        return slots.button({ value });
+        return slots.button({ value, dragging });
       }
 
       return (

packages/vant/src/slider/test/index.spec.ts

@@ -16,6 +16,16 @@ function mockRect(vertical?: boolean) {
   });
 }
 
+function testSlotReceivedParams(
+  slot: ReturnType<typeof jest.fn>,
+  dragging: boolean,
+  dragIndex?: number
+) {
+  const latestParams = slot.mock.calls.at(-1)![0];
+  expect(latestParams.dragging).toEqual(dragging);
+  expect(latestParams.dragIndex).toEqual(dragIndex);
+}
+
 test('should emit "update:modelValue" event after dragging button', () => {
   const wrapper = mount(Slider, {
     props: {
@@ -225,20 +235,84 @@ test('should format v-model with step correctly', async () => {
   expect(wrapper.emitted('update:modelValue')![0]).toEqual([31]);
 });
 
+test('should render button slot correctly', async () => {
+  const buttonSlot = jest.fn();
+  const wrapper = mount(Slider, {
+    props: {
+      modelValue: 30,
+    },
+    slots: {
+      button: buttonSlot,
+    },
+  });
+
+  expect(buttonSlot.mock.calls[0]).toEqual([{ value: 30, dragging: false }]);
+
+  const button = wrapper.find('.van-slider__button-wrapper');
+
+  trigger(button, 'touchstart', 50, 0);
+  trigger(button, 'touchmove', 50, 0);
+  await later();
+  testSlotReceivedParams(buttonSlot, true);
+
+  trigger(button, 'touchend', 50, 0);
+  await later();
+  testSlotReceivedParams(buttonSlot, false);
+});
+
 test('should render left-button、right-button slot correctly', async () => {
+  const leftButtonSlot = jest.fn();
+  const rightButtonSlot = jest.fn();
   const wrapper = mount(Slider, {
     props: {
       range: true,
       modelValue: [30, 80],
     },
     slots: {
-      'left-button': ({ value }) => `left-${value}`,
-      'right-button': ({ value }) => `right-${value}`,
+      'left-button': (params) => {
+        leftButtonSlot(params);
+        return `left-${params.value}`;
+      },
+      'right-button': (params) => {
+        rightButtonSlot(params);
+        return `right-${params.value}`;
+      },
     },
   });
 
-  await later();
+  expect(leftButtonSlot.mock.calls[0]).toEqual([
+    { value: 30, dragging: false, dragIndex: undefined },
+  ]);
+  expect(rightButtonSlot.mock.calls[0]).toEqual([
+    { value: 80, dragging: false, dragIndex: undefined },
+  ]);
   expect(wrapper.html()).toMatchSnapshot();
+
+  const [leftButton, rightButton] = wrapper.findAll(
+    '.van-slider__button-wrapper'
+  );
+
+  trigger(leftButton, 'touchstart', 50, 0);
+  trigger(leftButton, 'touchmove', 50, 0);
+  await later();
+  testSlotReceivedParams(leftButtonSlot, true, 0);
+  testSlotReceivedParams(rightButtonSlot, true, 0);
+
+  trigger(leftButton, 'touchend', 50, 0);
+  await later();
+  testSlotReceivedParams(leftButtonSlot, false, undefined);
+  testSlotReceivedParams(rightButtonSlot, false, undefined);
+
+  trigger(rightButton, 'touchstart', 50, 0);
+  trigger(rightButton, 'touchmove', 50, 0);
+  await later();
+  testSlotReceivedParams(leftButtonSlot, true, 1);
+  testSlotReceivedParams(rightButtonSlot, true, 1);
+
+  trigger(rightButton, 'touchend', 50, 0);
+  await later();
+  testSlotReceivedParams(leftButtonSlot, false, undefined);
+  testSlotReceivedParams(rightButtonSlot, false, undefined);
 });
 
 test('should render reversed slider correctly', () => {