KGPython/vue/node_modules/@antv/g6/esm/utils/pinch.js

import { CommonEvent } from '../constants';
/**
 * <zh/> 捏合手势处理器
 *
 * <en/> Pinch gesture handler
 * @remarks
 * <zh/> 处理双指触摸事件，计算缩放比例并触发回调。通过跟踪两个触摸点的位置变化，计算两点间距离变化率来确定缩放比例。
 *
 * <en/> Handles two-finger touch events, calculates zoom ratio and triggers callbacks. Tracks position changes of two touch points to determine zoom ratio based on distance variation.
 */
export class PinchHandler {
    constructor(emitter, phase, callback) {
        this.phase = phase;
        /**
         * <zh/> 当前跟踪的触摸点集合
         *
         * <en/> Currently tracked touch points collection
         */
        this.pointerByTouch = [];
        /**
         * <zh/> 初始两点间距离
         *
         * <en/> Initial distance between two points
         */
        this.initialDistance = null;
        this.emitter = emitter;
        if (PinchHandler.instance) {
            PinchHandler.callbacks[this.phase].push(callback);
            return PinchHandler.instance;
        }
        this.onPointerDown = this.onPointerDown.bind(this);
        this.onPointerMove = this.onPointerMove.bind(this);
        this.onPointerUp = this.onPointerUp.bind(this);
        this.bindEvents();
        PinchHandler.instance = this;
        PinchHandler.callbacks[this.phase].push(callback);
    }
    bindEvents() {
        const { emitter } = this;
        emitter.on(CommonEvent.POINTER_DOWN, this.onPointerDown);
        emitter.on(CommonEvent.POINTER_MOVE, this.onPointerMove);
        emitter.on(CommonEvent.POINTER_UP, this.onPointerUp);
    }
    /**
     * <zh/> 更新指定指针的位置
     *
     * <en/> Update position of specified pointer
     * @param pointerId - <zh/> 指针唯一标识符 | <en/> Pointer unique identifier<sup>1</sup>
     * @param x - <zh/> 新的X坐标 | <en/> New X coordinate
     * @param y - <zh/> 新的Y坐标 | <en/> New Y coordinate
     */
    updatePointerPosition(pointerId, x, y) {
        const index = this.pointerByTouch.findIndex((p) => p.pointerId === pointerId);
        if (index >= 0) {
            this.pointerByTouch[index] = { x, y, pointerId };
        }
    }
    /**
     * <zh/> 处理指针按下事件
     *
     * <en/> Handle pointer down event
     * @param event - <zh/> 指针事件对象 | <en/> Pointer event object
     * @remarks
     * <zh/> 当检测到两个触摸点时记录初始距离
     *
     * <en/> Record initial distance when detecting two touch points
     */
    onPointerDown(event) {
        const { x, y } = event.client || {};
        if (x === undefined || y === undefined)
            return;
        this.pointerByTouch.push({ x, y, pointerId: event.pointerId });
        if (event.pointerType === 'touch' && this.pointerByTouch.length === 2) {
            PinchHandler.isPinching = true;
            const dx = this.pointerByTouch[0].x - this.pointerByTouch[1].x;
            const dy = this.pointerByTouch[0].y - this.pointerByTouch[1].y;
            this.initialDistance = Math.sqrt(dx * dx + dy * dy);
            PinchHandler.callbacks.pinchstart.forEach((cb) => cb(event, { scale: 0 }));
        }
    }
    /**
     * <zh/> 处理指针移动事件
     *
     * <en/> Handle pointer move event
     * @param event - <zh/> 指针事件对象 | <en/> Pointer event object
     * @remarks
     * <zh/> 当存在两个有效触摸点时计算缩放比例
     *
     * <en/> Calculate zoom ratio when two valid touch points exist
     */
    onPointerMove(event) {
        if (this.pointerByTouch.length !== 2 || this.initialDistance === null)
            return;
        const { x, y } = event.client || {};
        if (x === undefined || y === undefined)
            return;
        this.updatePointerPosition(event.pointerId, x, y);
        const dx = this.pointerByTouch[0].x - this.pointerByTouch[1].x;
        const dy = this.pointerByTouch[0].y - this.pointerByTouch[1].y;
        const currentDistance = Math.sqrt(dx * dx + dy * dy);
        const ratio = currentDistance / this.initialDistance;
        PinchHandler.callbacks.pinchmove.forEach((cb) => cb(event, { scale: (ratio - 1) * 5 }));
    }
    /**
     * <zh/> 处理指针抬起事件
     *
     * <en/> Handle pointer up event
     * @param event
     * @remarks
     * <zh/> 重置触摸状态和初始距离
     *
     * <en/> Reset touch state and initial distance
     */
    onPointerUp(event) {
        var _a;
        PinchHandler.callbacks.pinchend.forEach((cb) => cb(event, { scale: 0 }));
        PinchHandler.isPinching = false;
        this.initialDistance = null;
        this.pointerByTouch = [];
        (_a = PinchHandler.instance) === null || _a === void 0 ? void 0 : _a.tryDestroy();
    }
    /**
     * <zh/> 销毁捏合手势相关监听
     *
     * <en/> Destroy pinch gesture listeners
     * @remarks
     * <zh/> 移除指针按下、移动、抬起事件的监听
     *
     * <en/> Remove listeners for pointer down, move, and up events
     */
    destroy() {
        this.emitter.off(CommonEvent.POINTER_DOWN, this.onPointerDown);
        this.emitter.off(CommonEvent.POINTER_MOVE, this.onPointerMove);
        this.emitter.off(CommonEvent.POINTER_UP, this.onPointerUp);
        PinchHandler.instance = null;
    }
    /**
     * <zh/> 解绑指定阶段的手势回调
     * <en/> Unregister gesture callback for specific phase
     * @param phase - <zh/> 手势阶段：开始(pinchstart)/移动(pinchmove)/结束(pinchend) | <en/> Gesture phase: start/move/end
     * @param callback - <zh/> 要解绑的回调函数 | <en/> Callback function to unregister
     * @remarks
     * <zh/> 从指定阶段的回调列表中移除特定回调，当所有回调都解绑后自动销毁事件监听
     * <en/> Remove specific callback from the phase's callback list, auto-destroy event listeners when all callbacks are unregistered
     */
    off(phase, callback) {
        const index = PinchHandler.callbacks[phase].indexOf(callback);
        if (index > -1)
            PinchHandler.callbacks[phase].splice(index, 1);
        this.tryDestroy();
    }
    /**
     * <zh/> 尝试销毁手势处理器
     * <en/> Attempt to destroy the gesture handler
     * @remarks
     * <zh/> 当所有阶段（开始/移动/结束）的回调列表都为空时，执行实际销毁操作
     * <en/> Perform actual destruction when all phase (pinchstart/pinchmove/pinchend) callback lists are empty
     * <zh/> 自动解除事件监听并重置单例实例
     * <en/> Automatically remove event listeners and reset singleton instance
     */
    tryDestroy() {
        if (Object.values(PinchHandler.callbacks).every((arr) => arr.length === 0)) {
            this.destroy();
        }
    }
}
/**
 * <zh/> 是否处于 Pinch 阶段
 *
 * <en/> Whether it is in the Pinch stage
 */
PinchHandler.isPinching = false;
PinchHandler.instance = null;
PinchHandler.callbacks = { pinchstart: [], pinchmove: [], pinchend: [] };
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