enable pitch zoom

src/components/common/ImageLoadingWrapper/index.tsx

@@ -1,4 +1,10 @@
-import React, { CSSProperties, FC, useMemo, useReducer } from 'react';
+import React, {
+  CSSProperties,
+  ReactNode,
+  forwardRef,
+  useMemo,
+  useReducer,
+} from 'react';
 
 import classNames from 'classnames';
 
@@ -8,17 +14,14 @@ import { DivProps } from '~/utils/types';
 import styles from './styles.module.scss';
 
 interface ImageLoadingWrapperProps extends Omit<DivProps, 'children'> {
-  children: (props: { loading: boolean; onLoad: () => void }) => void;
+  children: (props: { loading: boolean; onLoad: () => void }) => ReactNode;
   preview?: string;
 }
 
-const ImageLoadingWrapper: FC<ImageLoadingWrapperProps> = ({
-  className,
-  children,
-  preview,
-  color,
-  ...props
-}) => {
+const ImageLoadingWrapper = forwardRef<
+  HTMLDivElement,
+  ImageLoadingWrapperProps
+>(({ className, children, preview, color, ...props }, ref) => {
   const [loading, onLoad] = useReducer(() => false, true);
 
   const style = useMemo<CSSProperties>(
@@ -30,7 +33,7 @@ const ImageLoadingWrapper: FC<ImageLoadingWrapperProps> = ({
   );
 
   return (
-    <div className={classNames(styles.wrapper, className)} {...props}>
+    <div className={classNames(styles.wrapper, className)} {...props} ref={ref}>
       {!!loading && !!preview && (
         <div className={styles.preview}>
           <div className={styles.thumbnail} style={style} />
@@ -40,6 +43,6 @@ const ImageLoadingWrapper: FC<ImageLoadingWrapperProps> = ({
       {children({ loading, onLoad })}
     </div>
   );
-};
+});
 
 export { ImageLoadingWrapper };

src/components/media/PinchZoom/index.tsx

@@ -0,0 +1,108 @@
+import {
+  FC,
+  ReactElement,
+  useCallback,
+  useEffect,
+  useRef,
+  useState,
+} from 'react';
+
+interface Props {
+  children: (props: {
+    setRef: (ref: HTMLElement | null) => void;
+  }) => ReactElement;
+}
+
+const getDistance = (event: TouchEvent) => {
+  return Math.hypot(
+    event.touches[0].pageX - event.touches[1].pageX,
+    event.touches[0].pageY - event.touches[1].pageY,
+  );
+};
+
+interface Start {
+  x: number;
+  y: number;
+  distance: number;
+}
+
+const PinchZoom: FC<Props> = ({ children }) => {
+  const start = useRef<Start>({ x: 0, y: 0, distance: 0 });
+  const [ref, setRef] = useState<HTMLElement | null>(null);
+  const imageElementScale = useRef(1);
+
+  const onTouchStart = useCallback((event: TouchEvent) => {
+    if (event.touches.length !== 2) {
+      return;
+    }
+    event.preventDefault(); // Prevent page scroll
+
+    // Calculate where the fingers have started on the X and Y axis
+    start.current.x = (event.touches[0].pageX + event.touches[1].pageX) / 2;
+    start.current.y = (event.touches[0].pageY + event.touches[1].pageY) / 2;
+    start.current.distance = getDistance(event);
+  }, []);
+
+  const onTouchMove = useCallback(
+    (event) => {
+      if (event.touches.length !== 2 || !ref) {
+        return;
+      }
+      event.preventDefault(); // Prevent page scroll
+
+      // Safari provides event.scale as two fingers move on the screen
+      // For other browsers just calculate the scale manually
+      const scale = event.scale ?? getDistance(event) / start.current.distance;
+      imageElementScale.current = Math.min(Math.max(1, scale), 4);
+
+      // Calculate how much the fingers have moved on the X and Y axis
+      const deltaX =
+        ((event.touches[0].pageX + event.touches[1].pageX) / 2 -
+          start.current.x) *
+        2; // x2 for accelarated movement
+      const deltaY =
+        ((event.touches[0].pageY + event.touches[1].pageY) / 2 -
+          start.current.y) *
+        2; // x2 for accelarated movement
+
+      // Transform the image to make it grow and move with fingers
+      const transform = `translate3d(${deltaX}px, ${deltaY}px, 0) scale(${imageElementScale})`;
+      ref.style.transform = transform;
+      ref.style.zIndex = '9999';
+    },
+    [ref],
+  );
+
+  const onTouchEnd = useCallback(
+    (event) => {
+      if (!ref) {
+        return;
+      }
+
+      // Reset image to it's original format
+      ref.style.transform = '';
+      ref.style.zIndex = '';
+    },
+    [ref],
+  );
+
+  useEffect(() => {
+    if (!ref) {
+      return;
+    }
+
+    ref.addEventListener('touchstart', onTouchStart);
+    ref.addEventListener('touchmove', onTouchMove);
+    ref.addEventListener('touchend', onTouchEnd);
+
+    return () => {
+      ref.removeEventListener('touchstart', onTouchStart);
+      ref.removeEventListener('touchmove', onTouchMove);
+      ref.removeEventListener('touchend', onTouchEnd);
+    };
+  }, [onTouchEnd, onTouchMove, onTouchStart, ref]);
+
+  return children({ setRef });
+};
+
+export { PinchZoom };

src/components/node/NodeImageSwiperBlock/index.tsx

@@ -7,6 +7,7 @@ import { Swiper, SwiperSlide } from 'swiper/react';
 import SwiperClass from 'swiper/types/swiper-class';
 
 import { ImageLoadingWrapper } from '~/components/common/ImageLoadingWrapper/index';
+import { PinchZoom } from '~/components/media/PinchZoom';
 import { NodeComponentProps } from '~/constants/node';
 import { imagePresets } from '~/constants/urls';
 import { useWindowSize } from '~/hooks/dom/useWindowSize';
@@ -100,26 +101,37 @@ const NodeImageSwiperBlock: FC<IProps> = observer(({ node }) => {
       >
         {images.map((file, index) => (
           <SwiperSlide className={styles.slide} key={file.id}>
-            <ImageLoadingWrapper
-              preview={getURL(file, imagePresets['300'])}
-              color={file.metadata?.dominant_color}
-            >
-              {({ loading, onLoad }) => (
-                <NodeImageLazy
-                  src={getURL(file)}
-                  width={file.metadata?.width}
-                  height={file.metadata?.height}
-                  color={normalizeBrightColor(file?.metadata?.dominant_color)}
-                  onLoad={onLoad}
-                  onClick={() => onOpenPhotoSwipe(index)}
-                  className={classNames(styles.image, 'swiper-lazy', {
-                    [styles.loading]: loading,
-                  })}
-                  sizes={getNodeSwiperImageSizes(file, innerWidth, innerHeight)}
-                  quality={90}
-                />
+            <PinchZoom>
+              {({ setRef }) => (
+                <ImageLoadingWrapper
+                  preview={getURL(file, imagePresets['300'])}
+                  color={file.metadata?.dominant_color}
+                  ref={setRef}
+                >
+                  {({ loading, onLoad }) => (
+                    <NodeImageLazy
+                      src={getURL(file)}
+                      width={file.metadata?.width}
+                      height={file.metadata?.height}
+                      color={normalizeBrightColor(
+                        file?.metadata?.dominant_color,
+                      )}
+                      onLoad={onLoad}
+                      onClick={() => onOpenPhotoSwipe(index)}
+                      className={classNames(styles.image, 'swiper-lazy', {
+                        [styles.loading]: loading,
+                      })}
+                      sizes={getNodeSwiperImageSizes(
+                        file,
+                        innerWidth,
+                        innerHeight,
+                      )}
+                      quality={90}
+                    />
+                  )}
+                </ImageLoadingWrapper>
               )}
-            </ImageLoadingWrapper>
+            </PinchZoom>
           </SwiperSlide>
         ))}
       </Swiper>