swiper/src/components/zoom/zoom.js

Most modern mobile touch slider and framework with hardware accelerated transitions

import $ from '../../utils/dom';
import Utils from '../../utils/utils';
import Device from '../../utils/device';
import Support from '../../utils/support';

const Zoom = {
  // Calc Scale From Multi-touches
  getDistanceBetweenTouches(e) {
    if (e.targetTouches.length < 2) return 1;
    const x1 = e.targetTouches[0].pageX;
    const y1 = e.targetTouches[0].pageY;
    const x2 = e.targetTouches[1].pageX;
    const y2 = e.targetTouches[1].pageY;
    const distance = Math.sqrt(((x2 - x1) ** 2) + ((y2 - y1) ** 2));
    return distance;
  },
  // Events
  onGestureStart(e) {
    const swiper = this;
    const params = swiper.params.zoom;
    const zoom = swiper.zoom;
    const { gesture } = zoom;
    zoom.fakeGestureTouched = false;
    zoom.fakeGestureMoved = false;
    if (!Support.gestures) {
      if (e.type !== 'touchstart' || (e.type === 'touchstart' && e.targetTouches.length < 2)) {
        return;
      }
      zoom.fakeGestureTouched = true;
      gesture.scaleStart = Zoom.getDistanceBetweenTouches(e);
    }
    if (!gesture.$slideEl || !gesture.$slideEl.length) {
      gesture.$slideEl = $(e.target).closest(`.${swiper.params.slideClass}`);
      if (gesture.$slideEl.length === 0) gesture.$slideEl = swiper.slides.eq(swiper.activeIndex);
      gesture.$imageEl = gesture.$slideEl.find('img, svg, canvas, picture, .swiper-zoom-target');
      gesture.$imageWrapEl = gesture.$imageEl.parent(`.${params.containerClass}`);
      gesture.maxRatio = gesture.$imageWrapEl.attr('data-swiper-zoom') || params.maxRatio;
      if (gesture.$imageWrapEl.length === 0) {
        gesture.$imageEl = undefined;
        return;
      }
    }
    if (gesture.$imageEl) {
      gesture.$imageEl.transition(0);
    }
    swiper.zoom.isScaling = true;
  },
  onGestureChange(e) {
    const swiper = this;
    const params = swiper.params.zoom;
    const zoom = swiper.zoom;
    const { gesture } = zoom;
    if (!Support.gestures) {
      if (e.type !== 'touchmove' || (e.type === 'touchmove' && e.targetTouches.length < 2)) {
        return;
      }
      zoom.fakeGestureMoved = true;
      gesture.scaleMove = Zoom.getDistanceBetweenTouches(e);
    }
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;
    if (Support.gestures) {
      zoom.scale = e.scale * zoom.currentScale;
    } else {
      zoom.scale = (gesture.scaleMove / gesture.scaleStart) * zoom.currentScale;
    }
    if (zoom.scale > gesture.maxRatio) {
      zoom.scale = (gesture.maxRatio - 1) + (((zoom.scale - gesture.maxRatio) + 1) ** 0.5);
    }
    if (zoom.scale < params.minRatio) {
      zoom.scale = (params.minRatio + 1) - (((params.minRatio - zoom.scale) + 1) ** 0.5);
    }
    gesture.$imageEl.transform(`translate3d(0,0,0) scale(${zoom.scale})`);
  },
  onGestureEnd(e) {
    const swiper = this;
    const params = swiper.params.zoom;
    const zoom = swiper.zoom;
    const { gesture } = zoom;
    if (!Support.gestures) {
      if (!zoom.fakeGestureTouched || !zoom.fakeGestureMoved) {
        return;
      }
      if (e.type !== 'touchend' || (e.type === 'touchend' && e.changedTouches.length < 2 && !Device.android)) {
        return;
      }
      zoom.fakeGestureTouched = false;
      zoom.fakeGestureMoved = false;
    }
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;
    zoom.scale = Math.max(Math.min(zoom.scale, gesture.maxRatio), params.minRatio);
    gesture.$imageEl.transition(swiper.params.speed).transform(`translate3d(0,0,0) scale(${zoom.scale})`);
    zoom.currentScale = zoom.scale;
    zoom.isScaling = false;
    if (zoom.scale === 1) gesture.$slideEl = undefined;
  },
  onTouchStart(e) {
    const swiper = this;
    const zoom = swiper.zoom;
    const { gesture, image } = zoom;
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;
    if (image.isTouched) return;
    if (Device.android && e.cancelable) e.preventDefault();
    image.isTouched = true;
    image.touchesStart.x = e.type === 'touchstart' ? e.targetTouches[0].pageX : e.pageX;
    image.touchesStart.y = e.type === 'touchstart' ? e.targetTouches[0].pageY : e.pageY;
  },
  onTouchMove(e) {
    const swiper = this;
    const zoom = swiper.zoom;
    const { gesture, image, velocity } = zoom;
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;
    swiper.allowClick = false;
    if (!image.isTouched || !gesture.$slideEl) return;

    if (!image.isMoved) {
      image.width = gesture.$imageEl[0].offsetWidth;
      image.height = gesture.$imageEl[0].offsetHeight;
      image.startX = Utils.getTranslate(gesture.$imageWrapEl[0], 'x') || 0;
      image.startY = Utils.getTranslate(gesture.$imageWrapEl[0], 'y') || 0;
      gesture.slideWidth = gesture.$slideEl[0].offsetWidth;
      gesture.slideHeight = gesture.$slideEl[0].offsetHeight;
      gesture.$imageWrapEl.transition(0);
      if (swiper.rtl) {
        image.startX = -image.startX;
        image.startY = -image.startY;
      }
    }
    // Define if we need image drag
    const scaledWidth = image.width * zoom.scale;
    const scaledHeight = image.height * zoom.scale;

    if (scaledWidth < gesture.slideWidth && scaledHeight < gesture.slideHeight) return;

    image.minX = Math.min(((gesture.slideWidth / 2) - (scaledWidth / 2)), 0);
    image.maxX = -image.minX;
    image.minY = Math.min(((gesture.slideHeight / 2) - (scaledHeight / 2)), 0);
    image.maxY = -image.minY;

    image.touchesCurrent.x = e.type === 'touchmove' ? e.targetTouches[0].pageX : e.pageX;
    image.touchesCurrent.y = e.type === 'touchmove' ? e.targetTouches[0].pageY : e.pageY;

    if (!image.isMoved && !zoom.isScaling) {
      if (
        swiper.isHorizontal()
        && (
          (Math.floor(image.minX) === Math.floor(image.startX) && image.touchesCurrent.x < image.touchesStart.x)
          || (Math.floor(image.maxX) === Math.floor(image.startX) && image.touchesCurrent.x > image.touchesStart.x)
        )
      ) {
        image.isTouched = false;
        return;
      } if (
        !swiper.isHorizontal()
        && (
          (Math.floor(image.minY) === Math.floor(image.startY) && image.touchesCurrent.y < image.touchesStart.y)
          || (Math.floor(image.maxY) === Math.floor(image.startY) && image.touchesCurrent.y > image.touchesStart.y)
        )
      ) {
        image.isTouched = false;
        return;
      }
    }
    if (e.cancelable) {
      e.preventDefault();
    }
    e.stopPropagation();

    image.isMoved = true;
    image.currentX = (image.touchesCurrent.x - image.touchesStart.x) + image.startX;
    image.currentY = (image.touchesCurrent.y - image.touchesStart.y) + image.startY;

    if (image.currentX < image.minX) {
      image.currentX = (image.minX + 1) - (((image.minX - image.currentX) + 1) ** 0.8);
    }
    if (image.currentX > image.maxX) {
      image.currentX = (image.maxX - 1) + (((image.currentX - image.maxX) + 1) ** 0.8);
    }

    if (image.currentY < image.minY) {
      image.currentY = (image.minY + 1) - (((image.minY - image.currentY) + 1) ** 0.8);
    }
    if (image.currentY > image.maxY) {
      image.currentY = (image.maxY - 1) + (((image.currentY - image.maxY) + 1) ** 0.8);
    }

    // Velocity
    if (!velocity.prevPositionX) velocity.prevPositionX = image.touchesCurrent.x;
    if (!velocity.prevPositionY) velocity.prevPositionY = image.touchesCurrent.y;
    if (!velocity.prevTime) velocity.prevTime = Date.now();
    velocity.x = (image.touchesCurrent.x - velocity.prevPositionX) / (Date.now() - velocity.prevTime) / 2;
    velocity.y = (image.touchesCurrent.y - velocity.prevPositionY) / (Date.now() - velocity.prevTime) / 2;
    if (Math.abs(image.touchesCurrent.x - velocity.prevPositionX) < 2) velocity.x = 0;
    if (Math.abs(image.touchesCurrent.y - velocity.prevPositionY) < 2) velocity.y = 0;
    velocity.prevPositionX = image.touchesCurrent.x;
    velocity.prevPositionY = image.touchesCurrent.y;
    velocity.prevTime = Date.now();

    gesture.$imageWrapEl.transform(`translate3d(${image.currentX}px, ${image.currentY}px,0)`);
  },
  onTouchEnd() {
    const swiper = this;
    const zoom = swiper.zoom;
    const { gesture, image, velocity } = zoom;
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;
    if (!image.isTouched || !image.isMoved) {
      image.isTouched = false;
      image.isMoved = false;
      return;
    }
    image.isTouched = false;
    image.isMoved = false;
    let momentumDurationX = 300;
    let momentumDurationY = 300;
    const momentumDistanceX = velocity.x * momentumDurationX;
    const newPositionX = image.currentX + momentumDistanceX;
    const momentumDistanceY = velocity.y * momentumDurationY;
    const newPositionY = image.currentY + momentumDistanceY;

    // Fix duration
    if (velocity.x !== 0) momentumDurationX = Math.abs((newPositionX - image.currentX) / velocity.x);
    if (velocity.y !== 0) momentumDurationY = Math.abs((newPositionY - image.currentY) / velocity.y);
    const momentumDuration = Math.max(momentumDurationX, momentumDurationY);

    image.currentX = newPositionX;
    image.currentY = newPositionY;

    // Define if we need image drag
    const scaledWidth = image.width * zoom.scale;
    const scaledHeight = image.height * zoom.scale;
    image.minX = Math.min(((gesture.slideWidth / 2) - (scaledWidth / 2)), 0);
    image.maxX = -image.minX;
    image.minY = Math.min(((gesture.slideHeight / 2) - (scaledHeight / 2)), 0);
    image.maxY = -image.minY;
    image.currentX = Math.max(Math.min(image.currentX, image.maxX), image.minX);
    image.currentY = Math.max(Math.min(image.currentY, image.maxY), image.minY);

    gesture.$imageWrapEl.transition(momentumDuration).transform(`translate3d(${image.currentX}px, ${image.currentY}px,0)`);
  },
  onTransitionEnd() {
    const swiper = this;
    const zoom = swiper.zoom;
    const { gesture } = zoom;
    if (gesture.$slideEl && swiper.previousIndex !== swiper.activeIndex) {
      if (gesture.$imageEl) {
        gesture.$imageEl.transform('translate3d(0,0,0) scale(1)');
      }
      if (gesture.$imageWrapEl) {
        gesture.$imageWrapEl.transform('translate3d(0,0,0)');
      }

      zoom.scale = 1;
      zoom.currentScale = 1;

      gesture.$slideEl = undefined;
      gesture.$imageEl = undefined;
      gesture.$imageWrapEl = undefined;
    }
  },
  // Toggle Zoom
  toggle(e) {
    const swiper = this;
    const zoom = swiper.zoom;

    if (zoom.scale && zoom.scale !== 1) {
      // Zoom Out
      zoom.out();
    } else {
      // Zoom In
      zoom.in(e);
    }
  },
  in(e) {
    const swiper = this;

    const zoom = swiper.zoom;
    const params = swiper.params.zoom;
    const { gesture, image } = zoom;

    if (!gesture.$slideEl) {
      if (swiper.params.virtual && swiper.params.virtual.enabled && swiper.virtual) {
        gesture.$slideEl = swiper.$wrapperEl.children(`.${swiper.params.slideActiveClass}`);
      } else {
        gesture.$slideEl = swiper.slides.eq(swiper.activeIndex);
      }
      gesture.$imageEl = gesture.$slideEl.find('img, svg, canvas, picture, .swiper-zoom-target');
      gesture.$imageWrapEl = gesture.$imageEl.parent(`.${params.containerClass}`);
    }
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;

    gesture.$slideEl.addClass(`${params.zoomedSlideClass}`);

    let touchX;
    let touchY;
    let offsetX;
    let offsetY;
    let diffX;
    let diffY;
    let translateX;
    let translateY;
    let imageWidth;
    let imageHeight;
    let scaledWidth;
    let scaledHeight;
    let translateMinX;
    let translateMinY;
    let translateMaxX;
    let translateMaxY;
    let slideWidth;
    let slideHeight;

    if (typeof image.touchesStart.x === 'undefined' && e) {
      touchX = e.type === 'touchend' ? e.changedTouches[0].pageX : e.pageX;
      touchY = e.type === 'touchend' ? e.changedTouches[0].pageY : e.pageY;
    } else {
      touchX = image.touchesStart.x;
      touchY = image.touchesStart.y;
    }

    zoom.scale = gesture.$imageWrapEl.attr('data-swiper-zoom') || params.maxRatio;
    zoom.currentScale = gesture.$imageWrapEl.attr('data-swiper-zoom') || params.maxRatio;
    if (e) {
      slideWidth = gesture.$slideEl[0].offsetWidth;
      slideHeight = gesture.$slideEl[0].offsetHeight;
      offsetX = gesture.$slideEl.offset().left;
      offsetY = gesture.$slideEl.offset().top;
      diffX = (offsetX + (slideWidth / 2)) - touchX;
      diffY = (offsetY + (slideHeight / 2)) - touchY;

      imageWidth = gesture.$imageEl[0].offsetWidth;
      imageHeight = gesture.$imageEl[0].offsetHeight;
      scaledWidth = imageWidth * zoom.scale;
      scaledHeight = imageHeight * zoom.scale;

      translateMinX = Math.min(((slideWidth / 2) - (scaledWidth / 2)), 0);
      translateMinY = Math.min(((slideHeight / 2) - (scaledHeight / 2)), 0);
      translateMaxX = -translateMinX;
      translateMaxY = -translateMinY;

      translateX = diffX * zoom.scale;
      translateY = diffY * zoom.scale;

      if (translateX < translateMinX) {
        translateX = translateMinX;
      }
      if (translateX > translateMaxX) {
        translateX = translateMaxX;
      }

      if (translateY < translateMinY) {
        translateY = translateMinY;
      }
      if (translateY > translateMaxY) {
        translateY = translateMaxY;
      }
    } else {
      translateX = 0;
      translateY = 0;
    }
    gesture.$imageWrapEl.transition(300).transform(`translate3d(${translateX}px, ${translateY}px,0)`);
    gesture.$imageEl.transition(300).transform(`translate3d(0,0,0) scale(${zoom.scale})`);
  },
  out() {
    const swiper = this;

    const zoom = swiper.zoom;
    const params = swiper.params.zoom;
    const { gesture } = zoom;

    if (!gesture.$slideEl) {
      if (swiper.params.virtual && swiper.params.virtual.enabled && swiper.virtual) {
        gesture.$slideEl = swiper.$wrapperEl.children(`.${swiper.params.slideActiveClass}`);
      } else {
        gesture.$slideEl = swiper.slides.eq(swiper.activeIndex);
      }
      gesture.$imageEl = gesture.$slideEl.find('img, svg, canvas, picture, .swiper-zoom-target');
      gesture.$imageWrapEl = gesture.$imageEl.parent(`.${params.containerClass}`);
    }
    if (!gesture.$imageEl || gesture.$imageEl.length === 0) return;

    zoom.scale = 1;
    zoom.currentScale = 1;
    gesture.$imageWrapEl.transition(300).transform('translate3d(0,0,0)');
    gesture.$imageEl.transition(300).transform('translate3d(0,0,0) scale(1)');
    gesture.$slideEl.removeClass(`${params.zoomedSlideClass}`);
    gesture.$slideEl = undefined;
  },
  // Attach/Detach Events
  enable() {
    const swiper = this;
    const zoom = swiper.zoom;
    if (zoom.enabled) return;
    zoom.enabled = true;

    const passiveListener = swiper.touchEvents.start === 'touchstart' && Support.passiveListener && swiper.params.passiveListeners ? { passive: true, capture: false } : false;
    const activeListenerWithCapture = Support.passiveListener ? { passive: false, capture: true } : true;

    const slideSelector = `.${swiper.params.slideClass}`;

    // Scale image
    if (Support.gestures) {
      swiper.$wrapperEl.on('gesturestart', slideSelector, zoom.onGestureStart, passiveListener);
      swiper.$wrapperEl.on('gesturechange', slideSelector, zoom.onGestureChange, passiveListener);
      swiper.$wrapperEl.on('gestureend', slideSelector, zoom.onGestureEnd, passiveListener);
    } else if (swiper.touchEvents.start === 'touchstart') {
      swiper.$wrapperEl.on(swiper.touchEvents.start, slideSelector, zoom.onGestureStart, passiveListener);
      swiper.$wrapperEl.on(swiper.touchEvents.move, slideSelector, zoom.onGestureChange, activeListenerWithCapture);
      swiper.$wrapperEl.on(swiper.touchEvents.end, slideSelector, zoom.onGestureEnd, passiveListener);
      if (swiper.touchEvents.cancel) {
        swiper.$wrapperEl.on(swiper.touchEvents.cancel, slideSelector, zoom.onGestureEnd, passiveListener);
      }
    }

    // Move image
    swiper.$wrapperEl.on(swiper.touchEvents.move, `.${swiper.params.zoom.containerClass}`, zoom.onTouchMove, activeListenerWithCapture);
  },
  disable() {
    const swiper = this;
    const zoom = swiper.zoom;
    if (!zoom.enabled) return;

    swiper.zoom.enabled = false;

    const passiveListener = swiper.touchEvents.start === 'touchstart' && Support.passiveListener && swiper.params.passiveListeners ? { passive: true, capture: false } : false;
    const activeListenerWithCapture = Support.passiveListener ? { passive: false, capture: true } : true;

    const slideSelector = `.${swiper.params.slideClass}`;

    // Scale image
    if (Support.gestures) {
      swiper.$wrapperEl.off('gesturestart', slideSelector, zoom.onGestureStart, passiveListener);
      swiper.$wrapperEl.off('gesturechange', slideSelector, zoom.onGestureChange, passiveListener);
      swiper.$wrapperEl.off('gestureend', slideSelector, zoom.onGestureEnd, passiveListener);
    } else if (swiper.touchEvents.start === 'touchstart') {
      swiper.$wrapperEl.off(swiper.touchEvents.start, slideSelector, zoom.onGestureStart, passiveListener);
      swiper.$wrapperEl.off(swiper.touchEvents.move, slideSelector, zoom.onGestureChange, activeListenerWithCapture);
      swiper.$wrapperEl.off(swiper.touchEvents.end, slideSelector, zoom.onGestureEnd, passiveListener);
      if (swiper.touchEvents.cancel) {
        swiper.$wrapperEl.off(swiper.touchEvents.cancel, slideSelector, zoom.onGestureEnd, passiveListener);
      }
    }

    // Move image
    swiper.$wrapperEl.off(swiper.touchEvents.move, `.${swiper.params.zoom.containerClass}`, zoom.onTouchMove, activeListenerWithCapture);
  },
};

export default {
  name: 'zoom',
  params: {
    zoom: {
      enabled: false,
      maxRatio: 3,
      minRatio: 1,
      toggle: true,
      containerClass: 'swiper-zoom-container',
      zoomedSlideClass: 'swiper-slide-zoomed',
    },
  },
  create() {
    const swiper = this;
    const zoom = {
      enabled: false,
      scale: 1,
      currentScale: 1,
      isScaling: false,
      gesture: {
        $slideEl: undefined,
        slideWidth: undefined,
        slideHeight: undefined,
        $imageEl: undefined,
        $imageWrapEl: undefined,
        maxRatio: 3,
      },
      image: {
        isTouched: undefined,
        isMoved: undefined,
        currentX: undefined,
        currentY: undefined,
        minX: undefined,
        minY: undefined,
        maxX: undefined,
        maxY: undefined,
        width: undefined,
        height: undefined,
        startX: undefined,
        startY: undefined,
        touchesStart: {},
        touchesCurrent: {},
      },
      velocity: {
        x: undefined,
        y: undefined,
        prevPositionX: undefined,
        prevPositionY: undefined,
        prevTime: undefined,
      },
    };

    ('onGestureStart onGestureChange onGestureEnd onTouchStart onTouchMove onTouchEnd onTransitionEnd toggle enable disable in out').split(' ').forEach((methodName) => {
      zoom[methodName] = Zoom[methodName].bind(swiper);
    });
    Utils.extend(swiper, {
      zoom,
    });

    let scale = 1;
    Object.defineProperty(swiper.zoom, 'scale', {
      get() {
        return scale;
      },
      set(value) {
        if (scale !== value) {
          const imageEl = swiper.zoom.gesture.$imageEl ? swiper.zoom.gesture.$imageEl[0] : undefined;
          const slideEl = swiper.zoom.gesture.$slideEl ? swiper.zoom.gesture.$slideEl[0] : undefined;
          swiper.emit('zoomChange', value, imageEl, slideEl);
        }
        scale = value;
      },
    });
  },
  on: {
    init() {
      const swiper = this;
      if (swiper.params.zoom.enabled) {
        swiper.zoom.enable();
      }
    },
    destroy() {
      const swiper = this;
      swiper.zoom.disable();
    },
    touchStart(e) {
      const swiper = this;
      if (!swiper.zoom.enabled) return;
      swiper.zoom.onTouchStart(e);
    },
    touchEnd(e) {
      const swiper = this;
      if (!swiper.zoom.enabled) return;
      swiper.zoom.onTouchEnd(e);
    },
    doubleTap(e) {
      const swiper = this;
      if (swiper.params.zoom.enabled && swiper.zoom.enabled && swiper.params.zoom.toggle) {
        swiper.zoom.toggle(e);
      }
    },
    transitionEnd() {
      const swiper = this;
      if (swiper.zoom.enabled && swiper.params.zoom.enabled) {
        swiper.zoom.onTransitionEnd();
      }
    },
    slideChange() {
      const swiper = this;
      if (swiper.zoom.enabled && swiper.params.zoom.enabled && swiper.params.cssMode) {
        swiper.zoom.onTransitionEnd();
      }
    },
  },
};